[PATCH 5/17]: SCST implementation of the SCSI target state machine

[Vladislav Bolkhovitin]

This patch contains implementation of the SCSI target state machine

Signed-off-by: Vladislav Bolkhovitin <vst@xxxxxxxx>
---
 scst_targ.c | 6318 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 6318 insertions(+)

diff -uprN orig/linux-2.6.35/drivers/scst/scst_targ.c linux-2.6.35/drivers/scst/scst_targ.c
--- orig/linux-2.6.35/drivers/scst/scst_targ.c
+++ linux-2.6.35/drivers/scst/scst_targ.c
@@ -0,0 +1,6318 @@
+/*
+ *  scst_targ.c
+ *
+ *  Copyright (C) 2004 - 2010 Vladislav Bolkhovitin <vst@xxxxxxxx>
+ *  Copyright (C) 2004 - 2005 Leonid Stoljar
+ *  Copyright (C) 2007 - 2010 ID7 Ltd.
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License
+ *  as published by the Free Software Foundation, version 2
+ *  of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *  GNU General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/smp_lock.h>
+#include <linux/unistd.h>
+#include <linux/string.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+#include <linux/ktime.h>
+
+#include <scst/scst.h>
+#include "scst_priv.h"
+#include "scst_pres.h"
+
+#if 0 /* Temporary left for future performance investigations */
+/* Deleting it don't forget to delete write_cmd_count */
+#define CONFIG_SCST_ORDERED_READS
+#endif
+
+#if 0 /* Let's disable it for now to see if users will complain about it */
+/* Deleting it don't forget to delete write_cmd_count */
+#define CONFIG_SCST_PER_DEVICE_CMD_COUNT_LIMIT
+#endif
+
+static void scst_cmd_set_sn(struct scst_cmd *cmd);
+static int __scst_init_cmd(struct scst_cmd *cmd);
+static void scst_finish_cmd_mgmt(struct scst_cmd *cmd);
+static struct scst_cmd *__scst_find_cmd_by_tag(struct scst_session *sess,
+	uint64_t tag, bool to_abort);
+static void scst_process_redirect_cmd(struct scst_cmd *cmd,
+	enum scst_exec_context context, int check_retries);
+
+/**
+ * scst_post_parse() - do post parse actions
+ *
+ * This function must be called by dev handler after its parse() callback
+ * returned SCST_CMD_STATE_STOP before calling scst_process_active_cmd().
+ */
+void scst_post_parse(struct scst_cmd *cmd)
+{
+	scst_set_parse_time(cmd);
+}
+EXPORT_SYMBOL_GPL(scst_post_parse);
+
+/**
+ * scst_post_alloc_data_buf() - do post alloc_data_buf actions
+ *
+ * This function must be called by dev handler after its alloc_data_buf()
+ * callback returned SCST_CMD_STATE_STOP before calling
+ * scst_process_active_cmd().
+ */
+void scst_post_alloc_data_buf(struct scst_cmd *cmd)
+{
+	scst_set_alloc_buf_time(cmd);
+}
+EXPORT_SYMBOL_GPL(scst_post_alloc_data_buf);
+
+static inline void scst_schedule_tasklet(struct scst_cmd *cmd)
+{
+	struct scst_tasklet *t = &scst_tasklets[smp_processor_id()];
+	unsigned long flags;
+
+	spin_lock_irqsave(&t->tasklet_lock, flags);
+	TRACE_DBG("Adding cmd %p to tasklet %d cmd list", cmd,
+		smp_processor_id());
+	list_add_tail(&cmd->cmd_list_entry, &t->tasklet_cmd_list);
+	spin_unlock_irqrestore(&t->tasklet_lock, flags);
+
+	tasklet_schedule(&t->tasklet);
+}
+
+/**
+ * scst_rx_cmd() - create new command
+ * @sess:	SCST session
+ * @lun:	LUN for the command
+ * @lun_len:	length of the LUN in bytes
+ * @cdb:	CDB of the command
+ * @cdb_len:	length of the CDB in bytes
+ * @atomic:	true, if current context is atomic
+ *
+ * Description:
+ *    Creates new SCST command. Returns new command on success or
+ *    NULL otherwise.
+ *
+ *    Must not be called in parallel with scst_unregister_session() for the
+ *    same session.
+ */
+struct scst_cmd *scst_rx_cmd(struct scst_session *sess,
+	const uint8_t *lun, int lun_len, const uint8_t *cdb,
+	unsigned int cdb_len, int atomic)
+{
+	struct scst_cmd *cmd;
+
+#ifdef CONFIG_SCST_EXTRACHECKS
+	if (unlikely(sess->shut_phase != SCST_SESS_SPH_READY)) {
+		PRINT_CRIT_ERROR("%s",
+			"New cmd while shutting down the session");
+		BUG();
+	}
+#endif
+
+	cmd = scst_alloc_cmd(atomic ? GFP_ATOMIC : GFP_KERNEL);
+	if (cmd == NULL)
+		goto out;
+
+	cmd->sess = sess;
+	cmd->tgt = sess->tgt;
+	cmd->tgtt = sess->tgt->tgtt;
+
+	cmd->lun = scst_unpack_lun(lun, lun_len);
+	if (unlikely(cmd->lun == NO_SUCH_LUN)) {
+		PRINT_ERROR("Wrong LUN %d, finishing cmd", -1);
+		scst_set_cmd_error(cmd,
+			   SCST_LOAD_SENSE(scst_sense_lun_not_supported));
+	}
+
+	/*
+	 * For cdb_len 0 defer the error reporting until scst_cmd_init_done(),
+	 * scst_set_cmd_error() supports nested calls.
+	 */
+	if (unlikely(cdb_len > SCST_MAX_CDB_SIZE)) {
+		PRINT_ERROR("Too big CDB len %d, finishing cmd", cdb_len);
+		cdb_len = SCST_MAX_CDB_SIZE;
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_message));
+	}
+
+	memcpy(cmd->cdb, cdb, cdb_len);
+	cmd->cdb_len = cdb_len;
+
+	TRACE_DBG("cmd %p, sess %p", cmd, sess);
+	scst_sess_get(sess);
+
+out:
+	return cmd;
+}
+EXPORT_SYMBOL(scst_rx_cmd);
+
+/*
+ * No locks, but might be on IRQ. Returns 0 on success, <0 if processing of
+ * this command should be stopped.
+ */
+static int scst_init_cmd(struct scst_cmd *cmd, enum scst_exec_context *context)
+{
+	int rc, res = 0;
+
+	/* See the comment in scst_do_job_init() */
+	if (unlikely(!list_empty(&scst_init_cmd_list))) {
+		TRACE_MGMT_DBG("%s", "init cmd list busy");
+		goto out_redirect;
+	}
+	/*
+	 * Memory barrier isn't necessary here, because CPU appears to
+	 * be self-consistent and we don't care about the race, described
+	 * in comment in scst_do_job_init().
+	 */
+
+	rc = __scst_init_cmd(cmd);
+	if (unlikely(rc > 0))
+		goto out_redirect;
+	else if (unlikely(rc != 0)) {
+		res = 1;
+		goto out;
+	}
+
+	EXTRACHECKS_BUG_ON(*context == SCST_CONTEXT_SAME);
+
+#ifdef CONFIG_SCST_TEST_IO_IN_SIRQ
+	scst_get_cdb_info(cmd);
+	if (cmd->op_flags & SCST_TEST_IO_IN_SIRQ_ALLOWED)
+		goto out;
+#endif
+
+	/* Small context optimization */
+	if (((*context == SCST_CONTEXT_TASKLET) ||
+	     (*context == SCST_CONTEXT_DIRECT_ATOMIC)) &&
+	      scst_cmd_is_expected_set(cmd)) {
+		if (cmd->expected_data_direction & SCST_DATA_WRITE) {
+			if (!test_bit(SCST_TGT_DEV_AFTER_INIT_WR_ATOMIC,
+					&cmd->tgt_dev->tgt_dev_flags))
+				*context = SCST_CONTEXT_THREAD;
+		} else
+			*context = SCST_CONTEXT_THREAD;
+	}
+
+out:
+	return res;
+
+out_redirect:
+	if (cmd->preprocessing_only) {
+		/*
+		 * Poor man solution for single threaded targets, where
+		 * blocking receiver at least sometimes means blocking all.
+		 * For instance, iSCSI target won't be able to receive
+		 * Data-Out PDUs.
+		 */
+		BUG_ON(*context != SCST_CONTEXT_DIRECT);
+		scst_set_busy(cmd);
+		scst_set_cmd_abnormal_done_state(cmd);
+		res = 1;
+		/* Keep initiator away from too many BUSY commands */
+		msleep(50);
+	} else {
+		unsigned long flags;
+		spin_lock_irqsave(&scst_init_lock, flags);
+		TRACE_MGMT_DBG("Adding cmd %p to init cmd list (scst_cmd_count "
+			"%d)", cmd, atomic_read(&scst_cmd_count));
+		list_add_tail(&cmd->cmd_list_entry, &scst_init_cmd_list);
+		if (test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags))
+			scst_init_poll_cnt++;
+		spin_unlock_irqrestore(&scst_init_lock, flags);
+		wake_up(&scst_init_cmd_list_waitQ);
+		res = -1;
+	}
+	goto out;
+}
+
+/**
+ * scst_cmd_init_done() - the command's initialization done
+ * @cmd:	SCST command
+ * @pref_context: preferred command execution context
+ *
+ * Description:
+ *    Notifies SCST that the driver finished its part of the command
+ *    initialization, and the command is ready for execution.
+ *    The second argument sets preferred command execition context.
+ *    See SCST_CONTEXT_* constants for details.
+ *
+ *    !!IMPORTANT!!
+ *
+ *    If cmd->set_sn_on_restart_cmd not set, this function, as well as
+ *    scst_cmd_init_stage1_done() and scst_restart_cmd(), must not be
+ *    called simultaneously for the same session (more precisely,
+ *    for the same session/LUN, i.e. tgt_dev), i.e. they must be
+ *    somehow externally serialized. This is needed to have lock free fast
+ *    path in scst_cmd_set_sn(). For majority of targets those functions are
+ *    naturally serialized by the single source of commands. Only iSCSI
+ *    immediate commands with multiple connections per session seems to be an
+ *    exception. For it, some mutex/lock shall be used for the serialization.
+ */
+void scst_cmd_init_done(struct scst_cmd *cmd,
+	enum scst_exec_context pref_context)
+{
+	unsigned long flags;
+	struct scst_session *sess = cmd->sess;
+	int rc;
+
+	scst_set_start_time(cmd);
+
+	TRACE_DBG("Preferred context: %d (cmd %p)", pref_context, cmd);
+	TRACE(TRACE_SCSI, "tag=%llu, lun=%lld, CDB len=%d, queue_type=%x "
+		"(cmd %p)", (long long unsigned int)cmd->tag,
+		(long long unsigned int)cmd->lun, cmd->cdb_len,
+		cmd->queue_type, cmd);
+	PRINT_BUFF_FLAG(TRACE_SCSI|TRACE_RCV_BOT, "Recieving CDB",
+		cmd->cdb, cmd->cdb_len);
+
+#ifdef CONFIG_SCST_EXTRACHECKS
+	if (unlikely((in_irq() || irqs_disabled())) &&
+	    ((pref_context == SCST_CONTEXT_DIRECT) ||
+	     (pref_context == SCST_CONTEXT_DIRECT_ATOMIC))) {
+		PRINT_ERROR("Wrong context %d in IRQ from target %s, use "
+			"SCST_CONTEXT_THREAD instead", pref_context,
+			cmd->tgtt->name);
+		pref_context = SCST_CONTEXT_THREAD;
+	}
+#endif
+
+	atomic_inc(&sess->sess_cmd_count);
+
+	spin_lock_irqsave(&sess->sess_list_lock, flags);
+
+	if (unlikely(sess->init_phase != SCST_SESS_IPH_READY)) {
+		/*
+		 * We must always keep commands in the sess list from the
+		 * very beginning, because otherwise they can be missed during
+		 * TM processing. This check is needed because there might be
+		 * old, i.e. deferred, commands and new, i.e. just coming, ones.
+		 */
+		if (cmd->sess_cmd_list_entry.next == NULL)
+			list_add_tail(&cmd->sess_cmd_list_entry,
+				&sess->sess_cmd_list);
+		switch (sess->init_phase) {
+		case SCST_SESS_IPH_SUCCESS:
+			break;
+		case SCST_SESS_IPH_INITING:
+			TRACE_DBG("Adding cmd %p to init deferred cmd list",
+				  cmd);
+			list_add_tail(&cmd->cmd_list_entry,
+				&sess->init_deferred_cmd_list);
+			spin_unlock_irqrestore(&sess->sess_list_lock, flags);
+			goto out;
+		case SCST_SESS_IPH_FAILED:
+			spin_unlock_irqrestore(&sess->sess_list_lock, flags);
+			scst_set_busy(cmd);
+			scst_set_cmd_abnormal_done_state(cmd);
+			goto active;
+		default:
+			BUG();
+		}
+	} else
+		list_add_tail(&cmd->sess_cmd_list_entry,
+			      &sess->sess_cmd_list);
+
+	spin_unlock_irqrestore(&sess->sess_list_lock, flags);
+
+	if (unlikely(cmd->cdb_len == 0)) {
+		PRINT_ERROR("%s", "Wrong CDB len 0, finishing cmd");
+		scst_set_cmd_error(cmd,
+			   SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+		scst_set_cmd_abnormal_done_state(cmd);
+		goto active;
+	}
+
+	if (unlikely(cmd->queue_type >= SCST_CMD_QUEUE_ACA)) {
+		PRINT_ERROR("Unsupported queue type %d", cmd->queue_type);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_message));
+		goto active;
+	}
+
+	/*
+	 * Cmd must be inited here to preserve the order. In case if cmd
+	 * already preliminary completed by target driver we need to init
+	 * cmd anyway to find out in which format we should return sense.
+	 */
+	cmd->state = SCST_CMD_STATE_INIT;
+	rc = scst_init_cmd(cmd, &pref_context);
+	if (unlikely(rc < 0))
+		goto out;
+
+active:
+	/* Here cmd must not be in any cmd list, no locks */
+	switch (pref_context) {
+	case SCST_CONTEXT_TASKLET:
+		scst_schedule_tasklet(cmd);
+		break;
+
+	case SCST_CONTEXT_DIRECT:
+		scst_process_active_cmd(cmd, false);
+		break;
+
+	case SCST_CONTEXT_DIRECT_ATOMIC:
+		scst_process_active_cmd(cmd, true);
+		break;
+
+	default:
+		PRINT_ERROR("Context %x is undefined, using the thread one",
+			pref_context);
+		/* go through */
+	case SCST_CONTEXT_THREAD:
+		spin_lock_irqsave(&cmd->cmd_threads->cmd_list_lock, flags);
+		TRACE_DBG("Adding cmd %p to active cmd list", cmd);
+		if (unlikely(cmd->queue_type == SCST_CMD_QUEUE_HEAD_OF_QUEUE))
+			list_add(&cmd->cmd_list_entry,
+				&cmd->cmd_threads->active_cmd_list);
+		else
+			list_add_tail(&cmd->cmd_list_entry,
+				&cmd->cmd_threads->active_cmd_list);
+		wake_up(&cmd->cmd_threads->cmd_list_waitQ);
+		spin_unlock_irqrestore(&cmd->cmd_threads->cmd_list_lock, flags);
+		break;
+	}
+
+out:
+	return;
+}
+EXPORT_SYMBOL(scst_cmd_init_done);
+
+static int scst_pre_parse(struct scst_cmd *cmd)
+{
+	int res = SCST_CMD_STATE_RES_CONT_SAME;
+	struct scst_device *dev = cmd->dev;
+	int rc;
+
+#ifdef CONFIG_SCST_STRICT_SERIALIZING
+	cmd->inc_expected_sn_on_done = 1;
+#else
+	cmd->inc_expected_sn_on_done = dev->handler->exec_sync ||
+	     (!dev->has_own_order_mgmt &&
+	      (dev->queue_alg == SCST_CONTR_MODE_QUEUE_ALG_RESTRICTED_REORDER ||
+	       cmd->queue_type == SCST_CMD_QUEUE_ORDERED));
+#endif
+
+	/*
+	 * Expected transfer data supplied by the SCSI transport via the
+	 * target driver are untrusted, so we prefer to fetch them from CDB.
+	 * Additionally, not all transports support supplying the expected
+	 * transfer data.
+	 */
+
+	rc = scst_get_cdb_info(cmd);
+	if (unlikely(rc != 0)) {
+		if (rc > 0) {
+			PRINT_BUFFER("Failed CDB", cmd->cdb, cmd->cdb_len);
+			goto out_err;
+		}
+
+		EXTRACHECKS_BUG_ON(cmd->op_flags & SCST_INFO_VALID);
+
+		TRACE(TRACE_MINOR, "Unknown opcode 0x%02x for %s. "
+			"Should you update scst_scsi_op_table?",
+			cmd->cdb[0], dev->handler->name);
+		PRINT_BUFF_FLAG(TRACE_MINOR, "Failed CDB", cmd->cdb,
+			cmd->cdb_len);
+	} else {
+		EXTRACHECKS_BUG_ON(!(cmd->op_flags & SCST_INFO_VALID));
+	}
+
+	cmd->state = SCST_CMD_STATE_DEV_PARSE;
+
+	TRACE_DBG("op_name <%s> (cmd %p), direction=%d "
+		"(expected %d, set %s), bufflen=%d, out_bufflen=%d (expected "
+		"len %d, out expected len %d), flags=%d", cmd->op_name, cmd,
+		cmd->data_direction, cmd->expected_data_direction,
+		scst_cmd_is_expected_set(cmd) ? "yes" : "no",
+		cmd->bufflen, cmd->out_bufflen, cmd->expected_transfer_len,
+		cmd->expected_out_transfer_len, cmd->op_flags);
+
+out:
+	return res;
+
+out_err:
+	scst_set_cmd_error(cmd, SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+	scst_set_cmd_abnormal_done_state(cmd);
+	res = SCST_CMD_STATE_RES_CONT_SAME;
+	goto out;
+}
+
+#ifndef CONFIG_SCST_USE_EXPECTED_VALUES
+static bool scst_is_allowed_to_mismatch_cmd(struct scst_cmd *cmd)
+{
+	bool res = false;
+
+	/* VERIFY commands with BYTCHK unset shouldn't fail here */
+	if ((cmd->op_flags & SCST_VERIFY_BYTCHK_MISMATCH_ALLOWED) &&
+	    (cmd->cdb[1] & BYTCHK) == 0) {
+		res = true;
+		goto out;
+	}
+
+	switch (cmd->cdb[0]) {
+	case TEST_UNIT_READY:
+		/* Crazy VMware people sometimes do TUR with READ direction */
+		if ((cmd->expected_data_direction == SCST_DATA_READ) ||
+		    (cmd->expected_data_direction == SCST_DATA_NONE))
+			res = true;
+		break;
+	}
+
+out:
+	return res;
+}
+#endif
+
+static int scst_parse_cmd(struct scst_cmd *cmd)
+{
+	int res = SCST_CMD_STATE_RES_CONT_SAME;
+	int state;
+	struct scst_device *dev = cmd->dev;
+	int orig_bufflen = cmd->bufflen;
+
+	if (likely(!scst_is_cmd_fully_local(cmd))) {
+		if (unlikely(!dev->handler->parse_atomic &&
+			     scst_cmd_atomic(cmd))) {
+			/*
+			 * It shouldn't be because of the SCST_TGT_DEV_AFTER_*
+			 * optimization.
+			 */
+			TRACE_DBG("Dev handler %s parse() needs thread "
+				"context, rescheduling", dev->handler->name);
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			goto out;
+		}
+
+		TRACE_DBG("Calling dev handler %s parse(%p)",
+		      dev->handler->name, cmd);
+		TRACE_BUFF_FLAG(TRACE_SND_BOT, "Parsing: ",
+				cmd->cdb, cmd->cdb_len);
+		scst_set_cur_start(cmd);
+		state = dev->handler->parse(cmd);
+		/* Caution: cmd can be already dead here */
+		TRACE_DBG("Dev handler %s parse() returned %d",
+			dev->handler->name, state);
+
+		switch (state) {
+		case SCST_CMD_STATE_NEED_THREAD_CTX:
+			scst_set_parse_time(cmd);
+			TRACE_DBG("Dev handler %s parse() requested thread "
+			      "context, rescheduling", dev->handler->name);
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			goto out;
+
+		case SCST_CMD_STATE_STOP:
+			TRACE_DBG("Dev handler %s parse() requested stop "
+				"processing", dev->handler->name);
+			res = SCST_CMD_STATE_RES_CONT_NEXT;
+			goto out;
+		}
+
+		scst_set_parse_time(cmd);
+
+		if (state == SCST_CMD_STATE_DEFAULT)
+			state = SCST_CMD_STATE_PREPARE_SPACE;
+	} else
+		state = SCST_CMD_STATE_PREPARE_SPACE;
+
+	if (unlikely(state == SCST_CMD_STATE_PRE_XMIT_RESP))
+		goto set_res;
+
+	if (unlikely(!(cmd->op_flags & SCST_INFO_VALID))) {
+#ifdef CONFIG_SCST_USE_EXPECTED_VALUES
+		if (scst_cmd_is_expected_set(cmd)) {
+			TRACE(TRACE_MINOR, "Using initiator supplied values: "
+				"direction %d, transfer_len %d/%d",
+				cmd->expected_data_direction,
+				cmd->expected_transfer_len,
+				cmd->expected_out_transfer_len);
+			cmd->data_direction = cmd->expected_data_direction;
+			cmd->bufflen = cmd->expected_transfer_len;
+			cmd->out_bufflen = cmd->expected_out_transfer_len;
+		} else {
+			PRINT_ERROR("Unknown opcode 0x%02x for %s and "
+			     "target %s not supplied expected values",
+			     cmd->cdb[0], dev->handler->name, cmd->tgtt->name);
+			scst_set_cmd_error(cmd,
+				   SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+			goto out_done;
+		}
+#else
+		/*
+		 * Let's ignore reporting T10/04-262r7 16-byte and 12-byte ATA
+		 * pass-thru commands to not pollute logs (udev(?) checks them
+		 * for some reason). If somebody has their description, please,
+		 * update scst_scsi_op_table.
+		 */
+		if ((cmd->cdb[0] != 0x85) && (cmd->cdb[0] != 0xa1))
+			PRINT_ERROR("Refusing unknown opcode %x", cmd->cdb[0]);
+		else
+			TRACE(TRACE_MINOR, "Refusing unknown opcode %x",
+				cmd->cdb[0]);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+		goto out_done;
+#endif
+	}
+
+	if (unlikely(cmd->cdb_len == 0)) {
+		PRINT_ERROR("Unable to get CDB length for "
+			"opcode 0x%02x. Returning INVALID "
+			"OPCODE", cmd->cdb[0]);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+		goto out_done;
+	}
+
+	EXTRACHECKS_BUG_ON(cmd->cdb_len == 0);
+
+	TRACE(TRACE_SCSI, "op_name <%s> (cmd %p), direction=%d "
+		"(expected %d, set %s), bufflen=%d, out_bufflen=%d, (expected "
+		"len %d, out expected len %d), flags=%x", cmd->op_name, cmd,
+		cmd->data_direction, cmd->expected_data_direction,
+		scst_cmd_is_expected_set(cmd) ? "yes" : "no",
+		cmd->bufflen, cmd->out_bufflen, cmd->expected_transfer_len,
+		cmd->expected_out_transfer_len, cmd->op_flags);
+
+	if (unlikely((cmd->op_flags & SCST_UNKNOWN_LENGTH) != 0)) {
+		if (scst_cmd_is_expected_set(cmd)) {
+			/*
+			 * Command data length can't be easily
+			 * determined from the CDB. ToDo, all such
+			 * commands processing should be fixed. Until
+			 * it's done, get the length from the supplied
+			 * expected value, but limit it to some
+			 * reasonable value (15MB).
+			 */
+			cmd->bufflen = min(cmd->expected_transfer_len,
+						15*1024*1024);
+			if (cmd->data_direction == SCST_DATA_BIDI)
+				cmd->out_bufflen = min(cmd->expected_out_transfer_len,
+							15*1024*1024);
+			cmd->op_flags &= ~SCST_UNKNOWN_LENGTH;
+		} else {
+			PRINT_ERROR("Unknown data transfer length for opcode "
+				"0x%x (handler %s, target %s)", cmd->cdb[0],
+				dev->handler->name, cmd->tgtt->name);
+			PRINT_BUFFER("Failed CDB", cmd->cdb, cmd->cdb_len);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_invalid_message));
+			goto out_done;
+		}
+	}
+
+	if (unlikely(cmd->cdb[cmd->cdb_len - 1] & CONTROL_BYTE_NACA_BIT)) {
+		PRINT_ERROR("NACA bit in control byte CDB is not supported "
+			    "(opcode 0x%02x)", cmd->cdb[0]);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out_done;
+	}
+
+	if (unlikely(cmd->cdb[cmd->cdb_len - 1] & CONTROL_BYTE_LINK_BIT)) {
+		PRINT_ERROR("Linked commands are not supported "
+			    "(opcode 0x%02x)", cmd->cdb[0]);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out_done;
+	}
+
+	if (cmd->dh_data_buf_alloced &&
+	    unlikely((orig_bufflen > cmd->bufflen))) {
+		PRINT_ERROR("Dev handler supplied data buffer (size %d), "
+			"is less, than required (size %d)", cmd->bufflen,
+			orig_bufflen);
+		PRINT_BUFFER("Failed CDB", cmd->cdb, cmd->cdb_len);
+		goto out_hw_error;
+	}
+
+#ifdef CONFIG_SCST_EXTRACHECKS
+	if ((cmd->bufflen != 0) &&
+	    ((cmd->data_direction == SCST_DATA_NONE) ||
+	     ((cmd->sg == NULL) && (state > SCST_CMD_STATE_PREPARE_SPACE)))) {
+		PRINT_ERROR("Dev handler %s parse() returned "
+			"invalid cmd data_direction %d, bufflen %d, state %d "
+			"or sg %p (opcode 0x%x)", dev->handler->name,
+			cmd->data_direction, cmd->bufflen, state, cmd->sg,
+			cmd->cdb[0]);
+		PRINT_BUFFER("Failed CDB", cmd->cdb, cmd->cdb_len);
+		goto out_hw_error;
+	}
+#endif
+
+	if (scst_cmd_is_expected_set(cmd)) {
+#ifdef CONFIG_SCST_USE_EXPECTED_VALUES
+		if (unlikely((cmd->data_direction != cmd->expected_data_direction) ||
+			     (cmd->bufflen != cmd->expected_transfer_len) ||
+			     (cmd->out_bufflen != cmd->expected_out_transfer_len))) {
+			TRACE(TRACE_MINOR, "Expected values don't match "
+				"decoded ones: data_direction %d, "
+				"expected_data_direction %d, "
+				"bufflen %d, expected_transfer_len %d, "
+				"out_bufflen %d, expected_out_transfer_len %d",
+				cmd->data_direction,
+				cmd->expected_data_direction,
+				cmd->bufflen, cmd->expected_transfer_len,
+				cmd->out_bufflen, cmd->expected_out_transfer_len);
+			PRINT_BUFF_FLAG(TRACE_MINOR, "Suspicious CDB",
+				cmd->cdb, cmd->cdb_len);
+			cmd->data_direction = cmd->expected_data_direction;
+			cmd->bufflen = cmd->expected_transfer_len;
+			cmd->out_bufflen = cmd->expected_out_transfer_len;
+			cmd->resid_possible = 1;
+		}
+#else
+		if (unlikely(cmd->data_direction !=
+				cmd->expected_data_direction)) {
+			if (((cmd->expected_data_direction != SCST_DATA_NONE) ||
+			     (cmd->bufflen != 0)) &&
+			    !scst_is_allowed_to_mismatch_cmd(cmd)) {
+				PRINT_ERROR("Expected data direction %d for "
+					"opcode 0x%02x (handler %s, target %s) "
+					"doesn't match decoded value %d",
+					cmd->expected_data_direction,
+					cmd->cdb[0], dev->handler->name,
+					cmd->tgtt->name, cmd->data_direction);
+				PRINT_BUFFER("Failed CDB", cmd->cdb,
+					cmd->cdb_len);
+				scst_set_cmd_error(cmd,
+				   SCST_LOAD_SENSE(scst_sense_invalid_message));
+				goto out_done;
+			}
+		}
+		if (unlikely(cmd->bufflen != cmd->expected_transfer_len)) {
+			TRACE(TRACE_MINOR, "Warning: expected "
+				"transfer length %d for opcode 0x%02x "
+				"(handler %s, target %s) doesn't match "
+				"decoded value %d. Faulty initiator "
+				"(e.g. VMware is known to be such) or "
+				"scst_scsi_op_table should be updated?",
+				cmd->expected_transfer_len, cmd->cdb[0],
+				dev->handler->name, cmd->tgtt->name,
+				cmd->bufflen);
+			PRINT_BUFF_FLAG(TRACE_MINOR, "Suspicious CDB",
+				cmd->cdb, cmd->cdb_len);
+			if ((cmd->data_direction & SCST_DATA_READ) ||
+			    (cmd->data_direction & SCST_DATA_WRITE))
+				cmd->resid_possible = 1;
+		}
+		if (unlikely(cmd->out_bufflen != cmd->expected_out_transfer_len)) {
+			TRACE(TRACE_MINOR, "Warning: expected bidirectional OUT "
+				"transfer length %d for opcode 0x%02x "
+				"(handler %s, target %s) doesn't match "
+				"decoded value %d. Faulty initiator "
+				"(e.g. VMware is known to be such) or "
+				"scst_scsi_op_table should be updated?",
+				cmd->expected_out_transfer_len, cmd->cdb[0],
+				dev->handler->name, cmd->tgtt->name,
+				cmd->out_bufflen);
+			PRINT_BUFF_FLAG(TRACE_MINOR, "Suspicious CDB",
+				cmd->cdb, cmd->cdb_len);
+			cmd->resid_possible = 1;
+		}
+#endif
+	}
+
+	if (unlikely(cmd->data_direction == SCST_DATA_UNKNOWN)) {
+		PRINT_ERROR("Unknown data direction. Opcode 0x%x, handler %s, "
+			"target %s", cmd->cdb[0], dev->handler->name,
+			cmd->tgtt->name);
+		PRINT_BUFFER("Failed CDB", cmd->cdb, cmd->cdb_len);
+		goto out_hw_error;
+	}
+
+set_res:
+	if (cmd->data_len == -1)
+		cmd->data_len = cmd->bufflen;
+
+	if (cmd->bufflen == 0) {
+		/*
+		 * According to SPC bufflen 0 for data transfer commands isn't
+		 * an error, so we need to fix the transfer direction.
+		 */
+		cmd->data_direction = SCST_DATA_NONE;
+	}
+
+#ifdef CONFIG_SCST_EXTRACHECKS
+	switch (state) {
+	case SCST_CMD_STATE_PREPARE_SPACE:
+	case SCST_CMD_STATE_PRE_PARSE:
+	case SCST_CMD_STATE_DEV_PARSE:
+	case SCST_CMD_STATE_RDY_TO_XFER:
+	case SCST_CMD_STATE_TGT_PRE_EXEC:
+	case SCST_CMD_STATE_SEND_FOR_EXEC:
+	case SCST_CMD_STATE_LOCAL_EXEC:
+	case SCST_CMD_STATE_REAL_EXEC:
+	case SCST_CMD_STATE_PRE_DEV_DONE:
+	case SCST_CMD_STATE_DEV_DONE:
+	case SCST_CMD_STATE_PRE_XMIT_RESP:
+	case SCST_CMD_STATE_XMIT_RESP:
+	case SCST_CMD_STATE_FINISHED:
+	case SCST_CMD_STATE_FINISHED_INTERNAL:
+#endif
+		cmd->state = state;
+		res = SCST_CMD_STATE_RES_CONT_SAME;
+#ifdef CONFIG_SCST_EXTRACHECKS
+		break;
+
+	default:
+		if (state >= 0) {
+			PRINT_ERROR("Dev handler %s parse() returned "
+			     "invalid cmd state %d (opcode %d)",
+			     dev->handler->name, state, cmd->cdb[0]);
+		} else {
+			PRINT_ERROR("Dev handler %s parse() returned "
+				"error %d (opcode %d)", dev->handler->name,
+				state, cmd->cdb[0]);
+		}
+		goto out_hw_error;
+	}
+#endif
+
+	if (cmd->resp_data_len == -1) {
+		if (cmd->data_direction & SCST_DATA_READ)
+			cmd->resp_data_len = cmd->bufflen;
+		else
+			 cmd->resp_data_len = 0;
+	}
+
+	/* We already completed (with an error) */
+	if (unlikely(cmd->completed))
+		goto out_done;
+
+out:
+	return res;
+
+out_hw_error:
+	/* dev_done() will be called as part of the regular cmd's finish */
+	scst_set_cmd_error(cmd, SCST_LOAD_SENSE(scst_sense_hardw_error));
+
+out_done:
+	scst_set_cmd_abnormal_done_state(cmd);
+	res = SCST_CMD_STATE_RES_CONT_SAME;
+	goto out;
+}
+
+static void scst_set_write_len(struct scst_cmd *cmd)
+{
+
+	EXTRACHECKS_BUG_ON(!(cmd->data_direction & SCST_DATA_WRITE));
+
+	if (cmd->data_direction & SCST_DATA_READ) {
+		cmd->write_len = cmd->out_bufflen;
+		cmd->write_sg = &cmd->out_sg;
+		cmd->write_sg_cnt = &cmd->out_sg_cnt;
+	} else {
+		cmd->write_len = cmd->bufflen;
+		/* write_sg and write_sg_cnt already initialized correctly */
+	}
+
+	TRACE_MEM("cmd %p, write_len %d, write_sg %p, write_sg_cnt %d, "
+		"resid_possible %d", cmd, cmd->write_len, *cmd->write_sg,
+		*cmd->write_sg_cnt, cmd->resid_possible);
+
+	if (unlikely(cmd->resid_possible)) {
+		if (cmd->data_direction & SCST_DATA_READ) {
+			cmd->write_len = min(cmd->out_bufflen,
+				cmd->expected_out_transfer_len);
+			if (cmd->write_len == cmd->out_bufflen)
+				goto out;
+		} else {
+			cmd->write_len = min(cmd->bufflen,
+				cmd->expected_transfer_len);
+			if (cmd->write_len == cmd->bufflen)
+				goto out;
+		}
+		scst_limit_sg_write_len(cmd);
+	}
+
+out:
+	return;
+}
+
+static int scst_prepare_space(struct scst_cmd *cmd)
+{
+	int r = 0, res = SCST_CMD_STATE_RES_CONT_SAME;
+	struct scst_device *dev = cmd->dev;
+
+	if (cmd->data_direction == SCST_DATA_NONE)
+		goto done;
+
+	if (likely(!scst_is_cmd_fully_local(cmd)) &&
+	    (dev->handler->alloc_data_buf != NULL)) {
+		int state;
+
+		if (unlikely(!dev->handler->alloc_data_buf_atomic &&
+			     scst_cmd_atomic(cmd))) {
+			/*
+			 * It shouldn't be because of the SCST_TGT_DEV_AFTER_*
+			 * optimization.
+			 */
+			TRACE_DBG("Dev handler %s alloc_data_buf() needs "
+				"thread context, rescheduling",
+				dev->handler->name);
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			goto out;
+		}
+
+		TRACE_DBG("Calling dev handler %s alloc_data_buf(%p)",
+		      dev->handler->name, cmd);
+		scst_set_cur_start(cmd);
+		state = dev->handler->alloc_data_buf(cmd);
+		/* Caution: cmd can be already dead here */
+		TRACE_DBG("Dev handler %s alloc_data_buf() returned %d",
+			dev->handler->name, state);
+
+		switch (state) {
+		case SCST_CMD_STATE_NEED_THREAD_CTX:
+			scst_set_alloc_buf_time(cmd);
+			TRACE_DBG("Dev handler %s alloc_data_buf() requested "
+				"thread context, rescheduling",
+				dev->handler->name);
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			goto out;
+
+		case SCST_CMD_STATE_STOP:
+			TRACE_DBG("Dev handler %s alloc_data_buf() requested "
+				"stop processing", dev->handler->name);
+			res = SCST_CMD_STATE_RES_CONT_NEXT;
+			goto out;
+		}
+
+		scst_set_alloc_buf_time(cmd);
+
+		if (unlikely(state != SCST_CMD_STATE_DEFAULT)) {
+			cmd->state = state;
+			goto out;
+		}
+	}
+
+	if (cmd->tgt_need_alloc_data_buf) {
+		int orig_bufflen = cmd->bufflen;
+
+		TRACE_MEM("Custom tgt data buf allocation requested (cmd %p)",
+			cmd);
+
+		scst_set_cur_start(cmd);
+		r = cmd->tgtt->alloc_data_buf(cmd);
+		scst_set_alloc_buf_time(cmd);
+
+		if (r > 0)
+			goto alloc;
+		else if (r == 0) {
+			if (unlikely(cmd->bufflen == 0)) {
+				/* See comment in scst_alloc_space() */
+				if (cmd->sg == NULL)
+					goto alloc;
+			}
+
+			cmd->tgt_data_buf_alloced = 1;
+
+			if (unlikely(orig_bufflen < cmd->bufflen)) {
+				PRINT_ERROR("Target driver allocated data "
+					"buffer (size %d), is less, than "
+					"required (size %d)", orig_bufflen,
+					cmd->bufflen);
+				goto out_error;
+			}
+			TRACE_MEM("tgt_data_buf_alloced (cmd %p)", cmd);
+		} else
+			goto check;
+	}
+
+alloc:
+	if (!cmd->tgt_data_buf_alloced && !cmd->dh_data_buf_alloced) {
+		r = scst_alloc_space(cmd);
+	} else if (cmd->dh_data_buf_alloced && !cmd->tgt_data_buf_alloced) {
+		TRACE_MEM("dh_data_buf_alloced set (cmd %p)", cmd);
+		r = 0;
+	} else if (cmd->tgt_data_buf_alloced && !cmd->dh_data_buf_alloced) {
+		TRACE_MEM("tgt_data_buf_alloced set (cmd %p)", cmd);
+		cmd->sg = cmd->tgt_sg;
+		cmd->sg_cnt = cmd->tgt_sg_cnt;
+		cmd->out_sg = cmd->tgt_out_sg;
+		cmd->out_sg_cnt = cmd->tgt_out_sg_cnt;
+		r = 0;
+	} else {
+		TRACE_MEM("Both *_data_buf_alloced set (cmd %p, sg %p, "
+			"sg_cnt %d, tgt_sg %p, tgt_sg_cnt %d)", cmd, cmd->sg,
+			cmd->sg_cnt, cmd->tgt_sg, cmd->tgt_sg_cnt);
+		r = 0;
+	}
+
+check:
+	if (r != 0) {
+		if (scst_cmd_atomic(cmd)) {
+			TRACE_MEM("%s", "Atomic memory allocation failed, "
+			      "rescheduling to the thread");
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			goto out;
+		} else
+			goto out_no_space;
+	}
+
+done:
+	if (cmd->preprocessing_only) {
+		cmd->state = SCST_CMD_STATE_PREPROCESSING_DONE;
+		if (cmd->data_direction & SCST_DATA_WRITE)
+			scst_set_write_len(cmd);
+	} else if (cmd->data_direction & SCST_DATA_WRITE) {
+		cmd->state = SCST_CMD_STATE_RDY_TO_XFER;
+		scst_set_write_len(cmd);
+	} else
+		cmd->state = SCST_CMD_STATE_TGT_PRE_EXEC;
+
+out:
+	return res;
+
+out_no_space:
+	TRACE(TRACE_OUT_OF_MEM, "Unable to allocate or build requested buffer "
+		"(size %d), sending BUSY or QUEUE FULL status", cmd->bufflen);
+	scst_set_busy(cmd);
+	scst_set_cmd_abnormal_done_state(cmd);
+	res = SCST_CMD_STATE_RES_CONT_SAME;
+	goto out;
+
+out_error:
+	scst_set_cmd_error(cmd,	SCST_LOAD_SENSE(scst_sense_hardw_error));
+	scst_set_cmd_abnormal_done_state(cmd);
+	res = SCST_CMD_STATE_RES_CONT_SAME;
+	goto out;
+}
+
+static int scst_preprocessing_done(struct scst_cmd *cmd)
+{
+	int res;
+
+	EXTRACHECKS_BUG_ON(!cmd->preprocessing_only);
+
+	cmd->preprocessing_only = 0;
+
+	res = SCST_CMD_STATE_RES_CONT_NEXT;
+	cmd->state = SCST_CMD_STATE_PREPROCESSING_DONE_CALLED;
+
+	TRACE_DBG("Calling preprocessing_done(cmd %p)", cmd);
+	scst_set_cur_start(cmd);
+	cmd->tgtt->preprocessing_done(cmd);
+	TRACE_DBG("%s", "preprocessing_done() returned");
+	return res;
+}
+
+/**
+ * scst_restart_cmd() - restart execution of the command
+ * @cmd:	SCST commands
+ * @status:	completion status
+ * @pref_context: preferred command execition context
+ *
+ * Description:
+ *    Notifies SCST that the driver finished its part of the command's
+ *    preprocessing and it is ready for further processing.
+ *
+ *    The second argument sets completion status
+ *    (see SCST_PREPROCESS_STATUS_* constants for details)
+ *
+ *    See also comment for scst_cmd_init_done() for the serialization
+ *    requirements.
+ */
+void scst_restart_cmd(struct scst_cmd *cmd, int status,
+	enum scst_exec_context pref_context)
+{
+
+	scst_set_restart_waiting_time(cmd);
+
+	TRACE_DBG("Preferred context: %d", pref_context);
+	TRACE_DBG("tag=%llu, status=%#x",
+		  (long long unsigned int)scst_cmd_get_tag(cmd),
+		  status);
+
+#ifdef CONFIG_SCST_EXTRACHECKS
+	if ((in_irq() || irqs_disabled()) &&
+	    ((pref_context == SCST_CONTEXT_DIRECT) ||
+	     (pref_context == SCST_CONTEXT_DIRECT_ATOMIC))) {
+		PRINT_ERROR("Wrong context %d in IRQ from target %s, use "
+			"SCST_CONTEXT_THREAD instead", pref_context,
+			cmd->tgtt->name);
+		pref_context = SCST_CONTEXT_THREAD;
+	}
+#endif
+
+	switch (status) {
+	case SCST_PREPROCESS_STATUS_SUCCESS:
+		if (cmd->data_direction & SCST_DATA_WRITE)
+			cmd->state = SCST_CMD_STATE_RDY_TO_XFER;
+		else
+			cmd->state = SCST_CMD_STATE_TGT_PRE_EXEC;
+		if (cmd->set_sn_on_restart_cmd)
+			scst_cmd_set_sn(cmd);
+#ifdef CONFIG_SCST_TEST_IO_IN_SIRQ
+		if (cmd->op_flags & SCST_TEST_IO_IN_SIRQ_ALLOWED)
+			break;
+#endif
+		/* Small context optimization */
+		if ((pref_context == SCST_CONTEXT_TASKLET) ||
+		    (pref_context == SCST_CONTEXT_DIRECT_ATOMIC) ||
+		    ((pref_context == SCST_CONTEXT_SAME) &&
+		     scst_cmd_atomic(cmd)))
+			pref_context = SCST_CONTEXT_THREAD;
+		break;
+
+	case SCST_PREPROCESS_STATUS_ERROR_SENSE_SET:
+		scst_set_cmd_abnormal_done_state(cmd);
+		break;
+
+	case SCST_PREPROCESS_STATUS_ERROR_FATAL:
+		set_bit(SCST_CMD_NO_RESP, &cmd->cmd_flags);
+		/* go through */
+	case SCST_PREPROCESS_STATUS_ERROR:
+		if (cmd->sense != NULL)
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+		scst_set_cmd_abnormal_done_state(cmd);
+		break;
+
+	default:
+		PRINT_ERROR("%s() received unknown status %x", __func__,
+			status);
+		scst_set_cmd_abnormal_done_state(cmd);
+		break;
+	}
+
+	scst_process_redirect_cmd(cmd, pref_context, 1);
+	return;
+}
+EXPORT_SYMBOL(scst_restart_cmd);
+
+static int scst_rdy_to_xfer(struct scst_cmd *cmd)
+{
+	int res, rc;
+	struct scst_tgt_template *tgtt = cmd->tgtt;
+
+	if (unlikely(test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags))) {
+		TRACE_MGMT_DBG("ABORTED set, aborting cmd %p", cmd);
+		goto out_dev_done;
+	}
+
+	if ((tgtt->rdy_to_xfer == NULL) || unlikely(cmd->internal)) {
+		cmd->state = SCST_CMD_STATE_TGT_PRE_EXEC;
+		res = SCST_CMD_STATE_RES_CONT_SAME;
+		goto out;
+	}
+
+	if (unlikely(!tgtt->rdy_to_xfer_atomic && scst_cmd_atomic(cmd))) {
+		/*
+		 * It shouldn't be because of the SCST_TGT_DEV_AFTER_*
+		 * optimization.
+		 */
+		TRACE_DBG("Target driver %s rdy_to_xfer() needs thread "
+			      "context, rescheduling", tgtt->name);
+		res = SCST_CMD_STATE_RES_NEED_THREAD;
+		goto out;
+	}
+
+	while (1) {
+		int finished_cmds = atomic_read(&cmd->tgt->finished_cmds);
+
+		res = SCST_CMD_STATE_RES_CONT_NEXT;
+		cmd->state = SCST_CMD_STATE_DATA_WAIT;
+
+		if (tgtt->on_hw_pending_cmd_timeout != NULL) {
+			struct scst_session *sess = cmd->sess;
+			cmd->hw_pending_start = jiffies;
+			cmd->cmd_hw_pending = 1;
+			if (!test_bit(SCST_SESS_HW_PENDING_WORK_SCHEDULED, &sess->sess_aflags)) {
+				TRACE_DBG("Sched HW pending work for sess %p "
+					"(max time %d)", sess,
+					tgtt->max_hw_pending_time);
+				set_bit(SCST_SESS_HW_PENDING_WORK_SCHEDULED,
+					&sess->sess_aflags);
+				schedule_delayed_work(&sess->hw_pending_work,
+					tgtt->max_hw_pending_time * HZ);
+			}
+		}
+
+		scst_set_cur_start(cmd);
+
+		TRACE_DBG("Calling rdy_to_xfer(%p)", cmd);
+#ifdef CONFIG_SCST_DEBUG_RETRY
+		if (((scst_random() % 100) == 75))
+			rc = SCST_TGT_RES_QUEUE_FULL;
+		else
+#endif
+			rc = tgtt->rdy_to_xfer(cmd);
+		TRACE_DBG("rdy_to_xfer() returned %d", rc);
+
+		if (likely(rc == SCST_TGT_RES_SUCCESS))
+			goto out;
+
+		scst_set_rdy_to_xfer_time(cmd);
+
+		cmd->cmd_hw_pending = 0;
+
+		/* Restore the previous state */
+		cmd->state = SCST_CMD_STATE_RDY_TO_XFER;
+
+		switch (rc) {
+		case SCST_TGT_RES_QUEUE_FULL:
+			if (scst_queue_retry_cmd(cmd, finished_cmds) == 0)
+				break;
+			else
+				continue;
+
+		case SCST_TGT_RES_NEED_THREAD_CTX:
+			TRACE_DBG("Target driver %s "
+			      "rdy_to_xfer() requested thread "
+			      "context, rescheduling", tgtt->name);
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			break;
+
+		default:
+			goto out_error_rc;
+		}
+		break;
+	}
+
+out:
+	return res;
+
+out_error_rc:
+	if (rc == SCST_TGT_RES_FATAL_ERROR) {
+		PRINT_ERROR("Target driver %s rdy_to_xfer() returned "
+		     "fatal error", tgtt->name);
+	} else {
+		PRINT_ERROR("Target driver %s rdy_to_xfer() returned invalid "
+			    "value %d", tgtt->name, rc);
+	}
+	scst_set_cmd_error(cmd, SCST_LOAD_SENSE(scst_sense_hardw_error));
+
+out_dev_done:
+	scst_set_cmd_abnormal_done_state(cmd);
+	res = SCST_CMD_STATE_RES_CONT_SAME;
+	goto out;
+}
+
+/* No locks, but might be in IRQ */
+static void scst_process_redirect_cmd(struct scst_cmd *cmd,
+	enum scst_exec_context context, int check_retries)
+{
+	struct scst_tgt *tgt = cmd->tgt;
+	unsigned long flags;
+
+	TRACE_DBG("Context: %x", context);
+
+	if (context == SCST_CONTEXT_SAME)
+		context = scst_cmd_atomic(cmd) ? SCST_CONTEXT_DIRECT_ATOMIC :
+						 SCST_CONTEXT_DIRECT;
+
+	switch (context) {
+	case SCST_CONTEXT_DIRECT_ATOMIC:
+		scst_process_active_cmd(cmd, true);
+		break;
+
+	case SCST_CONTEXT_DIRECT:
+		if (check_retries)
+			scst_check_retries(tgt);
+		scst_process_active_cmd(cmd, false);
+		break;
+
+	default:
+		PRINT_ERROR("Context %x is unknown, using the thread one",
+			    context);
+		/* go through */
+	case SCST_CONTEXT_THREAD:
+		if (check_retries)
+			scst_check_retries(tgt);
+		spin_lock_irqsave(&cmd->cmd_threads->cmd_list_lock, flags);
+		TRACE_DBG("Adding cmd %p to active cmd list", cmd);
+		if (unlikely(cmd->queue_type == SCST_CMD_QUEUE_HEAD_OF_QUEUE))
+			list_add(&cmd->cmd_list_entry,
+				&cmd->cmd_threads->active_cmd_list);
+		else
+			list_add_tail(&cmd->cmd_list_entry,
+				&cmd->cmd_threads->active_cmd_list);
+		wake_up(&cmd->cmd_threads->cmd_list_waitQ);
+		spin_unlock_irqrestore(&cmd->cmd_threads->cmd_list_lock, flags);
+		break;
+
+	case SCST_CONTEXT_TASKLET:
+		if (check_retries)
+			scst_check_retries(tgt);
+		scst_schedule_tasklet(cmd);
+		break;
+	}
+	return;
+}
+
+/**
+ * scst_rx_data() - the command's data received
+ * @cmd:	SCST commands
+ * @status:	data receiving completion status
+ * @pref_context: preferred command execution context
+ *
+ * Description:
+ *    Notifies SCST that the driver received all the necessary data
+ *    and the command is ready for further processing.
+ *
+ *    The second argument sets data receiving completion status
+ *    (see SCST_RX_STATUS_* constants for details)
+ */
+void scst_rx_data(struct scst_cmd *cmd, int status,
+	enum scst_exec_context pref_context)
+{
+
+	scst_set_rdy_to_xfer_time(cmd);
+
+	TRACE_DBG("Preferred context: %d", pref_context);
+	TRACE(TRACE_SCSI, "cmd %p, status %#x", cmd, status);
+
+	cmd->cmd_hw_pending = 0;
+
+#ifdef CONFIG_SCST_EXTRACHECKS
+	if ((in_irq() || irqs_disabled()) &&
+	    ((pref_context == SCST_CONTEXT_DIRECT) ||
+	     (pref_context == SCST_CONTEXT_DIRECT_ATOMIC))) {
+		PRINT_ERROR("Wrong context %d in IRQ from target %s, use "
+			"SCST_CONTEXT_THREAD instead", pref_context,
+			cmd->tgtt->name);
+		pref_context = SCST_CONTEXT_THREAD;
+	}
+#endif
+
+	switch (status) {
+	case SCST_RX_STATUS_SUCCESS:
+#if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
+		if (trace_flag & TRACE_RCV_BOT) {
+			int i, j;
+			struct scatterlist *sg;
+			if (cmd->out_sg != NULL)
+				sg = cmd->out_sg;
+			else if (cmd->tgt_out_sg != NULL)
+				sg = cmd->tgt_out_sg;
+			else if (cmd->tgt_sg != NULL)
+				sg = cmd->tgt_sg;
+			else
+				sg = cmd->sg;
+			if (sg != NULL) {
+				TRACE_RECV_BOT("RX data for cmd %p "
+					"(sg_cnt %d, sg %p, sg[0].page %p)",
+					cmd, cmd->tgt_sg_cnt, sg,
+					(void *)sg_page(&sg[0]));
+				for (i = 0, j = 0; i < cmd->tgt_sg_cnt; ++i, ++j) {
+					if (unlikely(sg_is_chain(&sg[j]))) {
+						sg = sg_chain_ptr(&sg[j]);
+						j = 0;
+					}
+					PRINT_BUFF_FLAG(TRACE_RCV_BOT, "RX sg",
+						sg_virt(&sg[j]), sg[j].length);
+				}
+			}
+		}
+#endif
+		cmd->state = SCST_CMD_STATE_TGT_PRE_EXEC;
+
+#ifdef CONFIG_SCST_TEST_IO_IN_SIRQ
+		if (cmd->op_flags & SCST_TEST_IO_IN_SIRQ_ALLOWED)
+			break;
+#endif
+
+		/* Small context optimization */
+		if ((pref_context == SCST_CONTEXT_TASKLET) ||
+		    (pref_context == SCST_CONTEXT_DIRECT_ATOMIC) ||
+		    ((pref_context == SCST_CONTEXT_SAME) &&
+		     scst_cmd_atomic(cmd)))
+			pref_context = SCST_CONTEXT_THREAD;
+		break;
+
+	case SCST_RX_STATUS_ERROR_SENSE_SET:
+		scst_set_cmd_abnormal_done_state(cmd);
+		break;
+
+	case SCST_RX_STATUS_ERROR_FATAL:
+		set_bit(SCST_CMD_NO_RESP, &cmd->cmd_flags);
+		/* go through */
+	case SCST_RX_STATUS_ERROR:
+		scst_set_cmd_error(cmd,
+			   SCST_LOAD_SENSE(scst_sense_hardw_error));
+		scst_set_cmd_abnormal_done_state(cmd);
+		break;
+
+	default:
+		PRINT_ERROR("scst_rx_data() received unknown status %x",
+			status);
+		scst_set_cmd_abnormal_done_state(cmd);
+		break;
+	}
+
+	scst_process_redirect_cmd(cmd, pref_context, 1);
+	return;
+}
+EXPORT_SYMBOL(scst_rx_data);
+
+static int scst_tgt_pre_exec(struct scst_cmd *cmd)
+{
+	int res = SCST_CMD_STATE_RES_CONT_SAME, rc;
+
+	if (unlikely(cmd->resid_possible)) {
+		if (cmd->data_direction & SCST_DATA_WRITE) {
+			bool do_zero = false;
+			if (cmd->data_direction & SCST_DATA_READ) {
+				if (cmd->write_len != cmd->out_bufflen)
+					do_zero = true;
+			} else {
+				if (cmd->write_len != cmd->bufflen)
+					do_zero = true;
+			}
+			if (do_zero) {
+				scst_check_restore_sg_buff(cmd);
+				scst_zero_write_rest(cmd);
+			}
+		}
+	}
+
+	cmd->state = SCST_CMD_STATE_SEND_FOR_EXEC;
+
+	if ((cmd->tgtt->pre_exec == NULL) || unlikely(cmd->internal))
+		goto out;
+
+	TRACE_DBG("Calling pre_exec(%p)", cmd);
+	scst_set_cur_start(cmd);
+	rc = cmd->tgtt->pre_exec(cmd);
+	scst_set_pre_exec_time(cmd);
+	TRACE_DBG("pre_exec() returned %d", rc);
+
+	if (unlikely(rc != SCST_PREPROCESS_STATUS_SUCCESS)) {
+		switch (rc) {
+		case SCST_PREPROCESS_STATUS_ERROR_SENSE_SET:
+			scst_set_cmd_abnormal_done_state(cmd);
+			break;
+		case SCST_PREPROCESS_STATUS_ERROR_FATAL:
+			set_bit(SCST_CMD_NO_RESP, &cmd->cmd_flags);
+			/* go through */
+		case SCST_PREPROCESS_STATUS_ERROR:
+			scst_set_cmd_error(cmd,
+				   SCST_LOAD_SENSE(scst_sense_hardw_error));
+			scst_set_cmd_abnormal_done_state(cmd);
+			break;
+		default:
+			BUG();
+			break;
+		}
+	}
+
+out:
+	return res;
+}
+
+static void scst_do_cmd_done(struct scst_cmd *cmd, int result,
+	const uint8_t *rq_sense, int rq_sense_len, int resid)
+{
+
+	scst_set_exec_time(cmd);
+
+	cmd->status = result & 0xff;
+	cmd->msg_status = msg_byte(result);
+	cmd->host_status = host_byte(result);
+	cmd->driver_status = driver_byte(result);
+	if (unlikely(resid != 0)) {
+		if ((cmd->data_direction & SCST_DATA_READ) &&
+		    (resid > 0) && (resid < cmd->resp_data_len))
+			scst_set_resp_data_len(cmd, cmd->resp_data_len - resid);
+		/*
+		 * We ignore write direction residue, because from the
+		 * initiator's POV we already transferred all the data.
+		 */
+	}
+
+	if (unlikely(cmd->status == SAM_STAT_CHECK_CONDITION)) {
+		/* We might have double reset UA here */
+		cmd->dbl_ua_orig_resp_data_len = cmd->resp_data_len;
+		cmd->dbl_ua_orig_data_direction = cmd->data_direction;
+
+		scst_alloc_set_sense(cmd, 1, rq_sense, rq_sense_len);
+	}
+
+	TRACE(TRACE_SCSI, "cmd %p, result %x, cmd->status %x, resid %d, "
+	      "cmd->msg_status %x, cmd->host_status %x, "
+	      "cmd->driver_status %x", cmd, result, cmd->status, resid,
+	      cmd->msg_status, cmd->host_status, cmd->driver_status);
+
+	cmd->completed = 1;
+	return;
+}
+
+/* For small context optimization */
+static inline enum scst_exec_context scst_optimize_post_exec_context(
+	struct scst_cmd *cmd, enum scst_exec_context context)
+{
+	if (((context == SCST_CONTEXT_SAME) && scst_cmd_atomic(cmd)) ||
+	    (context == SCST_CONTEXT_TASKLET) ||
+	    (context == SCST_CONTEXT_DIRECT_ATOMIC)) {
+		if (!test_bit(SCST_TGT_DEV_AFTER_EXEC_ATOMIC,
+				&cmd->tgt_dev->tgt_dev_flags))
+			context = SCST_CONTEXT_THREAD;
+	}
+	return context;
+}
+
+/**
+ * scst_pass_through_cmd_done - done callback for pass-through commands
+ * @data:	private opaque data
+ * @sense:	pointer to the sense data, if any
+ * @result:	command's execution result
+ * @resid:	residual, if any
+ */
+void scst_pass_through_cmd_done(void *data, char *sense, int result, int resid)
+{
+	struct scst_cmd *cmd;
+
+	cmd = (struct scst_cmd *)data;
+	if (cmd == NULL)
+		goto out;
+
+	scst_do_cmd_done(cmd, result, sense, SCSI_SENSE_BUFFERSIZE, resid);
+
+	cmd->state = SCST_CMD_STATE_PRE_DEV_DONE;
+
+	scst_process_redirect_cmd(cmd,
+	    scst_optimize_post_exec_context(cmd, scst_estimate_context()), 0);
+
+out:
+	return;
+}
+EXPORT_SYMBOL_GPL(scst_pass_through_cmd_done);
+
+static void scst_cmd_done_local(struct scst_cmd *cmd, int next_state,
+	enum scst_exec_context pref_context)
+{
+
+	EXTRACHECKS_BUG_ON(cmd->pr_abort_counter != NULL);
+
+	scst_set_exec_time(cmd);
+
+	TRACE(TRACE_SCSI, "cmd %p, status %x, msg_status %x, host_status %x, "
+	      "driver_status %x, resp_data_len %d", cmd, cmd->status,
+	      cmd->msg_status, cmd->host_status, cmd->driver_status,
+	      cmd->resp_data_len);
+
+	if (next_state == SCST_CMD_STATE_DEFAULT)
+		next_state = SCST_CMD_STATE_PRE_DEV_DONE;
+
+#if defined(CONFIG_SCST_DEBUG)
+	if (next_state == SCST_CMD_STATE_PRE_DEV_DONE) {
+		if ((trace_flag & TRACE_RCV_TOP) && (cmd->sg != NULL)) {
+			int i, j;
+			struct scatterlist *sg = cmd->sg;
+			TRACE_RECV_TOP("Exec'd %d S/G(s) at %p sg[0].page at "
+				"%p", cmd->sg_cnt, sg, (void *)sg_page(&sg[0]));
+			for (i = 0, j = 0; i < cmd->sg_cnt; ++i, ++j) {
+				if (unlikely(sg_is_chain(&sg[j]))) {
+					sg = sg_chain_ptr(&sg[j]);
+					j = 0;
+				}
+				TRACE_BUFF_FLAG(TRACE_RCV_TOP,
+					"Exec'd sg", sg_virt(&sg[j]),
+					sg[j].length);
+			}
+		}
+	}
+#endif
+
+	cmd->state = next_state;
+
+#ifdef CONFIG_SCST_EXTRACHECKS
+	if ((next_state != SCST_CMD_STATE_PRE_DEV_DONE) &&
+	    (next_state != SCST_CMD_STATE_PRE_XMIT_RESP) &&
+	    (next_state != SCST_CMD_STATE_FINISHED) &&
+	    (next_state != SCST_CMD_STATE_FINISHED_INTERNAL)) {
+		PRINT_ERROR("%s() received invalid cmd state %d (opcode %d)",
+			__func__, next_state, cmd->cdb[0]);
+		scst_set_cmd_error(cmd,
+				   SCST_LOAD_SENSE(scst_sense_hardw_error));
+		scst_set_cmd_abnormal_done_state(cmd);
+	}
+#endif
+	pref_context = scst_optimize_post_exec_context(cmd, pref_context);
+	scst_process_redirect_cmd(cmd, pref_context, 0);
+	return;
+}
+
+static int scst_report_luns_local(struct scst_cmd *cmd)
+{
+	int res = SCST_EXEC_COMPLETED, rc;
+	int dev_cnt = 0;
+	int buffer_size;
+	int i;
+	struct scst_tgt_dev *tgt_dev = NULL;
+	uint8_t *buffer;
+	int offs, overflow = 0;
+
+	rc = scst_check_local_events(cmd);
+	if (unlikely(rc != 0))
+		goto out_done;
+
+	cmd->status = 0;
+	cmd->msg_status = 0;
+	cmd->host_status = DID_OK;
+	cmd->driver_status = 0;
+
+	if ((cmd->cdb[2] != 0) && (cmd->cdb[2] != 2)) {
+		PRINT_ERROR("Unsupported SELECT REPORT value %x in REPORT "
+			"LUNS command", cmd->cdb[2]);
+		goto out_err;
+	}
+
+	buffer_size = scst_get_buf_first(cmd, &buffer);
+	if (unlikely(buffer_size == 0))
+		goto out_compl;
+	else if (unlikely(buffer_size < 0))
+		goto out_hw_err;
+
+	if (buffer_size < 16)
+		goto out_put_err;
+
+	memset(buffer, 0, buffer_size);
+	offs = 8;
+
+	/*
+	 * cmd won't allow to suspend activities, so we can access
+	 * sess->sess_tgt_dev_list_hash without any additional protection.
+	 */
+	for (i = 0; i < TGT_DEV_HASH_SIZE; i++) {
+		struct list_head *sess_tgt_dev_list_head =
+			&cmd->sess->sess_tgt_dev_list_hash[i];
+		list_for_each_entry(tgt_dev, sess_tgt_dev_list_head,
+				sess_tgt_dev_list_entry) {
+			if (!overflow) {
+				if (offs >= buffer_size) {
+					scst_put_buf(cmd, buffer);
+					buffer_size = scst_get_buf_next(cmd,
+								       &buffer);
+					if (buffer_size > 0) {
+						memset(buffer, 0, buffer_size);
+						offs = 0;
+					} else {
+						overflow = 1;
+						goto inc_dev_cnt;
+					}
+				}
+				if ((buffer_size - offs) < 8) {
+					PRINT_ERROR("Buffer allocated for "
+						"REPORT LUNS command doesn't "
+						"allow to fit 8 byte entry "
+						"(buffer_size=%d)",
+						buffer_size);
+					goto out_put_hw_err;
+				}
+				if ((cmd->sess->acg->addr_method == SCST_LUN_ADDR_METHOD_FLAT) &&
+				    (tgt_dev->lun != 0)) {
+					buffer[offs] = (tgt_dev->lun >> 8) & 0x3f;
+					buffer[offs] = buffer[offs] | 0x40;
+					buffer[offs+1] = tgt_dev->lun & 0xff;
+				} else {
+					buffer[offs] = (tgt_dev->lun >> 8) & 0xff;
+					buffer[offs+1] = tgt_dev->lun & 0xff;
+				}
+				offs += 8;
+			}
+inc_dev_cnt:
+			dev_cnt++;
+		}
+	}
+	if (!overflow)
+		scst_put_buf(cmd, buffer);
+
+	/* Set the response header */
+	buffer_size = scst_get_buf_first(cmd, &buffer);
+	if (unlikely(buffer_size == 0))
+		goto out_compl;
+	else if (unlikely(buffer_size < 0))
+		goto out_hw_err;
+
+	dev_cnt *= 8;
+	buffer[0] = (dev_cnt >> 24) & 0xff;
+	buffer[1] = (dev_cnt >> 16) & 0xff;
+	buffer[2] = (dev_cnt >> 8) & 0xff;
+	buffer[3] = dev_cnt & 0xff;
+
+	scst_put_buf(cmd, buffer);
+
+	dev_cnt += 8;
+	if (dev_cnt < cmd->resp_data_len)
+		scst_set_resp_data_len(cmd, dev_cnt);
+
+out_compl:
+	cmd->completed = 1;
+
+	/* Clear left sense_reported_luns_data_changed UA, if any. */
+
+	/*
+	 * cmd won't allow to suspend activities, so we can access
+	 * sess->sess_tgt_dev_list_hash without any additional protection.
+	 */
+	for (i = 0; i < TGT_DEV_HASH_SIZE; i++) {
+		struct list_head *sess_tgt_dev_list_head =
+			&cmd->sess->sess_tgt_dev_list_hash[i];
+
+		list_for_each_entry(tgt_dev, sess_tgt_dev_list_head,
+				sess_tgt_dev_list_entry) {
+			struct scst_tgt_dev_UA *ua;
+
+			spin_lock_bh(&tgt_dev->tgt_dev_lock);
+			list_for_each_entry(ua, &tgt_dev->UA_list,
+						UA_list_entry) {
+				if (scst_analyze_sense(ua->UA_sense_buffer,
+						ua->UA_valid_sense_len,
+						SCST_SENSE_ALL_VALID,
+						SCST_LOAD_SENSE(scst_sense_reported_luns_data_changed))) {
+					TRACE_MGMT_DBG("Freeing not needed "
+						"REPORTED LUNS DATA CHANGED UA "
+						"%p", ua);
+					list_del(&ua->UA_list_entry);
+					mempool_free(ua, scst_ua_mempool);
+					break;
+				}
+			}
+			spin_unlock_bh(&tgt_dev->tgt_dev_lock);
+		}
+	}
+
+out_done:
+	/* Report the result */
+	cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT, SCST_CONTEXT_SAME);
+	return res;
+
+out_put_err:
+	scst_put_buf(cmd, buffer);
+
+out_err:
+	scst_set_cmd_error(cmd,
+		   SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+	goto out_compl;
+
+out_put_hw_err:
+	scst_put_buf(cmd, buffer);
+
+out_hw_err:
+	scst_set_cmd_error(cmd, SCST_LOAD_SENSE(scst_sense_hardw_error));
+	goto out_compl;
+}
+
+static int scst_request_sense_local(struct scst_cmd *cmd)
+{
+	int res = SCST_EXEC_COMPLETED, rc;
+	struct scst_tgt_dev *tgt_dev = cmd->tgt_dev;
+	uint8_t *buffer;
+	int buffer_size = 0, sl = 0;
+
+	rc = scst_check_local_events(cmd);
+	if (unlikely(rc != 0))
+		goto out_done;
+
+	cmd->status = 0;
+	cmd->msg_status = 0;
+	cmd->host_status = DID_OK;
+	cmd->driver_status = 0;
+
+	spin_lock_bh(&tgt_dev->tgt_dev_lock);
+
+	if (tgt_dev->tgt_dev_valid_sense_len == 0)
+		goto out_unlock_not_completed;
+
+	TRACE(TRACE_SCSI, "%s: Returning stored sense", cmd->op_name);
+
+	buffer_size = scst_get_buf_first(cmd, &buffer);
+	if (unlikely(buffer_size == 0))
+		goto out_unlock_compl;
+	else if (unlikely(buffer_size < 0))
+		goto out_unlock_hw_err;
+
+	memset(buffer, 0, buffer_size);
+
+	if (((tgt_dev->tgt_dev_sense[0] == 0x70) ||
+	     (tgt_dev->tgt_dev_sense[0] == 0x71)) && (cmd->cdb[1] & 1)) {
+		PRINT_WARNING("%s: Fixed format of the saved sense, but "
+			"descriptor format requested. Convertion will "
+			"truncated data", cmd->op_name);
+		PRINT_BUFFER("Original sense", tgt_dev->tgt_dev_sense,
+			tgt_dev->tgt_dev_valid_sense_len);
+
+		buffer_size = min(SCST_STANDARD_SENSE_LEN, buffer_size);
+		sl = scst_set_sense(buffer, buffer_size, true,
+			tgt_dev->tgt_dev_sense[2], tgt_dev->tgt_dev_sense[12],
+			tgt_dev->tgt_dev_sense[13]);
+	} else if (((tgt_dev->tgt_dev_sense[0] == 0x72) ||
+		    (tgt_dev->tgt_dev_sense[0] == 0x73)) && !(cmd->cdb[1] & 1)) {
+		PRINT_WARNING("%s: Descriptor format of the "
+			"saved sense, but fixed format requested. Convertion "
+			"will truncated data", cmd->op_name);
+		PRINT_BUFFER("Original sense", tgt_dev->tgt_dev_sense,
+			tgt_dev->tgt_dev_valid_sense_len);
+
+		buffer_size = min(SCST_STANDARD_SENSE_LEN, buffer_size);
+		sl = scst_set_sense(buffer, buffer_size, false,
+			tgt_dev->tgt_dev_sense[1], tgt_dev->tgt_dev_sense[2],
+			tgt_dev->tgt_dev_sense[3]);
+	} else {
+		if (buffer_size >= tgt_dev->tgt_dev_valid_sense_len)
+			sl = tgt_dev->tgt_dev_valid_sense_len;
+		else {
+			sl = buffer_size;
+			TRACE(TRACE_MINOR, "%s: Being returned sense truncated "
+				"to size %d (needed %d)", cmd->op_name,
+				buffer_size, tgt_dev->tgt_dev_valid_sense_len);
+		}
+		memcpy(buffer, tgt_dev->tgt_dev_sense, sl);
+	}
+
+	scst_put_buf(cmd, buffer);
+
+	tgt_dev->tgt_dev_valid_sense_len = 0;
+
+	spin_unlock_bh(&tgt_dev->tgt_dev_lock);
+
+	scst_set_resp_data_len(cmd, sl);
+
+out_compl:
+	cmd->completed = 1;
+
+out_done:
+	/* Report the result */
+	cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT, SCST_CONTEXT_SAME);
+
+out:
+	return res;
+
+out_unlock_hw_err:
+	spin_unlock_bh(&tgt_dev->tgt_dev_lock);
+	scst_set_cmd_error(cmd, SCST_LOAD_SENSE(scst_sense_hardw_error));
+	goto out_compl;
+
+out_unlock_not_completed:
+	spin_unlock_bh(&tgt_dev->tgt_dev_lock);
+	res = SCST_EXEC_NOT_COMPLETED;
+	goto out;
+
+out_unlock_compl:
+	spin_unlock_bh(&tgt_dev->tgt_dev_lock);
+	goto out_compl;
+}
+
+static int scst_pre_select(struct scst_cmd *cmd)
+{
+	int res = SCST_EXEC_NOT_COMPLETED;
+
+	scst_block_dev_cmd(cmd, 1);
+
+	/* Check for local events will be done when cmd will be executed */
+	return res;
+}
+
+static int scst_reserve_local(struct scst_cmd *cmd)
+{
+	int res = SCST_EXEC_NOT_COMPLETED, rc;
+	struct scst_device *dev;
+	struct scst_tgt_dev *tgt_dev_tmp;
+
+	if ((cmd->cdb[0] == RESERVE_10) && (cmd->cdb[2] & SCST_RES_3RDPTY)) {
+		PRINT_ERROR("RESERVE_10: 3rdPty RESERVE not implemented "
+		     "(lun=%lld)", (long long unsigned int)cmd->lun);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out_done;
+	}
+
+	dev = cmd->dev;
+
+	/*
+	 * There's no need to block this device, even for
+	 * SCST_CONTR_MODE_ONE_TASK_SET, or anyhow else protect reservations
+	 * changes, because:
+	 *
+	 * 1. The reservation changes are (rather) atomic, i.e., in contrast
+	 *    to persistent reservations, don't have any invalid intermediate
+	 *    states during being changed.
+	 *
+	 * 2. It's a duty of initiators to ensure order of regular commands
+	 *    around the reservation command either by ORDERED attribute, or by
+	 *    queue draining, or etc. For case of SCST_CONTR_MODE_ONE_TASK_SET
+	 *    there are no target drivers which can ensure even for ORDERED
+	 *    comamnds order of their delivery, so, because initiators know
+	 *    it, also there's no point to do any extra protection actions.
+	 */
+
+	rc = scst_check_local_events(cmd);
+	if (unlikely(rc != 0))
+		goto out_done;
+
+	if (!list_empty(&dev->dev_registrants_list)) {
+		if (scst_pr_crh_case(cmd))
+			goto out_completed;
+		else {
+			scst_set_cmd_error_status(cmd,
+				SAM_STAT_RESERVATION_CONFLICT);
+			goto out_done;
+		}
+	}
+
+	spin_lock_bh(&dev->dev_lock);
+
+	if (test_bit(SCST_TGT_DEV_RESERVED, &cmd->tgt_dev->tgt_dev_flags)) {
+		spin_unlock_bh(&dev->dev_lock);
+		scst_set_cmd_error_status(cmd, SAM_STAT_RESERVATION_CONFLICT);
+		goto out_done;
+	}
+
+	list_for_each_entry(tgt_dev_tmp, &dev->dev_tgt_dev_list,
+			    dev_tgt_dev_list_entry) {
+		if (cmd->tgt_dev != tgt_dev_tmp)
+			set_bit(SCST_TGT_DEV_RESERVED,
+				&tgt_dev_tmp->tgt_dev_flags);
+	}
+	dev->dev_reserved = 1;
+
+	spin_unlock_bh(&dev->dev_lock);
+
+out:
+	return res;
+
+out_completed:
+	cmd->completed = 1;
+
+out_done:
+	/* Report the result */
+	cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT, SCST_CONTEXT_SAME);
+	res = SCST_EXEC_COMPLETED;
+	goto out;
+}
+
+static int scst_release_local(struct scst_cmd *cmd)
+{
+	int res = SCST_EXEC_NOT_COMPLETED, rc;
+	struct scst_tgt_dev *tgt_dev_tmp;
+	struct scst_device *dev;
+
+	dev = cmd->dev;
+
+	/*
+	 * See comment in scst_reserve_local() why no dev blocking or any
+	 * other protection is needed here.
+	 */
+
+	rc = scst_check_local_events(cmd);
+	if (unlikely(rc != 0))
+		goto out_done;
+
+	if (!list_empty(&dev->dev_registrants_list)) {
+		if (scst_pr_crh_case(cmd))
+			goto out_completed;
+		else {
+			scst_set_cmd_error_status(cmd,
+				SAM_STAT_RESERVATION_CONFLICT);
+			goto out_done;
+		}
+	}
+
+	spin_lock_bh(&dev->dev_lock);
+
+	/*
+	 * The device could be RELEASED behind us, if RESERVING session
+	 * is closed (see scst_free_tgt_dev()), but this actually doesn't
+	 * matter, so use lock and no retest for DEV_RESERVED bits again
+	 */
+	if (test_bit(SCST_TGT_DEV_RESERVED, &cmd->tgt_dev->tgt_dev_flags)) {
+		res = SCST_EXEC_COMPLETED;
+		cmd->status = 0;
+		cmd->msg_status = 0;
+		cmd->host_status = DID_OK;
+		cmd->driver_status = 0;
+		cmd->completed = 1;
+	} else {
+		list_for_each_entry(tgt_dev_tmp,
+				    &dev->dev_tgt_dev_list,
+				    dev_tgt_dev_list_entry) {
+			clear_bit(SCST_TGT_DEV_RESERVED,
+				&tgt_dev_tmp->tgt_dev_flags);
+		}
+		dev->dev_reserved = 0;
+	}
+
+	spin_unlock_bh(&dev->dev_lock);
+
+	if (res == SCST_EXEC_COMPLETED)
+		goto out_done;
+
+out:
+	return res;
+
+out_completed:
+	cmd->completed = 1;
+
+out_done:
+	res = SCST_EXEC_COMPLETED;
+	/* Report the result */
+	cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT, SCST_CONTEXT_SAME);
+	goto out;
+}
+
+/**
+ * scst_check_local_events() - check if there are any local SCSI events
+ *
+ * Description:
+ *    Checks if the command can be executed or there are local events,
+ *    like reservatons, pending UAs, etc. Returns < 0 if command must be
+ *    aborted, > 0 if there is an event and command should be immediately
+ *    completed, or 0 otherwise.
+ *
+ * !! Dev handlers implementing exec() callback must call this function there
+ * !! just before the actual command's execution!
+ *
+ *    On call no locks, no IRQ or IRQ-disabled context allowed.
+ */
+static int scst_persistent_reserve_in_local(struct scst_cmd *cmd)
+{
+	int rc;
+	struct scst_device *dev;
+	struct scst_tgt_dev *tgt_dev;
+	struct scst_session *session;
+	int action;
+	uint8_t *buffer;
+	int buffer_size;
+
+	EXTRACHECKS_BUG_ON(scst_cmd_atomic(cmd));
+
+	dev = cmd->dev;
+	tgt_dev = cmd->tgt_dev;
+	session = cmd->sess;
+
+	rc = scst_check_local_events(cmd);
+	if (unlikely(rc != 0))
+		goto out_done;
+
+	if (unlikely(dev->not_pr_supporting_tgt_devs_num != 0)) {
+		PRINT_WARNING("Persistent Reservation command %x refused for "
+			"device %s, because the device has not supporting PR "
+			"transports connected", cmd->cdb[0], dev->virt_name);
+		scst_set_cmd_error(cmd,
+				   SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+		goto out_done;
+	}
+
+	if (dev->dev_reserved) {
+		TRACE_PR("PR command rejected, because device %s holds regular "
+			"reservation", dev->virt_name);
+		scst_set_cmd_error_status(cmd, SAM_STAT_RESERVATION_CONFLICT);
+		goto out_done;
+	}
+
+	if (dev->scsi_dev != NULL) {
+		PRINT_WARNING("PR commands for pass-through devices not "
+			"supported (device %s)", dev->virt_name);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+		goto out_done;
+	}
+
+	buffer_size = scst_get_full_buf(cmd, &buffer);
+	if (unlikely(buffer_size <= 0)) {
+		if (buffer_size < 0)
+			scst_set_busy(cmd);
+		goto out_done;
+	}
+
+	scst_pr_write_lock(dev);
+
+	/* We can be aborted by another PR command while waiting for the lock */
+	if (unlikely(test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags))) {
+		TRACE_MGMT_DBG("ABORTED set, aborting cmd %p", cmd);
+		goto out_unlock;
+	}
+
+	action = cmd->cdb[1] & 0x1f;
+
+	TRACE(TRACE_SCSI, "PR action %x for '%s' (LUN %llx) from '%s'", action,
+	    dev->virt_name, tgt_dev->lun, session->initiator_name);
+
+	switch (action) {
+	case PR_READ_KEYS:
+		scst_pr_read_keys(cmd, buffer, buffer_size);
+		break;
+	case PR_READ_RESERVATION:
+		scst_pr_read_reservation(cmd, buffer, buffer_size);
+		break;
+	case PR_REPORT_CAPS:
+		scst_pr_report_caps(cmd, buffer, buffer_size);
+		break;
+	case PR_READ_FULL_STATUS:
+		scst_pr_read_full_status(cmd, buffer, buffer_size);
+		break;
+	default:
+		PRINT_ERROR("Unsupported action %x", action);
+		scst_pr_write_unlock(dev);
+		goto out_err;
+	}
+
+out_complete:
+	cmd->completed = 1;
+
+out_unlock:
+	scst_pr_write_unlock(dev);
+
+	scst_put_full_buf(cmd, buffer);
+
+out_done:
+	cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT, SCST_CONTEXT_SAME);
+	return SCST_EXEC_COMPLETED;
+
+out_err:
+	scst_set_cmd_error(cmd,
+		   SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+	goto out_complete;
+}
+
+/* No locks, no IRQ or IRQ-disabled context allowed */
+static int scst_persistent_reserve_out_local(struct scst_cmd *cmd)
+{
+	int res = SCST_EXEC_COMPLETED;
+	int rc;
+	struct scst_device *dev;
+	struct scst_tgt_dev *tgt_dev;
+	struct scst_session *session;
+	int action;
+	uint8_t *buffer;
+	int buffer_size;
+	bool aborted = false;
+
+	EXTRACHECKS_BUG_ON(scst_cmd_atomic(cmd));
+
+	dev = cmd->dev;
+	tgt_dev = cmd->tgt_dev;
+	session = cmd->sess;
+
+	rc = scst_check_local_events(cmd);
+	if (unlikely(rc != 0))
+		goto out_done;
+
+	if (unlikely(dev->not_pr_supporting_tgt_devs_num != 0)) {
+		PRINT_WARNING("Persistent Reservation command %x refused for "
+			"device %s, because the device has not supporting PR "
+			"transports connected", cmd->cdb[0], dev->virt_name);
+		scst_set_cmd_error(cmd,
+				   SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+		goto out_done;
+	}
+
+	action = cmd->cdb[1] & 0x1f;
+
+	TRACE(TRACE_SCSI, "PR action %x for '%s' (LUN %llx) from '%s'", action,
+	    dev->virt_name, tgt_dev->lun, session->initiator_name);
+
+	if (dev->dev_reserved) {
+		TRACE_PR("PR command rejected, because device %s holds regular "
+			"reservation", dev->virt_name);
+		scst_set_cmd_error_status(cmd, SAM_STAT_RESERVATION_CONFLICT);
+		goto out_done;
+	}
+
+	/*
+	 * Check if tgt_dev already registered. Also by this check we make
+	 * sure that table "PERSISTENT RESERVE OUT service actions that are
+	 * allowed in the presence of various reservations" is honored.
+	 * REGISTER AND MOVE and RESERVE will be additionally checked for
+	 * conflicts later.
+	 */
+	if ((action != PR_REGISTER) && (action != PR_REGISTER_AND_IGNORE) &&
+	    (tgt_dev->registrant == NULL)) {
+		TRACE_PR("'%s' not registered", cmd->sess->initiator_name);
+		scst_set_cmd_error_status(cmd, SAM_STAT_RESERVATION_CONFLICT);
+		goto out_done;
+	}
+
+	buffer_size = scst_get_full_buf(cmd, &buffer);
+	if (unlikely(buffer_size <= 0)) {
+		if (buffer_size < 0)
+			scst_set_busy(cmd);
+		goto out_done;
+	}
+
+	/* Check scope */
+	if ((action != PR_REGISTER) && (action != PR_REGISTER_AND_IGNORE) &&
+	    (action != PR_CLEAR) && ((cmd->cdb[2] & 0x0f) >> 4) != SCOPE_LU) {
+		TRACE_PR("Scope must be SCOPE_LU for action %x", action);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out_put_full_buf;
+	}
+
+	/* Check SPEC_I_PT (PR_REGISTER_AND_MOVE has another format) */
+	if ((action != PR_REGISTER) && (action != PR_REGISTER_AND_MOVE) &&
+	    ((buffer[20] >> 3) & 0x01)) {
+		TRACE_PR("SPEC_I_PT must be zero for action %x", action);
+		scst_set_cmd_error(cmd, SCST_LOAD_SENSE(
+					scst_sense_invalid_field_in_cdb));
+		goto out_put_full_buf;
+	}
+
+	/* Check ALL_TG_PT (PR_REGISTER_AND_MOVE has another format) */
+	if ((action != PR_REGISTER) && (action != PR_REGISTER_AND_IGNORE) &&
+	    (action != PR_REGISTER_AND_MOVE) && ((buffer[20] >> 2) & 0x01)) {
+		TRACE_PR("ALL_TG_PT must be zero for action %x", action);
+		scst_set_cmd_error(cmd, SCST_LOAD_SENSE(
+					scst_sense_invalid_field_in_cdb));
+		goto out_put_full_buf;
+	}
+
+	scst_pr_write_lock(dev);
+
+	/* We can be aborted by another PR command while waiting for the lock */
+	aborted = test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags);
+	if (unlikely(aborted)) {
+		TRACE_MGMT_DBG("ABORTED set, aborting cmd %p", cmd);
+		goto out_unlock;
+	}
+
+	switch (action) {
+	case PR_REGISTER:
+		scst_pr_register(cmd, buffer, buffer_size);
+		break;
+	case PR_RESERVE:
+		scst_pr_reserve(cmd, buffer, buffer_size);
+		break;
+	case PR_RELEASE:
+		scst_pr_release(cmd, buffer, buffer_size);
+		break;
+	case PR_CLEAR:
+		scst_pr_clear(cmd, buffer, buffer_size);
+		break;
+	case PR_PREEMPT:
+		scst_pr_preempt(cmd, buffer, buffer_size);
+		break;
+	case PR_PREEMPT_AND_ABORT:
+		scst_pr_preempt_and_abort(cmd, buffer, buffer_size);
+		break;
+	case PR_REGISTER_AND_IGNORE:
+		scst_pr_register_and_ignore(cmd, buffer, buffer_size);
+		break;
+	case PR_REGISTER_AND_MOVE:
+		scst_pr_register_and_move(cmd, buffer, buffer_size);
+		break;
+	default:
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out_unlock;
+	}
+
+	if (cmd->status == SAM_STAT_GOOD)
+		scst_pr_sync_device_file(tgt_dev, cmd);
+
+	if ((dev->handler->pr_cmds_notifications) &&
+	    (cmd->status == SAM_STAT_GOOD)) /* sync file may change status */
+		res = SCST_EXEC_NOT_COMPLETED;
+
+out_unlock:
+	scst_pr_write_unlock(dev);
+
+out_put_full_buf:
+	scst_put_full_buf(cmd, buffer);
+
+out_done:
+	if (SCST_EXEC_COMPLETED == res) {
+		if (!aborted)
+			cmd->completed = 1;
+		cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT,
+				SCST_CONTEXT_SAME);
+	}
+	return res;
+}
+
+/* No locks, no IRQ or IRQ-disabled context allowed */
+int scst_check_local_events(struct scst_cmd *cmd)
+{
+	int res, rc;
+	struct scst_tgt_dev *tgt_dev = cmd->tgt_dev;
+	struct scst_device *dev = cmd->dev;
+
+	/*
+	 * There's no race here, because we need to trace commands sent
+	 * *after* dev_double_ua_possible flag was set.
+	 */
+	if (unlikely(dev->dev_double_ua_possible))
+		cmd->double_ua_possible = 1;
+
+	/* Reserve check before Unit Attention */
+	if (unlikely(test_bit(SCST_TGT_DEV_RESERVED,
+			      &tgt_dev->tgt_dev_flags))) {
+		if ((cmd->op_flags & SCST_REG_RESERVE_ALLOWED) == 0) {
+			scst_set_cmd_error_status(cmd,
+				SAM_STAT_RESERVATION_CONFLICT);
+			goto out_complete;
+		}
+	}
+
+	if (dev->pr_is_set) {
+		if (unlikely(!scst_pr_is_cmd_allowed(cmd))) {
+			scst_set_cmd_error_status(cmd,
+				SAM_STAT_RESERVATION_CONFLICT);
+			goto out_complete;
+		}
+	}
+
+	/*
+	 * Let's check for ABORTED after scst_pr_is_cmd_allowed(), because
+	 * we might sleep for a while there.
+	 */
+	if (unlikely(test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags))) {
+		TRACE_MGMT_DBG("ABORTED set, aborting cmd %p", cmd);
+		goto out_uncomplete;
+	}
+
+	/* If we had internal bus reset, set the command error unit attention */
+	if ((dev->scsi_dev != NULL) &&
+	    unlikely(dev->scsi_dev->was_reset)) {
+		if (scst_is_ua_command(cmd)) {
+			int done = 0;
+			/*
+			 * Prevent more than 1 cmd to be triggered by
+			 * was_reset.
+			 */
+			spin_lock_bh(&dev->dev_lock);
+			if (dev->scsi_dev->was_reset) {
+				TRACE(TRACE_MGMT, "was_reset is %d", 1);
+				scst_set_cmd_error(cmd,
+					  SCST_LOAD_SENSE(scst_sense_reset_UA));
+				/*
+				 * It looks like it is safe to clear was_reset
+				 * here.
+				 */
+				dev->scsi_dev->was_reset = 0;
+				done = 1;
+			}
+			spin_unlock_bh(&dev->dev_lock);
+
+			if (done)
+				goto out_complete;
+		}
+	}
+
+	if (unlikely(test_bit(SCST_TGT_DEV_UA_PENDING,
+			&cmd->tgt_dev->tgt_dev_flags))) {
+		if (scst_is_ua_command(cmd)) {
+			rc = scst_set_pending_UA(cmd);
+			if (rc == 0)
+				goto out_complete;
+		}
+	}
+
+	res = 0;
+
+out:
+	return res;
+
+out_complete:
+	res = 1;
+	BUG_ON(!cmd->completed);
+	goto out;
+
+out_uncomplete:
+	res = -1;
+	goto out;
+}
+EXPORT_SYMBOL_GPL(scst_check_local_events);
+
+/* No locks */
+void scst_inc_expected_sn(struct scst_tgt_dev *tgt_dev, atomic_t *slot)
+{
+	if (slot == NULL)
+		goto inc;
+
+	/* Optimized for lockless fast path */
+
+	TRACE_SN("Slot %zd, *cur_sn_slot %d", slot - tgt_dev->sn_slots,
+		atomic_read(slot));
+
+	if (!atomic_dec_and_test(slot))
+		goto out;
+
+	TRACE_SN("Slot is 0 (num_free_sn_slots=%d)",
+		tgt_dev->num_free_sn_slots);
+	if (tgt_dev->num_free_sn_slots < (int)ARRAY_SIZE(tgt_dev->sn_slots)-1) {
+		spin_lock_irq(&tgt_dev->sn_lock);
+		if (likely(tgt_dev->num_free_sn_slots < (int)ARRAY_SIZE(tgt_dev->sn_slots)-1)) {
+			if (tgt_dev->num_free_sn_slots < 0)
+				tgt_dev->cur_sn_slot = slot;
+			/*
+			 * To be in-sync with SIMPLE case in scst_cmd_set_sn()
+			 */
+			smp_mb();
+			tgt_dev->num_free_sn_slots++;
+			TRACE_SN("Incremented num_free_sn_slots (%d)",
+				tgt_dev->num_free_sn_slots);
+
+		}
+		spin_unlock_irq(&tgt_dev->sn_lock);
+	}
+
+inc:
+	/*
+	 * No protection of expected_sn is needed, because only one thread
+	 * at time can be here (serialized by sn). Also it is supposed that
+	 * there could not be half-incremented halves.
+	 */
+	tgt_dev->expected_sn++;
+	/*
+	 * Write must be before def_cmd_count read to be in sync. with
+	 * scst_post_exec_sn(). See comment in scst_send_for_exec().
+	 */
+	smp_mb();
+	TRACE_SN("Next expected_sn: %d", tgt_dev->expected_sn);
+
+out:
+	return;
+}
+
+/* No locks */
+static struct scst_cmd *scst_post_exec_sn(struct scst_cmd *cmd,
+	bool make_active)
+{
+	/* For HQ commands SN is not set */
+	bool inc_expected_sn = !cmd->inc_expected_sn_on_done &&
+			       cmd->sn_set && !cmd->retry;
+	struct scst_tgt_dev *tgt_dev = cmd->tgt_dev;
+	struct scst_cmd *res;
+
+	if (inc_expected_sn)
+		scst_inc_expected_sn(tgt_dev, cmd->sn_slot);
+
+	if (make_active) {
+		scst_make_deferred_commands_active(tgt_dev);
+		res = NULL;
+	} else
+		res = scst_check_deferred_commands(tgt_dev);
+	return res;
+}
+
+/* cmd must be additionally referenced to not die inside */
+static int scst_do_real_exec(struct scst_cmd *cmd)
+{
+	int res = SCST_EXEC_NOT_COMPLETED;
+	int rc;
+	struct scst_device *dev = cmd->dev;
+	struct scst_dev_type *handler = dev->handler;
+	struct io_context *old_ctx = NULL;
+	bool ctx_changed = false;
+
+	ctx_changed = scst_set_io_context(cmd, &old_ctx);
+
+	cmd->state = SCST_CMD_STATE_REAL_EXECUTING;
+
+	if (handler->exec) {
+		TRACE_DBG("Calling dev handler %s exec(%p)",
+		      handler->name, cmd);
+		TRACE_BUFF_FLAG(TRACE_SND_TOP, "Execing: ", cmd->cdb,
+			cmd->cdb_len);
+		scst_set_cur_start(cmd);
+		res = handler->exec(cmd);
+		TRACE_DBG("Dev handler %s exec() returned %d",
+		      handler->name, res);
+
+		if (res == SCST_EXEC_COMPLETED)
+			goto out_complete;
+
+		scst_set_exec_time(cmd);
+
+		BUG_ON(res != SCST_EXEC_NOT_COMPLETED);
+	}
+
+	TRACE_DBG("Sending cmd %p to SCSI mid-level", cmd);
+
+	if (unlikely(dev->scsi_dev == NULL)) {
+		PRINT_ERROR("Command for virtual device must be "
+			"processed by device handler (LUN %lld)!",
+			(long long unsigned int)cmd->lun);
+		goto out_error;
+	}
+
+	res = scst_check_local_events(cmd);
+	if (unlikely(res != 0))
+		goto out_done;
+
+	scst_set_cur_start(cmd);
+
+	rc = scst_scsi_exec_async(cmd, cmd, scst_pass_through_cmd_done);
+	if (unlikely(rc != 0)) {
+		PRINT_ERROR("scst pass-through exec failed: %x", rc);
+		goto out_error;
+	}
+
+out_complete:
+	res = SCST_EXEC_COMPLETED;
+
+	if (ctx_changed)
+		scst_reset_io_context(cmd->tgt_dev, old_ctx);
+	return res;
+
+out_error:
+	scst_set_cmd_error(cmd, SCST_LOAD_SENSE(scst_sense_hardw_error));
+	goto out_done;
+
+out_done:
+	res = SCST_EXEC_COMPLETED;
+	/* Report the result */
+	cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT, SCST_CONTEXT_SAME);
+	goto out_complete;
+}
+
+static inline int scst_real_exec(struct scst_cmd *cmd)
+{
+	int res;
+
+	BUILD_BUG_ON(SCST_CMD_STATE_RES_CONT_SAME != SCST_EXEC_NOT_COMPLETED);
+	BUILD_BUG_ON(SCST_CMD_STATE_RES_CONT_NEXT != SCST_EXEC_COMPLETED);
+
+	__scst_cmd_get(cmd);
+
+	res = scst_do_real_exec(cmd);
+
+	if (likely(res == SCST_EXEC_COMPLETED)) {
+		scst_post_exec_sn(cmd, true);
+		if (cmd->dev->scsi_dev != NULL)
+			generic_unplug_device(
+				cmd->dev->scsi_dev->request_queue);
+	} else
+		BUG();
+
+	__scst_cmd_put(cmd);
+
+	/* SCST_EXEC_* match SCST_CMD_STATE_RES_* */
+	return res;
+}
+
+static int scst_do_local_exec(struct scst_cmd *cmd)
+{
+	int res;
+	struct scst_tgt_dev *tgt_dev = cmd->tgt_dev;
+
+	/* Check READ_ONLY device status */
+	if ((cmd->op_flags & SCST_WRITE_MEDIUM) &&
+	    (tgt_dev->acg_dev->rd_only || cmd->dev->swp ||
+	     cmd->dev->rd_only)) {
+		PRINT_WARNING("Attempt of write access to read-only device: "
+			"initiator %s, LUN %lld, op %x",
+			cmd->sess->initiator_name, cmd->lun, cmd->cdb[0]);
+		scst_set_cmd_error(cmd,
+			   SCST_LOAD_SENSE(scst_sense_data_protect));
+		goto out_done;
+	}
+
+	if (!scst_is_cmd_local(cmd)) {
+		res = SCST_EXEC_NOT_COMPLETED;
+		goto out;
+	}
+
+	switch (cmd->cdb[0]) {
+	case MODE_SELECT:
+	case MODE_SELECT_10:
+	case LOG_SELECT:
+		res = scst_pre_select(cmd);
+		break;
+	case RESERVE:
+	case RESERVE_10:
+		res = scst_reserve_local(cmd);
+		break;
+	case RELEASE:
+	case RELEASE_10:
+		res = scst_release_local(cmd);
+		break;
+	case PERSISTENT_RESERVE_IN:
+		res = scst_persistent_reserve_in_local(cmd);
+		break;
+	case PERSISTENT_RESERVE_OUT:
+		res = scst_persistent_reserve_out_local(cmd);
+		break;
+	case REPORT_LUNS:
+		res = scst_report_luns_local(cmd);
+		break;
+	case REQUEST_SENSE:
+		res = scst_request_sense_local(cmd);
+		break;
+	default:
+		res = SCST_EXEC_NOT_COMPLETED;
+		break;
+	}
+
+out:
+	return res;
+
+out_done:
+	/* Report the result */
+	cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT, SCST_CONTEXT_SAME);
+	res = SCST_EXEC_COMPLETED;
+	goto out;
+}
+
+static int scst_local_exec(struct scst_cmd *cmd)
+{
+	int res;
+
+	BUILD_BUG_ON(SCST_CMD_STATE_RES_CONT_SAME != SCST_EXEC_NOT_COMPLETED);
+	BUILD_BUG_ON(SCST_CMD_STATE_RES_CONT_NEXT != SCST_EXEC_COMPLETED);
+
+	__scst_cmd_get(cmd);
+
+	res = scst_do_local_exec(cmd);
+	if (likely(res == SCST_EXEC_NOT_COMPLETED))
+		cmd->state = SCST_CMD_STATE_REAL_EXEC;
+	else if (res == SCST_EXEC_COMPLETED)
+		scst_post_exec_sn(cmd, true);
+	else
+		BUG();
+
+	__scst_cmd_put(cmd);
+
+	/* SCST_EXEC_* match SCST_CMD_STATE_RES_* */
+	return res;
+}
+
+static int scst_exec(struct scst_cmd **active_cmd)
+{
+	struct scst_cmd *cmd = *active_cmd;
+	struct scst_cmd *ref_cmd;
+	struct scst_device *dev = cmd->dev;
+	int res = SCST_CMD_STATE_RES_CONT_NEXT, count;
+
+	if (unlikely(scst_inc_on_dev_cmd(cmd) != 0))
+		goto out;
+
+	/* To protect tgt_dev */
+	ref_cmd = cmd;
+	__scst_cmd_get(ref_cmd);
+
+	count = 0;
+	while (1) {
+		int rc;
+
+		cmd->sent_for_exec = 1;
+		/*
+		 * To sync with scst_abort_cmd(). The above assignment must
+		 * be before SCST_CMD_ABORTED test, done later in
+		 * scst_check_local_events(). It's far from here, so the order
+		 * is virtually guaranteed, but let's have it just in case.
+		 */
+		smp_mb();
+
+		cmd->scst_cmd_done = scst_cmd_done_local;
+		cmd->state = SCST_CMD_STATE_LOCAL_EXEC;
+
+		rc = scst_do_local_exec(cmd);
+		if (likely(rc == SCST_EXEC_NOT_COMPLETED))
+			/* Nothing to do */;
+		else {
+			BUG_ON(rc != SCST_EXEC_COMPLETED);
+			goto done;
+		}
+
+		cmd->state = SCST_CMD_STATE_REAL_EXEC;
+
+		rc = scst_do_real_exec(cmd);
+		BUG_ON(rc != SCST_EXEC_COMPLETED);
+
+done:
+		count++;
+
+		cmd = scst_post_exec_sn(cmd, false);
+		if (cmd == NULL)
+			break;
+
+		if (unlikely(scst_inc_on_dev_cmd(cmd) != 0))
+			break;
+
+		__scst_cmd_put(ref_cmd);
+		ref_cmd = cmd;
+		__scst_cmd_get(ref_cmd);
+	}
+
+	*active_cmd = cmd;
+
+	if (count == 0)
+		goto out_put;
+
+	if (dev->scsi_dev != NULL)
+		generic_unplug_device(dev->scsi_dev->request_queue);
+
+out_put:
+	__scst_cmd_put(ref_cmd);
+	/* !! At this point sess, dev and tgt_dev can be already freed !! */
+
+out:
+	return res;
+}
+
+static int scst_send_for_exec(struct scst_cmd **active_cmd)
+{
+	int res;
+	struct scst_cmd *cmd = *active_cmd;
+	struct scst_tgt_dev *tgt_dev = cmd->tgt_dev;
+	typeof(tgt_dev->expected_sn) expected_sn;
+
+	if (unlikely(cmd->internal))
+		goto exec;
+
+	if (unlikely(cmd->queue_type == SCST_CMD_QUEUE_HEAD_OF_QUEUE))
+		goto exec;
+
+	BUG_ON(!cmd->sn_set);
+
+	expected_sn = tgt_dev->expected_sn;
+	/* Optimized for lockless fast path */
+	if ((cmd->sn != expected_sn) || (tgt_dev->hq_cmd_count > 0)) {
+		spin_lock_irq(&tgt_dev->sn_lock);
+
+		tgt_dev->def_cmd_count++;
+		/*
+		 * Memory barrier is needed here to implement lockless fast
+		 * path. We need the exact order of read and write between
+		 * def_cmd_count and expected_sn. Otherwise, we can miss case,
+		 * when expected_sn was changed to be equal to cmd->sn while
+		 * we are queuing cmd the deferred list after the expected_sn
+		 * below. It will lead to a forever stuck command. But with
+		 * the barrier in such case __scst_check_deferred_commands()
+		 * will be called and it will take sn_lock, so we will be
+		 * synchronized.
+		 */
+		smp_mb();
+
+		expected_sn = tgt_dev->expected_sn;
+		if ((cmd->sn != expected_sn) || (tgt_dev->hq_cmd_count > 0)) {
+			if (unlikely(test_bit(SCST_CMD_ABORTED,
+					      &cmd->cmd_flags))) {
+				/* Necessary to allow aborting out of sn cmds */
+				TRACE_MGMT_DBG("Aborting out of sn cmd %p "
+					"(tag %llu, sn %u)", cmd,
+					(long long unsigned)cmd->tag, cmd->sn);
+				tgt_dev->def_cmd_count--;
+				scst_set_cmd_abnormal_done_state(cmd);
+				res = SCST_CMD_STATE_RES_CONT_SAME;
+			} else {
+				TRACE_SN("Deferring cmd %p (sn=%d, set %d, "
+					"expected_sn=%d)", cmd, cmd->sn,
+					cmd->sn_set, expected_sn);
+				list_add_tail(&cmd->sn_cmd_list_entry,
+					      &tgt_dev->deferred_cmd_list);
+				res = SCST_CMD_STATE_RES_CONT_NEXT;
+			}
+			spin_unlock_irq(&tgt_dev->sn_lock);
+			goto out;
+		} else {
+			TRACE_SN("Somebody incremented expected_sn %d, "
+				"continuing", expected_sn);
+			tgt_dev->def_cmd_count--;
+			spin_unlock_irq(&tgt_dev->sn_lock);
+		}
+	}
+
+exec:
+	res = scst_exec(active_cmd);
+
+out:
+	return res;
+}
+
+/* No locks supposed to be held */
+static int scst_check_sense(struct scst_cmd *cmd)
+{
+	int res = 0;
+	struct scst_device *dev = cmd->dev;
+
+	if (unlikely(cmd->ua_ignore))
+		goto out;
+
+	/* If we had internal bus reset behind us, set the command error UA */
+	if ((dev->scsi_dev != NULL) &&
+	    unlikely(cmd->host_status == DID_RESET) &&
+	    scst_is_ua_command(cmd)) {
+		TRACE(TRACE_MGMT, "DID_RESET: was_reset=%d host_status=%x",
+		      dev->scsi_dev->was_reset, cmd->host_status);
+		scst_set_cmd_error(cmd, SCST_LOAD_SENSE(scst_sense_reset_UA));
+		/* It looks like it is safe to clear was_reset here */
+		dev->scsi_dev->was_reset = 0;
+	}
+
+	if (unlikely(cmd->status == SAM_STAT_CHECK_CONDITION) &&
+	    SCST_SENSE_VALID(cmd->sense)) {
+		PRINT_BUFF_FLAG(TRACE_SCSI, "Sense", cmd->sense,
+			cmd->sense_valid_len);
+
+		/* Check Unit Attention Sense Key */
+		if (scst_is_ua_sense(cmd->sense, cmd->sense_valid_len)) {
+			if (scst_analyze_sense(cmd->sense, cmd->sense_valid_len,
+					SCST_SENSE_ASC_VALID,
+					0, SCST_SENSE_ASC_UA_RESET, 0)) {
+				if (cmd->double_ua_possible) {
+					TRACE_MGMT_DBG("Double UA "
+						"detected for device %p", dev);
+					TRACE_MGMT_DBG("Retrying cmd"
+						" %p (tag %llu)", cmd,
+						(long long unsigned)cmd->tag);
+
+					cmd->status = 0;
+					cmd->msg_status = 0;
+					cmd->host_status = DID_OK;
+					cmd->driver_status = 0;
+					cmd->completed = 0;
+
+					mempool_free(cmd->sense,
+						     scst_sense_mempool);
+					cmd->sense = NULL;
+
+					scst_check_restore_sg_buff(cmd);
+
+					BUG_ON(cmd->dbl_ua_orig_resp_data_len < 0);
+					cmd->data_direction =
+						cmd->dbl_ua_orig_data_direction;
+					cmd->resp_data_len =
+						cmd->dbl_ua_orig_resp_data_len;
+
+					cmd->state = SCST_CMD_STATE_REAL_EXEC;
+					cmd->retry = 1;
+					res = 1;
+					goto out;
+				}
+			}
+			scst_dev_check_set_UA(dev, cmd,	cmd->sense,
+				cmd->sense_valid_len);
+		}
+	}
+
+	if (unlikely(cmd->double_ua_possible)) {
+		if (scst_is_ua_command(cmd)) {
+			TRACE_MGMT_DBG("Clearing dbl_ua_possible flag (dev %p, "
+				"cmd %p)", dev, cmd);
+			/*
+			 * Lock used to protect other flags in the bitfield
+			 * (just in case, actually). Those flags can't be
+			 * changed in parallel, because the device is
+			 * serialized.
+			 */
+			spin_lock_bh(&dev->dev_lock);
+			dev->dev_double_ua_possible = 0;
+			spin_unlock_bh(&dev->dev_lock);
+		}
+	}
+
+out:
+	return res;
+}
+
+static int scst_check_auto_sense(struct scst_cmd *cmd)
+{
+	int res = 0;
+
+	if (unlikely(cmd->status == SAM_STAT_CHECK_CONDITION) &&
+	    (!SCST_SENSE_VALID(cmd->sense) ||
+	     SCST_NO_SENSE(cmd->sense))) {
+		TRACE(TRACE_SCSI|TRACE_MINOR_AND_MGMT_DBG, "CHECK_CONDITION, "
+			"but no sense: cmd->status=%x, cmd->msg_status=%x, "
+		      "cmd->host_status=%x, cmd->driver_status=%x (cmd %p)",
+		      cmd->status, cmd->msg_status, cmd->host_status,
+		      cmd->driver_status, cmd);
+		res = 1;
+	} else if (unlikely(cmd->host_status)) {
+		if ((cmd->host_status == DID_REQUEUE) ||
+		    (cmd->host_status == DID_IMM_RETRY) ||
+		    (cmd->host_status == DID_SOFT_ERROR) ||
+		    (cmd->host_status == DID_ABORT)) {
+			scst_set_busy(cmd);
+		} else {
+			TRACE(TRACE_SCSI|TRACE_MINOR_AND_MGMT_DBG, "Host "
+				"status %x received, returning HARDWARE ERROR "
+				"instead (cmd %p)", cmd->host_status, cmd);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+		}
+	}
+	return res;
+}
+
+static int scst_pre_dev_done(struct scst_cmd *cmd)
+{
+	int res = SCST_CMD_STATE_RES_CONT_SAME, rc;
+
+	if (unlikely(scst_check_auto_sense(cmd))) {
+		PRINT_INFO("Command finished with CHECK CONDITION, but "
+			    "without sense data (opcode 0x%x), issuing "
+			    "REQUEST SENSE", cmd->cdb[0]);
+		rc = scst_prepare_request_sense(cmd);
+		if (rc == 0)
+			res = SCST_CMD_STATE_RES_CONT_NEXT;
+		else {
+			PRINT_ERROR("%s", "Unable to issue REQUEST SENSE, "
+				    "returning HARDWARE ERROR");
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+		}
+		goto out;
+	} else if (unlikely(scst_check_sense(cmd)))
+		goto out;
+
+	if (likely(scsi_status_is_good(cmd->status))) {
+		unsigned char type = cmd->dev->type;
+		if (unlikely((cmd->cdb[0] == MODE_SENSE ||
+			      cmd->cdb[0] == MODE_SENSE_10)) &&
+		    (cmd->tgt_dev->acg_dev->rd_only || cmd->dev->swp ||
+		     cmd->dev->rd_only) &&
+		    (type == TYPE_DISK ||
+		     type == TYPE_WORM ||
+		     type == TYPE_MOD ||
+		     type == TYPE_TAPE)) {
+			int32_t length;
+			uint8_t *address;
+			bool err = false;
+
+			length = scst_get_buf_first(cmd, &address);
+			if (length < 0) {
+				PRINT_ERROR("%s", "Unable to get "
+					"MODE_SENSE buffer");
+				scst_set_cmd_error(cmd,
+					SCST_LOAD_SENSE(
+						scst_sense_hardw_error));
+				err = true;
+			} else if (length > 2 && cmd->cdb[0] == MODE_SENSE)
+				address[2] |= 0x80;   /* Write Protect*/
+			else if (length > 3 && cmd->cdb[0] == MODE_SENSE_10)
+				address[3] |= 0x80;   /* Write Protect*/
+			scst_put_buf(cmd, address);
+
+			if (err)
+				goto out;
+		}
+
+		/*
+		 * Check and clear NormACA option for the device, if necessary,
+		 * since we don't support ACA
+		 */
+		if (unlikely((cmd->cdb[0] == INQUIRY)) &&
+		    /* Std INQUIRY data (no EVPD) */
+		    !(cmd->cdb[1] & SCST_INQ_EVPD) &&
+		    (cmd->resp_data_len > SCST_INQ_BYTE3)) {
+			uint8_t *buffer;
+			int buflen;
+			bool err = false;
+
+			/* ToDo: all pages ?? */
+			buflen = scst_get_buf_first(cmd, &buffer);
+			if (buflen > SCST_INQ_BYTE3) {
+#ifdef CONFIG_SCST_EXTRACHECKS
+				if (buffer[SCST_INQ_BYTE3] & SCST_INQ_NORMACA_BIT) {
+					PRINT_INFO("NormACA set for device: "
+					    "lun=%lld, type 0x%02x. Clear it, "
+					    "since it's unsupported.",
+					    (long long unsigned int)cmd->lun,
+					    buffer[0]);
+				}
+#endif
+				buffer[SCST_INQ_BYTE3] &= ~SCST_INQ_NORMACA_BIT;
+			} else if (buflen != 0) {
+				PRINT_ERROR("%s", "Unable to get INQUIRY "
+				    "buffer");
+				scst_set_cmd_error(cmd,
+				       SCST_LOAD_SENSE(scst_sense_hardw_error));
+				err = true;
+			}
+			if (buflen > 0)
+				scst_put_buf(cmd, buffer);
+
+			if (err)
+				goto out;
+		}
+
+		if (unlikely((cmd->cdb[0] == MODE_SELECT) ||
+		    (cmd->cdb[0] == MODE_SELECT_10) ||
+		    (cmd->cdb[0] == LOG_SELECT))) {
+			TRACE(TRACE_SCSI,
+				"MODE/LOG SELECT succeeded (LUN %lld)",
+				(long long unsigned int)cmd->lun);
+			cmd->state = SCST_CMD_STATE_MODE_SELECT_CHECKS;
+			goto out;
+		}
+	} else {
+		TRACE(TRACE_SCSI, "cmd %p not succeeded with status %x",
+			cmd, cmd->status);
+
+		if ((cmd->cdb[0] == RESERVE) || (cmd->cdb[0] == RESERVE_10)) {
+			if (!test_bit(SCST_TGT_DEV_RESERVED,
+					&cmd->tgt_dev->tgt_dev_flags)) {
+				struct scst_tgt_dev *tgt_dev_tmp;
+				struct scst_device *dev = cmd->dev;
+
+				TRACE(TRACE_SCSI, "RESERVE failed lun=%lld, "
+					"status=%x",
+					(long long unsigned int)cmd->lun,
+					cmd->status);
+				PRINT_BUFF_FLAG(TRACE_SCSI, "Sense", cmd->sense,
+					cmd->sense_valid_len);
+
+				/* Clearing the reservation */
+				spin_lock_bh(&dev->dev_lock);
+				list_for_each_entry(tgt_dev_tmp,
+						    &dev->dev_tgt_dev_list,
+						    dev_tgt_dev_list_entry) {
+					clear_bit(SCST_TGT_DEV_RESERVED,
+						&tgt_dev_tmp->tgt_dev_flags);
+				}
+				dev->dev_reserved = 0;
+				spin_unlock_bh(&dev->dev_lock);
+			}
+		}
+
+		/* Check for MODE PARAMETERS CHANGED UA */
+		if ((cmd->dev->scsi_dev != NULL) &&
+		    (cmd->status == SAM_STAT_CHECK_CONDITION) &&
+		    scst_is_ua_sense(cmd->sense, cmd->sense_valid_len) &&
+		    scst_analyze_sense(cmd->sense, cmd->sense_valid_len,
+					SCST_SENSE_ASCx_VALID,
+					0, 0x2a, 0x01)) {
+			TRACE(TRACE_SCSI, "MODE PARAMETERS CHANGED UA (lun "
+				"%lld)", (long long unsigned int)cmd->lun);
+			cmd->state = SCST_CMD_STATE_MODE_SELECT_CHECKS;
+			goto out;
+		}
+	}
+
+	cmd->state = SCST_CMD_STATE_DEV_DONE;
+
+out:
+	return res;
+}
+
+static int scst_mode_select_checks(struct scst_cmd *cmd)
+{
+	int res = SCST_CMD_STATE_RES_CONT_SAME;
+
+	if (likely(scsi_status_is_good(cmd->status))) {
+		int atomic = scst_cmd_atomic(cmd);
+		if (unlikely((cmd->cdb[0] == MODE_SELECT) ||
+		    (cmd->cdb[0] == MODE_SELECT_10) ||
+		    (cmd->cdb[0] == LOG_SELECT))) {
+			struct scst_device *dev = cmd->dev;
+			int sl;
+			uint8_t sense_buffer[SCST_STANDARD_SENSE_LEN];
+
+			if (atomic && (dev->scsi_dev != NULL)) {
+				TRACE_DBG("%s", "MODE/LOG SELECT: thread "
+					"context required");
+				res = SCST_CMD_STATE_RES_NEED_THREAD;
+				goto out;
+			}
+
+			TRACE(TRACE_SCSI, "MODE/LOG SELECT succeeded, "
+				"setting the SELECT UA (lun=%lld)",
+				(long long unsigned int)cmd->lun);
+
+			spin_lock_bh(&dev->dev_lock);
+			if (cmd->cdb[0] == LOG_SELECT) {
+				sl = scst_set_sense(sense_buffer,
+					sizeof(sense_buffer),
+					dev->d_sense,
+					UNIT_ATTENTION, 0x2a, 0x02);
+			} else {
+				sl = scst_set_sense(sense_buffer,
+					sizeof(sense_buffer),
+					dev->d_sense,
+					UNIT_ATTENTION, 0x2a, 0x01);
+			}
+			scst_dev_check_set_local_UA(dev, cmd, sense_buffer, sl);
+			spin_unlock_bh(&dev->dev_lock);
+
+			if (dev->scsi_dev != NULL)
+				scst_obtain_device_parameters(dev);
+		}
+	} else if ((cmd->status == SAM_STAT_CHECK_CONDITION) &&
+		    scst_is_ua_sense(cmd->sense, cmd->sense_valid_len) &&
+		     /* mode parameters changed */
+		    (scst_analyze_sense(cmd->sense, cmd->sense_valid_len,
+					SCST_SENSE_ASCx_VALID,
+					0, 0x2a, 0x01) ||
+		     scst_analyze_sense(cmd->sense, cmd->sense_valid_len,
+					SCST_SENSE_ASC_VALID,
+					0, 0x29, 0) /* reset */ ||
+		     scst_analyze_sense(cmd->sense, cmd->sense_valid_len,
+					SCST_SENSE_ASC_VALID,
+					0, 0x28, 0) /* medium changed */ ||
+		     /* cleared by another ini (just in case) */
+		     scst_analyze_sense(cmd->sense, cmd->sense_valid_len,
+					SCST_SENSE_ASC_VALID,
+					0, 0x2F, 0))) {
+		int atomic = scst_cmd_atomic(cmd);
+		if (atomic) {
+			TRACE_DBG("Possible parameters changed UA %x: "
+				"thread context required", cmd->sense[12]);
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			goto out;
+		}
+
+		TRACE(TRACE_SCSI, "Possible parameters changed UA %x "
+			"(LUN %lld): getting new parameters", cmd->sense[12],
+			(long long unsigned int)cmd->lun);
+
+		scst_obtain_device_parameters(cmd->dev);
+	} else
+		BUG();
+
+	cmd->state = SCST_CMD_STATE_DEV_DONE;
+
+out:
+	return res;
+}
+
+static void scst_inc_check_expected_sn(struct scst_cmd *cmd)
+{
+	if (likely(cmd->sn_set))
+		scst_inc_expected_sn(cmd->tgt_dev, cmd->sn_slot);
+
+	scst_make_deferred_commands_active(cmd->tgt_dev);
+}
+
+static int scst_dev_done(struct scst_cmd *cmd)
+{
+	int res = SCST_CMD_STATE_RES_CONT_SAME;
+	int state;
+	struct scst_device *dev = cmd->dev;
+
+	state = SCST_CMD_STATE_PRE_XMIT_RESP;
+
+	if (likely(!scst_is_cmd_fully_local(cmd)) &&
+	    likely(dev->handler->dev_done != NULL)) {
+		int rc;
+
+		if (unlikely(!dev->handler->dev_done_atomic &&
+			     scst_cmd_atomic(cmd))) {
+			/*
+			 * It shouldn't be because of the SCST_TGT_DEV_AFTER_*
+			 * optimization.
+			 */
+			TRACE_DBG("Dev handler %s dev_done() needs thread "
+			      "context, rescheduling", dev->handler->name);
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			goto out;
+		}
+
+		TRACE_DBG("Calling dev handler %s dev_done(%p)",
+			dev->handler->name, cmd);
+		scst_set_cur_start(cmd);
+		rc = dev->handler->dev_done(cmd);
+		scst_set_dev_done_time(cmd);
+		TRACE_DBG("Dev handler %s dev_done() returned %d",
+		      dev->handler->name, rc);
+		if (rc != SCST_CMD_STATE_DEFAULT)
+			state = rc;
+	}
+
+	switch (state) {
+#ifdef CONFIG_SCST_EXTRACHECKS
+	case SCST_CMD_STATE_PRE_XMIT_RESP:
+	case SCST_CMD_STATE_DEV_PARSE:
+	case SCST_CMD_STATE_PRE_PARSE:
+	case SCST_CMD_STATE_PREPARE_SPACE:
+	case SCST_CMD_STATE_RDY_TO_XFER:
+	case SCST_CMD_STATE_TGT_PRE_EXEC:
+	case SCST_CMD_STATE_SEND_FOR_EXEC:
+	case SCST_CMD_STATE_LOCAL_EXEC:
+	case SCST_CMD_STATE_REAL_EXEC:
+	case SCST_CMD_STATE_PRE_DEV_DONE:
+	case SCST_CMD_STATE_MODE_SELECT_CHECKS:
+	case SCST_CMD_STATE_DEV_DONE:
+	case SCST_CMD_STATE_XMIT_RESP:
+	case SCST_CMD_STATE_FINISHED:
+	case SCST_CMD_STATE_FINISHED_INTERNAL:
+#else
+	default:
+#endif
+		cmd->state = state;
+		break;
+	case SCST_CMD_STATE_NEED_THREAD_CTX:
+		TRACE_DBG("Dev handler %s dev_done() requested "
+		      "thread context, rescheduling",
+		      dev->handler->name);
+		res = SCST_CMD_STATE_RES_NEED_THREAD;
+		break;
+#ifdef CONFIG_SCST_EXTRACHECKS
+	default:
+		if (state >= 0) {
+			PRINT_ERROR("Dev handler %s dev_done() returned "
+				"invalid cmd state %d",
+				dev->handler->name, state);
+		} else {
+			PRINT_ERROR("Dev handler %s dev_done() returned "
+				"error %d", dev->handler->name,
+				state);
+		}
+		scst_set_cmd_error(cmd,
+			   SCST_LOAD_SENSE(scst_sense_hardw_error));
+		scst_set_cmd_abnormal_done_state(cmd);
+		break;
+#endif
+	}
+
+	if (cmd->needs_unblocking)
+		scst_unblock_dev_cmd(cmd);
+
+	if (likely(cmd->dec_on_dev_needed))
+		scst_dec_on_dev_cmd(cmd);
+
+	if (cmd->inc_expected_sn_on_done && cmd->sent_for_exec)
+		scst_inc_check_expected_sn(cmd);
+
+	if (unlikely(cmd->internal))
+		cmd->state = SCST_CMD_STATE_FINISHED_INTERNAL;
+
+out:
+	return res;
+}
+
+static int scst_pre_xmit_response(struct scst_cmd *cmd)
+{
+	int res;
+
+	EXTRACHECKS_BUG_ON(cmd->internal);
+
+#ifdef CONFIG_SCST_DEBUG_TM
+	if (cmd->tm_dbg_delayed &&
+			!test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags)) {
+		if (scst_cmd_atomic(cmd)) {
+			TRACE_MGMT_DBG("%s",
+				"DEBUG_TM delayed cmd needs a thread");
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			return res;
+		}
+		TRACE_MGMT_DBG("Delaying cmd %p (tag %llu) for 1 second",
+			cmd, cmd->tag);
+		schedule_timeout_uninterruptible(HZ);
+	}
+#endif
+
+	if (likely(cmd->tgt_dev != NULL)) {
+		/*
+		 * Those counters protect from not getting too long processing
+		 * latency, so we should decrement them after cmd completed.
+		 */
+		atomic_dec(&cmd->tgt_dev->tgt_dev_cmd_count);
+#ifdef CONFIG_SCST_PER_DEVICE_CMD_COUNT_LIMIT
+		atomic_dec(&cmd->dev->dev_cmd_count);
+#endif
+#ifdef CONFIG_SCST_ORDERED_READS
+		/* If expected values not set, expected direction is UNKNOWN */
+		if (cmd->expected_data_direction & SCST_DATA_WRITE)
+			atomic_dec(&cmd->dev->write_cmd_count);
+#endif
+		if (unlikely(cmd->queue_type == SCST_CMD_QUEUE_HEAD_OF_QUEUE))
+			scst_on_hq_cmd_response(cmd);
+
+		if (unlikely(!cmd->sent_for_exec)) {
+			TRACE_SN("cmd %p was not sent to mid-lev"
+				" (sn %d, set %d)",
+				cmd, cmd->sn, cmd->sn_set);
+			scst_unblock_deferred(cmd->tgt_dev, cmd);
+			cmd->sent_for_exec = 1;
+		}
+	}
+
+	cmd->done = 1;
+	smp_mb(); /* to sync with scst_abort_cmd() */
+
+	if (unlikely(test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags)))
+		scst_xmit_process_aborted_cmd(cmd);
+	else if (unlikely(cmd->status == SAM_STAT_CHECK_CONDITION))
+		scst_store_sense(cmd);
+
+	if (unlikely(test_bit(SCST_CMD_NO_RESP, &cmd->cmd_flags))) {
+		TRACE_MGMT_DBG("Flag NO_RESP set for cmd %p (tag %llu), "
+			"skipping", cmd, (long long unsigned int)cmd->tag);
+		cmd->state = SCST_CMD_STATE_FINISHED;
+		res = SCST_CMD_STATE_RES_CONT_SAME;
+		goto out;
+	}
+
+	if (unlikely(cmd->resid_possible))
+		scst_adjust_resp_data_len(cmd);
+	else
+		cmd->adjusted_resp_data_len = cmd->resp_data_len;
+
+	cmd->state = SCST_CMD_STATE_XMIT_RESP;
+	res = SCST_CMD_STATE_RES_CONT_SAME;
+
+out:
+	return res;
+}
+
+static int scst_xmit_response(struct scst_cmd *cmd)
+{
+	struct scst_tgt_template *tgtt = cmd->tgtt;
+	int res, rc;
+
+	EXTRACHECKS_BUG_ON(cmd->internal);
+
+	if (unlikely(!tgtt->xmit_response_atomic &&
+		     scst_cmd_atomic(cmd))) {
+		/*
+		 * It shouldn't be because of the SCST_TGT_DEV_AFTER_*
+		 * optimization.
+		 */
+		TRACE_DBG("Target driver %s xmit_response() needs thread "
+			      "context, rescheduling", tgtt->name);
+		res = SCST_CMD_STATE_RES_NEED_THREAD;
+		goto out;
+	}
+
+	while (1) {
+		int finished_cmds = atomic_read(&cmd->tgt->finished_cmds);
+
+		res = SCST_CMD_STATE_RES_CONT_NEXT;
+		cmd->state = SCST_CMD_STATE_XMIT_WAIT;
+
+		TRACE_DBG("Calling xmit_response(%p)", cmd);
+
+#if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
+		if (trace_flag & TRACE_SND_BOT) {
+			int i, j;
+			struct scatterlist *sg;
+			if (cmd->tgt_sg != NULL)
+				sg = cmd->tgt_sg;
+			else
+				sg = cmd->sg;
+			if (sg != NULL) {
+				TRACE(TRACE_SND_BOT, "Xmitting data for cmd %p "
+					"(sg_cnt %d, sg %p, sg[0].page %p)",
+					cmd, cmd->tgt_sg_cnt, sg,
+					(void *)sg_page(&sg[0]));
+				for (i = 0, j = 0; i < cmd->tgt_sg_cnt; ++i, ++j) {
+					if (unlikely(sg_is_chain(&sg[j]))) {
+						sg = sg_chain_ptr(&sg[j]);
+						j = 0;
+					}
+					PRINT_BUFF_FLAG(TRACE_SND_BOT,
+						"Xmitting sg", sg_virt(&sg[j]),
+						sg[j].length);
+				}
+			}
+		}
+#endif
+
+		if (tgtt->on_hw_pending_cmd_timeout != NULL) {
+			struct scst_session *sess = cmd->sess;
+			cmd->hw_pending_start = jiffies;
+			cmd->cmd_hw_pending = 1;
+			if (!test_bit(SCST_SESS_HW_PENDING_WORK_SCHEDULED, &sess->sess_aflags)) {
+				TRACE_DBG("Sched HW pending work for sess %p "
+					"(max time %d)", sess,
+					tgtt->max_hw_pending_time);
+				set_bit(SCST_SESS_HW_PENDING_WORK_SCHEDULED,
+					&sess->sess_aflags);
+				schedule_delayed_work(&sess->hw_pending_work,
+					tgtt->max_hw_pending_time * HZ);
+			}
+		}
+
+		scst_set_cur_start(cmd);
+
+#ifdef CONFIG_SCST_DEBUG_RETRY
+		if (((scst_random() % 100) == 77))
+			rc = SCST_TGT_RES_QUEUE_FULL;
+		else
+#endif
+			rc = tgtt->xmit_response(cmd);
+		TRACE_DBG("xmit_response() returned %d", rc);
+
+		if (likely(rc == SCST_TGT_RES_SUCCESS))
+			goto out;
+
+		scst_set_xmit_time(cmd);
+
+		cmd->cmd_hw_pending = 0;
+
+		/* Restore the previous state */
+		cmd->state = SCST_CMD_STATE_XMIT_RESP;
+
+		switch (rc) {
+		case SCST_TGT_RES_QUEUE_FULL:
+			if (scst_queue_retry_cmd(cmd, finished_cmds) == 0)
+				break;
+			else
+				continue;
+
+		case SCST_TGT_RES_NEED_THREAD_CTX:
+			TRACE_DBG("Target driver %s xmit_response() "
+			      "requested thread context, rescheduling",
+			      tgtt->name);
+			res = SCST_CMD_STATE_RES_NEED_THREAD;
+			break;
+
+		default:
+			goto out_error;
+		}
+		break;
+	}
+
+out:
+	/* Caution: cmd can be already dead here */
+	return res;
+
+out_error:
+	if (rc == SCST_TGT_RES_FATAL_ERROR) {
+		PRINT_ERROR("Target driver %s xmit_response() returned "
+			"fatal error", tgtt->name);
+	} else {
+		PRINT_ERROR("Target driver %s xmit_response() returned "
+			"invalid value %d", tgtt->name, rc);
+	}
+	scst_set_cmd_error(cmd, SCST_LOAD_SENSE(scst_sense_hardw_error));
+	cmd->state = SCST_CMD_STATE_FINISHED;
+	res = SCST_CMD_STATE_RES_CONT_SAME;
+	goto out;
+}
+
+/**
+ * scst_tgt_cmd_done() - the command's processing done
+ * @cmd:	SCST command
+ * @pref_context: preferred command execution context
+ *
+ * Description:
+ *    Notifies SCST that the driver sent the response and the command
+ *    can be freed now. Don't forget to set the delivery status, if it
+ *    isn't success, using scst_set_delivery_status() before calling
+ *    this function. The third argument sets preferred command execition
+ *    context (see SCST_CONTEXT_* constants for details)
+ */
+void scst_tgt_cmd_done(struct scst_cmd *cmd,
+	enum scst_exec_context pref_context)
+{
+
+	BUG_ON(cmd->state != SCST_CMD_STATE_XMIT_WAIT);
+
+	scst_set_xmit_time(cmd);
+
+	cmd->cmd_hw_pending = 0;
+
+	cmd->state = SCST_CMD_STATE_FINISHED;
+	scst_process_redirect_cmd(cmd, pref_context, 1);
+	return;
+}
+EXPORT_SYMBOL(scst_tgt_cmd_done);
+
+static int scst_finish_cmd(struct scst_cmd *cmd)
+{
+	int res;
+	struct scst_session *sess = cmd->sess;
+
+	scst_update_lat_stats(cmd);
+
+	if (unlikely(cmd->delivery_status != SCST_CMD_DELIVERY_SUCCESS)) {
+		if ((cmd->tgt_dev != NULL) &&
+		    scst_is_ua_sense(cmd->sense, cmd->sense_valid_len)) {
+			/* This UA delivery failed, so we need to requeue it */
+			if (scst_cmd_atomic(cmd) &&
+			    scst_is_ua_global(cmd->sense, cmd->sense_valid_len)) {
+				TRACE_MGMT_DBG("Requeuing of global UA for "
+					"failed cmd %p needs a thread", cmd);
+				res = SCST_CMD_STATE_RES_NEED_THREAD;
+				goto out;
+			}
+			scst_requeue_ua(cmd);
+		}
+	}
+
+	atomic_dec(&sess->sess_cmd_count);
+
+	spin_lock_irq(&sess->sess_list_lock);
+	list_del(&cmd->sess_cmd_list_entry);
+	spin_unlock_irq(&sess->sess_list_lock);
+
+	cmd->finished = 1;
+	smp_mb(); /* to sync with scst_abort_cmd() */
+
+	if (unlikely(test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags))) {
+		TRACE_MGMT_DBG("Aborted cmd %p finished (cmd_ref %d, "
+			"scst_cmd_count %d)", cmd, atomic_read(&cmd->cmd_ref),
+			atomic_read(&scst_cmd_count));
+
+		scst_finish_cmd_mgmt(cmd);
+	}
+
+	__scst_cmd_put(cmd);
+
+	res = SCST_CMD_STATE_RES_CONT_NEXT;
+
+out:
+	return res;
+}
+
+/*
+ * No locks, but it must be externally serialized (see comment for
+ * scst_cmd_init_done() in scst.h)
+ */
+static void scst_cmd_set_sn(struct scst_cmd *cmd)
+{
+	struct scst_tgt_dev *tgt_dev = cmd->tgt_dev;
+	unsigned long flags;
+
+	if (scst_is_implicit_hq(cmd) &&
+	    likely(cmd->queue_type == SCST_CMD_QUEUE_SIMPLE)) {
+		TRACE_SN("Implicit HQ cmd %p", cmd);
+		cmd->queue_type = SCST_CMD_QUEUE_HEAD_OF_QUEUE;
+	}
+
+	EXTRACHECKS_BUG_ON(cmd->sn_set || cmd->hq_cmd_inced);
+
+	/* Optimized for lockless fast path */
+
+	scst_check_debug_sn(cmd);
+
+#ifdef CONFIG_SCST_STRICT_SERIALIZING
+	cmd->queue_type = SCST_CMD_QUEUE_ORDERED;
+#endif
+
+	if (cmd->dev->queue_alg == SCST_CONTR_MODE_QUEUE_ALG_RESTRICTED_REORDER) {
+		/*
+		 * Not the best way, but good enough until there is a
+		 * possibility to specify queue type during pass-through
+		 * commands submission.
+		 */
+		cmd->queue_type = SCST_CMD_QUEUE_ORDERED;
+	}
+
+	switch (cmd->queue_type) {
+	case SCST_CMD_QUEUE_SIMPLE:
+	case SCST_CMD_QUEUE_UNTAGGED:
+#ifdef CONFIG_SCST_ORDERED_READS
+		if (scst_cmd_is_expected_set(cmd)) {
+			if ((cmd->expected_data_direction == SCST_DATA_READ) &&
+			    (atomic_read(&cmd->dev->write_cmd_count) == 0))
+				goto ordered;
+		} else
+			goto ordered;
+#endif
+		if (likely(tgt_dev->num_free_sn_slots >= 0)) {
+			/*
+			 * atomic_inc_return() implies memory barrier to sync
+			 * with scst_inc_expected_sn()
+			 */
+			if (atomic_inc_return(tgt_dev->cur_sn_slot) == 1) {
+				tgt_dev->curr_sn++;
+				TRACE_SN("Incremented curr_sn %d",
+					tgt_dev->curr_sn);
+			}
+			cmd->sn_slot = tgt_dev->cur_sn_slot;
+			cmd->sn = tgt_dev->curr_sn;
+
+			tgt_dev->prev_cmd_ordered = 0;
+		} else {
+			TRACE(TRACE_MINOR, "***WARNING*** Not enough SN slots "
+				"%zd", ARRAY_SIZE(tgt_dev->sn_slots));
+			goto ordered;
+		}
+		break;
+
+	case SCST_CMD_QUEUE_ORDERED:
+		TRACE_SN("ORDERED cmd %p (op %x)", cmd, cmd->cdb[0]);
+ordered:
+		if (!tgt_dev->prev_cmd_ordered) {
+			spin_lock_irqsave(&tgt_dev->sn_lock, flags);
+			if (tgt_dev->num_free_sn_slots >= 0) {
+				tgt_dev->num_free_sn_slots--;
+				if (tgt_dev->num_free_sn_slots >= 0) {
+					int i = 0;
+					/* Commands can finish in any order, so
+					 * we don't know which slot is empty.
+					 */
+					while (1) {
+						tgt_dev->cur_sn_slot++;
+						if (tgt_dev->cur_sn_slot ==
+						      tgt_dev->sn_slots + ARRAY_SIZE(tgt_dev->sn_slots))
+							tgt_dev->cur_sn_slot = tgt_dev->sn_slots;
+
+						if (atomic_read(tgt_dev->cur_sn_slot) == 0)
+							break;
+
+						i++;
+						BUG_ON(i == ARRAY_SIZE(tgt_dev->sn_slots));
+					}
+					TRACE_SN("New cur SN slot %zd",
+						tgt_dev->cur_sn_slot -
+						tgt_dev->sn_slots);
+				}
+			}
+			spin_unlock_irqrestore(&tgt_dev->sn_lock, flags);
+		}
+		tgt_dev->prev_cmd_ordered = 1;
+		tgt_dev->curr_sn++;
+		cmd->sn = tgt_dev->curr_sn;
+		break;
+
+	case SCST_CMD_QUEUE_HEAD_OF_QUEUE:
+		TRACE_SN("HQ cmd %p (op %x)", cmd, cmd->cdb[0]);
+		spin_lock_irqsave(&tgt_dev->sn_lock, flags);
+		tgt_dev->hq_cmd_count++;
+		spin_unlock_irqrestore(&tgt_dev->sn_lock, flags);
+		cmd->hq_cmd_inced = 1;
+		goto out;
+
+	default:
+		BUG();
+	}
+
+	TRACE_SN("cmd(%p)->sn: %d (tgt_dev %p, *cur_sn_slot %d, "
+		"num_free_sn_slots %d, prev_cmd_ordered %ld, "
+		"cur_sn_slot %zd)", cmd, cmd->sn, tgt_dev,
+		atomic_read(tgt_dev->cur_sn_slot),
+		tgt_dev->num_free_sn_slots, tgt_dev->prev_cmd_ordered,
+		tgt_dev->cur_sn_slot-tgt_dev->sn_slots);
+
+	cmd->sn_set = 1;
+
+out:
+	return;
+}
+
+/*
+ * Returns 0 on success, > 0 when we need to wait for unblock,
+ * < 0 if there is no device (lun) or device type handler.
+ *
+ * No locks, but might be on IRQ, protection is done by the
+ * suspended activity.
+ */
+static int scst_translate_lun(struct scst_cmd *cmd)
+{
+	struct scst_tgt_dev *tgt_dev = NULL;
+	int res;
+
+	/* See comment about smp_mb() in scst_suspend_activity() */
+	__scst_get(1);
+
+	if (likely(!test_bit(SCST_FLAG_SUSPENDED, &scst_flags))) {
+		struct list_head *sess_tgt_dev_list_head =
+			&cmd->sess->sess_tgt_dev_list_hash[HASH_VAL(cmd->lun)];
+		TRACE_DBG("Finding tgt_dev for cmd %p (lun %lld)", cmd,
+			(long long unsigned int)cmd->lun);
+		res = -1;
+		list_for_each_entry(tgt_dev, sess_tgt_dev_list_head,
+				sess_tgt_dev_list_entry) {
+			if (tgt_dev->lun == cmd->lun) {
+				TRACE_DBG("tgt_dev %p found", tgt_dev);
+
+				if (unlikely(tgt_dev->dev->handler ==
+						&scst_null_devtype)) {
+					PRINT_INFO("Dev handler for device "
+					  "%lld is NULL, the device will not "
+					  "be visible remotely",
+					   (long long unsigned int)cmd->lun);
+					break;
+				}
+
+				cmd->cmd_threads = tgt_dev->active_cmd_threads;
+				cmd->tgt_dev = tgt_dev;
+				cmd->dev = tgt_dev->dev;
+
+				res = 0;
+				break;
+			}
+		}
+		if (res != 0) {
+			TRACE(TRACE_MINOR,
+				"tgt_dev for LUN %lld not found, command to "
+				"unexisting LU?",
+				(long long unsigned int)cmd->lun);
+			__scst_put();
+		}
+	} else {
+		TRACE_MGMT_DBG("%s", "FLAG SUSPENDED set, skipping");
+		__scst_put();
+		res = 1;
+	}
+	return res;
+}
+
+/*
+ * No locks, but might be on IRQ.
+ *
+ * Returns 0 on success, > 0 when we need to wait for unblock,
+ * < 0 if there is no device (lun) or device type handler.
+ */
+static int __scst_init_cmd(struct scst_cmd *cmd)
+{
+	int res = 0;
+
+	res = scst_translate_lun(cmd);
+	if (likely(res == 0)) {
+		int cnt;
+		bool failure = false;
+
+		cmd->state = SCST_CMD_STATE_PRE_PARSE;
+
+		cnt = atomic_inc_return(&cmd->tgt_dev->tgt_dev_cmd_count);
+		if (unlikely(cnt > SCST_MAX_TGT_DEV_COMMANDS)) {
+			TRACE(TRACE_FLOW_CONTROL,
+				"Too many pending commands (%d) in "
+				"session, returning BUSY to initiator \"%s\"",
+				cnt, (cmd->sess->initiator_name[0] == '\0') ?
+				  "Anonymous" : cmd->sess->initiator_name);
+			failure = true;
+		}
+
+#ifdef CONFIG_SCST_PER_DEVICE_CMD_COUNT_LIMIT
+		cnt = atomic_inc_return(&cmd->dev->dev_cmd_count);
+		if (unlikely(cnt > SCST_MAX_DEV_COMMANDS)) {
+			if (!failure) {
+				TRACE(TRACE_FLOW_CONTROL,
+					"Too many pending device "
+					"commands (%d), returning BUSY to "
+					"initiator \"%s\"", cnt,
+					(cmd->sess->initiator_name[0] == '\0') ?
+						"Anonymous" :
+						cmd->sess->initiator_name);
+				failure = true;
+			}
+		}
+#endif
+
+#ifdef CONFIG_SCST_ORDERED_READS
+		/* If expected values not set, expected direction is UNKNOWN */
+		if (cmd->expected_data_direction & SCST_DATA_WRITE)
+			atomic_inc(&cmd->dev->write_cmd_count);
+#endif
+
+		if (unlikely(failure))
+			goto out_busy;
+
+		if (!cmd->set_sn_on_restart_cmd)
+			scst_cmd_set_sn(cmd);
+	} else if (res < 0) {
+		TRACE_DBG("Finishing cmd %p", cmd);
+		scst_set_cmd_error(cmd,
+			   SCST_LOAD_SENSE(scst_sense_lun_not_supported));
+		scst_set_cmd_abnormal_done_state(cmd);
+	} else
+		goto out;
+
+out:
+	return res;
+
+out_busy:
+	scst_set_busy(cmd);
+	scst_set_cmd_abnormal_done_state(cmd);
+	goto out;
+}
+
+/* Called under scst_init_lock and IRQs disabled */
+static void scst_do_job_init(void)
+	__releases(&scst_init_lock)
+	__acquires(&scst_init_lock)
+{
+	struct scst_cmd *cmd;
+	int susp;
+
+restart:
+	/*
+	 * There is no need for read barrier here, because we don't care where
+	 * this check will be done.
+	 */
+	susp = test_bit(SCST_FLAG_SUSPENDED, &scst_flags);
+	if (scst_init_poll_cnt > 0)
+		scst_init_poll_cnt--;
+
+	list_for_each_entry(cmd, &scst_init_cmd_list, cmd_list_entry) {
+		int rc;
+		if (susp && !test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags))
+			continue;
+		if (!test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags)) {
+			spin_unlock_irq(&scst_init_lock);
+			rc = __scst_init_cmd(cmd);
+			spin_lock_irq(&scst_init_lock);
+			if (rc > 0) {
+				TRACE_MGMT_DBG("%s",
+					"FLAG SUSPENDED set, restarting");
+				goto restart;
+			}
+		} else {
+			TRACE_MGMT_DBG("Aborting not inited cmd %p (tag %llu)",
+				       cmd, (long long unsigned int)cmd->tag);
+			scst_set_cmd_abnormal_done_state(cmd);
+		}
+
+		/*
+		 * Deleting cmd from init cmd list after __scst_init_cmd()
+		 * is necessary to keep the check in scst_init_cmd() correct
+		 * to preserve the commands order.
+		 *
+		 * We don't care about the race, when init cmd list is empty
+		 * and one command detected that it just was not empty, so
+		 * it's inserting to it, but another command at the same time
+		 * seeing init cmd list empty and goes directly, because it
+		 * could affect only commands from the same initiator to the
+		 * same tgt_dev, but scst_cmd_init_done*() doesn't guarantee
+		 * the order in case of simultaneous such calls anyway.
+		 */
+		TRACE_MGMT_DBG("Deleting cmd %p from init cmd list", cmd);
+		smp_wmb(); /* enforce the required order */
+		list_del(&cmd->cmd_list_entry);
+		spin_unlock(&scst_init_lock);
+
+		spin_lock(&cmd->cmd_threads->cmd_list_lock);
+		TRACE_MGMT_DBG("Adding cmd %p to active cmd list", cmd);
+		if (unlikely(cmd->queue_type == SCST_CMD_QUEUE_HEAD_OF_QUEUE))
+			list_add(&cmd->cmd_list_entry,
+				&cmd->cmd_threads->active_cmd_list);
+		else
+			list_add_tail(&cmd->cmd_list_entry,
+				&cmd->cmd_threads->active_cmd_list);
+		wake_up(&cmd->cmd_threads->cmd_list_waitQ);
+		spin_unlock(&cmd->cmd_threads->cmd_list_lock);
+
+		spin_lock(&scst_init_lock);
+		goto restart;
+	}
+
+	/* It isn't really needed, but let's keep it */
+	if (susp != test_bit(SCST_FLAG_SUSPENDED, &scst_flags))
+		goto restart;
+	return;
+}
+
+static inline int test_init_cmd_list(void)
+{
+	int res = (!list_empty(&scst_init_cmd_list) &&
+		   !test_bit(SCST_FLAG_SUSPENDED, &scst_flags)) ||
+		  unlikely(kthread_should_stop()) ||
+		  (scst_init_poll_cnt > 0);
+	return res;
+}
+
+int scst_init_thread(void *arg)
+{
+
+	PRINT_INFO("Init thread started, PID %d", current->pid);
+
+	current->flags |= PF_NOFREEZE;
+
+	set_user_nice(current, -10);
+
+	spin_lock_irq(&scst_init_lock);
+	while (!kthread_should_stop()) {
+		wait_queue_t wait;
+		init_waitqueue_entry(&wait, current);
+
+		if (!test_init_cmd_list()) {
+			add_wait_queue_exclusive(&scst_init_cmd_list_waitQ,
+						 &wait);
+			for (;;) {
+				set_current_state(TASK_INTERRUPTIBLE);
+				if (test_init_cmd_list())
+					break;
+				spin_unlock_irq(&scst_init_lock);
+				schedule();
+				spin_lock_irq(&scst_init_lock);
+			}
+			set_current_state(TASK_RUNNING);
+			remove_wait_queue(&scst_init_cmd_list_waitQ, &wait);
+		}
+		scst_do_job_init();
+	}
+	spin_unlock_irq(&scst_init_lock);
+
+	/*
+	 * If kthread_should_stop() is true, we are guaranteed to be
+	 * on the module unload, so scst_init_cmd_list must be empty.
+	 */
+	BUG_ON(!list_empty(&scst_init_cmd_list));
+
+	PRINT_INFO("Init thread PID %d finished", current->pid);
+	return 0;
+}
+
+/**
+ * scst_process_active_cmd() - process active command
+ *
+ * Description:
+ *    Main SCST commands processing routing. Must be used only by dev handlers.
+ *
+ *    Argument atomic is true, if function called in atomic context.
+ *
+ *    Must be called with no locks held.
+ */
+void scst_process_active_cmd(struct scst_cmd *cmd, bool atomic)
+{
+	int res;
+
+	/*
+	 * Checkpatch will complain on the use of in_atomic() below. You
+	 * can safely ignore this warning since in_atomic() is used here only
+	 * for debugging purposes.
+	 */
+	EXTRACHECKS_BUG_ON(in_irq() || irqs_disabled());
+	EXTRACHECKS_WARN_ON((in_atomic() || in_interrupt() || irqs_disabled()) &&
+			     !atomic);
+
+	cmd->atomic = atomic;
+
+	TRACE_DBG("cmd %p, atomic %d", cmd, atomic);
+
+	do {
+		switch (cmd->state) {
+		case SCST_CMD_STATE_PRE_PARSE:
+			res = scst_pre_parse(cmd);
+			EXTRACHECKS_BUG_ON(res ==
+				SCST_CMD_STATE_RES_NEED_THREAD);
+			break;
+
+		case SCST_CMD_STATE_DEV_PARSE:
+			res = scst_parse_cmd(cmd);
+			break;
+
+		case SCST_CMD_STATE_PREPARE_SPACE:
+			res = scst_prepare_space(cmd);
+			break;
+
+		case SCST_CMD_STATE_PREPROCESSING_DONE:
+			res = scst_preprocessing_done(cmd);
+			break;
+
+		case SCST_CMD_STATE_RDY_TO_XFER:
+			res = scst_rdy_to_xfer(cmd);
+			break;
+
+		case SCST_CMD_STATE_TGT_PRE_EXEC:
+			res = scst_tgt_pre_exec(cmd);
+			break;
+
+		case SCST_CMD_STATE_SEND_FOR_EXEC:
+			if (tm_dbg_check_cmd(cmd) != 0) {
+				res = SCST_CMD_STATE_RES_CONT_NEXT;
+				TRACE_MGMT_DBG("Skipping cmd %p (tag %llu), "
+					"because of TM DBG delay", cmd,
+					(long long unsigned int)cmd->tag);
+				break;
+			}
+			res = scst_send_for_exec(&cmd);
+			/*
+			 * !! At this point cmd, sess & tgt_dev can already be
+			 * freed !!
+			 */
+			break;
+
+		case SCST_CMD_STATE_LOCAL_EXEC:
+			res = scst_local_exec(cmd);
+			/*
+			 * !! At this point cmd, sess & tgt_dev can already be
+			 * freed !!
+			 */
+			break;
+
+		case SCST_CMD_STATE_REAL_EXEC:
+			res = scst_real_exec(cmd);
+			/*
+			 * !! At this point cmd, sess & tgt_dev can already be
+			 * freed !!
+			 */
+			break;
+
+		case SCST_CMD_STATE_PRE_DEV_DONE:
+			res = scst_pre_dev_done(cmd);
+			EXTRACHECKS_BUG_ON(res ==
+				SCST_CMD_STATE_RES_NEED_THREAD);
+			break;
+
+		case SCST_CMD_STATE_MODE_SELECT_CHECKS:
+			res = scst_mode_select_checks(cmd);
+			break;
+
+		case SCST_CMD_STATE_DEV_DONE:
+			res = scst_dev_done(cmd);
+			break;
+
+		case SCST_CMD_STATE_PRE_XMIT_RESP:
+			res = scst_pre_xmit_response(cmd);
+			EXTRACHECKS_BUG_ON(res ==
+				SCST_CMD_STATE_RES_NEED_THREAD);
+			break;
+
+		case SCST_CMD_STATE_XMIT_RESP:
+			res = scst_xmit_response(cmd);
+			break;
+
+		case SCST_CMD_STATE_FINISHED:
+			res = scst_finish_cmd(cmd);
+			break;
+
+		case SCST_CMD_STATE_FINISHED_INTERNAL:
+			res = scst_finish_internal_cmd(cmd);
+			EXTRACHECKS_BUG_ON(res ==
+				SCST_CMD_STATE_RES_NEED_THREAD);
+			break;
+
+		default:
+			PRINT_CRIT_ERROR("cmd (%p) in state %d, but shouldn't "
+				"be", cmd, cmd->state);
+			BUG();
+			res = SCST_CMD_STATE_RES_CONT_NEXT;
+			break;
+		}
+	} while (res == SCST_CMD_STATE_RES_CONT_SAME);
+
+	if (res == SCST_CMD_STATE_RES_CONT_NEXT) {
+		/* None */
+	} else if (res == SCST_CMD_STATE_RES_NEED_THREAD) {
+		spin_lock_irq(&cmd->cmd_threads->cmd_list_lock);
+#ifdef CONFIG_SCST_EXTRACHECKS
+		switch (cmd->state) {
+		case SCST_CMD_STATE_DEV_PARSE:
+		case SCST_CMD_STATE_PREPARE_SPACE:
+		case SCST_CMD_STATE_RDY_TO_XFER:
+		case SCST_CMD_STATE_TGT_PRE_EXEC:
+		case SCST_CMD_STATE_SEND_FOR_EXEC:
+		case SCST_CMD_STATE_LOCAL_EXEC:
+		case SCST_CMD_STATE_REAL_EXEC:
+		case SCST_CMD_STATE_DEV_DONE:
+		case SCST_CMD_STATE_XMIT_RESP:
+#endif
+			TRACE_DBG("Adding cmd %p to head of active cmd list",
+				  cmd);
+			list_add(&cmd->cmd_list_entry,
+				&cmd->cmd_threads->active_cmd_list);
+#ifdef CONFIG_SCST_EXTRACHECKS
+			break;
+		default:
+			PRINT_CRIT_ERROR("cmd %p is in invalid state %d)", cmd,
+				cmd->state);
+			spin_unlock_irq(&cmd->cmd_threads->cmd_list_lock);
+			BUG();
+			spin_lock_irq(&cmd->cmd_threads->cmd_list_lock);
+			break;
+		}
+#endif
+		wake_up(&cmd->cmd_threads->cmd_list_waitQ);
+		spin_unlock_irq(&cmd->cmd_threads->cmd_list_lock);
+	} else
+		BUG();
+	return;
+}
+EXPORT_SYMBOL_GPL(scst_process_active_cmd);
+
+/* Called under cmd_list_lock and IRQs disabled */
+static void scst_do_job_active(struct list_head *cmd_list,
+	spinlock_t *cmd_list_lock, bool atomic)
+	__releases(cmd_list_lock)
+	__acquires(cmd_list_lock)
+{
+
+	while (!list_empty(cmd_list)) {
+		struct scst_cmd *cmd = list_entry(cmd_list->next, typeof(*cmd),
+					cmd_list_entry);
+		TRACE_DBG("Deleting cmd %p from active cmd list", cmd);
+		list_del(&cmd->cmd_list_entry);
+		spin_unlock_irq(cmd_list_lock);
+		scst_process_active_cmd(cmd, atomic);
+		spin_lock_irq(cmd_list_lock);
+	}
+	return;
+}
+
+static inline int test_cmd_threads(struct scst_cmd_threads *p_cmd_threads)
+{
+	int res = !list_empty(&p_cmd_threads->active_cmd_list) ||
+	    unlikely(kthread_should_stop()) ||
+	    tm_dbg_is_release();
+	return res;
+}
+
+int scst_cmd_thread(void *arg)
+{
+	struct scst_cmd_threads *p_cmd_threads = (struct scst_cmd_threads *)arg;
+	static DEFINE_MUTEX(io_context_mutex);
+
+	PRINT_INFO("Processing thread %s (PID %d) started", current->comm,
+		current->pid);
+
+#if 0
+	set_user_nice(current, 10);
+#endif
+	current->flags |= PF_NOFREEZE;
+
+	mutex_lock(&io_context_mutex);
+
+	WARN_ON(current->io_context);
+
+	if (p_cmd_threads != &scst_main_cmd_threads) {
+		if (p_cmd_threads->io_context == NULL) {
+			p_cmd_threads->io_context = get_io_context(GFP_KERNEL, -1);
+			TRACE_MGMT_DBG("Alloced new IO context %p "
+				"(p_cmd_threads %p)",
+				p_cmd_threads->io_context,
+				p_cmd_threads);
+			/*
+			 * Put the extra reference. It isn't needed, because we
+			 * ref counted via nr_threads below.
+			 */
+			put_io_context(p_cmd_threads->io_context);
+		} else {
+			put_io_context(current->io_context);
+			current->io_context = ioc_task_link(p_cmd_threads->io_context);
+			TRACE_MGMT_DBG("Linked IO context %p "
+				"(p_cmd_threads %p)", p_cmd_threads->io_context,
+				p_cmd_threads);
+		}
+	}
+
+	mutex_unlock(&io_context_mutex);
+
+	p_cmd_threads->io_context_ready = true;
+
+	spin_lock_irq(&p_cmd_threads->cmd_list_lock);
+	while (!kthread_should_stop()) {
+		wait_queue_t wait;
+		init_waitqueue_entry(&wait, current);
+
+		if (!test_cmd_threads(p_cmd_threads)) {
+			add_wait_queue_exclusive_head(
+				&p_cmd_threads->cmd_list_waitQ,
+				&wait);
+			for (;;) {
+				set_current_state(TASK_INTERRUPTIBLE);
+				if (test_cmd_threads(p_cmd_threads))
+					break;
+				spin_unlock_irq(&p_cmd_threads->cmd_list_lock);
+				schedule();
+				spin_lock_irq(&p_cmd_threads->cmd_list_lock);
+			}
+			set_current_state(TASK_RUNNING);
+			remove_wait_queue(&p_cmd_threads->cmd_list_waitQ, &wait);
+		}
+
+		if (tm_dbg_is_release()) {
+			spin_unlock_irq(&p_cmd_threads->cmd_list_lock);
+			tm_dbg_check_released_cmds();
+			spin_lock_irq(&p_cmd_threads->cmd_list_lock);
+		}
+
+		scst_do_job_active(&p_cmd_threads->active_cmd_list,
+			&p_cmd_threads->cmd_list_lock, false);
+	}
+	spin_unlock_irq(&p_cmd_threads->cmd_list_lock);
+
+	EXTRACHECKS_BUG_ON((p_cmd_threads->nr_threads == 1) &&
+		 !list_empty(&p_cmd_threads->active_cmd_list));
+
+	if (p_cmd_threads != &scst_main_cmd_threads) {
+		if (p_cmd_threads->nr_threads == 1)
+			p_cmd_threads->io_context = NULL;
+	}
+
+	PRINT_INFO("Processing thread %s (PID %d) finished", current->comm,
+		current->pid);
+	return 0;
+}
+
+void scst_cmd_tasklet(long p)
+{
+	struct scst_tasklet *t = (struct scst_tasklet *)p;
+
+	spin_lock_irq(&t->tasklet_lock);
+	scst_do_job_active(&t->tasklet_cmd_list, &t->tasklet_lock, true);
+	spin_unlock_irq(&t->tasklet_lock);
+	return;
+}
+
+/*
+ * Returns 0 on success, < 0 if there is no device handler or
+ * > 0 if SCST_FLAG_SUSPENDED set and SCST_FLAG_SUSPENDING - not.
+ * No locks, protection is done by the suspended activity.
+ */
+static int scst_mgmt_translate_lun(struct scst_mgmt_cmd *mcmd)
+{
+	struct scst_tgt_dev *tgt_dev = NULL;
+	struct list_head *sess_tgt_dev_list_head;
+	int res = -1;
+
+	TRACE_DBG("Finding tgt_dev for mgmt cmd %p (lun %lld)", mcmd,
+	      (long long unsigned int)mcmd->lun);
+
+	/* See comment about smp_mb() in scst_suspend_activity() */
+	__scst_get(1);
+
+	if (unlikely(test_bit(SCST_FLAG_SUSPENDED, &scst_flags) &&
+		     !test_bit(SCST_FLAG_SUSPENDING, &scst_flags))) {
+		TRACE_MGMT_DBG("%s", "FLAG SUSPENDED set, skipping");
+		__scst_put();
+		res = 1;
+		goto out;
+	}
+
+	sess_tgt_dev_list_head =
+		&mcmd->sess->sess_tgt_dev_list_hash[HASH_VAL(mcmd->lun)];
+	list_for_each_entry(tgt_dev, sess_tgt_dev_list_head,
+			sess_tgt_dev_list_entry) {
+		if (tgt_dev->lun == mcmd->lun) {
+			TRACE_DBG("tgt_dev %p found", tgt_dev);
+			mcmd->mcmd_tgt_dev = tgt_dev;
+			res = 0;
+			break;
+		}
+	}
+	if (mcmd->mcmd_tgt_dev == NULL)
+		__scst_put();
+
+out:
+	return res;
+}
+
+/* No locks */
+void scst_done_cmd_mgmt(struct scst_cmd *cmd)
+{
+	struct scst_mgmt_cmd_stub *mstb, *t;
+	bool wake = 0;
+	unsigned long flags;
+
+	TRACE_MGMT_DBG("cmd %p done (tag %llu)",
+		       cmd, (long long unsigned int)cmd->tag);
+
+	spin_lock_irqsave(&scst_mcmd_lock, flags);
+
+	list_for_each_entry_safe(mstb, t, &cmd->mgmt_cmd_list,
+			cmd_mgmt_cmd_list_entry) {
+		struct scst_mgmt_cmd *mcmd;
+
+		if (!mstb->done_counted)
+			continue;
+
+		mcmd = mstb->mcmd;
+		TRACE_MGMT_DBG("mcmd %p, mcmd->cmd_done_wait_count %d",
+			mcmd, mcmd->cmd_done_wait_count);
+
+		mcmd->cmd_done_wait_count--;
+
+		BUG_ON(mcmd->cmd_done_wait_count < 0);
+
+		if (mcmd->cmd_done_wait_count > 0) {
+			TRACE_MGMT_DBG("cmd_done_wait_count(%d) not 0, "
+				"skipping", mcmd->cmd_done_wait_count);
+			goto check_free;
+		}
+
+		if (mcmd->state == SCST_MCMD_STATE_WAITING_AFFECTED_CMDS_DONE) {
+			mcmd->state = SCST_MCMD_STATE_AFFECTED_CMDS_DONE;
+			TRACE_MGMT_DBG("Adding mgmt cmd %p to active mgmt cmd "
+				"list", mcmd);
+			list_add_tail(&mcmd->mgmt_cmd_list_entry,
+				&scst_active_mgmt_cmd_list);
+			wake = 1;
+		}
+
+check_free:
+		if (!mstb->finish_counted) {
+			TRACE_DBG("Releasing mstb %p", mstb);
+			list_del(&mstb->cmd_mgmt_cmd_list_entry);
+			mempool_free(mstb, scst_mgmt_stub_mempool);
+		}
+	}
+
+	spin_unlock_irqrestore(&scst_mcmd_lock, flags);
+
+	if (wake)
+		wake_up(&scst_mgmt_cmd_list_waitQ);
+	return;
+}
+
+/* Called under scst_mcmd_lock and IRQs disabled */
+static void __scst_dec_finish_wait_count(struct scst_mgmt_cmd *mcmd, bool *wake)
+{
+
+	mcmd->cmd_finish_wait_count--;
+
+	BUG_ON(mcmd->cmd_finish_wait_count < 0);
+
+	if (mcmd->cmd_finish_wait_count > 0) {
+		TRACE_MGMT_DBG("cmd_finish_wait_count(%d) not 0, "
+			"skipping", mcmd->cmd_finish_wait_count);
+		goto out;
+	}
+
+	if (mcmd->cmd_done_wait_count > 0) {
+		TRACE_MGMT_DBG("cmd_done_wait_count(%d) not 0, "
+			"skipping", mcmd->cmd_done_wait_count);
+		goto out;
+	}
+
+	if (mcmd->state == SCST_MCMD_STATE_WAITING_AFFECTED_CMDS_FINISHED) {
+		mcmd->state = SCST_MCMD_STATE_DONE;
+		TRACE_MGMT_DBG("Adding mgmt cmd %p to active mgmt cmd "
+			"list",	mcmd);
+		list_add_tail(&mcmd->mgmt_cmd_list_entry,
+			&scst_active_mgmt_cmd_list);
+		*wake = true;
+	}
+
+out:
+	return;
+}
+
+/**
+ * scst_prepare_async_mcmd() - prepare async management command
+ *
+ * Notifies SCST that management command is going to be async, i.e.
+ * will be completed in another context.
+ *
+ * No SCST locks supposed to be held on entrance.
+ */
+void scst_prepare_async_mcmd(struct scst_mgmt_cmd *mcmd)
+{
+	unsigned long flags;
+
+	TRACE_MGMT_DBG("Preparing mcmd %p for async execution "
+		"(cmd_finish_wait_count %d)", mcmd,
+		mcmd->cmd_finish_wait_count);
+
+	spin_lock_irqsave(&scst_mcmd_lock, flags);
+	mcmd->cmd_finish_wait_count++;
+	spin_unlock_irqrestore(&scst_mcmd_lock, flags);
+	return;
+}
+EXPORT_SYMBOL_GPL(scst_prepare_async_mcmd);
+
+/**
+ * scst_async_mcmd_completed() - async management command completed
+ *
+ * Notifies SCST that async management command, prepared by
+ * scst_prepare_async_mcmd(), completed.
+ *
+ * No SCST locks supposed to be held on entrance.
+ */
+void scst_async_mcmd_completed(struct scst_mgmt_cmd *mcmd, int status)
+{
+	unsigned long flags;
+	bool wake = false;
+
+	TRACE_MGMT_DBG("Async mcmd %p completed (status %d)", mcmd, status);
+
+	spin_lock_irqsave(&scst_mcmd_lock, flags);
+
+	if (status != SCST_MGMT_STATUS_SUCCESS)
+		mcmd->status = status;
+
+	__scst_dec_finish_wait_count(mcmd, &wake);
+
+	spin_unlock_irqrestore(&scst_mcmd_lock, flags);
+
+	if (wake)
+		wake_up(&scst_mgmt_cmd_list_waitQ);
+	return;
+}
+EXPORT_SYMBOL_GPL(scst_async_mcmd_completed);
+
+/* No locks */
+static void scst_finish_cmd_mgmt(struct scst_cmd *cmd)
+{
+	struct scst_mgmt_cmd_stub *mstb, *t;
+	bool wake = false;
+	unsigned long flags;
+
+	TRACE_MGMT_DBG("cmd %p finished (tag %llu)",
+		       cmd, (long long unsigned int)cmd->tag);
+
+	spin_lock_irqsave(&scst_mcmd_lock, flags);
+
+	list_for_each_entry_safe(mstb, t, &cmd->mgmt_cmd_list,
+			cmd_mgmt_cmd_list_entry) {
+		struct scst_mgmt_cmd *mcmd = mstb->mcmd;
+
+		TRACE_MGMT_DBG("mcmd %p, mcmd->cmd_finish_wait_count %d", mcmd,
+			mcmd->cmd_finish_wait_count);
+
+		BUG_ON(!mstb->finish_counted);
+
+		if (cmd->completed)
+			mcmd->completed_cmd_count++;
+
+		__scst_dec_finish_wait_count(mcmd, &wake);
+
+		TRACE_DBG("Releasing mstb %p", mstb);
+		list_del(&mstb->cmd_mgmt_cmd_list_entry);
+		mempool_free(mstb, scst_mgmt_stub_mempool);
+	}
+
+	spin_unlock_irqrestore(&scst_mcmd_lock, flags);
+
+	if (wake)
+		wake_up(&scst_mgmt_cmd_list_waitQ);
+	return;
+}
+
+static int scst_call_dev_task_mgmt_fn(struct scst_mgmt_cmd *mcmd,
+	struct scst_tgt_dev *tgt_dev, int set_status)
+{
+	int res = SCST_DEV_TM_NOT_COMPLETED;
+	struct scst_dev_type *h = tgt_dev->dev->handler;
+
+	if (h->task_mgmt_fn) {
+		TRACE_MGMT_DBG("Calling dev handler %s task_mgmt_fn(fn=%d)",
+			h->name, mcmd->fn);
+		EXTRACHECKS_BUG_ON(in_irq() || irqs_disabled());
+		res = h->task_mgmt_fn(mcmd, tgt_dev);
+		TRACE_MGMT_DBG("Dev handler %s task_mgmt_fn() returned %d",
+		      h->name, res);
+		if (set_status && (res != SCST_DEV_TM_NOT_COMPLETED))
+			mcmd->status = res;
+	}
+	return res;
+}
+
+static inline int scst_is_strict_mgmt_fn(int mgmt_fn)
+{
+	switch (mgmt_fn) {
+#ifdef CONFIG_SCST_ABORT_CONSIDER_FINISHED_TASKS_AS_NOT_EXISTING
+	case SCST_ABORT_TASK:
+#endif
+#if 0
+	case SCST_ABORT_TASK_SET:
+	case SCST_CLEAR_TASK_SET:
+#endif
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+/* Might be called under sess_list_lock and IRQ off + BHs also off */
+void scst_abort_cmd(struct scst_cmd *cmd, struct scst_mgmt_cmd *mcmd,
+	bool other_ini, bool call_dev_task_mgmt_fn)
+{
+	unsigned long flags;
+	static DEFINE_SPINLOCK(other_ini_lock);
+
+	TRACE(TRACE_MGMT, "Aborting cmd %p (tag %llu, op %x)",
+		cmd, (long long unsigned int)cmd->tag, cmd->cdb[0]);
+
+	/* To protect from concurrent aborts */
+	spin_lock_irqsave(&other_ini_lock, flags);
+
+	if (other_ini) {
+		struct scst_device *dev = NULL;
+
+		/* Might be necessary if command aborted several times */
+		if (!test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags))
+			set_bit(SCST_CMD_ABORTED_OTHER, &cmd->cmd_flags);
+
+		/* Necessary for scst_xmit_process_aborted_cmd */
+		if (cmd->dev != NULL)
+			dev = cmd->dev;
+		else if ((mcmd != NULL) && (mcmd->mcmd_tgt_dev != NULL))
+			dev = mcmd->mcmd_tgt_dev->dev;
+
+		if (dev != NULL) {
+			if (dev->tas)
+				set_bit(SCST_CMD_DEVICE_TAS, &cmd->cmd_flags);
+		} else
+			PRINT_WARNING("Abort cmd %p from other initiator, but "
+				"neither cmd, nor mcmd %p have tgt_dev set, so "
+				"TAS information can be lost", cmd, mcmd);
+	} else {
+		/* Might be necessary if command aborted several times */
+		clear_bit(SCST_CMD_ABORTED_OTHER, &cmd->cmd_flags);
+	}
+
+	set_bit(SCST_CMD_ABORTED, &cmd->cmd_flags);
+
+	spin_unlock_irqrestore(&other_ini_lock, flags);
+
+	/*
+	 * To sync with cmd->finished/done set in
+	 * scst_finish_cmd()/scst_pre_xmit_response()
+	 */
+	smp_mb__after_set_bit();
+
+	if (cmd->tgt_dev == NULL) {
+		spin_lock_irqsave(&scst_init_lock, flags);
+		scst_init_poll_cnt++;
+		spin_unlock_irqrestore(&scst_init_lock, flags);
+		wake_up(&scst_init_cmd_list_waitQ);
+	}
+
+	if (call_dev_task_mgmt_fn && (cmd->tgt_dev != NULL)) {
+		EXTRACHECKS_BUG_ON(irqs_disabled());
+		scst_call_dev_task_mgmt_fn(mcmd, cmd->tgt_dev, 1);
+	}
+
+	spin_lock_irqsave(&scst_mcmd_lock, flags);
+	if ((mcmd != NULL) && !cmd->finished) {
+		struct scst_mgmt_cmd_stub *mstb;
+
+		mstb = mempool_alloc(scst_mgmt_stub_mempool, GFP_ATOMIC);
+		if (mstb == NULL) {
+			PRINT_CRIT_ERROR("Allocation of management command "
+				"stub failed (mcmd %p, cmd %p)", mcmd, cmd);
+			goto unlock;
+		}
+		memset(mstb, 0, sizeof(*mstb));
+
+		TRACE_DBG("mstb %p, mcmd %p", mstb, mcmd);
+
+		mstb->mcmd = mcmd;
+
+		/*
+		 * Delay the response until the command's finish in order to
+		 * guarantee that "no further responses from the task are sent
+		 * to the SCSI initiator port" after response from the TM
+		 * function is sent (SAM). Plus, we must wait here to be sure
+		 * that we won't receive double commands with the same tag.
+		 * Moreover, if we don't wait here, we might have a possibility
+		 * for data corruption, when aborted and reported as completed
+		 * command actually gets executed *after* new commands sent
+		 * after this TM command completed.
+		 */
+
+		if (cmd->sent_for_exec && !cmd->done) {
+			TRACE_MGMT_DBG("cmd %p (tag %llu) is being executed",
+				cmd, (long long unsigned int)cmd->tag);
+			mstb->done_counted = 1;
+			mcmd->cmd_done_wait_count++;
+		}
+
+		/*
+		 * We don't have to wait the command's status delivery finish
+		 * to other initiators + it can affect MPIO failover.
+		 */
+		if (!other_ini) {
+			mstb->finish_counted = 1;
+			mcmd->cmd_finish_wait_count++;
+		}
+
+		if (mstb->done_counted || mstb->finish_counted) {
+			TRACE_MGMT_DBG("cmd %p (tag %llu, sn %u) being "
+				"executed/xmitted (state %d, op %x, proc time "
+				"%ld sec., timeout %d sec.), deferring ABORT "
+				"(cmd_done_wait_count %d, cmd_finish_wait_count "
+				"%d)", cmd, (long long unsigned int)cmd->tag,
+				cmd->sn, cmd->state, cmd->cdb[0],
+				(long)(jiffies - cmd->start_time) / HZ,
+				cmd->timeout / HZ, mcmd->cmd_done_wait_count,
+				mcmd->cmd_finish_wait_count);
+			/*
+			 * cmd can't die here or sess_list_lock already taken
+			 * and cmd is in the sess list
+			 */
+			list_add_tail(&mstb->cmd_mgmt_cmd_list_entry,
+				&cmd->mgmt_cmd_list);
+		} else {
+			/* We don't need to wait for this cmd */
+			mempool_free(mstb, scst_mgmt_stub_mempool);
+		}
+	}
+
+unlock:
+	spin_unlock_irqrestore(&scst_mcmd_lock, flags);
+
+	tm_dbg_release_cmd(cmd);
+	return;
+}
+
+/* No locks. Returns 0, if mcmd should be processed further. */
+static int scst_set_mcmd_next_state(struct scst_mgmt_cmd *mcmd)
+{
+	int res;
+
+	spin_lock_irq(&scst_mcmd_lock);
+
+	switch (mcmd->state) {
+	case SCST_MCMD_STATE_INIT:
+	case SCST_MCMD_STATE_EXEC:
+		if (mcmd->cmd_done_wait_count == 0) {
+			mcmd->state = SCST_MCMD_STATE_AFFECTED_CMDS_DONE;
+			res = 0;
+		} else {
+			TRACE_MGMT_DBG("cmd_done_wait_count(%d) not 0, "
+				"preparing to wait", mcmd->cmd_done_wait_count);
+			mcmd->state = SCST_MCMD_STATE_WAITING_AFFECTED_CMDS_DONE;
+			res = -1;
+		}
+		break;
+
+	case SCST_MCMD_STATE_AFFECTED_CMDS_DONE:
+		if (mcmd->cmd_finish_wait_count == 0) {
+			mcmd->state = SCST_MCMD_STATE_DONE;
+			res = 0;
+		} else {
+			TRACE_MGMT_DBG("cmd_finish_wait_count(%d) not 0, "
+				"preparing to wait",
+				mcmd->cmd_finish_wait_count);
+			mcmd->state = SCST_MCMD_STATE_WAITING_AFFECTED_CMDS_FINISHED;
+			res = -1;
+		}
+		break;
+
+	case SCST_MCMD_STATE_DONE:
+		mcmd->state = SCST_MCMD_STATE_FINISHED;
+		res = 0;
+		break;
+
+	default:
+		PRINT_CRIT_ERROR("Wrong mcmd %p state %d (fn %d, "
+			"cmd_finish_wait_count %d, cmd_done_wait_count %d)",
+			mcmd, mcmd->state, mcmd->fn,
+			mcmd->cmd_finish_wait_count, mcmd->cmd_done_wait_count);
+		spin_unlock_irq(&scst_mcmd_lock);
+		res = -1;
+		BUG();
+		goto out;
+	}
+
+	spin_unlock_irq(&scst_mcmd_lock);
+
+out:
+	return res;
+}
+
+/* IRQs supposed to be disabled */
+static bool __scst_check_unblock_aborted_cmd(struct scst_cmd *cmd,
+	struct list_head *list_entry)
+{
+	bool res;
+	if (test_bit(SCST_CMD_ABORTED, &cmd->cmd_flags)) {
+		list_del(list_entry);
+		spin_lock(&cmd->cmd_threads->cmd_list_lock);
+		list_add_tail(&cmd->cmd_list_entry,
+			&cmd->cmd_threads->active_cmd_list);
+		wake_up(&cmd->cmd_threads->cmd_list_waitQ);
+		spin_unlock(&cmd->cmd_threads->cmd_list_lock);
+		res = 1;
+	} else
+		res = 0;
+	return res;
+}
+
+static void scst_unblock_aborted_cmds(int scst_mutex_held)
+{
+	struct scst_device *dev;
+
+	if (!scst_mutex_held)
+		mutex_lock(&scst_mutex);
+
+	list_for_each_entry(dev, &scst_dev_list, dev_list_entry) {
+		struct scst_cmd *cmd, *tcmd;
+		struct scst_tgt_dev *tgt_dev;
+		spin_lock_bh(&dev->dev_lock);
+		local_irq_disable();
+		list_for_each_entry_safe(cmd, tcmd, &dev->blocked_cmd_list,
+					blocked_cmd_list_entry) {
+			if (__scst_check_unblock_aborted_cmd(cmd,
+					&cmd->blocked_cmd_list_entry)) {
+				TRACE_MGMT_DBG("Unblock aborted blocked cmd %p",
+					cmd);
+			}
+		}
+		local_irq_enable();
+		spin_unlock_bh(&dev->dev_lock);
+
+		local_irq_disable();
+		list_for_each_entry(tgt_dev, &dev->dev_tgt_dev_list,
+					 dev_tgt_dev_list_entry) {
+			spin_lock(&tgt_dev->sn_lock);
+			list_for_each_entry_safe(cmd, tcmd,
+					&tgt_dev->deferred_cmd_list,
+					sn_cmd_list_entry) {
+				if (__scst_check_unblock_aborted_cmd(cmd,
+						&cmd->sn_cmd_list_entry)) {
+					TRACE_MGMT_DBG("Unblocked aborted SN "
+						"cmd %p (sn %u)",
+						cmd, cmd->sn);
+					tgt_dev->def_cmd_count--;
+				}
+			}
+			spin_unlock(&tgt_dev->sn_lock);
+		}
+		local_irq_enable();
+	}
+
+	if (!scst_mutex_held)
+		mutex_unlock(&scst_mutex);
+	return;
+}
+
+static void __scst_abort_task_set(struct scst_mgmt_cmd *mcmd,
+	struct scst_tgt_dev *tgt_dev)
+{
+	struct scst_cmd *cmd;
+	struct scst_session *sess = tgt_dev->sess;
+	bool other_ini;
+
+	if ((mcmd->fn == SCST_PR_ABORT_ALL) &&
+	    (mcmd->origin_pr_cmd->sess != sess))
+		other_ini = true;
+	else
+		other_ini = false;
+
+	spin_lock_irq(&sess->sess_list_lock);
+
+	TRACE_DBG("Searching in sess cmd list (sess=%p)", sess);
+	list_for_each_entry(cmd, &sess->sess_cmd_list,
+			    sess_cmd_list_entry) {
+		if ((mcmd->fn == SCST_PR_ABORT_ALL) &&
+		    (mcmd->origin_pr_cmd == cmd))
+			continue;
+		if ((cmd->tgt_dev == tgt_dev) ||
+		    ((cmd->tgt_dev == NULL) &&
+		     (cmd->lun == tgt_dev->lun))) {
+			if (mcmd->cmd_sn_set) {
+				BUG_ON(!cmd->tgt_sn_set);
+				if (scst_sn_before(mcmd->cmd_sn, cmd->tgt_sn) ||
+				    (mcmd->cmd_sn == cmd->tgt_sn))
+					continue;
+			}
+			scst_abort_cmd(cmd, mcmd, other_ini, 0);
+		}
+	}
+	spin_unlock_irq(&sess->sess_list_lock);
+	return;
+}
+
+/* Returns 0 if the command processing should be continued, <0 otherwise */
+static int scst_abort_task_set(struct scst_mgmt_cmd *mcmd)
+{
+	int res;
+	struct scst_tgt_dev *tgt_dev = mcmd->mcmd_tgt_dev;
+
+	TRACE(TRACE_MGMT, "Aborting task set (lun=%lld, mcmd=%p)",
+	      (long long unsigned int)tgt_dev->lun, mcmd);
+
+	__scst_abort_task_set(mcmd, tgt_dev);
+
+	if (atomic_dec_and_test(&mcmd->origin_pr_cmd->pr_abort_counter->pr_aborting_cnt))
+		complete_all(&mcmd->origin_pr_cmd->pr_abort_counter->pr_aborting_cmpl);
+
+	tm_dbg_task_mgmt(mcmd->mcmd_tgt_dev->dev, "ABORT TASK SET/PR ABORT", 0);
+
+	scst_unblock_aborted_cmds(0);
+
+	scst_call_dev_task_mgmt_fn(mcmd, tgt_dev, 0);
+
+	res = scst_set_mcmd_next_state(mcmd);
+	return res;
+}
+
+static int scst_is_cmd_belongs_to_dev(struct scst_cmd *cmd,
+	struct scst_device *dev)
+{
+	struct scst_tgt_dev *tgt_dev = NULL;
+	struct list_head *sess_tgt_dev_list_head;
+	int res = 0;
+
+	TRACE_DBG("Finding match for dev %p and cmd %p (lun %lld)", dev, cmd,
+	      (long long unsigned int)cmd->lun);
+
+	sess_tgt_dev_list_head =
+		&cmd->sess->sess_tgt_dev_list_hash[HASH_VAL(cmd->lun)];
+	list_for_each_entry(tgt_dev, sess_tgt_dev_list_head,
+			sess_tgt_dev_list_entry) {
+		if (tgt_dev->lun == cmd->lun) {
+			TRACE_DBG("dev %p found", tgt_dev->dev);
+			res = (tgt_dev->dev == dev);
+			goto out;
+		}
+	}
+
+out:
+	return res;
+}
+
+/* Returns 0 if the command processing should be continued, <0 otherwise */
+static int scst_clear_task_set(struct scst_mgmt_cmd *mcmd)
+{
+	int res;
+	struct scst_device *dev = mcmd->mcmd_tgt_dev->dev;
+	struct scst_tgt_dev *tgt_dev;
+	LIST_HEAD(UA_tgt_devs);
+
+	TRACE(TRACE_MGMT, "Clearing task set (lun=%lld, mcmd=%p)",
+		(long long unsigned int)mcmd->lun, mcmd);
+
+#if 0 /* we are SAM-3 */
+	/*
+	 * When a logical unit is aborting one or more tasks from a SCSI
+	 * initiator port with the TASK ABORTED status it should complete all
+	 * of those tasks before entering additional tasks from that SCSI
+	 * initiator port into the task set - SAM2
+	 */
+	mcmd->needs_unblocking = 1;
+	spin_lock_bh(&dev->dev_lock);
+	__scst_block_dev(dev);
+	spin_unlock_bh(&dev->dev_lock);
+#endif
+
+	__scst_abort_task_set(mcmd, mcmd->mcmd_tgt_dev);
+
+	mutex_lock(&scst_mutex);
+
+	list_for_each_entry(tgt_dev, &dev->dev_tgt_dev_list,
+			dev_tgt_dev_list_entry) {
+		struct scst_session *sess = tgt_dev->sess;
+		struct scst_cmd *cmd;
+		int aborted = 0;
+
+		if (tgt_dev == mcmd->mcmd_tgt_dev)
+			continue;
+
+		spin_lock_irq(&sess->sess_list_lock);
+
+		TRACE_DBG("Searching in sess cmd list (sess=%p)", sess);
+		list_for_each_entry(cmd, &sess->sess_cmd_list,
+				    sess_cmd_list_entry) {
+			if ((cmd->dev == dev) ||
+			    ((cmd->dev == NULL) &&
+			     scst_is_cmd_belongs_to_dev(cmd, dev))) {
+				scst_abort_cmd(cmd, mcmd, 1, 0);
+				aborted = 1;
+			}
+		}
+		spin_unlock_irq(&sess->sess_list_lock);
+
+		if (aborted)
+			list_add_tail(&tgt_dev->extra_tgt_dev_list_entry,
+					&UA_tgt_devs);
+	}
+
+	tm_dbg_task_mgmt(mcmd->mcmd_tgt_dev->dev, "CLEAR TASK SET", 0);
+
+	scst_unblock_aborted_cmds(1);
+
+	mutex_unlock(&scst_mutex);
+
+	if (!dev->tas) {
+		uint8_t sense_buffer[SCST_STANDARD_SENSE_LEN];
+		int sl;
+
+		sl = scst_set_sense(sense_buffer, sizeof(sense_buffer),
+			dev->d_sense,
+			SCST_LOAD_SENSE(scst_sense_cleared_by_another_ini_UA));
+
+		list_for_each_entry(tgt_dev, &UA_tgt_devs,
+				extra_tgt_dev_list_entry) {
+			scst_check_set_UA(tgt_dev, sense_buffer, sl, 0);
+		}
+	}
+
+	scst_call_dev_task_mgmt_fn(mcmd, mcmd->mcmd_tgt_dev, 0);
+
+	res = scst_set_mcmd_next_state(mcmd);
+	return res;
+}
+
+/* Returns 0 if the command processing should be continued,
+ * >0, if it should be requeued, <0 otherwise */
+static int scst_mgmt_cmd_init(struct scst_mgmt_cmd *mcmd)
+{
+	int res = 0, rc;
+
+	switch (mcmd->fn) {
+	case SCST_ABORT_TASK:
+	{
+		struct scst_session *sess = mcmd->sess;
+		struct scst_cmd *cmd;
+
+		spin_lock_irq(&sess->sess_list_lock);
+		cmd = __scst_find_cmd_by_tag(sess, mcmd->tag, true);
+		if (cmd == NULL) {
+			TRACE_MGMT_DBG("ABORT TASK: command "
+			      "for tag %llu not found",
+			      (long long unsigned int)mcmd->tag);
+			mcmd->status = SCST_MGMT_STATUS_TASK_NOT_EXIST;
+			spin_unlock_irq(&sess->sess_list_lock);
+			res = scst_set_mcmd_next_state(mcmd);
+			goto out;
+		}
+		__scst_cmd_get(cmd);
+		spin_unlock_irq(&sess->sess_list_lock);
+		TRACE_DBG("Cmd to abort %p for tag %llu found",
+			cmd, (long long unsigned int)mcmd->tag);
+		mcmd->cmd_to_abort = cmd;
+		mcmd->state = SCST_MCMD_STATE_EXEC;
+		break;
+	}
+
+	case SCST_TARGET_RESET:
+	case SCST_NEXUS_LOSS_SESS:
+	case SCST_ABORT_ALL_TASKS_SESS:
+	case SCST_NEXUS_LOSS:
+	case SCST_ABORT_ALL_TASKS:
+	case SCST_UNREG_SESS_TM:
+		mcmd->state = SCST_MCMD_STATE_EXEC;
+		break;
+
+	case SCST_ABORT_TASK_SET:
+	case SCST_CLEAR_ACA:
+	case SCST_CLEAR_TASK_SET:
+	case SCST_LUN_RESET:
+	case SCST_PR_ABORT_ALL:
+		rc = scst_mgmt_translate_lun(mcmd);
+		if (rc == 0)
+			mcmd->state = SCST_MCMD_STATE_EXEC;
+		else if (rc < 0) {
+			PRINT_ERROR("Corresponding device for LUN %lld not "
+				"found", (long long unsigned int)mcmd->lun);
+			mcmd->status = SCST_MGMT_STATUS_LUN_NOT_EXIST;
+			res = scst_set_mcmd_next_state(mcmd);
+		} else
+			res = rc;
+		break;
+
+	default:
+		BUG();
+	}
+
+out:
+	return res;
+}
+
+/* Returns 0 if the command processing should be continued, <0 otherwise */
+static int scst_target_reset(struct scst_mgmt_cmd *mcmd)
+{
+	int res, rc;
+	struct scst_device *dev;
+	struct scst_acg *acg = mcmd->sess->acg;
+	struct scst_acg_dev *acg_dev;
+	int cont, c;
+	LIST_HEAD(host_devs);
+
+	TRACE(TRACE_MGMT, "Target reset (mcmd %p, cmd count %d)",
+		mcmd, atomic_read(&mcmd->sess->sess_cmd_count));
+
+	mcmd->needs_unblocking = 1;
+
+	mutex_lock(&scst_mutex);
+
+	list_for_each_entry(acg_dev, &acg->acg_dev_list, acg_dev_list_entry) {
+		struct scst_device *d;
+		struct scst_tgt_dev *tgt_dev;
+		int found = 0;
+
+		dev = acg_dev->dev;
+
+		spin_lock_bh(&dev->dev_lock);
+		__scst_block_dev(dev);
+		scst_process_reset(dev, mcmd->sess, NULL, mcmd, true);
+		spin_unlock_bh(&dev->dev_lock);
+
+		cont = 0;
+		c = 0;
+		list_for_each_entry(tgt_dev, &dev->dev_tgt_dev_list,
+				dev_tgt_dev_list_entry) {
+			cont = 1;
+			if (mcmd->sess == tgt_dev->sess) {
+				rc = scst_call_dev_task_mgmt_fn(mcmd,
+						tgt_dev, 0);
+				if (rc == SCST_DEV_TM_NOT_COMPLETED)
+					c = 1;
+				else if ((rc < 0) &&
+					 (mcmd->status == SCST_MGMT_STATUS_SUCCESS))
+					mcmd->status = rc;
+				break;
+			}
+		}
+		if (cont && !c)
+			continue;
+
+		if (dev->scsi_dev == NULL)
+			continue;
+
+		list_for_each_entry(d, &host_devs, tm_dev_list_entry) {
+			if (dev->scsi_dev->host->host_no ==
+				    d->scsi_dev->host->host_no) {
+				found = 1;
+				break;
+			}
+		}
+		if (!found)
+			list_add_tail(&dev->tm_dev_list_entry, &host_devs);
+
+		tm_dbg_task_mgmt(dev, "TARGET RESET", 0);
+	}
+
+	scst_unblock_aborted_cmds(1);
+
+	/*
+	 * We suppose here that for all commands that already on devices
+	 * on/after scsi_reset_provider() completion callbacks will be called.
+	 */
+
+	list_for_each_entry(dev, &host_devs, tm_dev_list_entry) {
+		/* dev->scsi_dev must be non-NULL here */
+		TRACE(TRACE_MGMT, "Resetting host %d bus ",
+			dev->scsi_dev->host->host_no);
+		rc = scsi_reset_provider(dev->scsi_dev, SCSI_TRY_RESET_TARGET);
+		TRACE(TRACE_MGMT, "Result of host %d target reset: %s",
+		      dev->scsi_dev->host->host_no,
+		      (rc == SUCCESS) ? "SUCCESS" : "FAILED");
+#if 0
+		if ((rc != SUCCESS) &&
+		    (mcmd->status == SCST_MGMT_STATUS_SUCCESS)) {
+			/*
+			 * SCSI_TRY_RESET_BUS is also done by
+			 * scsi_reset_provider()
+			 */
+			mcmd->status = SCST_MGMT_STATUS_FAILED;
+		}
+#else
+	/*
+	 * scsi_reset_provider() returns very weird status, so let's
+	 * always succeed
+	 */
+#endif
+	}
+
+	list_for_each_entry(acg_dev, &acg->acg_dev_list, acg_dev_list_entry) {
+		dev = acg_dev->dev;
+		if (dev->scsi_dev != NULL)
+			dev->scsi_dev->was_reset = 0;
+	}
+
+	mutex_unlock(&scst_mutex);
+
+	res = scst_set_mcmd_next_state(mcmd);
+	return res;
+}
+
+/* Returns 0 if the command processing should be continued, <0 otherwise */
+static int scst_lun_reset(struct scst_mgmt_cmd *mcmd)
+{
+	int res, rc;
+	struct scst_tgt_dev *tgt_dev = mcmd->mcmd_tgt_dev;
+	struct scst_device *dev = tgt_dev->dev;
+
+	TRACE(TRACE_MGMT, "Resetting LUN %lld (mcmd %p)",
+	      (long long unsigned int)tgt_dev->lun, mcmd);
+
+	mcmd->needs_unblocking = 1;
+
+	spin_lock_bh(&dev->dev_lock);
+	__scst_block_dev(dev);
+	scst_process_reset(dev, mcmd->sess, NULL, mcmd, true);
+	spin_unlock_bh(&dev->dev_lock);
+
+	rc = scst_call_dev_task_mgmt_fn(mcmd, tgt_dev, 1);
+	if (rc != SCST_DEV_TM_NOT_COMPLETED)
+		goto out_tm_dbg;
+
+	if (dev->scsi_dev != NULL) {
+		TRACE(TRACE_MGMT, "Resetting host %d bus ",
+		      dev->scsi_dev->host->host_no);
+		rc = scsi_reset_provider(dev->scsi_dev, SCSI_TRY_RESET_DEVICE);
+#if 0
+		if (rc != SUCCESS && mcmd->status == SCST_MGMT_STATUS_SUCCESS)
+			mcmd->status = SCST_MGMT_STATUS_FAILED;
+#else
+		/*
+		 * scsi_reset_provider() returns very weird status, so let's
+		 * always succeed
+		 */
+#endif
+		dev->scsi_dev->was_reset = 0;
+	}
+
+	scst_unblock_aborted_cmds(0);
+
+out_tm_dbg:
+	tm_dbg_task_mgmt(mcmd->mcmd_tgt_dev->dev, "LUN RESET", 0);
+
+	res = scst_set_mcmd_next_state(mcmd);
+	return res;
+}
+
+/* scst_mutex supposed to be held */
+static void scst_do_nexus_loss_sess(struct scst_mgmt_cmd *mcmd)
+{
+	int i;
+	struct scst_session *sess = mcmd->sess;
+	struct scst_tgt_dev *tgt_dev;
+
+	for (i = 0; i < TGT_DEV_HASH_SIZE; i++) {
+		struct list_head *sess_tgt_dev_list_head =
+			&sess->sess_tgt_dev_list_hash[i];
+		list_for_each_entry(tgt_dev, sess_tgt_dev_list_head,
+				sess_tgt_dev_list_entry) {
+			scst_nexus_loss(tgt_dev,
+				(mcmd->fn != SCST_UNREG_SESS_TM));
+		}
+	}
+	return;
+}
+
+/* Returns 0 if the command processing should be continued, <0 otherwise */
+static int scst_abort_all_nexus_loss_sess(struct scst_mgmt_cmd *mcmd,
+	int nexus_loss)
+{
+	int res;
+	int i;
+	struct scst_session *sess = mcmd->sess;
+	struct scst_tgt_dev *tgt_dev;
+
+	if (nexus_loss) {
+		TRACE_MGMT_DBG("Nexus loss for sess %p (mcmd %p)",
+			sess, mcmd);
+	} else {
+		TRACE_MGMT_DBG("Aborting all from sess %p (mcmd %p)",
+			sess, mcmd);
+	}
+
+	mutex_lock(&scst_mutex);
+
+	for (i = 0; i < TGT_DEV_HASH_SIZE; i++) {
+		struct list_head *sess_tgt_dev_list_head =
+			&sess->sess_tgt_dev_list_hash[i];
+		list_for_each_entry(tgt_dev, sess_tgt_dev_list_head,
+				sess_tgt_dev_list_entry) {
+			int rc;
+
+			__scst_abort_task_set(mcmd, tgt_dev);
+
+			rc = scst_call_dev_task_mgmt_fn(mcmd, tgt_dev, 0);
+			if (rc < 0 && mcmd->status == SCST_MGMT_STATUS_SUCCESS)
+				mcmd->status = rc;
+
+			tm_dbg_task_mgmt(tgt_dev->dev, "NEXUS LOSS SESS or "
+				"ABORT ALL SESS or UNREG SESS",
+				(mcmd->fn == SCST_UNREG_SESS_TM));
+		}
+	}
+
+	scst_unblock_aborted_cmds(1);
+
+	mutex_unlock(&scst_mutex);
+
+	res = scst_set_mcmd_next_state(mcmd);
+	return res;
+}
+
+/* scst_mutex supposed to be held */
+static void scst_do_nexus_loss_tgt(struct scst_mgmt_cmd *mcmd)
+{
+	int i;
+	struct scst_tgt *tgt = mcmd->sess->tgt;
+	struct scst_session *sess;
+
+	list_for_each_entry(sess, &tgt->sess_list, sess_list_entry) {
+		for (i = 0; i < TGT_DEV_HASH_SIZE; i++) {
+			struct list_head *sess_tgt_dev_list_head =
+				&sess->sess_tgt_dev_list_hash[i];
+			struct scst_tgt_dev *tgt_dev;
+			list_for_each_entry(tgt_dev, sess_tgt_dev_list_head,
+					sess_tgt_dev_list_entry) {
+				scst_nexus_loss(tgt_dev, true);
+			}
+		}
+	}
+	return;
+}
+
+static int scst_abort_all_nexus_loss_tgt(struct scst_mgmt_cmd *mcmd,
+	int nexus_loss)
+{
+	int res;
+	int i;
+	struct scst_tgt *tgt = mcmd->sess->tgt;
+	struct scst_session *sess;
+
+	if (nexus_loss) {
+		TRACE_MGMT_DBG("I_T Nexus loss (tgt %p, mcmd %p)",
+			tgt, mcmd);
+	} else {
+		TRACE_MGMT_DBG("Aborting all from tgt %p (mcmd %p)",
+			tgt, mcmd);
+	}
+
+	mutex_lock(&scst_mutex);
+
+	list_for_each_entry(sess, &tgt->sess_list, sess_list_entry) {
+		for (i = 0; i < TGT_DEV_HASH_SIZE; i++) {
+			struct list_head *sess_tgt_dev_list_head =
+				&sess->sess_tgt_dev_list_hash[i];
+			struct scst_tgt_dev *tgt_dev;
+			list_for_each_entry(tgt_dev, sess_tgt_dev_list_head,
+					sess_tgt_dev_list_entry) {
+				int rc;
+
+				__scst_abort_task_set(mcmd, tgt_dev);
+
+				if (nexus_loss)
+					scst_nexus_loss(tgt_dev, true);
+
+				if (mcmd->sess == tgt_dev->sess) {
+					rc = scst_call_dev_task_mgmt_fn(
+						mcmd, tgt_dev, 0);
+					if ((rc < 0) &&
+					    (mcmd->status == SCST_MGMT_STATUS_SUCCESS))
+						mcmd->status = rc;
+				}
+
+				tm_dbg_task_mgmt(tgt_dev->dev, "NEXUS LOSS or "
+					"ABORT ALL", 0);
+			}
+		}
+	}
+
+	scst_unblock_aborted_cmds(1);
+
+	mutex_unlock(&scst_mutex);
+
+	res = scst_set_mcmd_next_state(mcmd);
+	return res;
+}
+
+static int scst_abort_task(struct scst_mgmt_cmd *mcmd)
+{
+	int res;
+	struct scst_cmd *cmd = mcmd->cmd_to_abort;
+
+	TRACE_MGMT_DBG("Abortind task (cmd %p, sn %d, set %d, tag %llu, "
+		"queue_type %x)", cmd, cmd->sn, cmd->sn_set,
+		(long long unsigned int)mcmd->tag, cmd->queue_type);
+
+	if (mcmd->lun_set && (mcmd->lun != cmd->lun)) {
+		PRINT_ERROR("ABORT TASK: LUN mismatch: mcmd LUN %llx, "
+			"cmd LUN %llx, cmd tag %llu",
+			(long long unsigned int)mcmd->lun,
+			(long long unsigned int)cmd->lun,
+			(long long unsigned int)mcmd->tag);
+		mcmd->status = SCST_MGMT_STATUS_REJECTED;
+	} else if (mcmd->cmd_sn_set &&
+		   (scst_sn_before(mcmd->cmd_sn, cmd->tgt_sn) ||
+		    (mcmd->cmd_sn == cmd->tgt_sn))) {
+		PRINT_ERROR("ABORT TASK: SN mismatch: mcmd SN %x, "
+			"cmd SN %x, cmd tag %llu", mcmd->cmd_sn,
+			cmd->tgt_sn, (long long unsigned int)mcmd->tag);
+		mcmd->status = SCST_MGMT_STATUS_REJECTED;
+	} else {
+		scst_abort_cmd(cmd, mcmd, 0, 1);
+		scst_unblock_aborted_cmds(0);
+	}
+
+	res = scst_set_mcmd_next_state(mcmd);
+
+	mcmd->cmd_to_abort = NULL; /* just in case */
+
+	__scst_cmd_put(cmd);
+	return res;
+}
+
+/* Returns 0 if the command processing should be continued, <0 otherwise */
+static int scst_mgmt_cmd_exec(struct scst_mgmt_cmd *mcmd)
+{
+	int res = 0;
+
+	mcmd->status = SCST_MGMT_STATUS_SUCCESS;
+
+	switch (mcmd->fn) {
+	case SCST_ABORT_TASK:
+		res = scst_abort_task(mcmd);
+		break;
+
+	case SCST_ABORT_TASK_SET:
+	case SCST_PR_ABORT_ALL:
+		res = scst_abort_task_set(mcmd);
+		break;
+
+	case SCST_CLEAR_TASK_SET:
+		if (mcmd->mcmd_tgt_dev->dev->tst ==
+				SCST_CONTR_MODE_SEP_TASK_SETS)
+			res = scst_abort_task_set(mcmd);
+		else
+			res = scst_clear_task_set(mcmd);
+		break;
+
+	case SCST_LUN_RESET:
+		res = scst_lun_reset(mcmd);
+		break;
+
+	case SCST_TARGET_RESET:
+		res = scst_target_reset(mcmd);
+		break;
+
+	case SCST_ABORT_ALL_TASKS_SESS:
+		res = scst_abort_all_nexus_loss_sess(mcmd, 0);
+		break;
+
+	case SCST_NEXUS_LOSS_SESS:
+	case SCST_UNREG_SESS_TM:
+		res = scst_abort_all_nexus_loss_sess(mcmd, 1);
+		break;
+
+	case SCST_ABORT_ALL_TASKS:
+		res = scst_abort_all_nexus_loss_tgt(mcmd, 0);
+		break;
+
+	case SCST_NEXUS_LOSS:
+		res = scst_abort_all_nexus_loss_tgt(mcmd, 1);
+		break;
+
+	case SCST_CLEAR_ACA:
+		if (scst_call_dev_task_mgmt_fn(mcmd, mcmd->mcmd_tgt_dev, 1) ==
+				SCST_DEV_TM_NOT_COMPLETED) {
+			mcmd->status = SCST_MGMT_STATUS_FN_NOT_SUPPORTED;
+			/* Nothing to do (yet) */
+		}
+		goto out_done;
+
+	default:
+		PRINT_ERROR("Unknown task management function %d", mcmd->fn);
+		mcmd->status = SCST_MGMT_STATUS_REJECTED;
+		goto out_done;
+	}
+
+out:
+	return res;
+
+out_done:
+	res = scst_set_mcmd_next_state(mcmd);
+	goto out;
+}
+
+static void scst_call_task_mgmt_affected_cmds_done(struct scst_mgmt_cmd *mcmd)
+{
+	struct scst_session *sess = mcmd->sess;
+
+	if ((sess->tgt->tgtt->task_mgmt_affected_cmds_done != NULL) &&
+	    (mcmd->fn != SCST_UNREG_SESS_TM) &&
+	    (mcmd->fn != SCST_PR_ABORT_ALL)) {
+		TRACE_DBG("Calling target %s task_mgmt_affected_cmds_done(%p)",
+			sess->tgt->tgtt->name, sess);
+		sess->tgt->tgtt->task_mgmt_affected_cmds_done(mcmd);
+		TRACE_MGMT_DBG("Target's %s task_mgmt_affected_cmds_done() "
+			"returned", sess->tgt->tgtt->name);
+	}
+	return;
+}
+
+static int scst_mgmt_affected_cmds_done(struct scst_mgmt_cmd *mcmd)
+{
+	int res;
+
+	mutex_lock(&scst_mutex);
+
+	switch (mcmd->fn) {
+	case SCST_NEXUS_LOSS_SESS:
+	case SCST_UNREG_SESS_TM:
+		scst_do_nexus_loss_sess(mcmd);
+		break;
+
+	case SCST_NEXUS_LOSS:
+		scst_do_nexus_loss_tgt(mcmd);
+		break;
+	}
+
+	mutex_unlock(&scst_mutex);
+
+	scst_call_task_mgmt_affected_cmds_done(mcmd);
+
+	res = scst_set_mcmd_next_state(mcmd);
+	return res;
+}
+
+static void scst_mgmt_cmd_send_done(struct scst_mgmt_cmd *mcmd)
+{
+	struct scst_device *dev;
+	struct scst_session *sess = mcmd->sess;
+
+	mcmd->state = SCST_MCMD_STATE_FINISHED;
+	if (scst_is_strict_mgmt_fn(mcmd->fn) && (mcmd->completed_cmd_count > 0))
+		mcmd->status = SCST_MGMT_STATUS_TASK_NOT_EXIST;
+
+	TRACE(TRACE_MINOR_AND_MGMT_DBG, "TM command fn %d finished, "
+		"status %x", mcmd->fn, mcmd->status);
+
+	if (mcmd->fn == SCST_PR_ABORT_ALL) {
+		mcmd->origin_pr_cmd->scst_cmd_done(mcmd->origin_pr_cmd,
+					SCST_CMD_STATE_DEFAULT,
+					SCST_CONTEXT_THREAD);
+	} else if ((sess->tgt->tgtt->task_mgmt_fn_done != NULL) &&
+		   (mcmd->fn != SCST_UNREG_SESS_TM)) {
+		TRACE_DBG("Calling target %s task_mgmt_fn_done(%p)",
+			sess->tgt->tgtt->name, sess);
+		sess->tgt->tgtt->task_mgmt_fn_done(mcmd);
+		TRACE_MGMT_DBG("Target's %s task_mgmt_fn_done() "
+			"returned", sess->tgt->tgtt->name);
+	}
+
+	if (mcmd->needs_unblocking) {
+		switch (mcmd->fn) {
+		case SCST_LUN_RESET:
+		case SCST_CLEAR_TASK_SET:
+			scst_unblock_dev(mcmd->mcmd_tgt_dev->dev);
+			break;
+
+		case SCST_TARGET_RESET:
+		{
+			struct scst_acg *acg = mcmd->sess->acg;
+			struct scst_acg_dev *acg_dev;
+
+			mutex_lock(&scst_mutex);
+			list_for_each_entry(acg_dev, &acg->acg_dev_list,
+					acg_dev_list_entry) {
+				dev = acg_dev->dev;
+				scst_unblock_dev(dev);
+			}
+			mutex_unlock(&scst_mutex);
+			break;
+		}
+
+		default:
+			BUG();
+			break;
+		}
+	}
+
+	mcmd->tgt_priv = NULL;
+	return;
+}
+
+/* Returns >0, if cmd should be requeued */
+static int scst_process_mgmt_cmd(struct scst_mgmt_cmd *mcmd)
+{
+	int res = 0;
+
+	/*
+	 * We are in the TM thread and mcmd->state guaranteed to not be
+	 * changed behind us.
+	 */
+
+	TRACE_DBG("mcmd %p, state %d", mcmd, mcmd->state);
+
+	while (1) {
+		switch (mcmd->state) {
+		case SCST_MCMD_STATE_INIT:
+			res = scst_mgmt_cmd_init(mcmd);
+			if (res)
+				goto out;
+			break;
+
+		case SCST_MCMD_STATE_EXEC:
+			if (scst_mgmt_cmd_exec(mcmd))
+				goto out;
+			break;
+
+		case SCST_MCMD_STATE_AFFECTED_CMDS_DONE:
+			if (scst_mgmt_affected_cmds_done(mcmd))
+				goto out;
+			break;
+
+		case SCST_MCMD_STATE_DONE:
+			scst_mgmt_cmd_send_done(mcmd);
+			break;
+
+		case SCST_MCMD_STATE_FINISHED:
+			scst_free_mgmt_cmd(mcmd);
+			/* mcmd is dead */
+			goto out;
+
+		default:
+			PRINT_CRIT_ERROR("Wrong mcmd %p state %d (fn %d, "
+				"cmd_finish_wait_count %d, cmd_done_wait_count "
+				"%d)", mcmd, mcmd->state, mcmd->fn,
+				mcmd->cmd_finish_wait_count,
+				mcmd->cmd_done_wait_count);
+			BUG();
+			res = -1;
+			goto out;
+		}
+	}
+
+out:
+	return res;
+}
+
+static inline int test_mgmt_cmd_list(void)
+{
+	int res = !list_empty(&scst_active_mgmt_cmd_list) ||
+		  unlikely(kthread_should_stop());
+	return res;
+}
+
+int scst_tm_thread(void *arg)
+{
+
+	PRINT_INFO("Task management thread started, PID %d", current->pid);
+
+	current->flags |= PF_NOFREEZE;
+
+	set_user_nice(current, -10);
+
+	spin_lock_irq(&scst_mcmd_lock);
+	while (!kthread_should_stop()) {
+		wait_queue_t wait;
+		init_waitqueue_entry(&wait, current);
+
+		if (!test_mgmt_cmd_list()) {
+			add_wait_queue_exclusive(&scst_mgmt_cmd_list_waitQ,
+						 &wait);
+			for (;;) {
+				set_current_state(TASK_INTERRUPTIBLE);
+				if (test_mgmt_cmd_list())
+					break;
+				spin_unlock_irq(&scst_mcmd_lock);
+				schedule();
+				spin_lock_irq(&scst_mcmd_lock);
+			}
+			set_current_state(TASK_RUNNING);
+			remove_wait_queue(&scst_mgmt_cmd_list_waitQ, &wait);
+		}
+
+		while (!list_empty(&scst_active_mgmt_cmd_list)) {
+			int rc;
+			struct scst_mgmt_cmd *mcmd;
+			mcmd = list_entry(scst_active_mgmt_cmd_list.next,
+					  typeof(*mcmd), mgmt_cmd_list_entry);
+			TRACE_MGMT_DBG("Deleting mgmt cmd %p from active cmd "
+				"list", mcmd);
+			list_del(&mcmd->mgmt_cmd_list_entry);
+			spin_unlock_irq(&scst_mcmd_lock);
+			rc = scst_process_mgmt_cmd(mcmd);
+			spin_lock_irq(&scst_mcmd_lock);
+			if (rc > 0) {
+				if (test_bit(SCST_FLAG_SUSPENDED, &scst_flags) &&
+				    !test_bit(SCST_FLAG_SUSPENDING,
+						&scst_flags)) {
+					TRACE_MGMT_DBG("Adding mgmt cmd %p to "
+						"head of delayed mgmt cmd list",
+						mcmd);
+					list_add(&mcmd->mgmt_cmd_list_entry,
+						&scst_delayed_mgmt_cmd_list);
+				} else {
+					TRACE_MGMT_DBG("Adding mgmt cmd %p to "
+						"head of active mgmt cmd list",
+						mcmd);
+					list_add(&mcmd->mgmt_cmd_list_entry,
+					       &scst_active_mgmt_cmd_list);
+				}
+			}
+		}
+	}
+	spin_unlock_irq(&scst_mcmd_lock);
+
+	/*
+	 * If kthread_should_stop() is true, we are guaranteed to be
+	 * on the module unload, so scst_active_mgmt_cmd_list must be empty.
+	 */
+	BUG_ON(!list_empty(&scst_active_mgmt_cmd_list));
+
+	PRINT_INFO("Task management thread PID %d finished", current->pid);
+	return 0;
+}
+
+static struct scst_mgmt_cmd *scst_pre_rx_mgmt_cmd(struct scst_session
+	*sess, int fn, int atomic, void *tgt_priv)
+{
+	struct scst_mgmt_cmd *mcmd = NULL;
+
+	if (unlikely(sess->tgt->tgtt->task_mgmt_fn_done == NULL)) {
+		PRINT_ERROR("New mgmt cmd, but task_mgmt_fn_done() is NULL "
+			    "(target %s)", sess->tgt->tgtt->name);
+		goto out;
+	}
+
+	mcmd = scst_alloc_mgmt_cmd(atomic ? GFP_ATOMIC : GFP_KERNEL);
+	if (mcmd == NULL) {
+		PRINT_CRIT_ERROR("Lost TM fn %d, initiator %s", fn,
+			sess->initiator_name);
+		goto out;
+	}
+
+	mcmd->sess = sess;
+	mcmd->fn = fn;
+	mcmd->state = SCST_MCMD_STATE_INIT;
+	mcmd->tgt_priv = tgt_priv;
+
+	if (fn == SCST_PR_ABORT_ALL) {
+		atomic_inc(&mcmd->origin_pr_cmd->pr_abort_counter->pr_abort_pending_cnt);
+		atomic_inc(&mcmd->origin_pr_cmd->pr_abort_counter->pr_aborting_cnt);
+	}
+
+out:
+	return mcmd;
+}
+
+static int scst_post_rx_mgmt_cmd(struct scst_session *sess,
+	struct scst_mgmt_cmd *mcmd)
+{
+	unsigned long flags;
+	int res = 0;
+
+	scst_sess_get(sess);
+
+	if (unlikely(sess->shut_phase != SCST_SESS_SPH_READY)) {
+		PRINT_CRIT_ERROR("New mgmt cmd while shutting down the "
+			"session %p shut_phase %ld", sess, sess->shut_phase);
+		BUG();
+	}
+
+	local_irq_save(flags);
+
+	spin_lock(&sess->sess_list_lock);
+	atomic_inc(&sess->sess_cmd_count);
+
+	if (unlikely(sess->init_phase != SCST_SESS_IPH_READY)) {
+		switch (sess->init_phase) {
+		case SCST_SESS_IPH_INITING:
+			TRACE_DBG("Adding mcmd %p to init deferred mcmd list",
+				mcmd);
+			list_add_tail(&mcmd->mgmt_cmd_list_entry,
+				&sess->init_deferred_mcmd_list);
+			goto out_unlock;
+		case SCST_SESS_IPH_SUCCESS:
+			break;
+		case SCST_SESS_IPH_FAILED:
+			res = -1;
+			goto out_unlock;
+		default:
+			BUG();
+		}
+	}
+
+	spin_unlock(&sess->sess_list_lock);
+
+	TRACE_MGMT_DBG("Adding mgmt cmd %p to active mgmt cmd list", mcmd);
+	spin_lock(&scst_mcmd_lock);
+	list_add_tail(&mcmd->mgmt_cmd_list_entry, &scst_active_mgmt_cmd_list);
+	spin_unlock(&scst_mcmd_lock);
+
+	local_irq_restore(flags);
+
+	wake_up(&scst_mgmt_cmd_list_waitQ);
+
+out:
+	return res;
+
+out_unlock:
+	spin_unlock(&sess->sess_list_lock);
+	local_irq_restore(flags);
+	goto out;
+}
+
+/**
+ * scst_rx_mgmt_fn() - create new management command and send it for execution
+ *
+ * Description:
+ *    Creates new management command and sends it for execution.
+ *
+ *    Returns 0 for success, error code otherwise.
+ *
+ *    Must not be called in parallel with scst_unregister_session() for the
+ *    same sess.
+ */
+int scst_rx_mgmt_fn(struct scst_session *sess,
+	const struct scst_rx_mgmt_params *params)
+{
+	int res = -EFAULT;
+	struct scst_mgmt_cmd *mcmd = NULL;
+
+	switch (params->fn) {
+	case SCST_ABORT_TASK:
+		BUG_ON(!params->tag_set);
+		break;
+	case SCST_TARGET_RESET:
+	case SCST_ABORT_ALL_TASKS:
+	case SCST_NEXUS_LOSS:
+		break;
+	default:
+		BUG_ON(!params->lun_set);
+	}
+
+	mcmd = scst_pre_rx_mgmt_cmd(sess, params->fn, params->atomic,
+		params->tgt_priv);
+	if (mcmd == NULL)
+		goto out;
+
+	if (params->lun_set) {
+		mcmd->lun = scst_unpack_lun(params->lun, params->lun_len);
+		if (mcmd->lun == NO_SUCH_LUN)
+			goto out_free;
+		mcmd->lun_set = 1;
+	}
+
+	if (params->tag_set)
+		mcmd->tag = params->tag;
+
+	mcmd->cmd_sn_set = params->cmd_sn_set;
+	mcmd->cmd_sn = params->cmd_sn;
+
+	if (params->fn <= SCST_TARGET_RESET)
+		TRACE(TRACE_MGMT, "TM fn %d", params->fn);
+	else
+		TRACE_MGMT_DBG("TM fn %d", params->fn);
+
+	TRACE_MGMT_DBG("sess=%p, tag_set %d, tag %lld, lun_set %d, "
+		"lun=%lld, cmd_sn_set %d, cmd_sn %d, priv %p", sess,
+		params->tag_set,
+		(long long unsigned int)params->tag,
+		params->lun_set,
+		(long long unsigned int)mcmd->lun,
+		params->cmd_sn_set,
+		params->cmd_sn,
+		params->tgt_priv);
+
+	if (scst_post_rx_mgmt_cmd(sess, mcmd) != 0)
+		goto out_free;
+
+	res = 0;
+
+out:
+	return res;
+
+out_free:
+	scst_free_mgmt_cmd(mcmd);
+	mcmd = NULL;
+	goto out;
+}
+EXPORT_SYMBOL(scst_rx_mgmt_fn);
+
+/*
+ * Written by Jack Handy - jakkhandy@xxxxxxxxxxx
+ * Taken by Gennadiy Nerubayev <parakie@xxxxxxxxx> from
+ * http://www.codeproject.com/KB/string/wildcmp.aspx. No license attached
+ * to it, and it's posted on a free site; assumed to be free for use.
+ *
+ * Added the negative sign support - VLNB
+ *
+ * Also see comment for wildcmp().
+ *
+ * User space part of iSCSI-SCST also has a copy of this code, so fixing a bug
+ * here, don't forget to fix the copy too!
+ */
+static bool __wildcmp(const char *wild, const char *string, int recursion_level)
+{
+	const char *cp = NULL, *mp = NULL;
+
+	while ((*string) && (*wild != '*')) {
+		if ((*wild == '!') && (recursion_level == 0))
+			return !__wildcmp(++wild, string, ++recursion_level);
+
+		if ((*wild != *string) && (*wild != '?'))
+			return false;
+
+		wild++;
+		string++;
+	}
+
+	while (*string) {
+		if ((*wild == '!') && (recursion_level == 0))
+			return !__wildcmp(++wild, string, ++recursion_level);
+
+		if (*wild == '*') {
+			if (!*++wild)
+				return true;
+
+			mp = wild;
+			cp = string+1;
+		} else if ((*wild == *string) || (*wild == '?')) {
+			wild++;
+			string++;
+		} else {
+			wild = mp;
+			string = cp++;
+		}
+	}
+
+	while (*wild == '*')
+		wild++;
+
+	return !*wild;
+}
+
+/*
+ * Returns true if string "string" matches pattern "wild", false otherwise.
+ * Pattern is a regular DOS-type pattern, containing '*' and '?' symbols.
+ * '*' means match all any symbols, '?' means match only any single symbol.
+ *
+ * For instance:
+ * if (wildcmp("bl?h.*", "blah.jpg")) {
+ *   // match
+ *  } else {
+ *   // no match
+ *  }
+ *
+ * Also it supports boolean inversion sign '!', which does boolean inversion of
+ * the value of the rest of the string. Only one '!' allowed in the pattern,
+ * other '!' are treated as regular symbols. For instance:
+ * if (wildcmp("bl!?h.*", "blah.jpg")) {
+ *   // no match
+ *  } else {
+ *   // match
+ *  }
+ *
+ * Also see comment for __wildcmp().
+ */
+static bool wildcmp(const char *wild, const char *string)
+{
+	return __wildcmp(wild, string, 0);
+}
+
+/* scst_mutex supposed to be held */
+static struct scst_acg *scst_find_tgt_acg_by_name_wild(struct scst_tgt *tgt,
+	const char *initiator_name)
+{
+	struct scst_acg *acg, *res = NULL;
+	struct scst_acn *n;
+
+	if (initiator_name == NULL)
+		goto out;
+
+	list_for_each_entry(acg, &tgt->tgt_acg_list, acg_list_entry) {
+		list_for_each_entry(n, &acg->acn_list, acn_list_entry) {
+			if (wildcmp(n->name, initiator_name)) {
+				TRACE_DBG("Access control group %s found",
+					acg->acg_name);
+				res = acg;
+				goto out;
+			}
+		}
+	}
+
+out:
+	return res;
+}
+
+/* Must be called under scst_mutex */
+static struct scst_acg *__scst_find_acg(struct scst_tgt *tgt,
+	const char *initiator_name)
+{
+	struct scst_acg *acg = NULL;
+
+	acg = scst_find_tgt_acg_by_name_wild(tgt, initiator_name);
+	if (acg == NULL)
+		acg = tgt->default_acg;
+	return acg;
+}
+
+/* Must be called under scst_mutex */
+struct scst_acg *scst_find_acg(const struct scst_session *sess)
+{
+	return __scst_find_acg(sess->tgt, sess->initiator_name);
+}
+
+/**
+ * scst_initiator_has_luns() - check if this initiator will see any LUNs
+ *
+ * Checks if this initiator will see any LUNs upon connect to this target.
+ * Returns true if yes and false otherwise.
+ */
+bool scst_initiator_has_luns(struct scst_tgt *tgt, const char *initiator_name)
+{
+	bool res;
+	struct scst_acg *acg;
+
+	mutex_lock(&scst_mutex);
+
+	acg = __scst_find_acg(tgt, initiator_name);
+
+	res = !list_empty(&acg->acg_dev_list);
+
+	mutex_unlock(&scst_mutex);
+	return res;
+}
+EXPORT_SYMBOL_GPL(scst_initiator_has_luns);
+
+static int scst_init_session(struct scst_session *sess)
+{
+	int res = 0;
+	struct scst_cmd *cmd;
+	struct scst_mgmt_cmd *mcmd, *tm;
+	int mwake = 0;
+
+	mutex_lock(&scst_mutex);
+
+	sess->acg = scst_find_acg(sess);
+
+	PRINT_INFO("Using security group \"%s\" for initiator \"%s\"",
+		sess->acg->acg_name, sess->initiator_name);
+
+	list_add_tail(&sess->acg_sess_list_entry, &sess->acg->acg_sess_list);
+
+	TRACE_DBG("Adding sess %p to tgt->sess_list", sess);
+	list_add_tail(&sess->sess_list_entry, &sess->tgt->sess_list);
+
+	if (sess->tgt->tgtt->get_initiator_port_transport_id != NULL) {
+		res = sess->tgt->tgtt->get_initiator_port_transport_id(sess,
+				&sess->transport_id);
+		if (res != 0) {
+			PRINT_ERROR("Unable to make initiator %s port "
+				"transport id", sess->initiator_name);
+			goto failed;
+		}
+		TRACE_PR("sess %p (ini %s), transport id %s/%d", sess,
+			sess->initiator_name,
+			debug_transport_id_to_initiator_name(
+				sess->transport_id), sess->tgt->rel_tgt_id);
+	}
+
+	res = scst_sess_sysfs_create(sess);
+	if (res != 0)
+		goto failed;
+
+	res = scst_sess_alloc_tgt_devs(sess);
+
+failed:
+	mutex_unlock(&scst_mutex);
+
+	if (sess->init_result_fn) {
+		TRACE_DBG("Calling init_result_fn(%p)", sess);
+		sess->init_result_fn(sess, sess->reg_sess_data, res);
+		TRACE_DBG("%s", "init_result_fn() returned");
+	}
+
+	spin_lock_irq(&sess->sess_list_lock);
+
+	if (res == 0)
+		sess->init_phase = SCST_SESS_IPH_SUCCESS;
+	else
+		sess->init_phase = SCST_SESS_IPH_FAILED;
+
+restart:
+	list_for_each_entry(cmd, &sess->init_deferred_cmd_list,
+				cmd_list_entry) {
+		TRACE_DBG("Deleting cmd %p from init deferred cmd list", cmd);
+		list_del(&cmd->cmd_list_entry);
+		atomic_dec(&sess->sess_cmd_count);
+		spin_unlock_irq(&sess->sess_list_lock);
+		scst_cmd_init_done(cmd, SCST_CONTEXT_THREAD);
+		spin_lock_irq(&sess->sess_list_lock);
+		goto restart;
+	}
+
+	spin_lock(&scst_mcmd_lock);
+	list_for_each_entry_safe(mcmd, tm, &sess->init_deferred_mcmd_list,
+				mgmt_cmd_list_entry) {
+		TRACE_DBG("Moving mgmt command %p from init deferred mcmd list",
+			mcmd);
+		list_move_tail(&mcmd->mgmt_cmd_list_entry,
+			&scst_active_mgmt_cmd_list);
+		mwake = 1;
+	}
+
+	spin_unlock(&scst_mcmd_lock);
+	/*
+	 * In case of an error at this point the caller target driver supposed
+	 * to already call this sess's unregistration.
+	 */
+	sess->init_phase = SCST_SESS_IPH_READY;
+	spin_unlock_irq(&sess->sess_list_lock);
+
+	if (mwake)
+		wake_up(&scst_mgmt_cmd_list_waitQ);
+
+	scst_sess_put(sess);
+	return res;
+}
+
+/**
+ * scst_register_session() - register session
+ * @tgt:	target
+ * @atomic:	true, if the function called in the atomic context. If false,
+ *		 this function will block until the session registration is
+ *		 completed.
+ * @initiator_name: remote initiator's name, any NULL-terminated string,
+ *		    e.g. iSCSI name, which used as the key to found appropriate
+ *		    access control group. Could be NULL, then the default
+ *		    target's LUNs are used.
+ * @tgt_priv:	pointer to target driver's private data
+ * @result_fn_data: any target driver supplied data
+ * @result_fn:	pointer to the function that will be asynchronously called
+ *		 when session initialization finishes.
+ *		 Can be NULL. Parameters:
+ *		    - sess - session
+ *		    - data - target driver supplied to scst_register_session()
+ *			     data
+ *		    - result - session initialization result, 0 on success or
+ *			      appropriate error code otherwise
+ *
+ * Description:
+ *    Registers new session. Returns new session on success or NULL otherwise.
+ *
+ *    Note: A session creation and initialization is a complex task,
+ *    which requires sleeping state, so it can't be fully done
+ *    in interrupt context. Therefore the "bottom half" of it, if
+ *    scst_register_session() is called from atomic context, will be
+ *    done in SCST thread context. In this case scst_register_session()
+ *    will return not completely initialized session, but the target
+ *    driver can supply commands to this session via scst_rx_cmd().
+ *    Those commands processing will be delayed inside SCST until
+ *    the session initialization is finished, then their processing
+ *    will be restarted. The target driver will be notified about
+ *    finish of the session initialization by function result_fn().
+ *    On success the target driver could do nothing, but if the
+ *    initialization fails, the target driver must ensure that
+ *    no more new commands being sent or will be sent to SCST after
+ *    result_fn() returns. All already sent to SCST commands for
+ *    failed session will be returned in xmit_response() with BUSY status.
+ *    In case of failure the driver shall call scst_unregister_session()
+ *    inside result_fn(), it will NOT be called automatically.
+ */
+struct scst_session *scst_register_session(struct scst_tgt *tgt, int atomic,
+	const char *initiator_name, void *tgt_priv, void *result_fn_data,
+	void (*result_fn) (struct scst_session *sess, void *data, int result))
+{
+	struct scst_session *sess;
+	int res;
+	unsigned long flags;
+
+	sess = scst_alloc_session(tgt, atomic ? GFP_ATOMIC : GFP_KERNEL,
+		initiator_name);
+	if (sess == NULL)
+		goto out;
+
+	scst_sess_set_tgt_priv(sess, tgt_priv);
+
+	scst_sess_get(sess); /* one for registered session */
+	scst_sess_get(sess); /* one held until sess is inited */
+
+	if (atomic) {
+		sess->reg_sess_data = result_fn_data;
+		sess->init_result_fn = result_fn;
+		spin_lock_irqsave(&scst_mgmt_lock, flags);
+		TRACE_DBG("Adding sess %p to scst_sess_init_list", sess);
+		list_add_tail(&sess->sess_init_list_entry,
+			      &scst_sess_init_list);
+		spin_unlock_irqrestore(&scst_mgmt_lock, flags);
+		wake_up(&scst_mgmt_waitQ);
+	} else {
+		res = scst_init_session(sess);
+		if (res != 0)
+			goto out_free;
+	}
+
+out:
+	return sess;
+
+out_free:
+	scst_free_session(sess);
+	sess = NULL;
+	goto out;
+}
+EXPORT_SYMBOL_GPL(scst_register_session);
+
+/**
+ * scst_register_session_non_gpl() - register session (non-GPL version)
+ * @tgt:	target
+ * @initiator_name: remote initiator's name, any NULL-terminated string,
+ *		    e.g. iSCSI name, which used as the key to found appropriate
+ *		    access control group. Could be NULL, then the default
+ *		    target's LUNs are used.
+ * @tgt_priv:	pointer to target driver's private data
+ *
+ * Description:
+ *    Registers new session. Returns new session on success or NULL otherwise.
+ */
+struct scst_session *scst_register_session_non_gpl(struct scst_tgt *tgt,
+	const char *initiator_name, void *tgt_priv)
+{
+	return scst_register_session(tgt, 0, initiator_name, tgt_priv,
+			NULL, NULL);
+}
+EXPORT_SYMBOL(scst_register_session_non_gpl);
+
+/**
+ * scst_unregister_session() - unregister session
+ * @sess:	session to be unregistered
+ * @wait:	if true, instructs to wait until all commands, which
+ *		currently is being executed and belonged to the session,
+ *		finished. Otherwise, target driver should be prepared to
+ *		receive xmit_response() for the session's command after
+ *		scst_unregister_session() returns.
+ * @unreg_done_fn: pointer to the function that will be asynchronously called
+ *		   when the last session's command finishes and
+ *		   the session is about to be completely freed. Can be NULL.
+ *		   Parameter:
+ *			- sess - session
+ *
+ * Unregisters session.
+ *
+ * Notes:
+ * - All outstanding commands will be finished regularly. After
+ *   scst_unregister_session() returned, no new commands must be sent to
+ *   SCST via scst_rx_cmd().
+ *
+ * - The caller must ensure that no scst_rx_cmd() or scst_rx_mgmt_fn_*() is
+ *   called in paralell with scst_unregister_session().
+ *
+ * - Can be called before result_fn() of scst_register_session() called,
+ *   i.e. during the session registration/initialization.
+ *
+ * - It is highly recommended to call scst_unregister_session() as soon as it
+ *   gets clear that session will be unregistered and not to wait until all
+ *   related commands finished. This function provides the wait functionality,
+ *   but it also starts recovering stuck commands, if there are any.
+ *   Otherwise, your target driver could wait for those commands forever.
+ */
+void scst_unregister_session(struct scst_session *sess, int wait,
+	void (*unreg_done_fn) (struct scst_session *sess))
+{
+	unsigned long flags;
+	DECLARE_COMPLETION_ONSTACK(c);
+	int rc, lun;
+
+	TRACE_MGMT_DBG("Unregistering session %p (wait %d)", sess, wait);
+
+	sess->unreg_done_fn = unreg_done_fn;
+
+	/* Abort all outstanding commands and clear reservation, if necessary */
+	lun = 0;
+	rc = scst_rx_mgmt_fn_lun(sess, SCST_UNREG_SESS_TM,
+		(uint8_t *)&lun, sizeof(lun), SCST_ATOMIC, NULL);
+	if (rc != 0) {
+		PRINT_ERROR("SCST_UNREG_SESS_TM failed %d (sess %p)",
+			rc, sess);
+	}
+
+	sess->shut_phase = SCST_SESS_SPH_SHUTDOWN;
+
+	spin_lock_irqsave(&scst_mgmt_lock, flags);
+
+	if (wait)
+		sess->shutdown_compl = &c;
+
+	spin_unlock_irqrestore(&scst_mgmt_lock, flags);
+
+	scst_sess_put(sess);
+
+	if (wait) {
+		TRACE_DBG("Waiting for session %p to complete", sess);
+		wait_for_completion(&c);
+	}
+	return;
+}
+EXPORT_SYMBOL_GPL(scst_unregister_session);
+
+/**
+ * scst_unregister_session_non_gpl() - unregister session, non-GPL version
+ * @sess:	session to be unregistered
+ *
+ * Unregisters session.
+ *
+ * See notes for scst_unregister_session() above.
+ */
+void scst_unregister_session_non_gpl(struct scst_session *sess)
+{
+
+	scst_unregister_session(sess, 1, NULL);
+	return;
+}
+EXPORT_SYMBOL(scst_unregister_session_non_gpl);
+
+static inline int test_mgmt_list(void)
+{
+	int res = !list_empty(&scst_sess_init_list) ||
+		  !list_empty(&scst_sess_shut_list) ||
+		  unlikely(kthread_should_stop());
+	return res;
+}
+
+int scst_global_mgmt_thread(void *arg)
+{
+	struct scst_session *sess;
+
+	PRINT_INFO("Management thread started, PID %d", current->pid);
+
+	current->flags |= PF_NOFREEZE;
+
+	set_user_nice(current, -10);
+
+	spin_lock_irq(&scst_mgmt_lock);
+	while (!kthread_should_stop()) {
+		wait_queue_t wait;
+		init_waitqueue_entry(&wait, current);
+
+		if (!test_mgmt_list()) {
+			add_wait_queue_exclusive(&scst_mgmt_waitQ, &wait);
+			for (;;) {
+				set_current_state(TASK_INTERRUPTIBLE);
+				if (test_mgmt_list())
+					break;
+				spin_unlock_irq(&scst_mgmt_lock);
+				schedule();
+				spin_lock_irq(&scst_mgmt_lock);
+			}
+			set_current_state(TASK_RUNNING);
+			remove_wait_queue(&scst_mgmt_waitQ, &wait);
+		}
+
+		while (!list_empty(&scst_sess_init_list)) {
+			sess = list_entry(scst_sess_init_list.next,
+				typeof(*sess), sess_init_list_entry);
+			TRACE_DBG("Removing sess %p from scst_sess_init_list",
+				sess);
+			list_del(&sess->sess_init_list_entry);
+			spin_unlock_irq(&scst_mgmt_lock);
+
+			if (sess->init_phase == SCST_SESS_IPH_INITING)
+				scst_init_session(sess);
+			else {
+				PRINT_CRIT_ERROR("session %p is in "
+					"scst_sess_init_list, but in unknown "
+					"init phase %x", sess,
+					sess->init_phase);
+				BUG();
+			}
+
+			spin_lock_irq(&scst_mgmt_lock);
+		}
+
+		while (!list_empty(&scst_sess_shut_list)) {
+			sess = list_entry(scst_sess_shut_list.next,
+				typeof(*sess), sess_shut_list_entry);
+			TRACE_DBG("Removing sess %p from scst_sess_shut_list",
+				sess);
+			list_del(&sess->sess_shut_list_entry);
+			spin_unlock_irq(&scst_mgmt_lock);
+
+			switch (sess->shut_phase) {
+			case SCST_SESS_SPH_SHUTDOWN:
+				BUG_ON(atomic_read(&sess->refcnt) != 0);
+				scst_free_session_callback(sess);
+				break;
+			default:
+				PRINT_CRIT_ERROR("session %p is in "
+					"scst_sess_shut_list, but in unknown "
+					"shut phase %lx", sess,
+					sess->shut_phase);
+				BUG();
+				break;
+			}
+
+			spin_lock_irq(&scst_mgmt_lock);
+		}
+	}
+	spin_unlock_irq(&scst_mgmt_lock);
+
+	/*
+	 * If kthread_should_stop() is true, we are guaranteed to be
+	 * on the module unload, so both lists must be empty.
+	 */
+	BUG_ON(!list_empty(&scst_sess_init_list));
+	BUG_ON(!list_empty(&scst_sess_shut_list));
+
+	PRINT_INFO("Management thread PID %d finished", current->pid);
+	return 0;
+}
+
+/* Called under sess->sess_list_lock */
+static struct scst_cmd *__scst_find_cmd_by_tag(struct scst_session *sess,
+	uint64_t tag, bool to_abort)
+{
+	struct scst_cmd *cmd, *res = NULL;
+
+	/* ToDo: hash list */
+
+	TRACE_DBG("%s (sess=%p, tag=%llu)", "Searching in sess cmd list",
+		  sess, (long long unsigned int)tag);
+
+	list_for_each_entry(cmd, &sess->sess_cmd_list,
+			sess_cmd_list_entry) {
+		if (cmd->tag == tag) {
+			/*
+			 * We must not count done commands, because
+			 * they were submitted for transmittion.
+			 * Otherwise we can have a race, when for
+			 * some reason cmd's release delayed
+			 * after transmittion and initiator sends
+			 * cmd with the same tag => it can be possible
+			 * that a wrong cmd will be returned.
+			 */
+			if (cmd->done) {
+				if (to_abort) {
+					/*
+					 * We should return the latest not
+					 * aborted cmd with this tag.
+					 */
+					if (res == NULL)
+						res = cmd;
+					else {
+						if (test_bit(SCST_CMD_ABORTED,
+								&res->cmd_flags)) {
+							res = cmd;
+						} else if (!test_bit(SCST_CMD_ABORTED,
+								&cmd->cmd_flags))
+							res = cmd;
+					}
+				}
+				continue;
+			} else {
+				res = cmd;
+				break;
+			}
+		}
+	}
+	return res;
+}
+
+/**
+ * scst_find_cmd() - find command by custom comparison function
+ *
+ * Finds a command based on user supplied data and comparision
+ * callback function, that should return true, if the command is found.
+ * Returns the command on success or NULL otherwise.
+ */
+struct scst_cmd *scst_find_cmd(struct scst_session *sess, void *data,
+			       int (*cmp_fn) (struct scst_cmd *cmd,
+					      void *data))
+{
+	struct scst_cmd *cmd = NULL;
+	unsigned long flags = 0;
+
+	if (cmp_fn == NULL)
+		goto out;
+
+	spin_lock_irqsave(&sess->sess_list_lock, flags);
+
+	TRACE_DBG("Searching in sess cmd list (sess=%p)", sess);
+	list_for_each_entry(cmd, &sess->sess_cmd_list, sess_cmd_list_entry) {
+		/*
+		 * We must not count done commands, because they were
+		 * submitted for transmittion. Otherwise we can have a race,
+		 * when for some reason cmd's release delayed after
+		 * transmittion and initiator sends cmd with the same tag =>
+		 * it can be possible that a wrong cmd will be returned.
+		 */
+		if (cmd->done)
+			continue;
+		if (cmp_fn(cmd, data))
+			goto out_unlock;
+	}
+
+	cmd = NULL;
+
+out_unlock:
+	spin_unlock_irqrestore(&sess->sess_list_lock, flags);
+
+out:
+	return cmd;
+}
+EXPORT_SYMBOL(scst_find_cmd);
+
+/**
+ * scst_find_cmd_by_tag() - find command by tag
+ *
+ * Finds a command based on the supplied tag comparing it with one
+ * that previously set by scst_cmd_set_tag(). Returns the found command on
+ * success or NULL otherwise.
+ */
+struct scst_cmd *scst_find_cmd_by_tag(struct scst_session *sess,
+	uint64_t tag)
+{
+	unsigned long flags;
+	struct scst_cmd *cmd;
+	spin_lock_irqsave(&sess->sess_list_lock, flags);
+	cmd = __scst_find_cmd_by_tag(sess, tag, false);
+	spin_unlock_irqrestore(&sess->sess_list_lock, flags);
+	return cmd;
+}
+EXPORT_SYMBOL(scst_find_cmd_by_tag);

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