[RFC PATCH 19/19] Target_Core_Mod Unit Attention emulation support

[Nicholas A. Bellinger]

This patch adds support for SPC-3 compliant UNIT Attention emulation that is used
by the Persistent Reservations code.

Signed-off-by: Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx>

diff --git a/drivers/target/target_core_ua.c b/drivers/target/target_core_ua.c
new file mode 100644
index 0000000..af8c67a
--- /dev/null
+++ b/drivers/target/target_core_ua.c
@@ -0,0 +1,334 @@
+/*******************************************************************************
+ * Filename: target_core_ua.c
+ *
+ * This file contains logic for SPC-3 Unit Attention emulation
+ *
+ * Copyright (c) 2009 Rising Tide, Inc.
+ * Copyright (c) 2009 Linux-iSCSI.org
+ *
+ * Nicholas A. Bellinger <nab@xxxxxxxxxx>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ ******************************************************************************/
+
+#define TARGET_CORE_UA_C
+
+#include <linux/version.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+
+#include <target/target_core_base.h>
+#include <target/target_core_device.h>
+#include <target/target_core_hba.h>
+#include <target/target_core_transport.h>
+#include <target/target_core_alua.h>
+#include <target/target_core_pr.h>
+#include <target/target_core_ua.h>
+#include <target/target_core_transport_plugin.h>
+#include <target/target_core_fabric_ops.h>
+#include <target/target_core_configfs.h>
+
+#undef TARGET_CORE_UA_C
+
+int core_scsi3_ua_check(
+	se_cmd_t *cmd,
+	unsigned char *cdb)
+{
+	se_dev_entry_t *deve;
+	se_session_t *sess = cmd->se_sess;
+	se_node_acl_t *nacl;
+
+	if (!(sess))
+		return 0;
+
+	nacl = sess->se_node_acl;
+	if (!(nacl))
+		return 0;
+
+	deve = &nacl->device_list[cmd->orig_fe_lun];
+	if (!(atomic_read(&deve->ua_count)))
+		return 0;
+	/*
+	 * From sam4r14, section 5.14 Unit attention condition:
+	 *
+	 * a) if an INQUIRY command enters the enabled command state, the
+	 *    device server shall process the INQUIRY command and shall neither
+	 *    report nor clear any unit attention condition;
+	 * b) if a REPORT LUNS command enters the enabled command state, the
+	 *    device server shall process the REPORT LUNS command and shall not
+	 *    report any unit attention condition;
+	 * e) if a REQUEST SENSE command enters the enabled command state while
+	 *    a unit attention condition exists for the SCSI initiator port
+	 *    associated with the I_T nexus on which the REQUEST SENSE command
+	 *    was received, then the device server shall process the command
+	 *    and either:
+	 */
+	switch (cdb[0]) {
+	case INQUIRY:
+	case REPORT_LUNS:
+	case REQUEST_SENSE:
+		return 0;
+	default:
+		return -1;
+	}
+
+	return -1;
+}
+
+int core_scsi3_ua_allocate(
+	se_node_acl_t *nacl,
+	u32 unpacked_lun,
+	u8 asc,
+	u8 ascq)
+{
+	se_dev_entry_t *deve;
+	se_ua_t *ua, *ua_p, *ua_tmp;
+	/*
+	 * PASSTHROUGH OPS
+	 */
+	if (!(nacl))
+		return -1;
+
+	ua = kmem_cache_zalloc(se_ua_cache, GFP_ATOMIC);
+	if (!(ua)) {
+		printk(KERN_ERR "Unable to allocate se_ua_t\n");
+		return -1;
+	}
+	INIT_LIST_HEAD(&ua->ua_dev_list);
+	INIT_LIST_HEAD(&ua->ua_nacl_list);
+
+	ua->ua_nacl = nacl;
+	ua->ua_asc = asc;
+	ua->ua_ascq = ascq;
+
+	spin_lock(&nacl->device_list_lock);
+	deve = &nacl->device_list[unpacked_lun];
+
+	spin_lock(&deve->ua_lock);
+	list_for_each_entry_safe(ua_p, ua_tmp, &deve->ua_list, ua_nacl_list) {
+		/*
+		 * Do not report the same UNIT ATTENTION twice..
+		 */
+		if ((ua_p->ua_asc == asc) && (ua_p->ua_ascq == ascq)) {
+			spin_unlock(&deve->ua_lock);
+			kmem_cache_free(se_ua_cache, ua);
+			return 0;
+		}
+		/*
+		 * Attach the highest priority Unit Attention to
+		 * the head of the list following sam4r14,
+		 * Section 5.14 Unit Attention Condition:
+		 *
+		 * POWER ON, RESET, OR BUS DEVICE RESET OCCURRED highest
+		 * POWER ON OCCURRED or
+		 * DEVICE INTERNAL RESET
+		 * SCSI BUS RESET OCCURRED or
+		 * MICROCODE HAS BEEN CHANGED or
+		 * protocol specific
+		 * BUS DEVICE RESET FUNCTION OCCURRED
+		 * I_T NEXUS LOSS OCCURRED
+		 * COMMANDS CLEARED BY POWER LOSS NOTIFICATION
+		 * all others                                    Lowest
+		 *
+		 * Each of the ASCQ codes listed above are defined in
+		 * the 29h ASC family, see spc4r17 Table D.1
+		 */
+		if (ua_p->ua_asc == 0x29) {
+			if ((asc == 0x29) && (ascq > ua_p->ua_ascq))
+				list_add(&ua->ua_nacl_list,
+						&deve->ua_list);
+			else
+				list_add_tail(&ua->ua_nacl_list,
+						&deve->ua_list);
+		} else if (ua_p->ua_asc == 0x2a) {
+			/*
+			 * Incoming Family 29h ASCQ codes will override
+			 * Family 2AHh ASCQ codes for Unit Attention condition.
+			 */
+			if ((asc == 0x29) || (ascq > ua_p->ua_asc))
+				list_add(&ua->ua_nacl_list,
+					&deve->ua_list);
+			else
+				list_add_tail(&ua->ua_nacl_list,
+						&deve->ua_list);
+		} else
+			list_add_tail(&ua->ua_nacl_list,
+				&deve->ua_list);
+		spin_unlock(&deve->ua_lock);
+
+		atomic_inc(&deve->ua_count);
+		smp_mb__after_atomic_inc();
+		return 0;
+	}
+	list_add_tail(&ua->ua_nacl_list, &deve->ua_list);
+	spin_unlock(&deve->ua_lock);
+	spin_unlock(&nacl->device_list_lock);
+
+	printk(KERN_INFO "[%s]: Allocated UNIT ATTENTION, mapped LUN: %u, ASC:"
+		" 0x%02x, ASCQ: 0x%02x\n",
+		TPG_TFO(nacl->se_tpg)->get_fabric_name(), unpacked_lun,
+		asc, ascq);
+
+	atomic_inc(&deve->ua_count);
+	smp_mb__after_atomic_inc();
+	return 0;
+}
+
+void core_scsi3_ua_release_all(
+	se_dev_entry_t *deve)
+{
+	se_ua_t *ua, *ua_p;
+
+	spin_lock(&deve->ua_lock);
+	list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
+		list_del(&ua->ua_nacl_list);
+		kmem_cache_free(se_ua_cache, ua);
+
+		atomic_dec(&deve->ua_count);
+		smp_mb__after_atomic_dec();
+	}
+	spin_unlock(&deve->ua_lock);
+}
+
+void core_scsi3_ua_for_check_condition(
+	se_cmd_t *cmd,
+	u8 *asc,
+	u8 *ascq)
+{
+	se_device_t *dev = SE_DEV(cmd);
+	se_dev_entry_t *deve;
+	se_session_t *sess = cmd->se_sess;
+	se_node_acl_t *nacl;
+	se_ua_t *ua = NULL, *ua_p;
+	int head = 1;
+
+	if (!(sess))
+		return;
+
+	nacl = sess->se_node_acl;
+	if (!(nacl))
+		return;
+
+	spin_lock(&nacl->device_list_lock);
+	deve = &nacl->device_list[cmd->orig_fe_lun];
+	if (!(atomic_read(&deve->ua_count))) {
+		spin_unlock(&nacl->device_list_lock);
+		return;
+	}
+	/*
+	 * The highest priority Unit Attentions are placed at the head of the
+	 * se_dev_entry_t->ua_list, and will be returned in CHECK_CONDITION +
+	 * sense data for the received CDB.
+	 */
+	spin_lock(&deve->ua_lock);
+	list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
+		/*
+		 * For ua_intlck_ctrl code not equal to 00b, only report the
+		 * highest priority UNIT_ATTENTION and ASC/ASCQ without
+		 * clearing it.
+		 */
+		if (DEV_ATTRIB(dev)->emulate_ua_intlck_ctrl != 0) {
+			*asc = ua->ua_asc;
+			*ascq = ua->ua_ascq;
+			break;
+		}
+		/*
+		 * Otherwise for the default 00b, release the UNIT ATTENTION
+		 * condition.  Return the ASC/ASCQ of the higest priority UA
+		 * (head of the list) in the outgoing CHECK_CONDITION + sense.
+		 */
+		if (head) {
+			*asc = ua->ua_asc;
+			*ascq = ua->ua_ascq;
+			head = 0;
+		}
+		list_del(&ua->ua_nacl_list);
+		kmem_cache_free(se_ua_cache, ua);
+
+		atomic_dec(&deve->ua_count);
+		smp_mb__after_atomic_dec();
+	}
+	spin_unlock(&deve->ua_lock);
+	spin_unlock(&nacl->device_list_lock);
+
+	printk(KERN_INFO "[%s]: %s UNIT ATTENTION condition with"
+		" INTLCK_CTRL: %d, mapped LUN: %u, got CDB: 0x%02x"
+		" reported ASC: 0x%02x, ASCQ: 0x%02x\n",
+		TPG_TFO(nacl->se_tpg)->get_fabric_name(),
+		(DEV_ATTRIB(dev)->emulate_ua_intlck_ctrl != 0) ? "Reporting" :
+		"Releasing", DEV_ATTRIB(dev)->emulate_ua_intlck_ctrl,
+		cmd->orig_fe_lun, T_TASK(cmd)->t_task_cdb[0], *asc, *ascq);
+}
+
+int core_scsi3_ua_clear_for_request_sense(
+	se_cmd_t *cmd,
+	u8 *asc,
+	u8 *ascq)
+{
+	se_dev_entry_t *deve;
+	se_session_t *sess = cmd->se_sess;
+	se_node_acl_t *nacl;
+	se_ua_t *ua = NULL, *ua_p;
+	int head = 1;
+
+	if (!(sess))
+		return -1;
+
+	nacl = sess->se_node_acl;
+	if (!(nacl))
+		return -1;
+
+	spin_lock(&nacl->device_list_lock);
+	deve = &nacl->device_list[cmd->orig_fe_lun];
+	if (!(atomic_read(&deve->ua_count))) {
+		spin_unlock(&nacl->device_list_lock);
+		return -1;
+	}
+	/*
+	 * The highest priority Unit Attentions are placed at the head of the
+	 * se_dev_entry_t->ua_list.  The First (and hence highest priority)
+	 * ASC/ASCQ will be returned in REQUEST_SENSE payload data for the
+	 * matching se_lun_t.
+	 *
+	 * Once the returning ASC/ASCQ values are set, we go ahead and
+	 * release all of the Unit Attention conditions for the assoicated
+	 * se_lun_t.
+	 */
+	spin_lock(&deve->ua_lock);
+	list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
+		if (head) {
+			*asc = ua->ua_asc;
+			*ascq = ua->ua_ascq;
+			head = 0;
+		}
+		list_del(&ua->ua_nacl_list);
+		kmem_cache_free(se_ua_cache, ua);
+
+		atomic_dec(&deve->ua_count);
+		smp_mb__after_atomic_dec();
+	}
+	spin_unlock(&deve->ua_lock);
+	spin_unlock(&nacl->device_list_lock);
+
+	printk(KERN_INFO "[%s]: Released UNIT ATTENTION condition, mapped"
+		" LUN: %u, got REQUEST_SENSE reported ASC: 0x%02x,"
+		" ASCQ: 0x%02x\n", TPG_TFO(nacl->se_tpg)->get_fabric_name(),
+		cmd->orig_fe_lun, *asc, *ascq);
+
+	return (head) ? -1 : 0;
+}
diff --git a/include/target/target_core_ua.h b/include/target/target_core_ua.h
new file mode 100644
index 0000000..9e600d0
--- /dev/null
+++ b/include/target/target_core_ua.h
@@ -0,0 +1,36 @@
+#ifndef TARGET_CORE_UA_H
+
+/*
+ * From spc4r17, Table D.1: ASC and ASCQ Assignement
+ */
+#define ASCQ_29H_POWER_ON_RESET_OR_BUS_DEVICE_RESET_OCCURED	0x00
+#define ASCQ_29H_POWER_ON_OCCURRED				0x01
+#define ASCQ_29H_SCSI_BUS_RESET_OCCURED				0x02
+#define ASCQ_29H_BUS_DEVICE_RESET_FUNCTION_OCCURRED		0x03
+#define ASCQ_29H_DEVICE_INTERNAL_RESET				0x04
+#define ASCQ_29H_TRANSCEIVER_MODE_CHANGED_TO_SINGLE_ENDED	0x05
+#define ASCQ_29H_TRANSCEIVER_MODE_CHANGED_TO_LVD		0x06
+#define ASCQ_29H_NEXUS_LOSS_OCCURRED				0x07
+
+#define ASCQ_2AH_PARAMETERS_CHANGED				0x00
+#define ASCQ_2AH_MODE_PARAMETERS_CHANGED			0x01
+#define ASCQ_2AH_LOG_PARAMETERS_CHANGED				0x02
+#define ASCQ_2AH_RESERVATIONS_PREEMPTED				0x03
+#define ASCQ_2AH_RESERVATIONS_RELEASED				0x04
+#define ASCQ_2AH_REGISTRATIONS_PREEMPTED			0x05
+#define ASCQ_2AH_ASYMMETRIC_ACCESS_STATE_CHANGED		0x06
+#define ASCQ_2AH_IMPLICT_ASYMMETRIC_ACCESS_STATE_TRANSITION_FAILED 0x07
+#define ASCQ_2AH_PRIORITY_CHANGED				0x08
+
+#define ASCQ_2CH_PREVIOUS_RESERVATION_CONFLICT_STATUS		0x09
+
+extern struct kmem_cache *se_ua_cache;
+
+extern int core_scsi3_ua_check(struct se_cmd_s *, unsigned char *);
+extern int core_scsi3_ua_allocate(struct se_node_acl_s *, u32, u8, u8);
+extern void core_scsi3_ua_release_all(struct se_dev_entry_s *);
+extern void core_scsi3_ua_for_check_condition(struct se_cmd_s *, u8 *, u8 *);
+extern int core_scsi3_ua_clear_for_request_sense(struct se_cmd_s *,
+						u8 *, u8 *);
+
+#endif /* TARGET_CORE_UA_H */



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