[PATCH][SCSI][resend] Reduce sequential pointer derefs in scsi_error.cand reduce size as well

From: Jesper Juhl
Date: Mon Mar 21 2011 - 15:47:46 EST

This patch reduces the number of sequential pointer derefs in
drivers/scsi/scsi_error.c

This has been submitted a number of times over a couple of years. I
believe this version adresses all comments it has gathered over time.
Please apply or reject with a reason.

The bennefits are:

- makes the code easier to read. Lots of sequential derefs of the same
pointers is not easy on the eye.

- theoretically at least, just dereferencing the pointers once can allow
the compiler to generally slightly faster code, so in theory this could
also be a micro speed optimization.

- reduces size of object file.

- removes some pointless (mostly trailing) whitespace.

Signed-off-by: Jesper Juhl <jj@xxxxxxxxxxxxx>
---
scsi_error.c | 94 ++++++++++++++++++++++++++++++-----------------------------
1 file changed, 49 insertions(+), 45 deletions(-)

Patch against current Linus tree.

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 991de3c..633c239 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -3,14 +3,14 @@
*
* SCSI error/timeout handling
* Initial versions: Eric Youngdale. Based upon conversations with
- * Leonard Zubkoff and David Miller at Linux Expo,
+ * Leonard Zubkoff and David Miller at Linux Expo,
* ideas originating from all over the place.
*
* Restructured scsi_unjam_host and associated functions.
* September 04, 2002 Mike Anderson (andmike@xxxxxxxxxx)
*
* Forward port of Russell King's (rmk@xxxxxxxxxxxxxxxx) changes and
- * minor cleanups.
+ * minor cleanups.
* September 30, 2002 Mike Anderson (andmike@xxxxxxxxxx)
*/

@@ -129,14 +129,15 @@ enum blk_eh_timer_return scsi_times_out(struct request *req)
{
struct scsi_cmnd *scmd = req->special;
enum blk_eh_timer_return rtn = BLK_EH_NOT_HANDLED;
+ struct Scsi_Host *host = scmd->device->host;

trace_scsi_dispatch_cmd_timeout(scmd);
scsi_log_completion(scmd, TIMEOUT_ERROR);

- if (scmd->device->host->transportt->eh_timed_out)
- rtn = scmd->device->host->transportt->eh_timed_out(scmd);
- else if (scmd->device->host->hostt->eh_timed_out)
- rtn = scmd->device->host->hostt->eh_timed_out(scmd);
+ if (host->transportt->eh_timed_out)
+ rtn = host->transportt->eh_timed_out(scmd);
+ else if (host->hostt->eh_timed_out)
+ rtn = host->hostt->eh_timed_out(scmd);

if (unlikely(rtn == BLK_EH_NOT_HANDLED &&
!scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD))) {
@@ -195,7 +196,7 @@ static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
++total_failures;
if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD)
++cmd_cancel;
- else
+ else
++cmd_failed;
}
}
@@ -214,7 +215,7 @@ static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,

SCSI_LOG_ERROR_RECOVERY(2, printk("Total of %d commands on %d"
" devices require eh work\n",
- total_failures, devices_failed));
+ total_failures, devices_failed));
}
#endif

@@ -294,7 +295,7 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
return NEEDS_RETRY;
}
/*
- * if the device is in the process of becoming ready, we
+ * if the device is in the process of becoming ready, we
* should retry.
*/
if ((sshdr.asc == 0x04) && (sshdr.ascq == 0x01))
@@ -488,7 +489,7 @@ static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
*/
static void scsi_eh_done(struct scsi_cmnd *scmd)
{
- struct completion *eh_action;
+ struct completion *eh_action;

SCSI_LOG_ERROR_RECOVERY(3,
printk("%s scmd: %p result: %x\n",
@@ -507,22 +508,23 @@ static int scsi_try_host_reset(struct scsi_cmnd *scmd)
{
unsigned long flags;
int rtn;
+ struct Scsi_Host *host = scmd->device->host;
+ struct scsi_host_template *hostt = host->hostt;

SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Host RST\n",
__func__));

- if (!scmd->device->host->hostt->eh_host_reset_handler)
+ if (!hostt->eh_host_reset_handler)
return FAILED;

- rtn = scmd->device->host->hostt->eh_host_reset_handler(scmd);
+ rtn = hostt->eh_host_reset_handler(scmd);

if (rtn == SUCCESS) {
- if (!scmd->device->host->hostt->skip_settle_delay)
+ if (!hostt->skip_settle_delay)
ssleep(HOST_RESET_SETTLE_TIME);
- spin_lock_irqsave(scmd->device->host->host_lock, flags);
- scsi_report_bus_reset(scmd->device->host,
- scmd_channel(scmd));
- spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+ spin_lock_irqsave(host->host_lock, flags);
+ scsi_report_bus_reset(host, scmd_channel(scmd));
+ spin_unlock_irqrestore(host->host_lock, flags);
}

return rtn;
@@ -536,22 +538,23 @@ static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
{
unsigned long flags;
int rtn;
+ struct Scsi_Host *host = scmd->device->host;
+ struct scsi_host_template *hostt = host->hostt;

SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Bus RST\n",
__func__));

- if (!scmd->device->host->hostt->eh_bus_reset_handler)
+ if (!hostt->eh_bus_reset_handler)
return FAILED;

- rtn = scmd->device->host->hostt->eh_bus_reset_handler(scmd);
+ rtn = hostt->eh_bus_reset_handler(scmd);

if (rtn == SUCCESS) {
- if (!scmd->device->host->hostt->skip_settle_delay)
+ if (!hostt->skip_settle_delay)
ssleep(BUS_RESET_SETTLE_TIME);
- spin_lock_irqsave(scmd->device->host->host_lock, flags);
- scsi_report_bus_reset(scmd->device->host,
- scmd_channel(scmd));
- spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+ spin_lock_irqsave(host->host_lock, flags);
+ scsi_report_bus_reset(host, scmd_channel(scmd));
+ spin_unlock_irqrestore(host->host_lock, flags);
}

return rtn;
@@ -577,16 +580,18 @@ static int scsi_try_target_reset(struct scsi_cmnd *scmd)
{
unsigned long flags;
int rtn;
+ struct Scsi_Host *host = scmd->device->host;
+ struct scsi_host_template *hostt = host->hostt;

- if (!scmd->device->host->hostt->eh_target_reset_handler)
+ if (!hostt->eh_target_reset_handler)
return FAILED;

- rtn = scmd->device->host->hostt->eh_target_reset_handler(scmd);
+ rtn = hostt->eh_target_reset_handler(scmd);
if (rtn == SUCCESS) {
- spin_lock_irqsave(scmd->device->host->host_lock, flags);
+ spin_lock_irqsave(host->host_lock, flags);
__starget_for_each_device(scsi_target(scmd->device), NULL,
__scsi_report_device_reset);
- spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+ spin_unlock_irqrestore(host->host_lock, flags);
}

return rtn;
@@ -605,27 +610,28 @@ static int scsi_try_target_reset(struct scsi_cmnd *scmd)
static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
{
int rtn;
+ struct scsi_host_template *hostt = scmd->device->host->hostt;

- if (!scmd->device->host->hostt->eh_device_reset_handler)
+ if (!hostt->eh_device_reset_handler)
return FAILED;

- rtn = scmd->device->host->hostt->eh_device_reset_handler(scmd);
+ rtn = hostt->eh_device_reset_handler(scmd);
if (rtn == SUCCESS)
__scsi_report_device_reset(scmd->device, NULL);
return rtn;
}

-static int scsi_try_to_abort_cmd(struct scsi_cmnd *scmd)
+static int scsi_try_to_abort_cmd(struct scsi_host_template *hostt, struct scsi_cmnd *scmd)
{
- if (!scmd->device->host->hostt->eh_abort_handler)
+ if (!hostt->eh_abort_handler)
return FAILED;

- return scmd->device->host->hostt->eh_abort_handler(scmd);
+ return hostt->eh_abort_handler(scmd);
}

static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
{
- if (scsi_try_to_abort_cmd(scmd) != SUCCESS)
+ if (scsi_try_to_abort_cmd(scmd->device->host->hostt, scmd) != SUCCESS)
if (scsi_try_bus_device_reset(scmd) != SUCCESS)
if (scsi_try_target_reset(scmd) != SUCCESS)
if (scsi_try_bus_reset(scmd) != SUCCESS)
@@ -846,7 +852,7 @@ EXPORT_SYMBOL(scsi_eh_finish_cmd);
*
* Description:
* See if we need to request sense information. if so, then get it
- * now, so we have a better idea of what to do.
+ * now, so we have a better idea of what to do.
*
* Notes:
* This has the unfortunate side effect that if a shost adapter does
@@ -958,7 +964,7 @@ static int scsi_eh_abort_cmds(struct list_head *work_q,
SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
"0x%p\n", current->comm,
scmd));
- rtn = scsi_try_to_abort_cmd(scmd);
+ rtn = scsi_try_to_abort_cmd(scmd->device->host->hostt, scmd);
if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;
if (!scsi_device_online(scmd->device) ||
@@ -966,7 +972,6 @@ static int scsi_eh_abort_cmds(struct list_head *work_q,
!scsi_eh_tur(scmd)) {
scsi_eh_finish_cmd(scmd, done_q);
}
-
} else
SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting"
" cmd failed:"
@@ -1010,7 +1015,7 @@ static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
*
* Notes:
* If commands are failing due to not ready, initializing command required,
- * try revalidating the device, which will end up sending a start unit.
+ * try revalidating the device, which will end up sending a start unit.
*/
static int scsi_eh_stu(struct Scsi_Host *shost,
struct list_head *work_q,
@@ -1064,7 +1069,7 @@ static int scsi_eh_stu(struct Scsi_Host *shost,
* Try a bus device reset. Still, look to see whether we have multiple
* devices that are jammed or not - if we have multiple devices, it
* makes no sense to try bus_device_reset - we really would need to try
- * a bus_reset instead.
+ * a bus_reset instead.
*/
static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
struct list_head *work_q,
@@ -1164,7 +1169,7 @@ static int scsi_eh_target_reset(struct Scsi_Host *shost,
}

/**
- * scsi_eh_bus_reset - send a bus reset
+ * scsi_eh_bus_reset - send a bus reset
* @shost: &scsi host being recovered.
* @work_q: &list_head for pending commands.
* @done_q: &list_head for processed commands.
@@ -1181,7 +1186,7 @@ static int scsi_eh_bus_reset(struct Scsi_Host *shost,
* we really want to loop over the various channels, and do this on
* a channel by channel basis. we should also check to see if any
* of the failed commands are on soft_reset devices, and if so, skip
- * the reset.
+ * the reset.
*/

for (channel = 0; channel <= shost->max_channel; channel++) {
@@ -1223,7 +1228,7 @@ static int scsi_eh_bus_reset(struct Scsi_Host *shost,
}

/**
- * scsi_eh_host_reset - send a host reset
+ * scsi_eh_host_reset - send a host reset
* @work_q: list_head for processed commands.
* @done_q: list_head for processed commands.
*/
@@ -1376,7 +1381,7 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd)
return SUCCESS;
/*
* when the low level driver returns did_soft_error,
- * it is responsible for keeping an internal retry counter
+ * it is responsible for keeping an internal retry counter
* in order to avoid endless loops (db)
*
* actually this is a bug in this function here. we should
@@ -1414,7 +1419,6 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd)
*/
break;
/* fallthrough */
-
case DID_BUS_BUSY:
case DID_PARITY:
goto maybe_retry;
@@ -1982,7 +1986,7 @@ int scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
if (sb_len > 7)
sshdr->additional_length = sense_buffer[7];
} else {
- /*
+ /*
* fixed format
*/
if (sb_len > 2)


--
Jesper Juhl <jj@xxxxxxxxxxxxx> http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
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