Commit 0bf8c869 authored by Jesper Juhl's avatar Jesper Juhl Committed by Linus Torvalds
Browse files

Reduce sequential pointer derefs in scsi_error.c and reduce size as well 



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 benefits 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 (tiny effect: on x86-64, in at least one
   configuration, the text size decreased from 9439 bytes to 9400)

 - removes some pointless (mostly trailing) whitespace.

Signed-off-by: default avatarJesper Juhl <jj@chaosbits.net>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 38f7aa23

drivers/scsi/scsi_error.c

+49 −45
Original line number Diff line number Diff line
@@ -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))) {
@@ -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)
@@ -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:"
@@ -1414,7 +1419,6 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd) 
			 */

			break;

		/* fallthrough */



	case DID_BUS_BUSY:

	case DID_PARITY:

		goto maybe_retry;

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