Commit e494f6a7 authored by Hannes Reinecke's avatar Hannes Reinecke Committed by James Bottomley
Browse files

[SCSI] improved eh timeout handler 



When a command runs into a timeout we need to send an 'ABORT TASK'
TMF. This is typically done by the 'eh_abort_handler' LLDD callback.

Conceptually, however, this function is a normal SCSI command, so
there is no need to enter the error handler.

This patch implements a new scsi_abort_command() function which
invokes an asynchronous function scsi_eh_abort_handler() to
abort the commands via the usual 'eh_abort_handler'.

If abort succeeds the command is either retried or terminated,
depending on the number of allowed retries. However, 'eh_eflags'
records the abort, so if the retry would fail again the
command is pushed onto the error handler without trying to
abort it (again); it'll be cleared up from SCSI EH.

[hare: smatch detected stray switch fixed]
Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent 2451079b

drivers/scsi/hosts.c

+13 −1
Original line number Diff line number Diff line
@@ -169,6 +169,7 @@ void scsi_remove_host(struct Scsi_Host *shost) 
	spin_unlock_irqrestore(shost->host_lock, flags);



	scsi_autopm_get_host(shost);

	flush_workqueue(shost->tmf_work_q);

	scsi_forget_host(shost);

	mutex_unlock(&shost->scan_mutex);

	scsi_proc_host_rm(shost);
@@ -294,6 +295,8 @@ static void scsi_host_dev_release(struct device *dev) 


	scsi_proc_hostdir_rm(shost->hostt);



	if (shost->tmf_work_q)

		destroy_workqueue(shost->tmf_work_q);

	if (shost->ehandler)

		kthread_stop(shost->ehandler);

	if (shost->work_q)
@@ -360,7 +363,6 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) 
	INIT_LIST_HEAD(&shost->eh_cmd_q);

	INIT_LIST_HEAD(&shost->starved_list);

	init_waitqueue_head(&shost->host_wait);



	mutex_init(&shost->scan_mutex);



	/*
@@ -444,9 +446,19 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) 
		goto fail_kfree;

	}



	shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",

					    WQ_UNBOUND | WQ_MEM_RECLAIM,

					   1, shost->host_no);

	if (!shost->tmf_work_q) {

		printk(KERN_WARNING "scsi%d: failed to create tmf workq\n",

		       shost->host_no);

		goto fail_kthread;

	}

	scsi_proc_hostdir_add(shost->hostt);

	return shost;



 fail_kthread:

	kthread_stop(shost->ehandler);

 fail_kfree:

	kfree(shost);

	return NULL;

drivers/scsi/scsi.c

+3 −0
Original line number Diff line number Diff line
@@ -297,6 +297,7 @@ struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask) 


		cmd->device = dev;

		INIT_LIST_HEAD(&cmd->list);

		INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);

		spin_lock_irqsave(&dev->list_lock, flags);

		list_add_tail(&cmd->list, &dev->cmd_list);

		spin_unlock_irqrestore(&dev->list_lock, flags);
@@ -353,6 +354,8 @@ void scsi_put_command(struct scsi_cmnd *cmd) 
	list_del_init(&cmd->list);

	spin_unlock_irqrestore(&cmd->device->list_lock, flags);



	cancel_delayed_work(&cmd->abort_work);



	__scsi_put_command(cmd->device->host, cmd, &sdev->sdev_gendev);

}

EXPORT_SYMBOL(scsi_put_command);

drivers/scsi/scsi_error.c

+138 −13
Original line number Diff line number Diff line
@@ -53,6 +53,8 @@ static void scsi_eh_done(struct scsi_cmnd *scmd); 
#define HOST_RESET_SETTLE_TIME  (10)



static int scsi_eh_try_stu(struct scsi_cmnd *scmd);

static int scsi_try_to_abort_cmd(struct scsi_host_template *,

				 struct scsi_cmnd *);



/* called with shost->host_lock held */

void scsi_eh_wakeup(struct Scsi_Host *shost)
@@ -99,6 +101,116 @@ static int scsi_host_eh_past_deadline(struct Scsi_Host *shost) 
	return 1;

}



/**

 * scmd_eh_abort_handler - Handle command aborts

 * @work:	command to be aborted.

 */

void

scmd_eh_abort_handler(struct work_struct *work)

{

	struct scsi_cmnd *scmd =

		container_of(work, struct scsi_cmnd, abort_work.work);

	struct scsi_device *sdev = scmd->device;

	unsigned long flags;

	int rtn;



	spin_lock_irqsave(sdev->host->host_lock, flags);

	if (scsi_host_eh_past_deadline(sdev->host)) {

		spin_unlock_irqrestore(sdev->host->host_lock, flags);

		SCSI_LOG_ERROR_RECOVERY(3,

			scmd_printk(KERN_INFO, scmd,

				    "scmd %p eh timeout, not aborting\n",

				    scmd));

	} else {

		spin_unlock_irqrestore(sdev->host->host_lock, flags);

		SCSI_LOG_ERROR_RECOVERY(3,

			scmd_printk(KERN_INFO, scmd,

				    "aborting command %p\n", scmd));

		rtn = scsi_try_to_abort_cmd(sdev->host->hostt, scmd);

		if (rtn == SUCCESS) {

			scmd->result |= DID_TIME_OUT << 16;

			if (!scsi_noretry_cmd(scmd) &&

			    (++scmd->retries <= scmd->allowed)) {

				SCSI_LOG_ERROR_RECOVERY(3,

					scmd_printk(KERN_WARNING, scmd,

						    "scmd %p retry "

						    "aborted command\n", scmd));

				scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);

			} else {

				SCSI_LOG_ERROR_RECOVERY(3,

					scmd_printk(KERN_WARNING, scmd,

						    "scmd %p finish "

						    "aborted command\n", scmd));

				scsi_finish_command(scmd);

			}

			return;

		}

		SCSI_LOG_ERROR_RECOVERY(3,

			scmd_printk(KERN_INFO, scmd,

				    "scmd %p abort failed, rtn %d\n",

				    scmd, rtn));

	}



	if (!scsi_eh_scmd_add(scmd, 0)) {

		SCSI_LOG_ERROR_RECOVERY(3,

			scmd_printk(KERN_WARNING, scmd,

				    "scmd %p terminate "

				    "aborted command\n", scmd));

		scmd->result |= DID_TIME_OUT << 16;

		scsi_finish_command(scmd);

	}

}



/**

 * scsi_abort_command - schedule a command abort

 * @scmd:	scmd to abort.

 *

 * We only need to abort commands after a command timeout

 */

static int

scsi_abort_command(struct scsi_cmnd *scmd)

{

	struct scsi_device *sdev = scmd->device;

	struct Scsi_Host *shost = sdev->host;

	unsigned long flags;



	if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) {

		/*

		 * Retry after abort failed, escalate to next level.

		 */

		SCSI_LOG_ERROR_RECOVERY(3,

			scmd_printk(KERN_INFO, scmd,

				    "scmd %p previous abort failed\n", scmd));

		cancel_delayed_work(&scmd->abort_work);

		return FAILED;

	}



	/*

	 * Do not try a command abort if

	 * SCSI EH has already started.

	 */

	spin_lock_irqsave(shost->host_lock, flags);

	if (scsi_host_in_recovery(shost)) {

		spin_unlock_irqrestore(shost->host_lock, flags);

		SCSI_LOG_ERROR_RECOVERY(3,

			scmd_printk(KERN_INFO, scmd,

				    "scmd %p not aborting, host in recovery\n",

				    scmd));

		return FAILED;

	}



	if (shost->eh_deadline && !shost->last_reset)

		shost->last_reset = jiffies;

	spin_unlock_irqrestore(shost->host_lock, flags);



	scmd->eh_eflags |= SCSI_EH_ABORT_SCHEDULED;

	SCSI_LOG_ERROR_RECOVERY(3,

		scmd_printk(KERN_INFO, scmd,

			    "scmd %p abort scheduled\n", scmd));

	queue_delayed_work(shost->tmf_work_q, &scmd->abort_work, HZ / 100);

	return SUCCESS;

}



/**

 * scsi_eh_scmd_add - add scsi cmd to error handling.

 * @scmd:	scmd to run eh on.
@@ -125,6 +237,8 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag) 
		shost->last_reset = jiffies;



	ret = 1;

	if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED)

		eh_flag &= ~SCSI_EH_CANCEL_CMD;

	scmd->eh_eflags |= eh_flag;

	list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);

	shost->host_failed++;
@@ -161,6 +275,10 @@ enum blk_eh_timer_return scsi_times_out(struct request *req) 
	else if (host->hostt->eh_timed_out)

		rtn = host->hostt->eh_timed_out(scmd);



	if (rtn == BLK_EH_NOT_HANDLED && !host->hostt->no_async_abort)

		if (scsi_abort_command(scmd) == SUCCESS)

			return BLK_EH_NOT_HANDLED;



	scmd->result |= DID_TIME_OUT << 16;



	if (unlikely(rtn == BLK_EH_NOT_HANDLED &&
@@ -1577,7 +1695,7 @@ static void scsi_eh_offline_sdevs(struct list_head *work_q, 
}



/**

 * scsi_noretry_cmd - determinte if command should be failed fast

 * scsi_noretry_cmd - determine if command should be failed fast

 * @scmd:	SCSI cmd to examine.

 */

int scsi_noretry_cmd(struct scsi_cmnd *scmd)
@@ -1585,6 +1703,8 @@ int scsi_noretry_cmd(struct scsi_cmnd *scmd) 
	switch (host_byte(scmd->result)) {

	case DID_OK:

		break;

	case DID_TIME_OUT:

		goto check_type;

	case DID_BUS_BUSY:

		return (scmd->request->cmd_flags & REQ_FAILFAST_TRANSPORT);

	case DID_PARITY:
@@ -1598,17 +1718,18 @@ int scsi_noretry_cmd(struct scsi_cmnd *scmd) 
		return (scmd->request->cmd_flags & REQ_FAILFAST_DRIVER);

	}



	switch (status_byte(scmd->result)) {

	case CHECK_CONDITION:

	if (status_byte(scmd->result) != CHECK_CONDITION)

		return 0;



check_type:

	/*

		 * assume caller has checked sense and determinted

	 * assume caller has checked sense and determined

	 * the check condition was retryable.

	 */

	if (scmd->request->cmd_flags & REQ_FAILFAST_DEV ||

	    scmd->request->cmd_type == REQ_TYPE_BLOCK_PC)

		return 1;

	}



	else

		return 0;

}
@@ -1659,9 +1780,13 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd) 
		 * looks good.  drop through, and check the next byte.

		 */

		break;

	case DID_ABORT:

		if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) {

			scmd->result |= DID_TIME_OUT << 16;

			return SUCCESS;

		}

	case DID_NO_CONNECT:

	case DID_BAD_TARGET:

	case DID_ABORT:

		/*

		 * note - this means that we just report the status back

		 * to the top level driver, not that we actually think

drivers/scsi/scsi_priv.h

+2 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ struct scsi_nl_hdr; 
 * Scsi Error Handler Flags

 */

#define SCSI_EH_CANCEL_CMD	0x0001	/* Cancel this cmd */

#define SCSI_EH_ABORT_SCHEDULED	0x0002	/* Abort has been scheduled */



#define SCSI_SENSE_VALID(scmd) \

	(((scmd)->sense_buffer[0] & 0x70) == 0x70)
@@ -66,6 +67,7 @@ extern int __init scsi_init_devinfo(void); 
extern void scsi_exit_devinfo(void);



/* scsi_error.c */

extern void scmd_eh_abort_handler(struct work_struct *work);

extern enum blk_eh_timer_return scsi_times_out(struct request *req);

extern int scsi_error_handler(void *host);

extern int scsi_decide_disposition(struct scsi_cmnd *cmd);

include/scsi/scsi_cmnd.h

+1 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ struct scsi_cmnd { 
	struct scsi_device *device;

	struct list_head list;  /* scsi_cmnd participates in queue lists */

	struct list_head eh_entry; /* entry for the host eh_cmd_q */

	struct delayed_work abort_work;

	int eh_eflags;		/* Used by error handlr */



	/*

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