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Commit b4562022 authored by Hannes Reinecke's avatar Hannes Reinecke Committed by James Bottomley
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[SCSI] Add 'eh_deadline' to limit SCSI EH runtime 



This patchs adds an 'eh_deadline' sysfs attribute to the scsi
host which limits the overall runtime of the SCSI EH.
The 'eh_deadline' value is stored in the now obsolete field
'resetting'.
When a command is failed the start time of the EH is stored
in 'last_reset'. If the overall runtime of the SCSI EH is longer
than last_reset + eh_deadline, the EH is short-circuited and
falls through to issue a host reset only.

[jejb: add comments in Scsi_Host about new fields]
Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent 6b1e5a45

drivers/scsi/hosts.c

+7 −0
Original line number Diff line number Diff line
@@ -316,6 +316,12 @@ static void scsi_host_dev_release(struct device *dev) 
	kfree(shost);

}



static unsigned int shost_eh_deadline;



module_param_named(eh_deadline, shost_eh_deadline, uint, S_IRUGO|S_IWUSR);

MODULE_PARM_DESC(eh_deadline,

		 "SCSI EH timeout in seconds (should be between 1 and 2^32-1)");



static struct device_type scsi_host_type = {

	.name =		"scsi_host",

	.release =	scsi_host_dev_release,
@@ -388,6 +394,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) 
	shost->unchecked_isa_dma = sht->unchecked_isa_dma;

	shost->use_clustering = sht->use_clustering;

	shost->ordered_tag = sht->ordered_tag;

	shost->eh_deadline = shost_eh_deadline * HZ;



	if (sht->supported_mode == MODE_UNKNOWN)

		/* means we didn't set it ... default to INITIATOR */

drivers/scsi/scsi_error.c

+124 −6
Original line number Diff line number Diff line
@@ -87,6 +87,18 @@ void scsi_schedule_eh(struct Scsi_Host *shost) 
}

EXPORT_SYMBOL_GPL(scsi_schedule_eh);



static int scsi_host_eh_past_deadline(struct Scsi_Host *shost)

{

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

		return 0;



	if (time_before(jiffies,

			shost->last_reset + shost->eh_deadline))

		return 0;



	return 1;

}



/**

 * scsi_eh_scmd_add - add scsi cmd to error handling.

 * @scmd:	scmd to run eh on.
@@ -109,6 +121,9 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag) 
		if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY))

			goto out_unlock;



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

		shost->last_reset = jiffies;



	ret = 1;

	scmd->eh_eflags |= eh_flag;

	list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
@@ -138,6 +153,9 @@ enum blk_eh_timer_return scsi_times_out(struct request *req) 
	trace_scsi_dispatch_cmd_timeout(scmd);

	scsi_log_completion(scmd, TIMEOUT_ERROR);



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

		host->last_reset = jiffies;



	if (host->transportt->eh_timed_out)

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

	else if (host->hostt->eh_timed_out)
@@ -990,13 +1008,26 @@ int scsi_eh_get_sense(struct list_head *work_q, 
		      struct list_head *done_q)

{

	struct scsi_cmnd *scmd, *next;

	struct Scsi_Host *shost;

	int rtn;

	unsigned long flags;



	list_for_each_entry_safe(scmd, next, work_q, eh_entry) {

		if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||

		    SCSI_SENSE_VALID(scmd))

			continue;



		shost = scmd->device->host;

		spin_lock_irqsave(shost->host_lock, flags);

		if (scsi_host_eh_past_deadline(shost)) {

			spin_unlock_irqrestore(shost->host_lock, flags);

			SCSI_LOG_ERROR_RECOVERY(3,

				shost_printk(KERN_INFO, shost,

					    "skip %s, past eh deadline\n",

					     __func__));

			break;

		}

		spin_unlock_irqrestore(shost->host_lock, flags);

		SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,

						  "%s: requesting sense\n",

						  current->comm));
@@ -1082,11 +1113,28 @@ static int scsi_eh_test_devices(struct list_head *cmd_list, 
	struct scsi_cmnd *scmd, *next;

	struct scsi_device *sdev;

	int finish_cmds;

	unsigned long flags;



	while (!list_empty(cmd_list)) {

		scmd = list_entry(cmd_list->next, struct scsi_cmnd, eh_entry);

		sdev = scmd->device;



		if (!try_stu) {

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

			if (scsi_host_eh_past_deadline(sdev->host)) {

				/* Push items back onto work_q */

				list_splice_init(cmd_list, work_q);

				spin_unlock_irqrestore(sdev->host->host_lock,

						       flags);

				SCSI_LOG_ERROR_RECOVERY(3,

					shost_printk(KERN_INFO, sdev->host,

						     "skip %s, past eh deadline",

						     __func__));

				break;

			}

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

		}



		finish_cmds = !scsi_device_online(scmd->device) ||

			(try_stu && !scsi_eh_try_stu(scmd) &&

			 !scsi_eh_tur(scmd)) ||
@@ -1122,14 +1170,28 @@ static int scsi_eh_abort_cmds(struct list_head *work_q, 
	struct scsi_cmnd *scmd, *next;

	LIST_HEAD(check_list);

	int rtn;

	struct Scsi_Host *shost;

	unsigned long flags;



	list_for_each_entry_safe(scmd, next, work_q, eh_entry) {

		if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))

			continue;

		shost = scmd->device->host;

		spin_lock_irqsave(shost->host_lock, flags);

		if (scsi_host_eh_past_deadline(shost)) {

			spin_unlock_irqrestore(shost->host_lock, flags);

			list_splice_init(&check_list, work_q);

			SCSI_LOG_ERROR_RECOVERY(3,

				shost_printk(KERN_INFO, shost,

					    "skip %s, past eh deadline\n",

					     __func__));

			return list_empty(work_q);

		}

		spin_unlock_irqrestore(shost->host_lock, flags);

		SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"

						  "0x%p\n", current->comm,

						  scmd));

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

		rtn = scsi_try_to_abort_cmd(shost->hostt, scmd);

		if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {

			scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;

			if (rtn == FAST_IO_FAIL)
@@ -1187,8 +1249,19 @@ static int scsi_eh_stu(struct Scsi_Host *shost, 
{

	struct scsi_cmnd *scmd, *stu_scmd, *next;

	struct scsi_device *sdev;

	unsigned long flags;



	shost_for_each_device(sdev, shost) {

		spin_lock_irqsave(shost->host_lock, flags);

		if (scsi_host_eh_past_deadline(shost)) {

			spin_unlock_irqrestore(shost->host_lock, flags);

			SCSI_LOG_ERROR_RECOVERY(3,

				shost_printk(KERN_INFO, shost,

					    "skip %s, past eh deadline\n",

					     __func__));

			break;

		}

		spin_unlock_irqrestore(shost->host_lock, flags);

		stu_scmd = NULL;

		list_for_each_entry(scmd, work_q, eh_entry)

			if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
@@ -1241,9 +1314,20 @@ static int scsi_eh_bus_device_reset(struct Scsi_Host *shost, 
{

	struct scsi_cmnd *scmd, *bdr_scmd, *next;

	struct scsi_device *sdev;

	unsigned long flags;

	int rtn;



	shost_for_each_device(sdev, shost) {

		spin_lock_irqsave(shost->host_lock, flags);

		if (scsi_host_eh_past_deadline(shost)) {

			spin_unlock_irqrestore(shost->host_lock, flags);

			SCSI_LOG_ERROR_RECOVERY(3,

				shost_printk(KERN_INFO, shost,

					    "skip %s, past eh deadline\n",

					     __func__));

			break;

		}

		spin_unlock_irqrestore(shost->host_lock, flags);

		bdr_scmd = NULL;

		list_for_each_entry(scmd, work_q, eh_entry)

			if (scmd->device == sdev) {
@@ -1303,6 +1387,21 @@ static int scsi_eh_target_reset(struct Scsi_Host *shost, 
		struct scsi_cmnd *next, *scmd;

		int rtn;

		unsigned int id;

		unsigned long flags;



		spin_lock_irqsave(shost->host_lock, flags);

		if (scsi_host_eh_past_deadline(shost)) {

			spin_unlock_irqrestore(shost->host_lock, flags);

			/* push back on work queue for further processing */

			list_splice_init(&check_list, work_q);

			list_splice_init(&tmp_list, work_q);

			SCSI_LOG_ERROR_RECOVERY(3,

				shost_printk(KERN_INFO, shost,

					    "skip %s, past eh deadline\n",

					     __func__));

			return list_empty(work_q);

		}

		spin_unlock_irqrestore(shost->host_lock, flags);



		scmd = list_entry(tmp_list.next, struct scsi_cmnd, eh_entry);

		id = scmd_id(scmd);
@@ -1347,6 +1446,7 @@ static int scsi_eh_bus_reset(struct Scsi_Host *shost, 
	LIST_HEAD(check_list);

	unsigned int channel;

	int rtn;

	unsigned long flags;



	/*

	 * we really want to loop over the various channels, and do this on
@@ -1356,6 +1456,18 @@ static int scsi_eh_bus_reset(struct Scsi_Host *shost, 
	 */



	for (channel = 0; channel <= shost->max_channel; channel++) {

		spin_lock_irqsave(shost->host_lock, flags);

		if (scsi_host_eh_past_deadline(shost)) {

			spin_unlock_irqrestore(shost->host_lock, flags);

			list_splice_init(&check_list, work_q);

			SCSI_LOG_ERROR_RECOVERY(3,

				shost_printk(KERN_INFO, shost,

					    "skip %s, past eh deadline\n",

					     __func__));

			return list_empty(work_q);

		}

		spin_unlock_irqrestore(shost->host_lock, flags);



		chan_scmd = NULL;

		list_for_each_entry(scmd, work_q, eh_entry) {

			if (channel == scmd_channel(scmd)) {
@@ -1755,8 +1867,9 @@ static void scsi_restart_operations(struct Scsi_Host *shost) 
	 * will be requests for character device operations, and also for

	 * ioctls to queued block devices.

	 */

	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",

					  __func__));

	SCSI_LOG_ERROR_RECOVERY(3,

		printk("scsi_eh_%d waking up host to restart\n",

		       shost->host_no));



	spin_lock_irqsave(shost->host_lock, flags);

	if (scsi_host_set_state(shost, SHOST_RUNNING))
@@ -1883,6 +1996,10 @@ static void scsi_unjam_host(struct Scsi_Host *shost) 
		if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))

			scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);



	spin_lock_irqsave(shost->host_lock, flags);

	if (shost->eh_deadline)

		shost->last_reset = 0;

	spin_unlock_irqrestore(shost->host_lock, flags);

	scsi_eh_flush_done_q(&eh_done_q);

}
@@ -1909,7 +2026,7 @@ int scsi_error_handler(void *data) 
		if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||

		    shost->host_failed != shost->host_busy) {

			SCSI_LOG_ERROR_RECOVERY(1,

				printk("Error handler scsi_eh_%d sleeping\n",

				printk("scsi_eh_%d: sleeping\n",

					shost->host_no));

			schedule();

			continue;
@@ -1917,8 +2034,9 @@ int scsi_error_handler(void *data) 


		__set_current_state(TASK_RUNNING);

		SCSI_LOG_ERROR_RECOVERY(1,

			printk("Error handler scsi_eh_%d waking up\n",

				shost->host_no));

			printk("scsi_eh_%d: waking up %d/%d/%d\n",

			       shost->host_no, shost->host_eh_scheduled,

			       shost->host_failed, shost->host_busy));



		/*

		 * We have a host that is failing for some reason.  Figure out

drivers/scsi/scsi_sysfs.c

+37 −0
Original line number Diff line number Diff line
@@ -281,6 +281,42 @@ store_host_reset(struct device *dev, struct device_attribute *attr, 


static DEVICE_ATTR(host_reset, S_IWUSR, NULL, store_host_reset);



static ssize_t

show_shost_eh_deadline(struct device *dev,

		      struct device_attribute *attr, char *buf)

{

	struct Scsi_Host *shost = class_to_shost(dev);



	return sprintf(buf, "%d\n", shost->eh_deadline / HZ);

}



static ssize_t

store_shost_eh_deadline(struct device *dev, struct device_attribute *attr,

		const char *buf, size_t count)

{

	struct Scsi_Host *shost = class_to_shost(dev);

	int ret = -EINVAL;

	int deadline;

	unsigned long flags;



	if (shost->transportt && shost->transportt->eh_strategy_handler)

		return ret;



	if (sscanf(buf, "%d\n", &deadline) == 1) {

		spin_lock_irqsave(shost->host_lock, flags);

		if (scsi_host_in_recovery(shost))

			ret = -EBUSY;

		else {

			shost->eh_deadline = deadline * HZ;

			ret = count;

		}

		spin_unlock_irqrestore(shost->host_lock, flags);

	}

	return ret;

}



static DEVICE_ATTR(eh_deadline, S_IRUGO | S_IWUSR, show_shost_eh_deadline, store_shost_eh_deadline);



shost_rd_attr(unique_id, "%u\n");

shost_rd_attr(host_busy, "%hu\n");

shost_rd_attr(cmd_per_lun, "%hd\n");
@@ -308,6 +344,7 @@ static struct attribute *scsi_sysfs_shost_attrs[] = { 
	&dev_attr_prot_capabilities.attr,

	&dev_attr_prot_guard_type.attr,

	&dev_attr_host_reset.attr,

	&dev_attr_eh_deadline.attr,

	NULL

};

include/scsi/scsi_host.h

+5 −0
Original line number Diff line number Diff line
@@ -599,6 +599,11 @@ struct Scsi_Host { 
    

	unsigned int host_no;  /* Used for IOCTL_GET_IDLUN, /proc/scsi et al. */



	/* next two fields are used to bound the time spent in error handling */

	int eh_deadline;

	unsigned long last_reset;





	/*

	 * These three parameters can be used to allow for wide scsi,

	 * and for host adapters that support multiple busses