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[SCSI] Add 'eh_deadline' to limit SCSI EH runtime
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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: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
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Hannes Reinecke authored and James Bottomley committed Oct 25, 2013
1 parent 6b1e5a4 commit b456202
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Showing 4 changed files with 173 additions and 6 deletions.
7 changes: 7 additions & 0 deletions drivers/scsi/hosts.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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 */
Expand Down
130 changes: 124 additions & 6 deletions drivers/scsi/scsi_error.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand All @@ -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);
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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));
Expand Down Expand Up @@ -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)) ||
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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) &&
Expand Down Expand Up @@ -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) {
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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
Expand All @@ -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)) {
Expand Down Expand Up @@ -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))
Expand Down Expand Up @@ -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);
}

Expand All @@ -1909,16 +2026,17 @@ 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;
}

__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
Expand Down
37 changes: 37 additions & 0 deletions drivers/scsi/scsi_sysfs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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");
Expand Down Expand Up @@ -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
};

Expand Down
5 changes: 5 additions & 0 deletions include/scsi/scsi_host.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down

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