[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: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index a734710..8ff62c2 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -281,6 +281,42 @@
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 @@
&dev_attr_prot_capabilities.attr,
&dev_attr_prot_guard_type.attr,
&dev_attr_host_reset.attr,
+ &dev_attr_eh_deadline.attr,
NULL
};