[SCSI] libsas: fix timeout vs completion race
Until we have told the lldd to forget a task a timed out operation can
return from the hardware at any time. Since completion frees the task
we need to make sure that no tasks run their normal completion handler
once eh has decided to manage the task. Similar to
ata_scsi_cmd_error_handler() freeze completions to let eh judge the
outcome of the race.
Task collector mode is problematic because it presents a situation where
a task can be timed out and aborted before the lldd has even seen it.
For this case we need to guarantee that a task that an lldd has been
told to forget does not get queued after the lldd says "never seen it".
With sas_scsi_timed_out we achieve this with the ->task_queue_flush
mutex, rather than adding more time.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 903bb44..4c2a140 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -93,21 +93,30 @@
static void sas_ata_task_done(struct sas_task *task)
{
struct ata_queued_cmd *qc = task->uldd_task;
- struct domain_device *dev;
+ struct domain_device *dev = task->dev;
struct task_status_struct *stat = &task->task_status;
struct ata_task_resp *resp = (struct ata_task_resp *)stat->buf;
- struct sas_ha_struct *sas_ha;
+ struct sas_ha_struct *sas_ha = dev->port->ha;
enum ata_completion_errors ac;
unsigned long flags;
struct ata_link *link;
struct ata_port *ap;
+ spin_lock_irqsave(&dev->done_lock, flags);
+ if (test_bit(SAS_HA_FROZEN, &sas_ha->state))
+ task = NULL;
+ else if (qc && qc->scsicmd)
+ ASSIGN_SAS_TASK(qc->scsicmd, NULL);
+ spin_unlock_irqrestore(&dev->done_lock, flags);
+
+ /* check if libsas-eh got to the task before us */
+ if (unlikely(!task))
+ return;
+
if (!qc)
goto qc_already_gone;
ap = qc->ap;
- dev = ap->private_data;
- sas_ha = dev->port->ha;
link = &ap->link;
spin_lock_irqsave(ap->lock, flags);
@@ -156,8 +165,6 @@
}
qc->lldd_task = NULL;
- if (qc->scsicmd)
- ASSIGN_SAS_TASK(qc->scsicmd, NULL);
ata_qc_complete(qc);
spin_unlock_irqrestore(ap->lock, flags);
@@ -633,22 +640,6 @@
sas_enable_revalidation(sas_ha);
}
-int sas_ata_timed_out(struct scsi_cmnd *cmd, struct sas_task *task,
- enum blk_eh_timer_return *rtn)
-{
- struct domain_device *ddev = cmd_to_domain_dev(cmd);
-
- if (!dev_is_sata(ddev) || task)
- return 0;
-
- /* we're a sata device with no task, so this must be a libata
- * eh timeout. Ideally should hook into libata timeout
- * handling, but there's no point, it just wants to activate
- * the eh thread */
- *rtn = BLK_EH_NOT_HANDLED;
- return 1;
-}
-
int sas_ata_eh(struct Scsi_Host *shost, struct list_head *work_q,
struct list_head *done_q)
{