scsi: pm80xx: Fix TMF task completion race condition

The TMF timeout timer may trigger at the same time when the response from a
controller is being handled. When this happens the SAS task may get freed
before the response processing is finished.

Fix this by calling complete() only when SAS_TASK_STATE_DONE is not set.

A similar race condition was fixed in commit b90cd6f ("scsi: libsas:
fix a race condition when smp task timeout")

Link: https://lore.kernel.org/r/20210707185945.35559-1-ipylypiv@google.com
Reviewed-by: Vishakha Channapattan <vishakhavc@google.com>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: ipylypiv

drivers/scsi/pm8001/pm8001_sas.c

@@ -684,18 +684,22 @@ int pm8001_dev_found(struct domain_device *dev)
 
 void pm8001_task_done(struct sas_task *task)
 {
-	if (!del_timer(&task->slow_task->timer))
-		return;
+	del_timer(&task->slow_task->timer);
 	complete(&task->slow_task->completion);
 }
 
 static void pm8001_tmf_timedout(struct timer_list *t)
 {
 	struct sas_task_slow *slow = from_timer(slow, t, timer);
 	struct sas_task *task = slow->task;
+	unsigned long flags;
 
-	task->task_state_flags |= SAS_TASK_STATE_ABORTED;
-	complete(&task->slow_task->completion);
+	spin_lock_irqsave(&task->task_state_lock, flags);
+	if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
+		task->task_state_flags |= SAS_TASK_STATE_ABORTED;
+		complete(&task->slow_task->completion);
+	}
+	spin_unlock_irqrestore(&task->task_state_lock, flags);
 }
 
 #define PM8001_TASK_TIMEOUT 20
@@ -748,13 +752,10 @@ static int pm8001_exec_internal_tmf_task(struct domain_device *dev,
 		}
 		res = -TMF_RESP_FUNC_FAILED;
 		/* Even TMF timed out, return direct. */
-		if ((task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
-			if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
-				pm8001_dbg(pm8001_ha, FAIL,
-					   "TMF task[%x]timeout.\n",
-					   tmf->tmf);
-				goto ex_err;
-			}
+		if (task->task_state_flags & SAS_TASK_STATE_ABORTED) {
+			pm8001_dbg(pm8001_ha, FAIL, "TMF task[%x]timeout.\n",
+				   tmf->tmf);
+			goto ex_err;
 		}
 
 		if (task->task_status.resp == SAS_TASK_COMPLETE &&
@@ -834,12 +835,9 @@ pm8001_exec_internal_task_abort(struct pm8001_hba_info *pm8001_ha,
 		wait_for_completion(&task->slow_task->completion);
 		res = TMF_RESP_FUNC_FAILED;
 		/* Even TMF timed out, return direct. */
-		if ((task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
-			if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
-				pm8001_dbg(pm8001_ha, FAIL,
-					   "TMF task timeout.\n");
-				goto ex_err;
-			}
+		if (task->task_state_flags & SAS_TASK_STATE_ABORTED) {
+			pm8001_dbg(pm8001_ha, FAIL, "TMF task timeout.\n");
+			goto ex_err;
 		}
 
 		if (task->task_status.resp == SAS_TASK_COMPLETE &&