scsi: hisi_sas: Add some checks to avoid free'ing a sas_task twice

If the SCSI host enters EH, any pending IO will be processed by SCSI
EH. However it is possible that SCSI EH will try to abort the IO and
also at the same time the IO completes in the driver. In this situation
there is a small chance of freeing the sas_task twice.

Then if another IO re-uses freed sas_task before the second time of
free'ing sas_task, it is possible to free incorrect sas_task.

To avoid this situation, add some checks to increase reliability.  The
sas_task task state flag SAS_TASK_STATE_ABORTED is used to mutually
protect the LLDD and libsas freeing the task.
Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/hisi_sas/hisi_sas_main.c

@@ -1174,10 +1174,14 @@ static int hisi_sas_abort_task(struct sas_task *task)
 		return TMF_RESP_FUNC_FAILED;
 	}
 
+	spin_lock_irqsave(&task->task_state_lock, flags);
 	if (task->task_state_flags & SAS_TASK_STATE_DONE) {
+		spin_unlock_irqrestore(&task->task_state_lock, flags);
 		rc = TMF_RESP_FUNC_COMPLETE;
 		goto out;
 	}
+	task->task_state_flags |= SAS_TASK_STATE_ABORTED;
+	spin_unlock_irqrestore(&task->task_state_lock, flags);
 
 	sas_dev->dev_status = HISI_SAS_DEV_EH;
 	if (task->lldd_task && task->task_proto & SAS_PROTOCOL_SSP) {

drivers/scsi/hisi_sas/hisi_sas_v2_hw.c

@@ -2386,7 +2386,6 @@ slot_complete_v2_hw(struct hisi_hba *hisi_hba, struct hisi_sas_slot *slot)
 	struct hisi_sas_complete_v2_hdr *complete_hdr =
 			&complete_queue[slot->cmplt_queue_slot];
 	unsigned long flags;
-	int aborted;
 
 	if (unlikely(!task || !task->lldd_task || !task->dev))
 		return -EINVAL;
@@ -2396,7 +2395,6 @@ slot_complete_v2_hw(struct hisi_hba *hisi_hba, struct hisi_sas_slot *slot)
 	sas_dev = device->lldd_dev;
 
 	spin_lock_irqsave(&task->task_state_lock, flags);
-	aborted = task->task_state_flags & SAS_TASK_STATE_ABORTED;
 	task->task_state_flags &=
 		~(SAS_TASK_STATE_PENDING | SAS_TASK_AT_INITIATOR);
 	spin_unlock_irqrestore(&task->task_state_lock, flags);
@@ -2404,15 +2402,6 @@ slot_complete_v2_hw(struct hisi_hba *hisi_hba, struct hisi_sas_slot *slot)
 	memset(ts, 0, sizeof(*ts));
 	ts->resp = SAS_TASK_COMPLETE;
 
-	if (unlikely(aborted)) {
-		dev_dbg(dev, "slot_complete: task(%p) aborted\n", task);
-		ts->stat = SAS_ABORTED_TASK;
-		spin_lock_irqsave(&hisi_hba->lock, flags);
-		hisi_sas_slot_task_free(hisi_hba, task, slot);
-		spin_unlock_irqrestore(&hisi_hba->lock, flags);
-		return ts->stat;
-	}
-
 	if (unlikely(!sas_dev)) {
 		dev_dbg(dev, "slot complete: port has no device\n");
 		ts->stat = SAS_PHY_DOWN;
@@ -2523,13 +2512,16 @@ slot_complete_v2_hw(struct hisi_hba *hisi_hba, struct hisi_sas_slot *slot)
 	}
 
 out:
+	hisi_sas_slot_task_free(hisi_hba, task, slot);
+	sts = ts->stat;
 	spin_lock_irqsave(&task->task_state_lock, flags);
+	if (task->task_state_flags & SAS_TASK_STATE_ABORTED) {
+		spin_unlock_irqrestore(&task->task_state_lock, flags);
+		dev_info(dev, "slot complete: task(%p) aborted\n", task);
+		return SAS_ABORTED_TASK;
+	}
 	task->task_state_flags |= SAS_TASK_STATE_DONE;
 	spin_unlock_irqrestore(&task->task_state_lock, flags);
-	spin_lock_irqsave(&hisi_hba->lock, flags);
-	hisi_sas_slot_task_free(hisi_hba, task, slot);
-	spin_unlock_irqrestore(&hisi_hba->lock, flags);
-	sts = ts->stat;
 
 	if (task->task_done)
 		task->task_done(task);

drivers/scsi/hisi_sas/hisi_sas_v3_hw.c

@@ -1576,7 +1576,6 @@ slot_complete_v3_hw(struct hisi_hba *hisi_hba, struct hisi_sas_slot *slot)
 			hisi_hba->complete_hdr[slot->cmplt_queue];
 	struct hisi_sas_complete_v3_hdr *complete_hdr =
 			&complete_queue[slot->cmplt_queue_slot];
-	int aborted;
 	unsigned long flags;
 
 	if (unlikely(!task || !task->lldd_task || !task->dev))
@@ -1587,21 +1586,12 @@ slot_complete_v3_hw(struct hisi_hba *hisi_hba, struct hisi_sas_slot *slot)
 	sas_dev = device->lldd_dev;
 
 	spin_lock_irqsave(&task->task_state_lock, flags);
-	aborted = task->task_state_flags & SAS_TASK_STATE_ABORTED;
 	task->task_state_flags &=
 		~(SAS_TASK_STATE_PENDING | SAS_TASK_AT_INITIATOR);
 	spin_unlock_irqrestore(&task->task_state_lock, flags);
 
 	memset(ts, 0, sizeof(*ts));
 	ts->resp = SAS_TASK_COMPLETE;
-	if (unlikely(aborted)) {
-		dev_dbg(dev, "slot complete: task(%p) aborted\n", task);
-		ts->stat = SAS_ABORTED_TASK;
-		spin_lock_irqsave(&hisi_hba->lock, flags);
-		hisi_sas_slot_task_free(hisi_hba, task, slot);
-		spin_unlock_irqrestore(&hisi_hba->lock, flags);
-		return ts->stat;
-	}
 
 	if (unlikely(!sas_dev)) {
 		dev_dbg(dev, "slot complete: port has not device\n");
@@ -1699,13 +1689,16 @@ slot_complete_v3_hw(struct hisi_hba *hisi_hba, struct hisi_sas_slot *slot)
 	}
 
 out:
+	hisi_sas_slot_task_free(hisi_hba, task, slot);
+	sts = ts->stat;
 	spin_lock_irqsave(&task->task_state_lock, flags);
+	if (task->task_state_flags & SAS_TASK_STATE_ABORTED) {
+		spin_unlock_irqrestore(&task->task_state_lock, flags);
+		dev_info(dev, "slot complete: task(%p) aborted\n", task);
+		return SAS_ABORTED_TASK;
+	}
 	task->task_state_flags |= SAS_TASK_STATE_DONE;
 	spin_unlock_irqrestore(&task->task_state_lock, flags);
-	spin_lock_irqsave(&hisi_hba->lock, flags);
-	hisi_sas_slot_task_free(hisi_hba, task, slot);
-	spin_unlock_irqrestore(&hisi_hba->lock, flags);
-	sts = ts->stat;
 
 	if (task->task_done)
 		task->task_done(task);