[PATCH v2] scsi: ufs: Cleanup completed request without interrupt notification

[PATCH v2] scsi: ufs: Cleanup completed request without interrupt notification

[Stanley Chu]

If somehow no interrupt notification is raised for a completed request
and its doorbell bit is cleared by host, UFS driver needs to cleanup
its outstanding bit in ufshcd_abort().

Otherwise, system may crash by below abnormal flow:

After this request is requeued by SCSI layer with its
outstanding bit set, the next completed request will trigger
ufshcd_transfer_req_compl() to handle all "completed outstanding
bits". In this time, the "abnormal outstanding bit" will be detected
and the "requeued request" will be chosen to execute request
post-processing flow. This is wrong and blk_finish_request() will
BUG_ON because this request is still "alive".

It is worth mentioning that before ufshcd_abort() cleans the timed-out
request, driver needs to check again if this request is really not
handled by __ufshcd_transfer_req_compl() yet because it is possible
that its interrupt comes very lately before the cleaning.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
---
 drivers/scsi/ufs/ufshcd.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index cadfa9006972..0f4f3255e403 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6462,7 +6462,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
 			/* command completed already */
 			dev_err(hba->dev, "%s: cmd at tag %d successfully cleared from DB.\n",
 				__func__, tag);
-			goto out;
+			goto cleanup;
 		} else {
 			dev_err(hba->dev,
 				"%s: no response from device. tag = %d, err %d\n",
@@ -6496,9 +6496,14 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
 		goto out;
 	}
 
+cleanup:
+	spin_lock_irqsave(host->host_lock, flags);
+	if (!test_bit(tag, hba->outstanding_reqs)) {
+		spin_unlock_irqrestore(host->host_lock, flags);
+		goto out;
+	}
 	scsi_dma_unmap(cmd);
 
-	spin_lock_irqsave(host->host_lock, flags);
 	ufshcd_outstanding_req_clear(hba, tag);
 	hba->lrb[tag].cmd = NULL;
 	spin_unlock_irqrestore(host->host_lock, flags);
-- 
2.18.0