[PATCH V2 3/3] SCSI: don't grab queue usage counter before run queue

[Ming Lei <ming.lei@redhat.com>]

Now freeing hw queue resource is moved to hctx's release handler,
we don't need to worry about the possible race between blk_cleanup_queue
and run queue.

So don't grab the queue usage counter before run queue in
scsi_end_request().

This is basically revert of 8dc765d438f1 ("SCSI: fix queue cleanup race before queue
initialization is done").

Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: James Smart <james.smart@broadcom.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: linux-scsi@vger.kernel.org,
Cc: Martin K . Petersen <martin.petersen@oracle.com>,
Cc: Christoph Hellwig <hch@lst.de>,
Cc: James E . J . Bottomley <jejb@linux.vnet.ibm.com>,
Cc: jianchao wang <jianchao.w.wang@oracle.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/scsi/scsi_lib.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 601b9f1de267..18bf341d1236 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -604,12 +604,6 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
 	 */
 	scsi_mq_uninit_cmd(cmd);
 
-	/*
-	 * queue is still alive, so grab the ref for preventing it
-	 * from being cleaned up during running queue.
-	 */
-	percpu_ref_get(&q->q_usage_counter);
-
 	__blk_mq_end_request(req, error);
 
 	if (scsi_target(sdev)->single_lun ||
@@ -618,7 +612,6 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
 	else
 		blk_mq_run_hw_queues(q, true);
 
-	percpu_ref_put(&q->q_usage_counter);
 	put_device(&sdev->sdev_gendev);
 	return false;
 }
-- 
2.9.5