[PATCH v3 5/8] scsi: don't wait for quiesce in scsi_stop_queue()

[mwilck@suse.com]

From: Martin Wilck <mwilck@suse.com>

scsi_stop_queue() has just two callers, one with and one without
"nowait". As blk_mq_quiesce_queue() comes down to
blk_mq_quiesce_queue_nowait() followed by blk_mq_wait_quiesce_done(),
we might as well open-code this in scsi_device_block().

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 drivers/scsi/scsi_lib.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 26e7ce25fa05..657d10c57205 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2726,24 +2726,16 @@ void scsi_start_queue(struct scsi_device *sdev)
 		blk_mq_unquiesce_queue(sdev->request_queue);
 }
 
-static void scsi_stop_queue(struct scsi_device *sdev, bool nowait)
+static void scsi_stop_queue(struct scsi_device *sdev)
 {
 	/*
 	 * The atomic variable of ->queue_stopped covers that
 	 * blk_mq_quiesce_queue* is balanced with blk_mq_unquiesce_queue.
 	 *
-	 * However, we still need to wait until quiesce is done
-	 * in case that queue has been stopped.
+	 * After return, we still need to wait until quiesce is done.
 	 */
-	if (!cmpxchg(&sdev->queue_stopped, 0, 1)) {
-		if (nowait)
-			blk_mq_quiesce_queue_nowait(sdev->request_queue);
-		else
-			blk_mq_quiesce_queue(sdev->request_queue);
-	} else {
-		if (!nowait)
-			blk_mq_wait_quiesce_done(sdev->request_queue->tag_set);
-	}
+	if (!cmpxchg(&sdev->queue_stopped, 0, 1))
+		blk_mq_quiesce_queue_nowait(sdev->request_queue);
 }
 
 /**
@@ -2770,7 +2762,7 @@ int scsi_internal_device_block_nowait(struct scsi_device *sdev)
 	 * request queue.
 	 */
 	if (!ret)
-		scsi_stop_queue(sdev, true);
+		scsi_stop_queue(sdev);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait);
@@ -2796,8 +2788,10 @@ static void scsi_device_block(struct scsi_device *sdev, void *data)
 	mutex_lock(&sdev->state_mutex);
 	err = __scsi_internal_device_block_nowait(sdev);
 	mutex_unlock(&sdev->state_mutex);
-	if (err == 0)
-		scsi_stop_queue(sdev, false);
+	if (err == 0) {
+		scsi_stop_queue(sdev);
+		blk_mq_wait_quiesce_done(sdev->request_queue->tag_set);
+	}
 
 	WARN_ONCE(err, "__scsi_internal_device_block_nowait(%s) failed: err = %d\n",
 		  dev_name(&sdev->sdev_gendev), err);
-- 
2.40.1