[PATCH v3 6/9] blk-mq: update comments on blk_mq_quiesce_queue()
From: Ming Lei <hidden>
Date: 2017-05-31 12:38:23
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Actually what we want to get from blk_mq_quiesce_queue() isn't only to wait for completion of all ongoing .queue_rq(). In the typical context of canceling requests, we need to make sure that the following is done in the dispatch path before starting to cancel requests: - failed dispatched request is finished - busy dispatched request is requeued, and the STARTED flag is cleared So update comment to keep code, doc and our expection consistent. Signed-off-by: Ming Lei <redacted> --- block/blk-mq.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 56ba7e7a8c60..1faddaf005e2 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c@@ -155,12 +155,13 @@ void blk_mq_unfreeze_queue(struct request_queue *q) EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue); /** - * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished + * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished * @q: request queue. * * Note: this function does not prevent that the struct request end_io() - * callback function is invoked. Additionally, it is not prevented that - * new queue_rq() calls occur unless the queue has been stopped first. + * callback function is invoked. Once this function is returned, we make + * sure no dispatch can happen until the queue is unquiesced via + * blk_mq_unquiesce_queue(). */ void blk_mq_quiesce_queue(struct request_queue *q) {
--
2.9.4