Commit 2edd2c74 authored Sep 17, 2014 by Ming Lei Committed by Jens Axboe Sep 22, 2014

blk-mq: remove unnecessary blk_clear_rq_complete()



This patch removes two unnecessary blk_clear_rq_complete(),
the REQ_ATOM_COMPLETE flag is cleared inside blk_mq_start_request(),
so:

	- The blk_clear_rq_complete() in blk_flush_restore_request()
	needn't because the request will be freed later, and clearing
	it here may open a small race window with timeout.

	- The blk_clear_rq_complete() in blk_mq_requeue_request() isn't
	necessary too, even though REQ_ATOM_STARTED is cleared in
	__blk_mq_requeue_request(), in theory it still may cause a small
	race window with timeout since the two clear_bit() may be
	reordered.

Signed-off-by: Ming Lei <ming.lei@canoical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 0152fb6b

block/blk-flush.c

+0 −2

Original line number	Diff line number	Diff line
		@@ -126,8 +126,6 @@ static void blk_flush_restore_request(struct request *rq)
		/* make @rq a normal request */
		rq->cmd_flags &= ~REQ_FLUSH_SEQ;
		rq->end_io = rq->flush.saved_end_io;

		blk_clear_rq_complete(rq);
		}

		static bool blk_flush_queue_rq(struct request *rq, bool add_front)

block/blk-mq.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -439,7 +439,6 @@ static void __blk_mq_requeue_request(struct request *rq)
		void blk_mq_requeue_request(struct request *rq)
		{
		__blk_mq_requeue_request(rq);
		blk_clear_rq_complete(rq);

		BUG_ON(blk_queued_rq(rq));
		blk_mq_add_to_requeue_list(rq, true);