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Commit c27d53fb authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe
Browse files

blk-mq: Reduce the number of if-statements in blk_mq_mark_tag_wait() 



This patch does not change any functionality but makes the
blk_mq_mark_tag_wait() code slightly easier to read.

Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 33f782c4

block/blk-mq.c

+35 −34
Original line number Diff line number Diff line
@@ -1104,15 +1104,25 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx, 
				 struct request *rq)

{

	struct blk_mq_hw_ctx *this_hctx = *hctx;

	bool shared_tags = (this_hctx->flags & BLK_MQ_F_TAG_SHARED) != 0;

	struct sbq_wait_state *ws;

	wait_queue_entry_t *wait;

	bool ret;



	if (!shared_tags) {

	if (!(this_hctx->flags & BLK_MQ_F_TAG_SHARED)) {

		if (!test_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state))

			set_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state);

	} else {



		/*

		 * It's possible that a tag was freed in the window between the

		 * allocation failure and adding the hardware queue to the wait

		 * queue.

		 *

		 * Don't clear RESTART here, someone else could have set it.

		 * At most this will cost an extra queue run.

		 */

		return blk_mq_get_driver_tag(rq, hctx, false);

	}



	wait = &this_hctx->dispatch_wait;

	if (!list_empty_careful(&wait->entry))

		return false;
@@ -1125,7 +1135,6 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx, 


	ws = bt_wait_ptr(&this_hctx->tags->bitmap_tags, this_hctx);

	add_wait_queue(&ws->wait, wait);

	}



	/*

	 * It's possible that a tag was freed in the window between the
@@ -1133,14 +1142,6 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx, 
	 * queue.

	 */

	ret = blk_mq_get_driver_tag(rq, hctx, false);



	if (!shared_tags) {

		/*

		 * Don't clear RESTART here, someone else could have set it.

		 * At most this will cost an extra queue run.

		 */

		return ret;

	} else {

	if (!ret) {

		spin_unlock(&this_hctx->lock);

		return false;
@@ -1154,9 +1155,9 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx, 
	list_del_init(&wait->entry);

	spin_unlock_irq(&ws->wait.lock);

	spin_unlock(&this_hctx->lock);



	return true;

}

}



bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,

			     bool got_budget)