linux-kernel - [PATCH 6/6] blk-mq: Micro-optimize bt

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Date:	Tue, 09 Dec 2014 16:59:48 +0100
From:	Bart Van Assche <bvanassche@....org>
To:	Jens Axboe <axboe@...nel.dk>
CC:	Christoph Hellwig <hch@....de>, Robert Elliott <elliott@...com>,
	Ming Lei <ming.lei@...onical.com>,
	Alexander Gordeev <agordeev@...hat.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH 6/6] blk-mq: Micro-optimize bt_get()

Remove a superfluous finish_wait() call. Convert the two bt_wait_ptr()
calls into a single call.

Signed-off-by: Bart Van Assche <bvanassche@....org>
Cc: Christoph Hellwig <hch@....de>
Cc: Robert Elliott <elliott@...com>
Cc: Ming Lei <ming.lei@...onical.com>
Cc: Alexander Gordeev <agordeev@...hat.com>
---
 block/blk-mq-tag.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 795996e..2373724 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -248,8 +248,8 @@ static int bt_get(struct blk_mq_alloc_data *data,
 	if (!(data->gfp & __GFP_WAIT))
 		return -1;
 
-	bs = bt_wait_ptr(bt, hctx);
 	do {
+		bs = bt_wait_ptr(bt, hctx);
 		prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE);
 
 		tag = __bt_get(hctx, bt, last_tag);
@@ -276,8 +276,6 @@ static int bt_get(struct blk_mq_alloc_data *data,
 			hctx = data->hctx;
 			bt = &hctx->tags->bitmap_tags;
 		}
-		finish_wait(&bs->wait, &wait);
-		bs = bt_wait_ptr(bt, hctx);
 	} while (1);
 
 	finish_wait(&bs->wait, &wait);
-- 
2.1.2

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