From: Ming Lei <tom.leiming@gmail.com>
Date: Sat, 10 May 2014 17:01:49 +0000 (+0800)
Subject: blk-mq: bitmap tag: remove barrier in bt_clear_tag()
X-Git-Tag: v3.16-rc1~30^2~49^2~41^2~2
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=60f2df8a29df5f2db2c87fd23122a1cebdf2011a;p=linux.git

blk-mq: bitmap tag: remove barrier in bt_clear_tag()

The barrier isn't necessary because both atomic_dec_and_test()
and wake_up() implicate one barrier.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index a81b138e89fe..5a83d8e587f7 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -244,7 +244,6 @@ static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag)
 
 	bs = bt_wake_ptr(bt);
 	if (bs && atomic_dec_and_test(&bs->wait_cnt)) {
-		smp_mb__after_clear_bit();
 		atomic_set(&bs->wait_cnt, bt->wake_cnt);
 		bt_index_inc(&bt->wake_index);
 		wake_up(&bs->wait);