[PATCH] block: do not put mq context in blk_mq_alloc_request_hctx

From	Minchan Kim <minchan@kernel.org>
Newsgroups	linux.kernel
Subject	[PATCH] block: do not put mq context in blk_mq_alloc_request_hctx
Date	2017-03-30 07:30 +0200
Message-ID	<tqAOJ-1uk-3@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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In blk_mq_alloc_request_hctx, blk_mq_sched_get_request doesn't
get sw context so we don't need to put the context with
blk_mq_put_ctx. Unless, we will see preempt counter underflow.

Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---

Maybe, it would be fixed by someone but I have noticed preempt counter
undeflow problem a few weeks ago and still see the problem with
linux-next.

 block/blk-mq.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index a4546f060e80..a6f3998dc4ee 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -321,7 +321,6 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,

 	rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);

-	blk_mq_put_ctx(alloc_data.ctx);
 	blk_queue_exit(q);

 	if (!rq)
-- 
2.7.4

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[PATCH] block: do not put mq context in blk_mq_alloc_request_hctx Minchan Kim <minchan@kernel.org> - 2017-03-30 07:30 +0200
  Re: [PATCH] block: do not put mq context in blk_mq_alloc_request_hctx Sagi Grimberg <sagi@grimberg.me> - 2017-03-30 16:10 +0200

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