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From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@fb.com>,
	linux-block@vger.kernel.org,
	Christoph Hellwig <hch@infradead.org>
Cc: Bart Van Assche <bart.vanassche@sandisk.com>,
	linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org,
	dm-devel@redhat.com
Subject: [PATCH 6/6] blk-mq: clarify dispatching won't be blocked by stopping queue
Date: Fri, 26 May 2017 11:07:40 +0800	[thread overview]
Message-ID: <20170526030740.26959-8-ming.lei@redhat.com> (raw)
In-Reply-To: <20170526030740.26959-1-ming.lei@redhat.com>

BLK_MQ_S_STOPPED may be not observed in other concurrent I/O paths,
we can't guarantee that dispatching won't happen after queue
is stopped.

So clarify the fact and avoid potential misuse.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-mq.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 900eb91e0ece..32bed5bac7da 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1240,6 +1240,11 @@ static void __blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx, bool sync)
 	set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 }
 
+/*
+ * Do not expect that dispatching or .queue_rq() can be blocked
+ * after blk_mq_stop_hw_queue() returns. Please use
+ * blk_mq_quiesce_queue() for that requirement.
+ */
 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 {
 	__blk_mq_stop_hw_queue(hctx, false);
@@ -1255,6 +1260,11 @@ static void __blk_mq_stop_hw_queues(struct request_queue *q, bool sync)
 		__blk_mq_stop_hw_queue(hctx, sync);
 }
 
+/*
+ * Do not expect that dispatching or .queue_rq() can be blocked
+ * after blk_mq_stop_hw_queues() returns. Please use
+ * blk_mq_quiesce_queue() for that requirement.
+ */
 void blk_mq_stop_hw_queues(struct request_queue *q)
 {
 	__blk_mq_stop_hw_queues(q, false);
-- 
2.9.4

WARNING: multiple messages have this Message-ID (diff)
From: ming.lei@redhat.com (Ming Lei)
Subject: [PATCH 6/6] blk-mq: clarify dispatching won't be blocked by stopping queue
Date: Fri, 26 May 2017 11:07:40 +0800	[thread overview]
Message-ID: <20170526030740.26959-8-ming.lei@redhat.com> (raw)
In-Reply-To: <20170526030740.26959-1-ming.lei@redhat.com>

BLK_MQ_S_STOPPED may be not observed in other concurrent I/O paths,
we can't guarantee that dispatching won't happen after queue
is stopped.

So clarify the fact and avoid potential misuse.

Signed-off-by: Ming Lei <ming.lei at redhat.com>
---
 block/blk-mq.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 900eb91e0ece..32bed5bac7da 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1240,6 +1240,11 @@ static void __blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx, bool sync)
 	set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 }
 
+/*
+ * Do not expect that dispatching or .queue_rq() can be blocked
+ * after blk_mq_stop_hw_queue() returns. Please use
+ * blk_mq_quiesce_queue() for that requirement.
+ */
 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 {
 	__blk_mq_stop_hw_queue(hctx, false);
@@ -1255,6 +1260,11 @@ static void __blk_mq_stop_hw_queues(struct request_queue *q, bool sync)
 		__blk_mq_stop_hw_queue(hctx, sync);
 }
 
+/*
+ * Do not expect that dispatching or .queue_rq() can be blocked
+ * after blk_mq_stop_hw_queues() returns. Please use
+ * blk_mq_quiesce_queue() for that requirement.
+ */
 void blk_mq_stop_hw_queues(struct request_queue *q)
 {
 	__blk_mq_stop_hw_queues(q, false);
-- 
2.9.4

  parent reply	other threads:[~2017-05-26  3:09 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-26  3:07 [PATCH 0/6] blk-mq: fix & improve queue quiescing Ming Lei
2017-05-26  3:07 ` Ming Lei
2017-05-26  3:07 ` [PATCH 1/6] blk-mq: introduce blk_mq_unquiesce_queue Ming Lei
2017-05-26  3:07   ` Ming Lei
2017-05-26  3:07 ` [PATCH 2/6] blk-mq: use the introduced blk_mq_unquiesce_queue() Ming Lei
2017-05-26  3:07   ` Ming Lei
2017-05-26  7:46   ` kbuild test robot
2017-05-26  7:46     ` kbuild test robot
2017-05-26  7:46     ` kbuild test robot
2017-05-26  8:24     ` Ming Lei
2017-05-26  8:24       ` Ming Lei
2017-05-26  8:24       ` Ming Lei
2017-05-26  3:07 ` [PATCH 3/6] blk-mq: fix blk_mq_quiesce_queue Ming Lei
2017-05-26  3:07   ` Ming Lei
2017-05-26  3:07 ` [PATCH 4/6] blk-mq: update comments on blk_mq_quiesce_queue() Ming Lei
2017-05-26  3:07   ` Ming Lei
2017-05-26  3:07 ` [PATCH 5/6] blk-mq: don't stop queue for quiescing Ming Lei
2017-05-26  3:07   ` Ming Lei
2017-05-26  3:07 ` [PATCH 6/6] blk-mq: clarify dispatching may not be drained/blocked by stopping queue Ming Lei
2017-05-26  3:07   ` Ming Lei
2017-05-26  3:07 ` Ming Lei [this message]
2017-05-26  3:07   ` [PATCH 6/6] blk-mq: clarify dispatching won't be blocked " Ming Lei

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