From: Bart Van Assche <Bart.VanAssche@sandisk.com>
To: "hch@infradead.org" <hch@infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"axboe@fb.com" <axboe@fb.com>,
"ming.lei@redhat.com" <ming.lei@redhat.com>
Subject: Re: [PATCH v4 07/11] blk-mq: use QUEUE_FLAG_QUIESCED to quiesce queue
Date: Mon, 5 Jun 2017 21:32:59 +0000 [thread overview]
Message-ID: <1496698378.2623.28.camel@sandisk.com> (raw)
In-Reply-To: <20170605155925.7896-8-ming.lei@redhat.com>
On Mon, 2017-06-05 at 23:59 +0800, Ming Lei wrote:
> It is required that no dispatch can happen any more once
> blk_mq_quiesce_queue() returns, and we don't have such requirement
> on APIs of stopping queue.
>=20
> But blk_mq_quiesce_queue() still may not block/drain dispatch in the
> the case of BLK_MQ_S_START_ON_RUN, so use the new introduced flag of
> QUEUE_FLAG_QUIESCED and evaluate it inside RCU read-side critical
> sections for fixing this issue.
>=20
> Also blk_mq_quiesce_queue() is implemented via stopping queue, which
> limits its uses, and easy to cause race, because any queue restart in
> other paths may break blk_mq_quiesce_queue(). With the introduced
> flag of QUEUE_FLAG_QUIESCED, we don't need to depend on stopping queue
> for quiescing any more.
Hello Ming,
Since this patch depends on patch 1 I will wait with reviewing this patch
until there is agreement about patch 1 in this series.
Bart.=
next prev parent reply other threads:[~2017-06-05 21:33 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-05 15:59 [PATCH v4 00/11] blk-mq: fix & improve queue quiescing Ming Lei
2017-06-05 15:59 ` [PATCH v4 01/11] blk-mq: fix direct issue Ming Lei
2017-06-05 21:25 ` Bart Van Assche
2017-06-06 4:21 ` Ming Lei
2017-06-05 15:59 ` [PATCH v4 02/11] blk-mq: move blk_mq_quiesce_queue() into include/linux/blk-mq.h Ming Lei
2017-06-05 15:59 ` [PATCH v4 03/11] blk-mq: introduce blk_mq_quiesce_queue_nowait() Ming Lei
2017-06-05 21:29 ` Bart Van Assche
2017-06-05 15:59 ` [PATCH v4 04/11] blk-mq: introduce blk_mq_unquiesce_queue Ming Lei
2017-06-05 21:31 ` Bart Van Assche
2017-06-05 15:59 ` [PATCH v4 05/11] blk-mq: use the introduced blk_mq_unquiesce_queue() Ming Lei
2017-06-05 21:31 ` Bart Van Assche
2017-06-05 15:59 ` [PATCH v4 06/11] nvme: host: unquiesce queue in nvme_kill_queues() Ming Lei
2017-06-05 15:59 ` [PATCH v4 07/11] blk-mq: use QUEUE_FLAG_QUIESCED to quiesce queue Ming Lei
2017-06-05 21:32 ` Bart Van Assche [this message]
2017-06-05 15:59 ` [PATCH v4 08/11] blk-mq: update comments on blk_mq_quiesce_queue() Ming Lei
2017-06-05 15:59 ` [PATCH v4 09/11] blk-mq: don't stop queue for quiescing Ming Lei
2017-06-05 21:36 ` Bart Van Assche
2017-06-05 15:59 ` [PATCH v4 10/11] blk-mq: clarify dispatch may not be drained/blocked by stopping queue Ming Lei
2017-06-05 23:55 ` Bart Van Assche
2017-06-06 12:48 ` Ming Lei
2017-06-05 15:59 ` [PATCH v4 11/11] Revert "blk-mq: don't use sync workqueue flushing from drivers" Ming Lei
2017-06-05 21:39 ` Bart Van Assche
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