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From: "Steve Wise" <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
To: 'Bart Van Assche'
	<bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>,
	'James Bottomley'
	<jejb-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>,
	'Jens Axboe' <axboe-b10kYP2dOMg@public.gmane.org>
Cc: linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	"'Martin K. Petersen'"
	<martin.petersen-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>,
	'Mike Snitzer' <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	'Keith Busch'
	<keith.busch-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	'Doug Ledford' <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	'Christoph Hellwig' <hch-jcswGhMUV9g@public.gmane.org>
Subject: RE: [PATCH 9/9] [RFC] nvme: Fix a race condition
Date: Wed, 28 Sep 2016 09:23:03 -0500	[thread overview]
Message-ID: <009601d21993$d2d33670$7879a350$@opengridcomputing.com> (raw)
In-Reply-To: <3fb86a78-de3a-b764-a493-cb5bc5b6d8b6-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>

> 
> Hello James and Steve,
> 
> I will add a comment.
> 
> Please note that the above patch does not change the behavior of
> nvme_stop_queues() except that it causes nvme_stop_queues() to wait
> until any ongoing nvme_queue_rq() calls have finished.
> blk_resume_queue() does not affect the value of the BLK_MQ_S_STOPPED bit
> that has been set by blk_mq_stop_hw_queues(). All it does is to resume
> pending blk_queue_enter() calls and to ensure that future
> blk_queue_enter() calls do not block. Even after blk_resume_queue() has
> been called if a new request is queued queue_rq() won't be invoked
> because the BLK_MQ_S_STOPPED bit is still set. Patch "dm: Fix a race
> condition related to stopping and starting queues" realizes a similar
> change in the dm driver and that change has been tested extensively.
> 

Thanks for the detailed explanation!  I think your code, then, is correct as-is.   And this series doesn't fix the issue I'm hitting, so I'll keep digging. :)

Steve.  

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  parent reply	other threads:[~2016-09-28 14:23 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-26 18:25 [PATCH 0/9] Introduce blk_quiesce_queue() and blk_resume_queue() Bart Van Assche
     [not found] ` <7948dbb8-6333-dc62-2673-4da35b4dfdbc-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
2016-09-26 18:26   ` [PATCH 1/9] blk-mq: Introduce blk_mq_queue_stopped() Bart Van Assche
2016-09-27  6:20     ` Hannes Reinecke
2016-09-27  7:38     ` Johannes Thumshirn
2016-09-26 18:27   ` [PATCH 3/9] [RFC] nvme: Use BLK_MQ_S_STOPPED instead of QUEUE_FLAG_STOPPED in blk-mq code Bart Van Assche
2016-09-26 18:27   ` [PATCH 5/9] block: Extend blk_freeze_queue_start() to the non-blk-mq path Bart Van Assche
2016-09-27  7:50     ` Johannes Thumshirn
2016-09-27 13:22     ` Ming Lei
     [not found]       ` <CACVXFVO=GFp=ArC_FT+xPSmL84m01fX6bzReBQ8DeLQ4fUD5cQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-09-27 14:42         ` Bart Van Assche
     [not found]           ` <a8e8796e-7266-4c8a-a4eb-31cedf73ec8a-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
2016-09-27 15:55             ` Bart Van Assche
2016-09-26 18:33   ` [PATCH 0/9] Introduce blk_quiesce_queue() and blk_resume_queue() Mike Snitzer
     [not found]     ` <20160926183308.GA13309-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-09-26 18:46       ` Bart Van Assche
2016-09-26 22:26       ` Bart Van Assche
2016-09-26 18:26 ` [PATCH 2/9] dm: Fix a race condition related to stopping and starting queues Bart Van Assche
     [not found]   ` <ba8ddc16-b709-e7fb-1120-b6e1bd393540-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
2016-09-27  6:21     ` Hannes Reinecke
2016-09-27  7:47   ` Johannes Thumshirn
2016-09-26 18:27 ` [PATCH 4/9] block: Move blk_freeze_queue() and blk_unfreeze_queue() code Bart Van Assche
     [not found]   ` <f990694e-76ea-f6b1-10a4-c23b9a738b39-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
2016-09-27  6:26     ` Hannes Reinecke
     [not found]       ` <ffad7b3c-e7f5-56d7-0a75-574e65ac5b31-l3A5Bk7waGM@public.gmane.org>
2016-09-27  7:52         ` Johannes Thumshirn
2016-09-26 18:28 ` [PATCH 6/9] block: Rename mq_freeze_wq and mq_freeze_depth Bart Van Assche
2016-09-27  7:51   ` Johannes Thumshirn
2016-09-26 18:28 ` [PATCH 7/9] blk-mq: Introduce blk_quiesce_queue() and blk_resume_queue() Bart Van Assche
2016-09-26 18:28 ` [PATCH 8/9] SRP transport: Port srp_wait_for_queuecommand() to scsi-mq Bart Van Assche
2016-09-26 18:28 ` [PATCH 9/9] [RFC] nvme: Fix a race condition Bart Van Assche
2016-09-27 16:31   ` Steve Wise
2016-09-27 16:43     ` Bart Van Assche
2016-09-27 16:56       ` James Bottomley
     [not found]         ` <1474995360.2716.19.camel-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2016-09-27 17:09           ` Bart Van Assche
     [not found]             ` <3fb86a78-de3a-b764-a493-cb5bc5b6d8b6-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
2016-09-28 14:23               ` Steve Wise [this message]
2016-09-27 16:56       ` Steve Wise
2016-10-11 16:27 ` [PATCH 0/9] Introduce blk_quiesce_queue() and blk_resume_queue() Laurence Oberman

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