From: Keith Busch <kbusch@kernel.org>
To: "Singh, Balbir" <sblbir@amazon.com>
Cc: "sblbir@amzn.com" <sblbir@amzn.com>,
"sagi@grimberg.me" <sagi@grimberg.me>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"axboe@fb.com" <axboe@fb.com>, "hch@lst.de" <hch@lst.de>,
"bvanassche@acm.org" <bvanassche@acm.org>
Subject: Re: [PATCH v2 1/2] nvme/host/pci: Fix a race in controller removal
Date: Mon, 16 Sep 2019 14:07:34 -0600 [thread overview]
Message-ID: <20190916200734.GA17997@C02WT3WMHTD6.wdl.wdc.com> (raw)
In-Reply-To: <25d9badc90a1eb951cb5103774e8360edaa8ec15.camel@amazon.com>
On Mon, Sep 16, 2019 at 07:38:44PM +0000, Singh, Balbir wrote:
> On Mon, 2019-09-16 at 08:40 -0700, Bart Van Assche wrote:
> > The comment above revalidate_disk() looks wrong to me. I don't think
> > that blk_set_queue_dying() guarantees that ongoing commands have
> > finished by the time that function returns. All
> > blk_set_queue_dying()
> > does is to set the DYING flag, to kill q->q_usage_counter and to wake
> > up
> > threads that are waiting inside a request allocation function. It
> > does
> > not wait for pending commands to finish.
>
> I was referring to the combined effect of blk_set_queue_dying() and
> blk_mq_unquiesce_queue() which should invoke blk_mq_run_hw_queues().
> I can see how that might be misleading. I can reword it to say
>
> /*
> * revalidate_disk, after all pending IO is cleaned up
> * largely any races with block partition
> * reads that might come in after freezing the queues, otherwise
> * we'll end up waiting up on bd_mutex, creating a deadlock
> */
>
> Would that work?
How about:
/* Revalidate after unblocking dispatchers that may be holding bd_butex */
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prev parent reply other threads:[~2019-09-16 20:07 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-13 23:36 [PATCH v2 1/2] nvme/host/pci: Fix a race in controller removal Balbir Singh
2019-09-13 23:36 ` [PATCH v2 2/2] nvme/host/core: Allow overriding of wait_ready timeout Balbir Singh
2019-09-16 7:41 ` Christoph Hellwig
2019-09-16 12:33 ` Singh, Balbir
2019-09-16 16:01 ` hch
2019-09-16 21:04 ` Singh, Balbir
2019-09-17 1:14 ` Keith Busch
2019-09-17 2:56 ` Singh, Balbir
2019-09-17 3:17 ` Bart Van Assche
2019-09-17 5:02 ` Singh, Balbir
2019-09-17 17:21 ` James Smart
2019-09-17 20:08 ` James Smart
2019-09-17 3:54 ` Keith Busch
2019-09-16 7:49 ` [PATCH v2 1/2] nvme/host/pci: Fix a race in controller removal Christoph Hellwig
2019-09-16 12:07 ` Singh, Balbir
2019-09-16 15:40 ` Bart Van Assche
2019-09-16 19:38 ` Singh, Balbir
2019-09-16 19:56 ` Bart Van Assche
2019-09-16 20:40 ` Singh, Balbir
2019-09-17 17:55 ` Bart Van Assche
2019-09-17 20:30 ` Keith Busch
2019-09-17 20:44 ` Singh, Balbir
2019-09-16 20:07 ` Keith Busch [this message]
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