From: Bart Van Assche <bvanassche@acm.org>
To: Balbir Singh <sblbir@amzn.com>, linux-nvme@lists.infradead.org
Cc: kbusch@kernel.org, axboe@fb.com, hch@lst.de, sagi@grimberg.me
Subject: Re: [PATCH v2 1/2] nvme/host/pci: Fix a race in controller removal
Date: Mon, 16 Sep 2019 08:40:46 -0700 [thread overview]
Message-ID: <7017c4c1-75a9-1e37-eb54-6126dfbb251b@acm.org> (raw)
In-Reply-To: <20190913233631.15352-1-sblbir@amzn.com>
On 9/13/19 4:36 PM, Balbir Singh wrote:
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index b45f82d58be8..f6ddb58a7013 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -103,10 +103,16 @@ static void nvme_set_queue_dying(struct nvme_ns *ns)
> */
> if (!ns->disk || test_and_set_bit(NVME_NS_DEAD, &ns->flags))
> return;
> - revalidate_disk(ns->disk);
> blk_set_queue_dying(ns->queue);
> /* Forcibly unquiesce queues to avoid blocking dispatch */
> blk_mq_unquiesce_queue(ns->queue);
> + /*
> + * revalidate_disk, after all pending IO is cleaned up
> + * by blk_set_queue_dying, largely any races with blk parittion
> + * reads that might come in after freezing the queues, otherwise
> + * we'll end up waiting up on bd_mutex, creating a deadlock.
> + */
> + revalidate_disk(ns->disk);
> }
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.
Bart.
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next prev parent reply other threads:[~2019-09-16 15:41 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 [this message]
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
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