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From: Keith Busch <keith.busch@gmail.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme <linux-nvme@lists.infradead.org>,
	Keith Busch <keith.busch@intel.com>,
	Max Gurtovoy <maxg@mellanox.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 3/5] nvme: don't abort completed request in nvme_cancel_request
Date: Mon, 22 Jul 2019 17:22:33 -0600	[thread overview]
Message-ID: <CAOSXXT5TkrfH0AFZCV0c+YtbFCQ4MnShKM-gkZrj8Qex+Z7Png@mail.gmail.com> (raw)
In-Reply-To: <d82ead02-c893-4d14-307e-70a6d4596439@acm.org>

On Mon, Jul 22, 2019 at 9:27 AM Bart Van Assche <bvanassche@acm.org> wrote:
> On 7/21/19 10:39 PM, Ming Lei wrote:
> > Before aborting in-flight requests, all IO queues have been shutdown.
> > However, request's completion fn may not be done yet because it may
> > be scheduled to run via IPI.
> >
> > So don't abort one request if it is marked as completed, otherwise
> > we may abort one normal completed request.
> >
> > Cc: Max Gurtovoy <maxg@mellanox.com>
> > Cc: Sagi Grimberg <sagi@grimberg.me>
> > Cc: Keith Busch <keith.busch@intel.com>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> >   drivers/nvme/host/core.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> > index cc09b81fc7f4..cb8007cce4d1 100644
> > --- a/drivers/nvme/host/core.c
> > +++ b/drivers/nvme/host/core.c
> > @@ -285,6 +285,10 @@ EXPORT_SYMBOL_GPL(nvme_complete_rq);
> >
> >   bool nvme_cancel_request(struct request *req, void *data, bool reserved)
> >   {
> > +     /* don't abort one completed request */
> > +     if (blk_mq_request_completed(req))
> > +             return;
> > +
> >       dev_dbg_ratelimited(((struct nvme_ctrl *) data)->device,
> >                               "Cancelling I/O %d", req->tag);
>
> Something I probably already asked before: what prevents that
> nvme_cancel_request() is executed concurrently with the completion
> handler of the same request?

At least for pci, we've shutdown the queues and their interrupts prior
to tagset iteration, so we can't concurrently execute a natural
completion for in-flight requests while cancelling them.

WARNING: multiple messages have this Message-ID (diff)
From: keith.busch@gmail.com (Keith Busch)
Subject: [PATCH 3/5] nvme: don't abort completed request in nvme_cancel_request
Date: Mon, 22 Jul 2019 17:22:33 -0600	[thread overview]
Message-ID: <CAOSXXT5TkrfH0AFZCV0c+YtbFCQ4MnShKM-gkZrj8Qex+Z7Png@mail.gmail.com> (raw)
In-Reply-To: <d82ead02-c893-4d14-307e-70a6d4596439@acm.org>

On Mon, Jul 22, 2019@9:27 AM Bart Van Assche <bvanassche@acm.org> wrote:
> On 7/21/19 10:39 PM, Ming Lei wrote:
> > Before aborting in-flight requests, all IO queues have been shutdown.
> > However, request's completion fn may not be done yet because it may
> > be scheduled to run via IPI.
> >
> > So don't abort one request if it is marked as completed, otherwise
> > we may abort one normal completed request.
> >
> > Cc: Max Gurtovoy <maxg at mellanox.com>
> > Cc: Sagi Grimberg <sagi at grimberg.me>
> > Cc: Keith Busch <keith.busch at intel.com>
> > Cc: Christoph Hellwig <hch at lst.de>
> > Signed-off-by: Ming Lei <ming.lei at redhat.com>
> > ---
> >   drivers/nvme/host/core.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> > index cc09b81fc7f4..cb8007cce4d1 100644
> > --- a/drivers/nvme/host/core.c
> > +++ b/drivers/nvme/host/core.c
> > @@ -285,6 +285,10 @@ EXPORT_SYMBOL_GPL(nvme_complete_rq);
> >
> >   bool nvme_cancel_request(struct request *req, void *data, bool reserved)
> >   {
> > +     /* don't abort one completed request */
> > +     if (blk_mq_request_completed(req))
> > +             return;
> > +
> >       dev_dbg_ratelimited(((struct nvme_ctrl *) data)->device,
> >                               "Cancelling I/O %d", req->tag);
>
> Something I probably already asked before: what prevents that
> nvme_cancel_request() is executed concurrently with the completion
> handler of the same request?

At least for pci, we've shutdown the queues and their interrupts prior
to tagset iteration, so we can't concurrently execute a natural
completion for in-flight requests while cancelling them.

  reply	other threads:[~2019-07-22 23:22 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-22  5:39 [PATCH 0/5] blk-mq: wait until completed req's complete fn is run Ming Lei
2019-07-22  5:39 ` Ming Lei
2019-07-22  5:39 ` [PATCH 1/5] blk-mq: introduce blk_mq_request_completed() Ming Lei
2019-07-22  5:39   ` Ming Lei
2019-07-23 20:26   ` Sagi Grimberg
2019-07-23 20:26     ` Sagi Grimberg
2019-07-22  5:39 ` [PATCH 2/5] blk-mq: introduce blk_mq_tagset_wait_completed_request() Ming Lei
2019-07-22  5:39   ` Ming Lei
2019-07-22 15:25   ` Bart Van Assche
2019-07-22 15:25     ` Bart Van Assche
2019-07-23  1:06     ` Ming Lei
2019-07-23  1:06       ` Ming Lei
2019-07-23 20:54       ` Bart Van Assche
2019-07-23 20:54         ` Bart Van Assche
2019-07-24  1:34         ` Ming Lei
2019-07-24  1:34           ` Ming Lei
2019-07-23 20:27   ` Sagi Grimberg
2019-07-23 20:27     ` Sagi Grimberg
2019-07-22  5:39 ` [PATCH 3/5] nvme: don't abort completed request in nvme_cancel_request Ming Lei
2019-07-22  5:39   ` Ming Lei
2019-07-22 15:27   ` Bart Van Assche
2019-07-22 15:27     ` Bart Van Assche
2019-07-22 23:22     ` Keith Busch [this message]
2019-07-22 23:22       ` Keith Busch
2019-07-23  0:07       ` Sagi Grimberg
2019-07-23  0:07         ` Sagi Grimberg
2019-07-23  1:08     ` Ming Lei
2019-07-23  1:08       ` Ming Lei
2019-07-23 19:22       ` Bart Van Assche
2019-07-23 19:22         ` Bart Van Assche
2019-07-23 20:27   ` Sagi Grimberg
2019-07-23 20:27     ` Sagi Grimberg
2019-07-22  5:39 ` [PATCH 4/5] nvme: wait until all completed request's complete fn is called Ming Lei
2019-07-22  5:39   ` Ming Lei
2019-07-23 16:14   ` Dongli Zhang
2019-07-23 16:14     ` Dongli Zhang
2019-07-24  2:05     ` Ming Lei
2019-07-24  2:05       ` Ming Lei
2019-07-23 20:29   ` Sagi Grimberg
2019-07-23 20:29     ` Sagi Grimberg
2019-07-24  1:43     ` Ming Lei
2019-07-24  1:43       ` Ming Lei
2019-07-22  5:39 ` [PATCH 5/5] blk-mq: remove blk_mq_complete_request_sync Ming Lei
2019-07-22  5:39   ` Ming Lei
2019-07-23 20:30   ` Sagi Grimberg
2019-07-23 20:30     ` Sagi Grimberg
2019-07-22 23:27 ` [PATCH 0/5] blk-mq: wait until completed req's complete fn is run Bob Liu
2019-07-22 23:27   ` Bob Liu
2019-07-23  1:10   ` Ming Lei
2019-07-23  1:10     ` Ming Lei

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