From: Stefan Hajnoczi <stefanha@redhat.com>
To: Suwan Kim <suwan.kim027@gmail.com>
Cc: mst@redhat.com, jasowang@redhat.com, pbonzini@redhat.com,
acourbot@chromium.org, linux-block@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH] virtio-blk: Fix WARN_ON_ONCE in virtio_queue_rq()
Date: Tue, 23 Aug 2022 16:56:49 -0400 [thread overview]
Message-ID: <YwU/EVxT0a6q2BfD@fedora> (raw)
In-Reply-To: <20220823145005.26356-1-suwan.kim027@gmail.com>
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On Tue, Aug 23, 2022 at 11:50:05PM +0900, Suwan Kim wrote:
> @@ -409,6 +409,8 @@ static bool virtblk_add_req_batch(struct virtio_blk_vq *vq,
> virtblk_unmap_data(req, vbr);
> virtblk_cleanup_cmd(req);
> rq_list_add(requeue_list, req);
> + } else {
> + blk_mq_start_request(req);
> }
The device may see new requests as soon as virtblk_add_req() is called
above. Therefore the device may complete the request before
blk_mq_start_request() is called.
rq->io_start_time_ns = ktime_get_ns() will be after the request was
actually submitted.
I think blk_mq_start_request() needs to be called before
virtblk_add_req().
Stefan
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WARNING: multiple messages have this Message-ID (diff)
From: Stefan Hajnoczi <stefanha@redhat.com>
To: Suwan Kim <suwan.kim027@gmail.com>
Cc: acourbot@chromium.org, mst@redhat.com,
virtualization@lists.linux-foundation.org,
linux-block@vger.kernel.org, pbonzini@redhat.com
Subject: Re: [PATCH] virtio-blk: Fix WARN_ON_ONCE in virtio_queue_rq()
Date: Tue, 23 Aug 2022 16:56:49 -0400 [thread overview]
Message-ID: <YwU/EVxT0a6q2BfD@fedora> (raw)
In-Reply-To: <20220823145005.26356-1-suwan.kim027@gmail.com>
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On Tue, Aug 23, 2022 at 11:50:05PM +0900, Suwan Kim wrote:
> @@ -409,6 +409,8 @@ static bool virtblk_add_req_batch(struct virtio_blk_vq *vq,
> virtblk_unmap_data(req, vbr);
> virtblk_cleanup_cmd(req);
> rq_list_add(requeue_list, req);
> + } else {
> + blk_mq_start_request(req);
> }
The device may see new requests as soon as virtblk_add_req() is called
above. Therefore the device may complete the request before
blk_mq_start_request() is called.
rq->io_start_time_ns = ktime_get_ns() will be after the request was
actually submitted.
I think blk_mq_start_request() needs to be called before
virtblk_add_req().
Stefan
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next prev parent reply other threads:[~2022-08-23 20:57 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-23 14:50 [PATCH] virtio-blk: Fix WARN_ON_ONCE in virtio_queue_rq() Suwan Kim
2022-08-23 16:39 ` Christoph Hellwig
2022-08-23 16:39 ` Christoph Hellwig
2022-08-23 20:56 ` Stefan Hajnoczi [this message]
2022-08-23 20:56 ` Stefan Hajnoczi
2022-08-24 13:16 ` Kim Suwan
2022-08-24 17:32 ` Stefan Hajnoczi
2022-08-24 17:32 ` Stefan Hajnoczi
2022-08-25 14:49 ` Suwan Kim
2022-08-26 1:41 ` Alexandre Courbot
2022-08-29 2:48 ` Suwan Kim
2022-08-30 8:23 ` Alexandre Courbot
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