Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> writes:
>>From 11fd997d724f520ca628615e7ffbfd7901c40b62 Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Date: Fri, 6 Feb 2015 13:28:38 +0900
> Subject: [PATCH] virtio: Avoid possible kernel panic if DEBUG is enabled.
>
> The virtqueue_add() calls START_USE() upon entry. The virtqueue_kick() is
> called if vq->num_added == (1 << 16) - 1 before calling END_USE().
> The virtqueue_kick_prepare() called via virtqueue_kick() calls START_USE()
> upon entry, and will call panic() if DEBUG is enabled.
> Move this virtqueue_kick() call to after END_USE() call.
Thanks, applied.
Cheers,
Rusty.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio_ring.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 00ec6b3..596735b 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -245,14 +245,14 @@ static inline int virtqueue_add(struct virtqueue *_vq,
> vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, virtio16_to_cpu(_vq->vdev, vq->vring.avail->idx) + 1);
> vq->num_added++;
>
> + pr_debug("Added buffer head %i to %p\n", head, vq);
> + END_USE(vq);
> +
> /* This is very unlikely, but theoretically possible. Kick
> * just in case. */
> if (unlikely(vq->num_added == (1 << 16) - 1))
> virtqueue_kick(_vq);
>
> - pr_debug("Added buffer head %i to %p\n", head, vq);
> - END_USE(vq);
> -
> return 0;
> }
>
> --
> 1.8.3.1
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