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virtio: Avoid possible kernel panic if DEBUG is enabled.

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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.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Tetsuo Handa 2015-02-11 15:01:13 +10:30 committed by Rusty Russell
parent 1862ee22ce
commit 5e05bf5833
1 changed files with 3 additions and 3 deletions
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6
drivers/virtio/virtio_ring.c
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@ -244,14 +244,14 @@ 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->vring.avail->idx = cpu_to_virtio16(_vq->vdev, virtio16_to_cpu(_vq->vdev, vq->vring.avail->idx) + 1);
vq->num_added++; 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 /* This is very unlikely, but theoretically possible. Kick
* just in case. */ * just in case. */
if (unlikely(vq->num_added == (1 << 16) - 1)) if (unlikely(vq->num_added == (1 << 16) - 1))
virtqueue_kick(_vq); virtqueue_kick(_vq);
pr_debug("Added buffer head %i to %p\n", head, vq);
END_USE(vq);
return 0; return 0;
} }