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.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 95b9661..096b857 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -244,14 +244,14 @@
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;
}