From: Tetsuo Handa Date: Wed, 11 Feb 2015 04:31:13 +0000 (+1030) Subject: virtio: Avoid possible kernel panic if DEBUG is enabled. X-Git-Tag: firefly_0821_release~176^2~2282^2~52 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=5e05bf5833eb3dd97b6b6a52301d81e033714cb3;p=firefly-linux-kernel-4.4.55.git 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 Signed-off-by: Rusty Russell --- diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 95b9661554d1..096b857e7b75 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -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->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; }