virtio: ignore corrupted virtqueues rather than spinning.

A corrupt virtqueue (caused by the other end screwing up) can have
strange results such as a driver spinning: just bail when we try to
get a buffer from a known-broken queue.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index c2fa5c63081..937a49d6772 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -184,6 +184,11 @@ static void *vring_get_buf(struct virtqueue *_vq, unsigned int *len)
 
         START_USE(vq);
 
+        if (unlikely(vq->broken)) {
+                END_USE(vq);
+                return NULL;
+        }
+
         if (!more_used(vq)) {
                 pr_debug("No more buffers in queue\n");
                 END_USE(vq);