From: Rusty Russell <rusty@rustcorp.com.au>
Date: Sat, 3 May 2008 02:50:43 +0000 (-0500)
Subject: virtio: ignore corrupted virtqueues rather than spinning.
X-Git-Tag: firefly_0821_release~20492^2~14
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=5ef827526fc01820a7a80827802e9fad3f34f937;p=firefly-linux-kernel-4.4.55.git

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>
---

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index c2fa5c630813..937a49d6772c 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);