From: Michael S. Tsirkin <mst@redhat.com>
Date: Wed, 20 Jul 2011 10:41:31 +0000 (+0300)
Subject: vhost-net: update used ring on backend change
X-Git-Tag: upstream/snapshot3+hdmi~9624^2~1^2~1
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c047e5f3170c2595e66ed67f87cec01afd717212;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

vhost-net: update used ring on backend change

On backend change, we flushed out outstanding skbs
but forgot to update the used ring, so that
done entries were left in the ubuf_info ring.
As a result we lose heads or complete incorrect ones,
crashing the guest or leaking memory.
Fix by updating the used ring.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 70ac604..248b250 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -711,8 +711,12 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 
 	mutex_unlock(&vq->mutex);
 
-	if (oldubufs)
+	if (oldubufs) {
 		vhost_ubuf_put_and_wait(oldubufs);
+		mutex_lock(&vq->mutex);
+		vhost_zerocopy_signal_used(vq);
+		mutex_unlock(&vq->mutex);
+	}
 
 	if (oldsock) {
 		vhost_net_flush_vq(n, index);