Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
authorLinus Torvalds <torvalds@linux-foundation.org>
Fri, 14 May 2010 14:56:45 +0000 (07:56 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 14 May 2010 14:56:45 +0000 (07:56 -0700)
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
  vhost: fix barrier pairing

drivers/vhost/vhost.c

index e69d238c5af05254e16cad73b1456549cb8dbc35..49fa953aaf6e354be77e47ff708f8677cc58026b 100644 (file)
@@ -1035,7 +1035,12 @@ int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
 /* This actually signals the guest, using eventfd. */
 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
 {
-       __u16 flags = 0;
+       __u16 flags;
+       /* Flush out used index updates. This is paired
+        * with the barrier that the Guest executes when enabling
+        * interrupts. */
+       smp_mb();
+
        if (get_user(flags, &vq->avail->flags)) {
                vq_err(vq, "Failed to get flags");
                return;