Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6

[sfrench/cifs-2.6.git] / drivers / vhost / vhost.c

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 5be11c99e18f7e44f220baa67315e0c14aa1bd79..49fa953aaf6e354be77e47ff708f8677cc58026b 100644 (file)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -236,6 +236,10 @@ static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
                               int log_all)
 {
        int i;
+
+        if (!mem)
+                return 0;
+
        for (i = 0; i < mem->nregions; ++i) {
                struct vhost_memory_region *m = mem->regions + i;
                unsigned long a = m->userspace_addr;
@@ -1031,7 +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;