Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull misc fixes from Al Viro:
 "vhost race fix and a percpu_ref_init-caused cgroup double-free fix.

  The latter had manifested as buggered struct mount refcounting - those
  are also using percpu data structures, but anything that does percpu
  allocations could be hit"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  Fix double fget() in vhost_net_set_backend()
  percpu_ref_init(): clean ->percpu_count_ref on failure

drivers/vhost/net.c

@@ -1450,13 +1450,9 @@ static struct socket *get_raw_socket(int fd)
 	return ERR_PTR(r);
 }
 
-static struct ptr_ring *get_tap_ptr_ring(int fd)
+static struct ptr_ring *get_tap_ptr_ring(struct file *file)
 {
 	struct ptr_ring *ring;
-	struct file *file = fget(fd);
-
-	if (!file)
-		return NULL;
 	ring = tun_get_tx_ring(file);
 	if (!IS_ERR(ring))
 		goto out;
@@ -1465,7 +1461,6 @@ static struct ptr_ring *get_tap_ptr_ring(int fd)
 		goto out;
 	ring = NULL;
 out:
-	fput(file);
 	return ring;
 }
 
@@ -1552,8 +1547,12 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 		r = vhost_net_enable_vq(n, vq);
 		if (r)
 			goto err_used;
-		if (index == VHOST_NET_VQ_RX)
-			nvq->rx_ring = get_tap_ptr_ring(fd);
+		if (index == VHOST_NET_VQ_RX) {
+			if (sock)
+				nvq->rx_ring = get_tap_ptr_ring(sock->file);
+			else
+				nvq->rx_ring = NULL;
+		}
 
 		oldubufs = nvq->ubufs;
 		nvq->ubufs = ubufs;

lib/percpu-refcount.c

@@ -76,6 +76,7 @@ int percpu_ref_init(struct percpu_ref *ref, percpu_ref_func_t *release,
 	data = kzalloc(sizeof(*ref->data), gfp);
 	if (!data) {
 		free_percpu((void __percpu *)ref->percpu_count_ptr);
+		ref->percpu_count_ptr = 0;
 		return -ENOMEM;
 	}