macvtap: rcu_dereference outside read-lock section

rcu_dereference occurs in update section. Replacement by
rcu_dereference_protected in order to prevent lockdep
complaint.

Found by Linux Driver Verification project (linuxtesting.org)

Signed-off-by: Denis Efremov <yefremov.denis@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 0737bd4..0f0f9ce 100644 (file)
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -94,7 +94,8 @@ static int get_slot(struct macvlan_dev *vlan, struct macvtap_queue *q)
        int i;
 
        for (i = 0; i < MAX_MACVTAP_QUEUES; i++) {
-               if (rcu_dereference(vlan->taps[i]) == q)
+               if (rcu_dereference_protected(vlan->taps[i],
+                                             lockdep_is_held(&macvtap_lock)) == q)
                        return i;
        }