net: fix rcu use in ip_route_output_slow
authorEric Dumazet <eric.dumazet@gmail.com>
Thu, 23 Sep 2010 21:46:03 +0000 (21:46 +0000)
committerDavid S. Miller <davem@davemloft.net>
Mon, 27 Sep 2010 02:04:07 +0000 (19:04 -0700)
__in_dev_get_rtnl(dev_out) is called while RTNL is not held, thus
triggers a lockdep fault.

At this point, we only perform a raw test of dev_out->ip_ptr being NULL,
we dont need to make sure ip_ptr cant changed right after.

We can use rcu_dereference_raw() for this.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/route.c

index ae1d4a41f1c641dfaef8ec5998bff4ec3c741bc1..98beda47bc99f798c1803c29ccede8f2c1d67ef7 100644 (file)
@@ -2579,7 +2579,7 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
                        goto out;
 
                /* RACE: Check return value of inet_select_addr instead. */
-               if (__in_dev_get_rtnl(dev_out) == NULL) {
+               if (rcu_dereference_raw(dev_out->ip_ptr) == NULL) {
                        dev_put(dev_out);
                        goto out;       /* Wrong error code */
                }