Commit 83180af0 authored Sep 23, 2010 by Eric Dumazet Committed by David S. Miller Sep 26, 2010

net: fix rcu use in ip_route_output_slow



__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>

parent 1b4bf461

net/ipv4/route.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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 */
		}