netfilter: egress: avoid a lockdep splat

include/linux/netfilter_netdev.h:97 suspicious rcu_dereference_check() usage!
2 locks held by sd-resolve/1100:
 0: ..(rcu_read_lock_bh){1:3}, at: ip_finish_output2
 1: ..(rcu_read_lock_bh){1:3}, at: __dev_queue_xmit
 __dev_queue_xmit+0 ..

The helper has two callers, one uses rcu_read_lock, the other
rcu_read_lock_bh().  Annotate the dereference to reflect this.

Fixes: 0c0f505da7c89 ("netfilter: Introduce egress hook")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/linux/netfilter_netdev.h b/include/linux/netfilter_netdev.h
index b71b57a83bb4f0b011912cdd2e89f04b019e4ff7..b4dd96e4dc8dca30782ae9c1e8458fb9dae412f7 100644 (file)
--- a/include/linux/netfilter_netdev.h
+++ b/include/linux/netfilter_netdev.h
@@ -94,7 +94,7 @@ static inline struct sk_buff *nf_hook_egress(struct sk_buff *skb, int *rc,
                return skb;
 #endif
 
-       e = rcu_dereference(dev->nf_hooks_egress);
+       e = rcu_dereference_check(dev->nf_hooks_egress, rcu_read_lock_bh_held());
        if (!e)
                return skb;