[PATCH] lockdep: annotate bh_lock_sock()

Teach special (recursive) locking code to the lock validator.  Has no effect
on non-lockdep kernels.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/net/sock.h

@@ -751,6 +751,9 @@ extern void FASTCALL(release_sock(struct sock *sk));
 
 /* BH context may only use the following locking interface. */
 #define bh_lock_sock(__sk)	spin_lock(&((__sk)->sk_lock.slock))
+#define bh_lock_sock_nested(__sk) \
+				spin_lock_nested(&((__sk)->sk_lock.slock), \
+				SINGLE_DEPTH_NESTING)
 #define bh_unlock_sock(__sk)	spin_unlock(&((__sk)->sk_lock.slock))
 
 extern struct sock		*sk_alloc(int family,

net/ipv4/tcp_ipv4.c

@@ -1090,7 +1090,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
 
 	skb->dev = NULL;
 
-	bh_lock_sock(sk);
+	bh_lock_sock_nested(sk);
 	ret = 0;
 	if (!sock_owned_by_user(sk)) {
 #ifdef CONFIG_NET_DMA