From: Ingo Molnar <mingo@elte.hu>

Split off __icmpv6_socket's sk->sk_dst_lock class, because it gets used
from softirqs, which is safe for __icmpv6_sockets (because they never get
directly used via userspace syscalls), but unsafe for normal sockets.

Has no effect on non-lockdep kernels.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 net/ipv6/icmp.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

diff -puN net/ipv6/icmp.c~lockdep-fix-sk_dst_check-deadlock net/ipv6/icmp.c
--- a/net/ipv6/icmp.c~lockdep-fix-sk_dst_check-deadlock
+++ a/net/ipv6/icmp.c
@@ -714,6 +714,11 @@ discard_it:
 	return 0;
 }
 
+/*
+ * Special lock-class for __icmpv6_socket:
+ */
+static struct lock_class_key icmpv6_socket_sk_dst_lock_key;
+
 int __init icmpv6_init(struct net_proto_family *ops)
 {
 	struct sock *sk;
@@ -732,6 +737,14 @@ int __init icmpv6_init(struct net_proto_
 
 		sk = per_cpu(__icmpv6_socket, i)->sk;
 		sk->sk_allocation = GFP_ATOMIC;
+		/*
+		 * Split off their lock-class, because sk->sk_dst_lock
+		 * gets used from softirqs, which is safe for
+		 * __icmpv6_socket (because those never get directly used
+		 * via userspace syscalls), but unsafe for normal sockets.
+		 */
+		lockdep_set_class(&sk->sk_dst_lock,
+				  &icmpv6_socket_sk_dst_lock_key);
 
 		/* Enough space for 2 64K ICMP packets, including
 		 * sk_buff struct overhead.
_