[patch 25/42] udp: Drop socket lock for encapsulated packets

[Greg KH]

2.6.26-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit d97106ea52aa57e63ff40d04479016836bbb5a4e ]

The socket lock is there to protect the normal UDP receive path.
Encapsulation UDP sockets don't need that protection.  In fact
the locking is deadly for them as they may contain another UDP
packet within, possibly with the same addresses.

Also the nested bit was copied from TCP.  TCP needs it because
of accept(2) spawning sockets.  This simply doesn't apply to UDP
so I've removed it.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 net/ipv4/udp.c |    6 ++++--
 net/ipv6/udp.c |    6 +++---
 2 files changed, 7 insertions(+), 5 deletions(-)

--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -988,7 +988,9 @@ int udp_queue_rcv_skb(struct sock * sk, 
 		    up->encap_rcv != NULL) {
 			int ret;
 
+			bh_unlock_sock(sk);
 			ret = (*up->encap_rcv)(sk, skb);
+			bh_lock_sock(sk);
 			if (ret <= 0) {
 				UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS,
 						 is_udplite);
@@ -1087,7 +1089,7 @@ static int __udp4_lib_mcast_deliver(stru
 			if (skb1) {
 				int ret = 0;
 
-				bh_lock_sock_nested(sk);
+				bh_lock_sock(sk);
 				if (!sock_owned_by_user(sk))
 					ret = udp_queue_rcv_skb(sk, skb1);
 				else
@@ -1187,7 +1189,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, 
 
 	if (sk != NULL) {
 		int ret = 0;
-		bh_lock_sock_nested(sk);
+		bh_lock_sock(sk);
 		if (!sock_owned_by_user(sk))
 			ret = udp_queue_rcv_skb(sk, skb);
 		else
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -376,7 +376,7 @@ static int __udp6_lib_mcast_deliver(stru
 					uh->source, saddr, dif))) {
 		struct sk_buff *buff = skb_clone(skb, GFP_ATOMIC);
 		if (buff) {
-			bh_lock_sock_nested(sk2);
+			bh_lock_sock(sk2);
 			if (!sock_owned_by_user(sk2))
 				udpv6_queue_rcv_skb(sk2, buff);
 			else
@@ -384,7 +384,7 @@ static int __udp6_lib_mcast_deliver(stru
 			bh_unlock_sock(sk2);
 		}
 	}
-	bh_lock_sock_nested(sk);
+	bh_lock_sock(sk);
 	if (!sock_owned_by_user(sk))
 		udpv6_queue_rcv_skb(sk, skb);
 	else
@@ -502,7 +502,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, 
 
 	/* deliver */
 
-	bh_lock_sock_nested(sk);
+	bh_lock_sock(sk);
 	if (!sock_owned_by_user(sk))
 		udpv6_queue_rcv_skb(sk, skb);
 	else

-- 
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