From 8a74ad60a546b13bd1096b2a61a7a5c6fd9ae17c Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 26 May 2010 19:20:18 +0000 Subject: net: fix lock_sock_bh/unlock_sock_bh This new sock lock primitive was introduced to speedup some user context socket manipulation. But it is unsafe to protect two threads, one using regular lock_sock/release_sock, one using lock_sock_bh/unlock_sock_bh This patch changes lock_sock_bh to be careful against 'owned' state. If owned is found to be set, we must take the slow path. lock_sock_bh() now returns a boolean to say if the slow path was taken, and this boolean is used at unlock_sock_bh time to call the appropriate unlock function. After this change, BH are either disabled or enabled during the lock_sock_bh/unlock_sock_bh protected section. This might be misleading, so we rename these functions to lock_sock_fast()/unlock_sock_fast(). Reported-by: Anton Blanchard Signed-off-by: Eric Dumazet Tested-by: Anton Blanchard Signed-off-by: David S. Miller --- net/ipv4/udp.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'net/ipv4/udp.c') diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 9de6a698f91d..b9d0d409516f 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1063,10 +1063,11 @@ static unsigned int first_packet_length(struct sock *sk) spin_unlock_bh(&rcvq->lock); if (!skb_queue_empty(&list_kill)) { - lock_sock_bh(sk); + bool slow = lock_sock_fast(sk); + __skb_queue_purge(&list_kill); sk_mem_reclaim_partial(sk); - unlock_sock_bh(sk); + unlock_sock_fast(sk, slow); } return res; } @@ -1123,6 +1124,7 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, int peeked; int err; int is_udplite = IS_UDPLITE(sk); + bool slow; /* * Check any passed addresses @@ -1197,10 +1199,10 @@ out: return err; csum_copy_err: - lock_sock_bh(sk); + slow = lock_sock_fast(sk); if (!skb_kill_datagram(sk, skb, flags)) UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_INERRORS, is_udplite); - unlock_sock_bh(sk); + unlock_sock_fast(sk, slow); if (noblock) return -EAGAIN; @@ -1625,9 +1627,9 @@ int udp_rcv(struct sk_buff *skb) void udp_destroy_sock(struct sock *sk) { - lock_sock_bh(sk); + bool slow = lock_sock_fast(sk); udp_flush_pending_frames(sk); - unlock_sock_bh(sk); + unlock_sock_fast(sk, slow); } /* -- cgit v1.2.3-59-g8ed1b