Eric Dumazet f064af1e50 net: fix a lockdep splat ... We have for each socket : One spinlock (sk_slock.slock) One rwlock (sk_callback_lock) Possible scenarios are : (A) (this is used in net/sunrpc/xprtsock.c) read_lock(&sk->sk_callback_lock) (without blocking BH) <BH> spin_lock(&sk->sk_slock.slock); ... read_lock(&sk->sk_callback_lock); ... (B) write_lock_bh(&sk->sk_callback_lock) stuff write_unlock_bh(&sk->sk_callback_lock) (C) spin_lock_bh(&sk->sk_slock) ... write_lock_bh(&sk->sk_callback_lock) stuff write_unlock_bh(&sk->sk_callback_lock) spin_unlock_bh(&sk->sk_slock) This (C) case conflicts with (A) : CPU1 [A] CPU2 [C] read_lock(callback_lock) <BH> spin_lock_bh(slock) <wait to spin_lock(slock)> <wait to write_lock_bh(callback_lock)> We have one problematic (C) use case in inet_csk_listen_stop() : local_bh_disable(); bh_lock_sock(child); // spin_lock_bh(&sk->sk_slock) WARN_ON(sock_owned_by_user(child)); ... sock_orphan(child); // write_lock_bh(&sk->sk_callback_lock) lockdep is not happy with this, as reported by Tetsuo Handa It seems only way to deal with this is to use read_lock_bh(callbacklock) everywhere. Thanks to Jarek for pointing a bug in my first attempt and suggesting this solution. Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> CC: Jarek Poplawski <jarkao2@gmail.com> Tested-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2010-09-24 22:26:10 -07:00
..
af_rds.c	net: sk_sleep() helper	2010-04-20 16:37:13 -07:00
bind.c
cong.c
connection.c
ib_cm.c	net/rds: Add missing mutex_unlock	2010-05-29 00:18:48 -07:00
ib_rdma.c
ib_recv.c
ib_ring.c
ib_send.c
ib_stats.c
ib_sysctl.c
ib.c
ib.h
info.c
info.h
iw_cm.c	net/rds: Add missing mutex_unlock	2010-05-29 00:18:48 -07:00
iw_rdma.c
iw_recv.c
iw_ring.c
iw_send.c
iw_stats.c
iw_sysctl.c
iw.c
iw.h
Kconfig
loop.c
loop.h
Makefile
message.c
page.c
rdma_transport.c	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2010-04-27 12:49:13 -07:00
rdma_transport.h
rdma.c
rdma.h
rds.h	net: sk_sleep() helper	2010-04-20 16:37:13 -07:00
recv.c	rds: fix a leak of kernel memory	2010-08-18 23:40:03 -07:00
send.c	net: sk_sleep() helper	2010-04-20 16:37:13 -07:00
stats.c
sysctl.c
tcp_connect.c	net: fix a lockdep splat	2010-09-24 22:26:10 -07:00
tcp_listen.c	net: fix a lockdep splat	2010-09-24 22:26:10 -07:00
tcp_recv.c	net: fix a lockdep splat	2010-09-24 22:26:10 -07:00
tcp_send.c	net: fix a lockdep splat	2010-09-24 22:26:10 -07:00
tcp_stats.c
tcp.c
tcp.h
threads.c
transport.c