Re: bluetooth lockdep trace. (.25rc5-git4)
From: David Miller <davem@davemloft.net>
Date: 2008-03-29 01:20:21
From: Dave Jones <redacted> Date: Thu, 27 Mar 2008 12:21:56 -0400
Mar 27 08:10:57 localhost kernel: Pid: 3611, comm: obex-data-serve Not tainted 2.6.25-0.121.rc5.git4.fc9 #1 Mar 27 08:10:57 localhost kernel: [__lock_acquire+2287/3089] __lock_acquire+0x8ef/0xc11 Mar 27 08:10:57 localhost kernel: [sched_clock+8/11] ? sched_clock+0x8/0xb Mar 27 08:10:57 localhost kernel: [lock_acquire+106/144] lock_acquire+0x6a/0x90 Mar 27 08:10:57 localhost kernel: [<f8bd9321>] ? l2cap_sock_bind+0x29/0x108 [l2cap] Mar 27 08:10:57 localhost kernel: [lock_sock_nested+182/198] lock_sock_nested+0xb6/0xc6 Mar 27 08:10:57 localhost kernel: [<f8bd9321>] ? l2cap_sock_bind+0x29/0x108 [l2cap] Mar 27 08:10:57 localhost kernel: [security_socket_post_create+22/27] ? security_socket_post_create+0x16/0x1b Mar 27 08:10:57 localhost kernel: [__sock_create+388/472] ? __sock_create+0x184/0x1d8 Mar 27 08:10:57 localhost kernel: [<f8bd9321>] l2cap_sock_bind+0x29/0x108 [l2cap] Mar 27 08:10:57 localhost kernel: [kernel_bind+10/13] kernel_bind+0xa/0xd Mar 27 08:10:57 localhost kernel: [<f8dad3d7>] rfcomm_dlc_open+0xc8/0x294 [rfcomm] Mar 27 08:10:57 localhost kernel: [lock_sock_nested+187/198] ? lock_sock_nested+0xbb/0xc6 Mar 27 08:10:57 localhost kernel: [<f8dae18c>] rfcomm_sock_connect+0x8b/0xc2 [rfcomm] Mar 27 08:10:57 localhost kernel: [sys_connect+96/125] sys_connect+0x60/0x7d Mar 27 08:10:57 localhost kernel: [__lock_acquire+1370/3089] ? __lock_acquire+0x55a/0xc11 Mar 27 08:10:57 localhost kernel: [sys_socketcall+140/392] sys_socketcall+0x8c/0x188 Mar 27 08:10:57 localhost kernel: [syscall_call+7/11] syscall_call+0x7/0xb
rfcomm connect locks the socket, then does rfcomm_dlc_open which in turn can do a l2cap_sock_bind on a seperate second socket which in turn locks that second socket. Both of these sockets are AF_BLUETOOTH family, so lockdep thinks there is a locking conflict, even though what is happening here is perfectly fine since the two sockets are totally different AF_BLUETOOTH sub-types. Bluetooth will need to use sock_lock_init_class_and_name() and lock sub-classes per AF_BLUETOOTH socket sub-type. David, could you or someone else work on this? Thanks!