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Date: Thu, 24 Jan 2008 17:25:16 +0800
From: "Dave Young" <hidave.darkstar@...il.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: "Marcel Holtmann" <marcel@...tmann.org>,
"David Miller" <davem@...emloft.net>,
Netdev <netdev@...r.kernel.org>, bluez-devel@...ts.sf.net
Subject: Re: bluetooth : lockdep warning on rfcomm
On Jan 24, 2008 11:02 AM, Dave Young <hidave.darkstar@...il.com> wrote:
> =============================================
> [ INFO: possible recursive locking detected ]
> 2.6.24-rc8-mm1 #8
> ---------------------------------------------
> bluepush/3213 is trying to acquire lock:
> (sk_lock-AF_BLUETOOTH){--..}, at: [<f8978c80>]
> l2cap_sock_bind+0x40/0x100 [l2cap]
>
> but task is already holding lock:
> (sk_lock-AF_BLUETOOTH){--..}, at: [<f894a31e>]
> rfcomm_sock_connect+0x3e/0xe0 [rfcomm]
>
> other info that might help us debug this:
> 2 locks held by bluepush/3213:
> #0: (sk_lock-AF_BLUETOOTH){--..}, at: [<f894a31e>]
> rfcomm_sock_connect+0x3e/0xe0 [rfcomm]
> #1: (rfcomm_mutex){--..}, at: [<f8947556>] rfcomm_dlc_open+0x26/0x60 [rfcomm]
>
> stack backtrace:
> Pid: 3213, comm: bluepush Not tainted 2.6.24-rc8-mm1 #8
> [<c0132128>] ? printk+0x18/0x20
> [<c0154437>] print_deadlock_bug+0xc7/0xe0
> [<c01544bc>] check_deadlock+0x6c/0x80
> [<c01548fc>] validate_chain+0x14c/0x320
> [<c0156221>] __lock_acquire+0x1c1/0x730
> [<c0156d89>] lock_acquire+0x79/0xb0
> [<f8978c80>] ? l2cap_sock_bind+0x40/0x100 [l2cap]
> [<c03c05f5>] lock_sock_nested+0x55/0x70
> [<f8978c80>] ? l2cap_sock_bind+0x40/0x100 [l2cap]
> [<f8978c80>] l2cap_sock_bind+0x40/0x100 [l2cap]
> [<c03bdb4a>] kernel_bind+0xa/0x10
> [<f8947afc>] rfcomm_session_create+0x4c/0x110 [rfcomm]
> [<f8947509>] __rfcomm_dlc_open+0x129/0x150 [rfcomm]
> [<f8947568>] rfcomm_dlc_open+0x38/0x60 [rfcomm]
> [<f894a396>] rfcomm_sock_connect+0xb6/0xe0 [rfcomm]
> [<c03bcd39>] sys_connect+0x99/0xd0
> [<c010f509>] ? cache_add_dev+0x39/0x1a0
> [<c015323d>] ? put_lock_stats+0xd/0x30
> [<c01532c0>] ? lock_release_holdtime+0x60/0x80
> [<c018e86c>] ? fget+0x7c/0x100
> [<c0156b97>] ? __lock_release+0x47/0x70
> [<c018e86c>] ? fget+0x7c/0x100
> [<c02611b7>] ? copy_from_user+0x37/0x70
> [<c03bd855>] sys_socketcall+0xa5/0x230
> [<c0155659>] ? trace_hardirqs_on+0xb9/0x130
> [<c010501b>] ? restore_nocheck+0x12/0x15
>
While fixing this issue, another locking dependency confused me. Are
rfcomm_dev_lock and &d->lock in same lock class?
The warnings as following:
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.24-rc8-mm1 #8
-------------------------------------------------------
krfcommd/2912 is trying to acquire lock:
(rfcomm_dev_lock){-.--}, at: [<f89d5bf2>]
rfcomm_dev_state_change+0x92/0x160 [rfcomm]
but task is already holding lock:
(&d->lock){--..}, at: [<f89d15d3>] __rfcomm_dlc_close+0x43/0xd0 [rfcomm]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&d->lock){--..}:
[<c0153b13>] add_lock_to_list+0x33/0x70
[<c01545a3>] check_prev_add+0xd3/0x200
[<f89d5311>] rfcomm_dev_add+0x191/0x300 [rfcomm]
[<c0154765>] check_prevs_add+0x95/0xe0
[<c01549ef>] validate_chain+0x23f/0x320
[<c0156221>] __lock_acquire+0x1c1/0x730
[<c0155539>] mark_held_locks+0x39/0x80
[<c0156d89>] lock_acquire+0x79/0xb0
[<f89d5311>] rfcomm_dev_add+0x191/0x300 [rfcomm]
[<c0436749>] _spin_lock+0x39/0x80
[<f89d5311>] rfcomm_dev_add+0x191/0x300 [rfcomm]
[<f89d5b10>] rfcomm_dev_data_ready+0x0/0x50 [rfcomm]
[<f89d5311>] rfcomm_dev_add+0x191/0x300 [rfcomm]
[<f89d565e>] rfcomm_create_dev+0x6e/0x100 [rfcomm]
[<c03c05fa>] lock_sock_nested+0x5a/0x70
[<f89d5ae3>] rfcomm_dev_ioctl+0x33/0x60 [rfcomm]
[<f89d4c8c>] rfcomm_sock_ioctl+0x2c/0x50 [rfcomm]
[<c03bc001>] sock_ioctl+0xc1/0x220
[<c03bbf40>] sock_ioctl+0x0/0x220
[<c019a366>] vfs_ioctl+0x76/0x90
[<c019a616>] do_vfs_ioctl+0x56/0x140
[<c019a762>] sys_ioctl+0x62/0x70
[<c0104fba>] syscall_call+0x7/0xb
[<ffffffff>] 0xffffffff
-> #0 (rfcomm_dev_lock){-.--}:
[<c0154504>] check_prev_add+0x34/0x200
[<c012a9ab>] default_wake_function+0xb/0x10
[<c0154765>] check_prevs_add+0x95/0xe0
[<c01549ef>] validate_chain+0x23f/0x320
[<c0156221>] __lock_acquire+0x1c1/0x730
[<c0156d89>] lock_acquire+0x79/0xb0
[<f89d5bf2>] rfcomm_dev_state_change+0x92/0x160 [rfcomm]
[<c04361e9>] _read_lock+0x39/0x80
[<f89d5bf2>] rfcomm_dev_state_change+0x92/0x160 [rfcomm]
[<f89d5bf2>] rfcomm_dev_state_change+0x92/0x160 [rfcomm]
[<f89d15e8>] __rfcomm_dlc_close+0x58/0xd0 [rfcomm]
[<f89d2523>] rfcomm_recv_ua+0x73/0x140 [rfcomm]
[<f89d3151>] rfcomm_recv_frame+0x171/0x1e0 [rfcomm]
[<c0155659>] trace_hardirqs_on+0xb9/0x130
[<c0436a39>] _spin_unlock_irqrestore+0x39/0x70
[<f89d3447>] rfcomm_run+0xe7/0x590 [rfcomm]
[<c0120000>] hpet_legacy_next_event+0x20/0x50
[<f89d3360>] rfcomm_run+0x0/0x590 [rfcomm]
[<c0146e0c>] kthread+0x5c/0xa0
[<c0146db0>] kthread+0x0/0xa0
[<c0105c17>] kernel_thread_helper+0x7/0x10
[<ffffffff>] 0xffffffff
other info that might help us debug this:
2 locks held by krfcommd/2912:
#0: (rfcomm_mutex){--..}, at: [<f89d33db>] rfcomm_run+0x7b/0x590 [rfcomm]
#1: (&d->lock){--..}, at: [<f89d15d3>] __rfcomm_dlc_close+0x43/0xd0 [rfcomm]
stack backtrace:
Pid: 2912, comm: krfcommd Not tainted 2.6.24-rc8-mm1 #8
[<c0132128>] ? printk+0x18/0x20
[<c0153cff>] print_circular_bug_tail+0x6f/0x80
[<c0154504>] check_prev_add+0x34/0x200
[<c012a9ab>] ? default_wake_function+0xb/0x10
[<c0154765>] check_prevs_add+0x95/0xe0
[<c01549ef>] validate_chain+0x23f/0x320
[<c0156221>] __lock_acquire+0x1c1/0x730
[<c0156d89>] lock_acquire+0x79/0xb0
[<f89d5bf2>] ? rfcomm_dev_state_change+0x92/0x160 [rfcomm]
[<c04361e9>] _read_lock+0x39/0x80
[<f89d5bf2>] ? rfcomm_dev_state_change+0x92/0x160 [rfcomm]
[<f89d5bf2>] rfcomm_dev_state_change+0x92/0x160 [rfcomm]
[<f89d15e8>] __rfcomm_dlc_close+0x58/0xd0 [rfcomm]
[<f89d2523>] rfcomm_recv_ua+0x73/0x140 [rfcomm]
[<f89d3151>] rfcomm_recv_frame+0x171/0x1e0 [rfcomm]
[<c0155659>] ? trace_hardirqs_on+0xb9/0x130
[<c0436a39>] ? _spin_unlock_irqrestore+0x39/0x70
[<f89d3447>] rfcomm_run+0xe7/0x590 [rfcomm]
[<c0120000>] ? hpet_legacy_next_event+0x20/0x50
[<f89d3360>] ? rfcomm_run+0x0/0x590 [rfcomm]
[<c0146e0c>] kthread+0x5c/0xa0
[<c0146db0>] ? kthread+0x0/0xa0
[<c0105c17>] kernel_thread_helper+0x7/0x10
=======================
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