* gpiolib.c: possible circular locking dependency detected
@ 2011-07-11 12:19 Alexander Stein
2011-07-15 20:15 ` Grant Likely
0 siblings, 1 reply; 2+ messages in thread
From: Alexander Stein @ 2011-07-11 12:19 UTC (permalink / raw)
To: linux-kernel; +Cc: Grant Likely
Hello,
I used a shell script using /sys/class/gpio to export,set/unset and unexport
GPIOs. Upon unexporting GPIOs I get the dmesg shown below. I didn't find any
important change in gpiolib.c and fs/sysfs/dir.c between 2.6.39 and git master
which would fix this.
Has somebody an idea about this?
Regards,
Alexander
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.39+ #5
-------------------------------------------------------
gpio.sh/765 is trying to acquire lock:
(s_active#40){++++.+}, at: [<c10d566d>] sysfs_addrm_finish+0x27/0x4a
but task is already holding lock:
(sysfs_lock){+.+.+.}, at: [<c11664a8>] gpio_unexport+0x27/0x77
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (sysfs_lock){+.+.+.}:
[<c104f517>] validate_chain.clone.14+0x425/0x518
[<c10504d8>] __lock_acquire+0x653/0x6bb
[<c1050945>] lock_acquire+0x63/0x7b
[<c130b9e8>] mutex_lock_nested+0x45/0x291
[<c1166261>] gpio_direction_store+0x20/0xab
[<c11bf5e9>] dev_attr_store+0x22/0x27
[<c10d4684>] sysfs_write_file+0xb6/0xe9
[<c1094841>] vfs_write+0x91/0x10d
[<c1094a69>] sys_write+0x3e/0x63
[<c130da4c>] sysenter_do_call+0x12/0x32
-> #0 (s_active#40){++++.+}:
[<c104ecea>] check_prev_add+0xd5/0x4dd
[<c104f517>] validate_chain.clone.14+0x425/0x518
[<c10504d8>] __lock_acquire+0x653/0x6bb
[<c1050945>] lock_acquire+0x63/0x7b
[<c10d509e>] sysfs_deactivate+0x85/0xba
[<c10d566d>] sysfs_addrm_finish+0x27/0x4a
[<c10d5ac2>] sysfs_remove_dir+0x5f/0x6d
[<c115594d>] kobject_del+0xf/0x5e
[<c11c01bd>] device_del+0x12e/0x13a
[<c11c01d4>] device_unregister+0xb/0x15
[<c11664e9>] gpio_unexport+0x68/0x77
[<c1166514>] gpio_free+0x1c/0xa3
[<c11665df>] unexport_store+0x44/0x49
[<c11c29ec>] class_attr_store+0x25/0x2a
[<c10d4684>] sysfs_write_file+0xb6/0xe9
[<c1094841>] vfs_write+0x91/0x10d
[<c1094a69>] sys_write+0x3e/0x63
[<c130da4c>] sysenter_do_call+0x12/0x32
other info that might help us debug this:
3 locks held by gpio.sh/765:
#0: (&buffer->mutex){+.+.+.}, at: [<c10d45f3>] sysfs_write_file+0x25/0xe9
#1: (s_active#52){.+.+.+}, at: [<c10d4669>] sysfs_write_file+0x9b/0xe9
#2: (sysfs_lock){+.+.+.}, at: [<c11664a8>] gpio_unexport+0x27/0x77
stack backtrace:
Pid: 765, comm: gpio.sh Not tainted 2.6.39+ #5
Call Trace:
[<c130a450>] ? printk+0x19/0x1b
[<c104e2c6>] print_circular_bug+0x94/0x9d
[<c104ecea>] check_prev_add+0xd5/0x4dd
[<c104f517>] validate_chain.clone.14+0x425/0x518
[<c104fc9c>] ? mark_lock+0x208/0x2d7
[<c10504d8>] __lock_acquire+0x653/0x6bb
[<c104d433>] ? lockdep_init_map+0x8a/0x3c3
[<c1051079>] ? trace_hardirqs_on+0xb/0xd
[<c1050945>] lock_acquire+0x63/0x7b
[<c10d566d>] ? sysfs_addrm_finish+0x27/0x4a
[<c10d509e>] sysfs_deactivate+0x85/0xba
[<c10d566d>] ? sysfs_addrm_finish+0x27/0x4a
[<c10d566d>] sysfs_addrm_finish+0x27/0x4a
[<c10d5ac2>] sysfs_remove_dir+0x5f/0x6d
[<c115594d>] kobject_del+0xf/0x5e
[<c11c01bd>] device_del+0x12e/0x13a
[<c11c01d4>] device_unregister+0xb/0x15
[<c11664e9>] gpio_unexport+0x68/0x77
[<c1165417>] ? gpio_set_value_cansleep+0x1c/0x1c
[<c116659b>] ? gpio_free+0xa3/0xa3
[<c1166514>] gpio_free+0x1c/0xa3
[<c116659b>] ? gpio_free+0xa3/0xa3
[<c11665df>] unexport_store+0x44/0x49
[<c11c29ec>] class_attr_store+0x25/0x2a
[<c10d4684>] sysfs_write_file+0xb6/0xe9
[<c1094841>] vfs_write+0x91/0x10d
[<c10d45ce>] ? sysfs_poll+0x72/0x72
[<c1094a69>] sys_write+0x3e/0x63
[<c130da4c>] sysenter_do_call+0x12/0x32
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: gpiolib.c: possible circular locking dependency detected
2011-07-11 12:19 gpiolib.c: possible circular locking dependency detected Alexander Stein
@ 2011-07-15 20:15 ` Grant Likely
0 siblings, 0 replies; 2+ messages in thread
From: Grant Likely @ 2011-07-15 20:15 UTC (permalink / raw)
To: Alexander Stein; +Cc: linux-kernel
On Mon, Jul 11, 2011 at 02:19:55PM +0200, Alexander Stein wrote:
> Hello,
>
> I used a shell script using /sys/class/gpio to export,set/unset and unexport
> GPIOs. Upon unexporting GPIOs I get the dmesg shown below. I didn't find any
> important change in gpiolib.c and fs/sysfs/dir.c between 2.6.39 and git master
> which would fix this.
> Has somebody an idea about this?
Yeah, there are nasty locking problems in the gpio sysfs interface,
but nobody has completed the work of debugging it. Someone with some
free cycles could help out here.
g.
>
> Regards,
> Alexander
>
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 2.6.39+ #5
> -------------------------------------------------------
> gpio.sh/765 is trying to acquire lock:
> (s_active#40){++++.+}, at: [<c10d566d>] sysfs_addrm_finish+0x27/0x4a
> but task is already holding lock:
> (sysfs_lock){+.+.+.}, at: [<c11664a8>] gpio_unexport+0x27/0x77
>
> which lock already depends on the new lock.
> the existing dependency chain (in reverse order) is:
> -> #1 (sysfs_lock){+.+.+.}:
> [<c104f517>] validate_chain.clone.14+0x425/0x518
> [<c10504d8>] __lock_acquire+0x653/0x6bb
> [<c1050945>] lock_acquire+0x63/0x7b
> [<c130b9e8>] mutex_lock_nested+0x45/0x291
> [<c1166261>] gpio_direction_store+0x20/0xab
> [<c11bf5e9>] dev_attr_store+0x22/0x27
> [<c10d4684>] sysfs_write_file+0xb6/0xe9
> [<c1094841>] vfs_write+0x91/0x10d
> [<c1094a69>] sys_write+0x3e/0x63
> [<c130da4c>] sysenter_do_call+0x12/0x32
>
> -> #0 (s_active#40){++++.+}:
> [<c104ecea>] check_prev_add+0xd5/0x4dd
> [<c104f517>] validate_chain.clone.14+0x425/0x518
> [<c10504d8>] __lock_acquire+0x653/0x6bb
> [<c1050945>] lock_acquire+0x63/0x7b
> [<c10d509e>] sysfs_deactivate+0x85/0xba
> [<c10d566d>] sysfs_addrm_finish+0x27/0x4a
> [<c10d5ac2>] sysfs_remove_dir+0x5f/0x6d
> [<c115594d>] kobject_del+0xf/0x5e
> [<c11c01bd>] device_del+0x12e/0x13a
> [<c11c01d4>] device_unregister+0xb/0x15
> [<c11664e9>] gpio_unexport+0x68/0x77
> [<c1166514>] gpio_free+0x1c/0xa3
> [<c11665df>] unexport_store+0x44/0x49
> [<c11c29ec>] class_attr_store+0x25/0x2a
> [<c10d4684>] sysfs_write_file+0xb6/0xe9
> [<c1094841>] vfs_write+0x91/0x10d
> [<c1094a69>] sys_write+0x3e/0x63
> [<c130da4c>] sysenter_do_call+0x12/0x32
>
> other info that might help us debug this:
>
> 3 locks held by gpio.sh/765:
> #0: (&buffer->mutex){+.+.+.}, at: [<c10d45f3>] sysfs_write_file+0x25/0xe9
> #1: (s_active#52){.+.+.+}, at: [<c10d4669>] sysfs_write_file+0x9b/0xe9
> #2: (sysfs_lock){+.+.+.}, at: [<c11664a8>] gpio_unexport+0x27/0x77
>
> stack backtrace:
> Pid: 765, comm: gpio.sh Not tainted 2.6.39+ #5
> Call Trace:
> [<c130a450>] ? printk+0x19/0x1b
> [<c104e2c6>] print_circular_bug+0x94/0x9d
> [<c104ecea>] check_prev_add+0xd5/0x4dd
> [<c104f517>] validate_chain.clone.14+0x425/0x518
> [<c104fc9c>] ? mark_lock+0x208/0x2d7
> [<c10504d8>] __lock_acquire+0x653/0x6bb
> [<c104d433>] ? lockdep_init_map+0x8a/0x3c3
> [<c1051079>] ? trace_hardirqs_on+0xb/0xd
> [<c1050945>] lock_acquire+0x63/0x7b
> [<c10d566d>] ? sysfs_addrm_finish+0x27/0x4a
> [<c10d509e>] sysfs_deactivate+0x85/0xba
> [<c10d566d>] ? sysfs_addrm_finish+0x27/0x4a
> [<c10d566d>] sysfs_addrm_finish+0x27/0x4a
> [<c10d5ac2>] sysfs_remove_dir+0x5f/0x6d
> [<c115594d>] kobject_del+0xf/0x5e
> [<c11c01bd>] device_del+0x12e/0x13a
> [<c11c01d4>] device_unregister+0xb/0x15
> [<c11664e9>] gpio_unexport+0x68/0x77
> [<c1165417>] ? gpio_set_value_cansleep+0x1c/0x1c
> [<c116659b>] ? gpio_free+0xa3/0xa3
> [<c1166514>] gpio_free+0x1c/0xa3
> [<c116659b>] ? gpio_free+0xa3/0xa3
> [<c11665df>] unexport_store+0x44/0x49
> [<c11c29ec>] class_attr_store+0x25/0x2a
> [<c10d4684>] sysfs_write_file+0xb6/0xe9
> [<c1094841>] vfs_write+0x91/0x10d
> [<c10d45ce>] ? sysfs_poll+0x72/0x72
> [<c1094a69>] sys_write+0x3e/0x63
> [<c130da4c>] sysenter_do_call+0x12/0x32
^ permalink raw reply [flat|nested] 2+ messages in thread
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2011-07-11 12:19 gpiolib.c: possible circular locking dependency detected Alexander Stein
2011-07-15 20:15 ` Grant Likely
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