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clocksource: Resume clocksource without taking the clocksource mutex

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git commit 75c5158f70 converted the clocksource spinlock to a
mutex. This causes the following BUG:

BUG: sleeping function called from invalid context at
kernel/mutex.c:280 in_atomic(): 0, irqs_disabled(): 1, pid: 2473,
name: pm-suspend 2 locks held by pm-suspend/2473:
 #0:  (&buffer->mutex){......}, at: [<ffffffff8115ab13>]
sysfs_write_file+0x3c/0x137
 #1:  (pm_mutex){......}, at: [<ffffffff810865b5>]
enter_state+0x39/0x130 Pid: 2473, comm: pm-suspend Not tainted 2.6.31
#1 Call Trace:
 [<ffffffff810792f0>] ? __debug_show_held_locks+0x22/0x24
 [<ffffffff8104a2ef>] __might_sleep+0x107/0x10b
 [<ffffffff8141fca9>] mutex_lock_nested+0x25/0x43
 [<ffffffff81073537>] clocksource_resume+0x1c/0x60
 [<ffffffff81072902>] timekeeping_resume+0x1e/0x1c8
 [<ffffffff812aee62>] __sysdev_resume+0x25/0xcf
 [<ffffffff812aef79>] sysdev_resume+0x6d/0xae
 [<ffffffff810864f8>] suspend_devices_and_enter+0x12b/0x1af
 [<ffffffff8108665b>] enter_state+0xdf/0x130
 [<ffffffff81085dc3>] state_store+0xb6/0xd3
 [<ffffffff81204c73>] kobj_attr_store+0x17/0x19
 [<ffffffff8115abd2>] sysfs_write_file+0xfb/0x137
 [<ffffffff811057d2>] vfs_write+0xae/0x10b
 [<ffffffff81208392>] ? __up_read+0x1a/0x7f
 [<ffffffff811058ef>] sys_write+0x4a/0x6e
 [<ffffffff81011b82>] system_call_fastpath+0x16/0x1b

clocksource_resume is called early in the resume process, there is
only one cpu, no processes are running and the interrupts are
disabled. It is therefore possible to resume the clocksources
without taking the clocksource mutex.

Reported-by: Xiaotian Feng <[email protected]>
Signed-off-by: Martin Schwidefsky <[email protected]>
Tested-by: Michal Schmidt <[email protected]>
Cc: Xiaotian Feng <[email protected]>
Cc: John Stultz <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Martin Schwidefsky 2009-09-24 17:29:52 +02:00 • committed by Ingo Molnar
commit 89133f9350
1 changed files with 0 additions and 4 deletions
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4
kernel/time/clocksource.c
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@ -394,15 +394,11 @@ void clocksource_resume(void)
{
struct clocksource *cs;
mutex_lock(&clocksource_mutex);
list_for_each_entry(cs, &clocksource_list, list)
if (cs->resume)
cs->resume();
clocksource_resume_watchdog();
mutex_unlock(&clocksource_mutex);
}
/**