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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2009-09-24 17:29:52 +0200
committerIngo Molnar <mingo@elte.hu>2009-09-24 22:37:53 +0200
commit89133f93508137231251543d1732da638e6022e1 (patch)
tree8f94df8c650bbe2ec765de89ce70b9e762a5ba2f
parent94a8d5caba74211ec76dac80fc6e2d5c391530df (diff)
clocksource: Resume clocksource without taking the clocksource mutex
git commit 75c5158f70c065b9 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 <xtfeng@gmail.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Tested-by: Michal Schmidt <mschmidt@redhat.com> Cc: Xiaotian Feng <xtfeng@gmail.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20090924172952.49697825@mschwide.boeblingen.de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/time/clocksource.c4
1 files changed, 0 insertions, 4 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 09113347d32..5e18c6ab2c6 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -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);
}
/**