diff options
| author | Ingo Molnar <mingo@elte.hu> | 2010-02-08 08:55:43 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-02-08 08:55:46 +0100 |
| commit | 6d3e0907b8b239d16720d144e2675ecf10d3bc3b (patch) | |
| tree | e0b0743b5f6f82b057cafc4f3687396a6e01a0b4 /kernel/time/clocksource.c | |
| parent | 23577256953c870de9b724c3a2611ce7be6a1e4e (diff) | |
| parent | 50200df462023b187d80a99a52f5f2cfe3c86c26 (diff) | |
Merge branch 'sched/urgent' into sched/core
Merge reason: Merge dependent fix, update to latest -rc.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/time/clocksource.c')
| -rw-r--r-- | kernel/time/clocksource.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index e85c23404d3..13700833c18 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -343,7 +343,19 @@ static void clocksource_resume_watchdog(void) { unsigned long flags; - spin_lock_irqsave(&watchdog_lock, flags); + /* + * We use trylock here to avoid a potential dead lock when + * kgdb calls this code after the kernel has been stopped with + * watchdog_lock held. When watchdog_lock is held we just + * return and accept, that the watchdog might trigger and mark + * the monitored clock source (usually TSC) unstable. + * + * This does not affect the other caller clocksource_resume() + * because at this point the kernel is UP, interrupts are + * disabled and nothing can hold watchdog_lock. + */ + if (!spin_trylock_irqsave(&watchdog_lock, flags)) + return; clocksource_reset_watchdog(); spin_unlock_irqrestore(&watchdog_lock, flags); } @@ -458,8 +470,8 @@ void clocksource_resume(void) * clocksource_touch_watchdog - Update watchdog * * Update the watchdog after exception contexts such as kgdb so as not - * to incorrectly trip the watchdog. - * + * to incorrectly trip the watchdog. This might fail when the kernel + * was stopped in code which holds watchdog_lock. */ void clocksource_touch_watchdog(void) { |