diff options
| author | Mark Brown <broonie@opensource.wolfsonmicro.com> | 2010-03-10 15:02:37 +0000 |
|---|---|---|
| committer | Mark Brown <broonie@opensource.wolfsonmicro.com> | 2010-03-10 15:02:37 +0000 |
| commit | fad837c16cdd856c68ce2e1335ad0fe836ed8ecd (patch) | |
| tree | 1a6babdc2ac7e5388c482e93505fdfaf5ff97f61 /kernel/time/clocksource.c | |
| parent | 51c6ab130642ed975681df843c772dda48a1d2ed (diff) | |
| parent | 57d54889cd00db2752994b389ba714138652e60c (diff) | |
Merge commit 'v2.6.34-rc1' into for-2.6.35
Diffstat (limited to 'kernel/time/clocksource.c')
| -rw-r--r-- | kernel/time/clocksource.c | 32 |
1 files changed, 28 insertions, 4 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index e85c23404d34..1f663d23e85e 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); } @@ -441,6 +453,18 @@ static inline int clocksource_watchdog_kthread(void *data) { return 0; } #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ /** + * clocksource_suspend - suspend the clocksource(s) + */ +void clocksource_suspend(void) +{ + struct clocksource *cs; + + list_for_each_entry_reverse(cs, &clocksource_list, list) + if (cs->suspend) + cs->suspend(cs); +} + +/** * clocksource_resume - resume the clocksource(s) */ void clocksource_resume(void) @@ -449,7 +473,7 @@ void clocksource_resume(void) list_for_each_entry(cs, &clocksource_list, list) if (cs->resume) - cs->resume(); + cs->resume(cs); clocksource_resume_watchdog(); } @@ -458,8 +482,8 @@ 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) { |