diff options
| author | David Woodhouse <David.Woodhouse@intel.com> | 2010-02-26 19:04:15 +0000 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2010-02-26 19:06:24 +0000 |
| commit | a7790532f5b7358c33a6b1834dc2b318de209f31 (patch) | |
| tree | 0ceb9e24b3f54cb5c8453fb5a218e2a94a0f1cce /kernel/time/clocksource.c | |
| parent | 2764fb4244cc1bc08df3667924ca4a972e90ac70 (diff) | |
| parent | 60b341b778cc2929df16c0a504c91621b3c6a4ad (diff) | |
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
The SmartMedia FTL code depends on new kfifo bits from 2.6.33
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) { |