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Commit bdd84667 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'timers-fixes-for-linus' of... 

Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  clocksource: Prevent potential kgdb dead lock
parents 935cc932 7b7422a5

kernel/time/clocksource.c

+15 −3
Original line number Diff line number Diff line
@@ -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)

{