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-rw-r--r--kernel/time/clocksource.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index e85c23404d34..13700833c181 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -343,7 +343,19 @@ static void clocksource_resume_watchdog(void)
343{ 343{
344 unsigned long flags; 344 unsigned long flags;
345 345
346 spin_lock_irqsave(&watchdog_lock, flags); 346 /*
347 * We use trylock here to avoid a potential dead lock when
348 * kgdb calls this code after the kernel has been stopped with
349 * watchdog_lock held. When watchdog_lock is held we just
350 * return and accept, that the watchdog might trigger and mark
351 * the monitored clock source (usually TSC) unstable.
352 *
353 * This does not affect the other caller clocksource_resume()
354 * because at this point the kernel is UP, interrupts are
355 * disabled and nothing can hold watchdog_lock.
356 */
357 if (!spin_trylock_irqsave(&watchdog_lock, flags))
358 return;
347 clocksource_reset_watchdog(); 359 clocksource_reset_watchdog();
348 spin_unlock_irqrestore(&watchdog_lock, flags); 360 spin_unlock_irqrestore(&watchdog_lock, flags);
349} 361}
@@ -458,8 +470,8 @@ void clocksource_resume(void)
458 * clocksource_touch_watchdog - Update watchdog 470 * clocksource_touch_watchdog - Update watchdog
459 * 471 *
460 * Update the watchdog after exception contexts such as kgdb so as not 472 * Update the watchdog after exception contexts such as kgdb so as not
461 * to incorrectly trip the watchdog. 473 * to incorrectly trip the watchdog. This might fail when the kernel
462 * 474 * was stopped in code which holds watchdog_lock.
463 */ 475 */
464void clocksource_touch_watchdog(void) 476void clocksource_touch_watchdog(void)
465{ 477{