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Commit f79e0258 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Ingo Molnar
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clocksource: Resolve cpu hotplug dead lock with TSC unstable, fix crash 



The watchdog timer is started after the watchdog clocksource
and at least one watched clocksource have been registered. The
clocksource work element watchdog_work is initialized just
before the clocksource timer is started. This is too late for
the clocksource_mark_unstable call from native_cpu_up. To fix
this use a static initializer for watchdog_work.

This resolves a boot crash reported by multiple people.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <20090911153305.3fe9a361@skybase>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e500011f

kernel/time/clocksource.c

+3 −2
Original line number Diff line number Diff line
@@ -123,10 +123,12 @@ static DEFINE_MUTEX(clocksource_mutex); 
static char override_name[32];



#ifdef CONFIG_CLOCKSOURCE_WATCHDOG

static void clocksource_watchdog_work(struct work_struct *work);



static LIST_HEAD(watchdog_list);

static struct clocksource *watchdog;

static struct timer_list watchdog_timer;

static struct work_struct watchdog_work;

static DECLARE_WORK(watchdog_work, clocksource_watchdog_work);

static DEFINE_SPINLOCK(watchdog_lock);

static cycle_t watchdog_last;

static int watchdog_running;
@@ -257,7 +259,6 @@ static inline void clocksource_start_watchdog(void) 
{

	if (watchdog_running || !watchdog || list_empty(&watchdog_list))

		return;

	INIT_WORK(&watchdog_work, clocksource_watchdog_work);

	init_timer(&watchdog_timer);

	watchdog_timer.function = clocksource_watchdog;

	watchdog_last = watchdog->read(watchdog);