Commit 4135038a authored by Marcin Slusarz's avatar Marcin Slusarz Committed by Ingo Molnar
Browse files

watchdog: Fix broken nowatchdog logic 



Passing nowatchdog to kernel disables 2 things: creation of
watchdog threads AND initialization of percpu watchdog_hrtimer.
As hrtimers are initialized only at boot it's not possible to
enable watchdog later - for me all watchdog threads started to
eat 100% of CPU time, but they could just crash.

Additionally, even if these threads would start properly,
watchdog_disable_all_cpus was guarded by no_watchdog check, so
you couldn't disable watchdog.

To fix this, remove no_watchdog variable and use already
existing watchdog_enabled variable.

Signed-off-by: default avatarMarcin Slusarz <marcin.slusarz@gmail.com>
[ removed another no_watchdog instance ]
Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: <stable@kernel.org>
LKML-Reference: <1296230433-6261-1-git-send-email-dzickus@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d038b12c

kernel/watchdog.c

+6 −14
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ 
#include <asm/irq_regs.h>

#include <linux/perf_event.h>



int watchdog_enabled;

int watchdog_enabled = 1;

int __read_mostly softlockup_thresh = 60;



static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
@@ -43,9 +43,6 @@ static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); 
static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);

#endif



static int no_watchdog;





/* boot commands */

/*

 * Should we panic when a soft-lockup or hard-lockup occurs:
@@ -58,7 +55,7 @@ static int __init hardlockup_panic_setup(char *str) 
	if (!strncmp(str, "panic", 5))

		hardlockup_panic = 1;

	else if (!strncmp(str, "0", 1))

		no_watchdog = 1;

		watchdog_enabled = 0;

	return 1;

}

__setup("nmi_watchdog=", hardlockup_panic_setup);
@@ -77,7 +74,7 @@ __setup("softlockup_panic=", softlockup_panic_setup); 


static int __init nowatchdog_setup(char *str)

{

	no_watchdog = 1;

	watchdog_enabled = 0;

	return 1;

}

__setup("nowatchdog", nowatchdog_setup);
@@ -85,7 +82,7 @@ __setup("nowatchdog", nowatchdog_setup); 
/* deprecated */

static int __init nosoftlockup_setup(char *str)

{

	no_watchdog = 1;

	watchdog_enabled = 0;

	return 1;

}

__setup("nosoftlockup", nosoftlockup_setup);
@@ -476,9 +473,6 @@ static void watchdog_disable_all_cpus(void) 
{

	int cpu;



	if (no_watchdog)

		return;



	for_each_online_cpu(cpu)

		watchdog_disable(cpu);
@@ -530,6 +524,7 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) 
		break;

	case CPU_ONLINE:

	case CPU_ONLINE_FROZEN:

		if (watchdog_enabled)

			err = watchdog_enable(hotcpu);

		break;

#ifdef CONFIG_HOTPLUG_CPU
@@ -555,9 +550,6 @@ void __init lockup_detector_init(void) 
	void *cpu = (void *)(long)smp_processor_id();

	int err;



	if (no_watchdog)

		return;



	err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);

	WARN_ON(notifier_to_errno(err));

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