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watchdog: Fix broken nowatchdog logic

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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: Marcin Slusarz <marcin.slusarz@gmail.com>
[ removed another no_watchdog instance ]
Signed-off-by: Don 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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Marcin Slusarz 2011-01-28 11:00:31 -05:00 committed by Ingo Molnar
parent d038b12c6d
commit 4135038a58
1 changed files with 6 additions and 14 deletions
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20
kernel/watchdog.c
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@ -27,7 +27,7 @@
#include <asm/irq_regs.h> #include <asm/irq_regs.h>
#include <linux/perf_event.h> #include <linux/perf_event.h>
int watchdog_enabled; int watchdog_enabled = 1;
int __read_mostly softlockup_thresh = 60; int __read_mostly softlockup_thresh = 60;
static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); 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); static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
#endif #endif
static int no_watchdog;
/* boot commands */ /* boot commands */
/* /*
* Should we panic when a soft-lockup or hard-lockup occurs: * 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)) if (!strncmp(str, "panic", 5))
hardlockup_panic = 1; hardlockup_panic = 1;
else if (!strncmp(str, "0", 1)) else if (!strncmp(str, "0", 1))
no_watchdog = 1; watchdog_enabled = 0;
return 1; return 1;
} }
__setup("nmi_watchdog=", hardlockup_panic_setup); __setup("nmi_watchdog=", hardlockup_panic_setup);
@ -77,7 +74,7 @@ __setup("softlockup_panic=", softlockup_panic_setup);
static int __init nowatchdog_setup(char *str) static int __init nowatchdog_setup(char *str)
{ {
no_watchdog = 1; watchdog_enabled = 0;
return 1; return 1;
} }
__setup("nowatchdog", nowatchdog_setup); __setup("nowatchdog", nowatchdog_setup);
@ -85,7 +82,7 @@ __setup("nowatchdog", nowatchdog_setup);
/* deprecated */ /* deprecated */
static int __init nosoftlockup_setup(char *str) static int __init nosoftlockup_setup(char *str)
{ {
no_watchdog = 1; watchdog_enabled = 0;
return 1; return 1;
} }
__setup("nosoftlockup", nosoftlockup_setup); __setup("nosoftlockup", nosoftlockup_setup);
@ -476,9 +473,6 @@ static void watchdog_disable_all_cpus(void)
{ {
int cpu; int cpu;
if (no_watchdog)
return;
for_each_online_cpu(cpu) for_each_online_cpu(cpu)
watchdog_disable(cpu); watchdog_disable(cpu);
@ -530,7 +524,8 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
break; break;
case CPU_ONLINE: case CPU_ONLINE:
case CPU_ONLINE_FROZEN: case CPU_ONLINE_FROZEN:
err = watchdog_enable(hotcpu); if (watchdog_enabled)
err = watchdog_enable(hotcpu);
break; break;
#ifdef CONFIG_HOTPLUG_CPU #ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED: case CPU_UP_CANCELED:
@ -555,9 +550,6 @@ void __init lockup_detector_init(void)
void *cpu = (void *)(long)smp_processor_id(); void *cpu = (void *)(long)smp_processor_id();
int err; int err;
if (no_watchdog)
return;
err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
WARN_ON(notifier_to_errno(err)); WARN_ON(notifier_to_errno(err));