| Date | Tue, 15 Feb 2011 16:14:46 -0800 | From | Greg KH <> | Subject | [229/272] watchdog: Fix broken nowatchdog logic |
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2.6.37-stable review patch. If anyone has any objections, please let us know.
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From: Marcin Slusarz <marcin.slusarz@gmail.com>
commit 4135038a582c20ffdadfcf6564852e0b72a20968 upstream.
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> LKML-Reference: <1296230433-6261-1-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
--- kernel/watchdog.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-)
--- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -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, hrt 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: @@ -75,7 +72,7 @@ __setup("softlockup_panic=", softlockup_ static int __init nowatchdog_setup(char *str) { - no_watchdog = 1; + watchdog_enabled = 0; return 1; } __setup("nowatchdog", nowatchdog_setup); @@ -83,7 +80,7 @@ __setup("nowatchdog", nowatchdog_setup); /* deprecated */ static int __init nosoftlockup_setup(char *str) { - no_watchdog = 1; + watchdog_enabled = 0; return 1; } __setup("nosoftlockup", nosoftlockup_setup); @@ -475,9 +472,6 @@ static void watchdog_disable_all_cpus(vo { int cpu; - if (no_watchdog) - return; - for_each_online_cpu(cpu) watchdog_disable(cpu); @@ -531,7 +525,8 @@ cpu_callback(struct notifier_block *nfb, break; case CPU_ONLINE: case CPU_ONLINE_FROZEN: - err = watchdog_enable(hotcpu); + if (watchdog_enabled) + err = watchdog_enable(hotcpu); break; #ifdef CONFIG_HOTPLUG_CPU case CPU_UP_CANCELED: @@ -556,9 +551,6 @@ static int __init spawn_watchdog_task(vo void *cpu = (void *)(long)smp_processor_id(); int err; - if (no_watchdog) - return 0; - err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); WARN_ON(notifier_to_errno(err));
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