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 <[email protected]> Cc: Don Zickus <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: [email protected] --- kernel/watchdog.c | 18 +++++------------- 1 files changed, 5 insertions(+), 13 deletions(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 0a507b1..ba52aa3 100644 --- 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, 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: @@ -75,7 +72,7 @@ __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); @@ -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); @@ -469,9 +466,6 @@ static void watchdog_disable_all_cpus(void) { int cpu; - if (no_watchdog) - return; - for_each_online_cpu(cpu) watchdog_disable(cpu); @@ -523,7 +517,8 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) 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: @@ -548,9 +543,6 @@ static int __init spawn_watchdog_task(void) 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)); -- 1.7.3.3 _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
