From 4135038a582c20ffdadfcf6564852e0b72a20968 Mon Sep 17 00:00:00 2001 From: Marcin Slusarz Date: Fri, 28 Jan 2011 11:00:31 -0500 Subject: 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: Marcin Slusarz [ removed another no_watchdog instance ] Signed-off-by: Don Zickus Cc: Stephane Eranian Cc: Peter Zijlstra Cc: Frederic Weisbecker Cc: LKML-Reference: <1296230433-6261-1-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar --- kernel/watchdog.c | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) (limited to 'kernel/watchdog.c') diff --git a/kernel/watchdog.c b/kernel/watchdog.c index d7ebdf4..d9961ea 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -27,7 +27,7 @@ #include #include -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); @@ -530,7 +524,8 @@ 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: @@ -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)); -- cgit v1.1 From 397357666de6b5b6adb5fa99f9758ec8cf30ac34 Mon Sep 17 00:00:00 2001 From: Marcin Slusarz Date: Fri, 28 Jan 2011 11:00:32 -0500 Subject: watchdog: Fix sysctl consistency If it was not possible to enable watchdog for any cpu, switch watchdog_enabled back to 0, because it's visible via kernel.watchdog sysctl. Signed-off-by: Marcin Slusarz Signed-off-by: Don Zickus Cc: Peter Zijlstra Cc: Frederic Weisbecker Cc: LKML-Reference: <1296230433-6261-2-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar --- kernel/watchdog.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'kernel/watchdog.c') diff --git a/kernel/watchdog.c b/kernel/watchdog.c index d9961ea..c7e0049 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -429,9 +429,6 @@ static int watchdog_enable(int cpu) wake_up_process(p); } - /* if any cpu succeeds, watchdog is considered enabled for the system */ - watchdog_enabled = 1; - return 0; } @@ -459,12 +456,16 @@ static void watchdog_disable(int cpu) static void watchdog_enable_all_cpus(void) { int cpu; - int result = 0; + + watchdog_enabled = 0; for_each_online_cpu(cpu) - result += watchdog_enable(cpu); + if (!watchdog_enable(cpu)) + /* if any cpu succeeds, watchdog is considered + enabled for the system */ + watchdog_enabled = 1; - if (result) + if (!watchdog_enabled) printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n"); } -- cgit v1.1 From 9ffdc6c37df131f89d52001e0ef03091b158826f Mon Sep 17 00:00:00 2001 From: Marcin Slusarz Date: Fri, 28 Jan 2011 11:00:33 -0500 Subject: watchdog: Don't change watchdog state on read of sysctl Signed-off-by: Marcin Slusarz [ add {}'s to fix a warning ] Signed-off-by: Don Zickus Cc: Peter Zijlstra Cc: Frederic Weisbecker Cc: LKML-Reference: <1296230433-6261-3-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar --- kernel/watchdog.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'kernel/watchdog.c') diff --git a/kernel/watchdog.c b/kernel/watchdog.c index c7e0049..f37f974 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -493,10 +493,12 @@ int proc_dowatchdog_enabled(struct ctl_table *table, int write, { proc_dointvec(table, write, buffer, length, ppos); - if (watchdog_enabled) - watchdog_enable_all_cpus(); - else - watchdog_disable_all_cpus(); + if (write) { + if (watchdog_enabled) + watchdog_enable_all_cpus(); + else + watchdog_disable_all_cpus(); + } return 0; } -- cgit v1.1