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Diffstat (limited to 'kernel/watchdog.c')
-rw-r--r--kernel/watchdog.c121
1 files changed, 90 insertions, 31 deletions
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 64ed1c37bd1f..18f34cf75f74 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -57,8 +57,10 @@ int __read_mostly watchdog_thresh = 10;
#ifdef CONFIG_SMP
int __read_mostly sysctl_softlockup_all_cpu_backtrace;
+int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
#else
#define sysctl_softlockup_all_cpu_backtrace 0
+#define sysctl_hardlockup_all_cpu_backtrace 0
#endif
static struct cpumask watchdog_cpumask __read_mostly;
unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
@@ -110,8 +112,9 @@ static unsigned long soft_lockup_nmi_warn;
* Should we panic when a soft-lockup or hard-lockup occurs:
*/
#ifdef CONFIG_HARDLOCKUP_DETECTOR
-static int hardlockup_panic =
+unsigned int __read_mostly hardlockup_panic =
CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
+static unsigned long hardlockup_allcpu_dumped;
/*
* We may not want to enable hard lockup detection by default in all cases,
* for example when running the kernel as a guest on a hypervisor. In these
@@ -173,6 +176,13 @@ static int __init softlockup_all_cpu_backtrace_setup(char *str)
return 1;
}
__setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup);
+static int __init hardlockup_all_cpu_backtrace_setup(char *str)
+{
+ sysctl_hardlockup_all_cpu_backtrace =
+ !!simple_strtol(str, NULL, 0);
+ return 1;
+}
+__setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup);
#endif
/*
@@ -263,15 +273,15 @@ void touch_softlockup_watchdog_sync(void)
#ifdef CONFIG_HARDLOCKUP_DETECTOR
/* watchdog detector functions */
-static int is_hardlockup(void)
+static bool is_hardlockup(void)
{
unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
- return 1;
+ return true;
__this_cpu_write(hrtimer_interrupts_saved, hrint);
- return 0;
+ return false;
}
#endif
@@ -279,7 +289,7 @@ static int is_softlockup(unsigned long touch_ts)
{
unsigned long now = get_timestamp();
- if (watchdog_enabled & SOFT_WATCHDOG_ENABLED) {
+ if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){
/* Warn about unreasonable delays. */
if (time_after(now, touch_ts + get_softlockup_thresh()))
return now - touch_ts;
@@ -318,17 +328,30 @@ static void watchdog_overflow_callback(struct perf_event *event,
*/
if (is_hardlockup()) {
int this_cpu = smp_processor_id();
+ struct pt_regs *regs = get_irq_regs();
/* only print hardlockups once */
if (__this_cpu_read(hard_watchdog_warn) == true)
return;
- if (hardlockup_panic)
- panic("Watchdog detected hard LOCKUP on cpu %d",
- this_cpu);
+ pr_emerg("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
+ print_modules();
+ print_irqtrace_events(current);
+ if (regs)
+ show_regs(regs);
else
- WARN(1, "Watchdog detected hard LOCKUP on cpu %d",
- this_cpu);
+ dump_stack();
+
+ /*
+ * Perform all-CPU dump only once to avoid multiple hardlockups
+ * generating interleaving traces
+ */
+ if (sysctl_hardlockup_all_cpu_backtrace &&
+ !test_and_set_bit(0, &hardlockup_allcpu_dumped))
+ trigger_allbutself_cpu_backtrace();
+
+ if (hardlockup_panic)
+ panic("Hard LOCKUP");
__this_cpu_write(hard_watchdog_warn, true);
return;
@@ -347,6 +370,9 @@ static void watchdog_interrupt_count(void)
static int watchdog_nmi_enable(unsigned int cpu);
static void watchdog_nmi_disable(unsigned int cpu);
+static int watchdog_enable_all_cpus(void);
+static void watchdog_disable_all_cpus(void);
+
/* watchdog kicker functions */
static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
{
@@ -651,37 +677,41 @@ static struct smp_hotplug_thread watchdog_threads = {
/*
* park all watchdog threads that are specified in 'watchdog_cpumask'
+ *
+ * This function returns an error if kthread_park() of a watchdog thread
+ * fails. In this situation, the watchdog threads of some CPUs can already
+ * be parked and the watchdog threads of other CPUs can still be runnable.
+ * Callers are expected to handle this special condition as appropriate in
+ * their context.
+ *
+ * This function may only be called in a context that is protected against
+ * races with CPU hotplug - for example, via get_online_cpus().
*/
static int watchdog_park_threads(void)
{
int cpu, ret = 0;
- get_online_cpus();
for_each_watchdog_cpu(cpu) {
ret = kthread_park(per_cpu(softlockup_watchdog, cpu));
if (ret)
break;
}
- if (ret) {
- for_each_watchdog_cpu(cpu)
- kthread_unpark(per_cpu(softlockup_watchdog, cpu));
- }
- put_online_cpus();
return ret;
}
/*
* unpark all watchdog threads that are specified in 'watchdog_cpumask'
+ *
+ * This function may only be called in a context that is protected against
+ * races with CPU hotplug - for example, via get_online_cpus().
*/
static void watchdog_unpark_threads(void)
{
int cpu;
- get_online_cpus();
for_each_watchdog_cpu(cpu)
kthread_unpark(per_cpu(softlockup_watchdog, cpu));
- put_online_cpus();
}
/*
@@ -691,6 +721,7 @@ int lockup_detector_suspend(void)
{
int ret = 0;
+ get_online_cpus();
mutex_lock(&watchdog_proc_mutex);
/*
* Multiple suspend requests can be active in parallel (counted by
@@ -704,6 +735,11 @@ int lockup_detector_suspend(void)
if (ret == 0)
watchdog_suspended++;
+ else {
+ watchdog_disable_all_cpus();
+ pr_err("Failed to suspend lockup detectors, disabled\n");
+ watchdog_enabled = 0;
+ }
mutex_unlock(&watchdog_proc_mutex);
@@ -726,12 +762,20 @@ void lockup_detector_resume(void)
watchdog_unpark_threads();
mutex_unlock(&watchdog_proc_mutex);
+ put_online_cpus();
}
-static void update_watchdog_all_cpus(void)
+static int update_watchdog_all_cpus(void)
{
- watchdog_park_threads();
+ int ret;
+
+ ret = watchdog_park_threads();
+ if (ret)
+ return ret;
+
watchdog_unpark_threads();
+
+ return 0;
}
static int watchdog_enable_all_cpus(void)
@@ -750,15 +794,20 @@ static int watchdog_enable_all_cpus(void)
* Enable/disable the lockup detectors or
* change the sample period 'on the fly'.
*/
- update_watchdog_all_cpus();
+ err = update_watchdog_all_cpus();
+
+ if (err) {
+ watchdog_disable_all_cpus();
+ pr_err("Failed to update lockup detectors, disabled\n");
+ }
}
+ if (err)
+ watchdog_enabled = 0;
+
return err;
}
-/* prepare/enable/disable routines */
-/* sysctl functions */
-#ifdef CONFIG_SYSCTL
static void watchdog_disable_all_cpus(void)
{
if (watchdog_running) {
@@ -767,6 +816,8 @@ static void watchdog_disable_all_cpus(void)
}
}
+#ifdef CONFIG_SYSCTL
+
/*
* Update the run state of the lockup detectors.
*/
@@ -808,6 +859,7 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write,
int err, old, new;
int *watchdog_param = (int *)table->data;
+ get_online_cpus();
mutex_lock(&watchdog_proc_mutex);
if (watchdog_suspended) {
@@ -849,15 +901,17 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write,
} while (cmpxchg(&watchdog_enabled, old, new) != old);
/*
- * Update the run state of the lockup detectors.
- * Restore 'watchdog_enabled' on failure.
+ * Update the run state of the lockup detectors. There is _no_
+ * need to check the value returned by proc_watchdog_update()
+ * and to restore the previous value of 'watchdog_enabled' as
+ * both lockup detectors are disabled if proc_watchdog_update()
+ * returns an error.
*/
err = proc_watchdog_update();
- if (err)
- watchdog_enabled = old;
}
out:
mutex_unlock(&watchdog_proc_mutex);
+ put_online_cpus();
return err;
}
@@ -899,6 +953,7 @@ int proc_watchdog_thresh(struct ctl_table *table, int write,
{
int err, old;
+ get_online_cpus();
mutex_lock(&watchdog_proc_mutex);
if (watchdog_suspended) {
@@ -914,15 +969,17 @@ int proc_watchdog_thresh(struct ctl_table *table, int write,
goto out;
/*
- * Update the sample period.
- * Restore 'watchdog_thresh' on failure.
+ * Update the sample period. Restore on failure.
*/
set_sample_period();
err = proc_watchdog_update();
- if (err)
+ if (err) {
watchdog_thresh = old;
+ set_sample_period();
+ }
out:
mutex_unlock(&watchdog_proc_mutex);
+ put_online_cpus();
return err;
}
@@ -937,6 +994,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
{
int err;
+ get_online_cpus();
mutex_lock(&watchdog_proc_mutex);
if (watchdog_suspended) {
@@ -964,6 +1022,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
}
out:
mutex_unlock(&watchdog_proc_mutex);
+ put_online_cpus();
return err;
}