X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=kernel%2Fwatchdog.c;h=f6b32b8cbffe297b89d0437ad387cfb36517384b;hb=55537871ef666b4153fd1ef8782e4a13fee142cc;hp=64ed1c37bd1fdc6c2874f797e987b8bd4c4c5308;hpb=62886a367b59d7740f9db89fd418ab3e450ab7c7;p=mirror_ubuntu-artful-kernel.git

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 64ed1c37bd1f..f6b32b8cbffe 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);
@@ -112,6 +114,7 @@ static unsigned long soft_lockup_nmi_warn;
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 static int 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
 
@@ -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)
 {
@@ -651,6 +677,12 @@ 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.
  */
 static int watchdog_park_threads(void)
 {
@@ -662,10 +694,6 @@ static int watchdog_park_threads(void)
 		if (ret)
 			break;
 	}
-	if (ret) {
-		for_each_watchdog_cpu(cpu)
-			kthread_unpark(per_cpu(softlockup_watchdog, cpu));
-	}
 	put_online_cpus();
 
 	return ret;
@@ -704,6 +732,11 @@ 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);
 
@@ -728,10 +761,17 @@ void lockup_detector_resume(void)
 	mutex_unlock(&watchdog_proc_mutex);
 }
 
-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 +790,20 @@ 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 +812,8 @@ static void watchdog_disable_all_cpus(void)
 	}
 }
 
+#ifdef CONFIG_SYSCTL
+
 /*
  * Update the run state of the lockup detectors.
  */
@@ -849,12 +896,13 @@ 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);
@@ -914,13 +962,14 @@ 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);
 	return err;