Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 - watchdog fixes for full dynticks
 - improved debug output for full dynticks
 - remove an obsolete full dynticks check
 - two ARM SoC clocksource drivers for sharing across SoCs
 - tick broadcast fix for CPU hotplug

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick: broadcast: Check broadcast mode on CPU hotplug
  clocksource: arm_global_timer: Add ARM global timer support
  clocksource: Add Marvell Orion SoC timer
  nohz: Remove obsolete check for full dynticks CPUs to be RCU nocbs
  watchdog: Boot-disable by default on full dynticks
  watchdog: Rename confusing state variable
  watchdog: Register / unregister watchdog kthreads on sysctl control
  nohz: Warn if the machine can not perform nohz_full

4 files changed, 75 insertions, 62 deletions

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index e5b31aff67a..ac09d98490a 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -807,7 +807,7 @@ static struct ctl_table kern_table[] = {
 #if defined(CONFIG_LOCKUP_DETECTOR)
 	{
 		.procname       = "watchdog",
-		.data           = &watchdog_enabled,
+		.data           = &watchdog_user_enabled,
 		.maxlen         = sizeof (int),
 		.mode           = 0644,
 		.proc_handler   = proc_dowatchdog,
@@ -834,7 +834,7 @@ static struct ctl_table kern_table[] = {
 	},
 	{
 		.procname       = "nmi_watchdog",
-		.data           = &watchdog_enabled,
+		.data           = &watchdog_user_enabled,
 		.maxlen         = sizeof (int),
 		.mode           = 0644,
 		.proc_handler   = proc_dowatchdog,
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 6d3f91631de..218bcb565fe 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -157,7 +157,10 @@ int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
 		dev->event_handler = tick_handle_periodic;
 		tick_device_setup_broadcast_func(dev);
 		cpumask_set_cpu(cpu, tick_broadcast_mask);
-		tick_broadcast_start_periodic(bc);
+		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+			tick_broadcast_start_periodic(bc);
+		else
+			tick_broadcast_setup_oneshot(bc);
 		ret = 1;
 	} else {
 		/*
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 0cf1c145318..69601726a74 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -178,6 +178,11 @@ static bool can_stop_full_tick(void)
 	 */
 	if (!sched_clock_stable) {
 		trace_tick_stop(0, "unstable sched clock\n");
+		/*
+		 * Don't allow the user to think they can get
+		 * full NO_HZ with this machine.
+		 */
+		WARN_ONCE(1, "NO_HZ FULL will not work with unstable sched clock");
 		return false;
 	}
 #endif
@@ -346,16 +351,6 @@ void __init tick_nohz_init(void)
 	}
 
 	cpu_notifier(tick_nohz_cpu_down_callback, 0);
-
-	/* Make sure full dynticks CPU are also RCU nocbs */
-	for_each_cpu(cpu, nohz_full_mask) {
-		if (!rcu_is_nocb_cpu(cpu)) {
-			pr_warning("NO_HZ: CPU %d is not RCU nocb: "
-				   "cleared from nohz_full range", cpu);
-			cpumask_clear_cpu(cpu, nohz_full_mask);
-		}
-	}
-
 	cpulist_scnprintf(nohz_full_buf, sizeof(nohz_full_buf), nohz_full_mask);
 	pr_info("NO_HZ: Full dynticks CPUs: %s.\n", nohz_full_buf);
 }
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 05039e348f0..1241d8c91d5 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -29,9 +29,9 @@
 #include <linux/kvm_para.h>
 #include <linux/perf_event.h>
 
-int watchdog_enabled = 1;
+int watchdog_user_enabled = 1;
 int __read_mostly watchdog_thresh = 10;
-static int __read_mostly watchdog_disabled;
+static int __read_mostly watchdog_running;
 static u64 __read_mostly sample_period;
 
 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
@@ -63,7 +63,7 @@ static int __init hardlockup_panic_setup(char *str)
 	else if (!strncmp(str, "nopanic", 7))
 		hardlockup_panic = 0;
 	else if (!strncmp(str, "0", 1))
-		watchdog_enabled = 0;
+		watchdog_user_enabled = 0;
 	return 1;
 }
 __setup("nmi_watchdog=", hardlockup_panic_setup);
@@ -82,7 +82,7 @@ __setup("softlockup_panic=", softlockup_panic_setup);
 
 static int __init nowatchdog_setup(char *str)
 {
-	watchdog_enabled = 0;
+	watchdog_user_enabled = 0;
 	return 1;
 }
 __setup("nowatchdog", nowatchdog_setup);
@@ -90,7 +90,7 @@ __setup("nowatchdog", nowatchdog_setup);
 /* deprecated */
 static int __init nosoftlockup_setup(char *str)
 {
-	watchdog_enabled = 0;
+	watchdog_user_enabled = 0;
 	return 1;
 }
 __setup("nosoftlockup", nosoftlockup_setup);
@@ -158,7 +158,7 @@ void touch_all_softlockup_watchdogs(void)
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 void touch_nmi_watchdog(void)
 {
-	if (watchdog_enabled) {
+	if (watchdog_user_enabled) {
 		unsigned cpu;
 
 		for_each_present_cpu(cpu) {
@@ -347,11 +347,6 @@ static void watchdog_enable(unsigned int cpu)
 	hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	hrtimer->function = watchdog_timer_fn;
 
-	if (!watchdog_enabled) {
-		kthread_park(current);
-		return;
-	}
-
 	/* Enable the perf event */
 	watchdog_nmi_enable(cpu);
 
@@ -374,6 +369,11 @@ static void watchdog_disable(unsigned int cpu)
 	watchdog_nmi_disable(cpu);
 }
 
+static void watchdog_cleanup(unsigned int cpu, bool online)
+{
+	watchdog_disable(cpu);
+}
+
 static int watchdog_should_run(unsigned int cpu)
 {
 	return __this_cpu_read(hrtimer_interrupts) !=
@@ -475,28 +475,40 @@ static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
 static void watchdog_nmi_disable(unsigned int cpu) { return; }
 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
 
-/* prepare/enable/disable routines */
-/* sysctl functions */
-#ifdef CONFIG_SYSCTL
-static void watchdog_enable_all_cpus(void)
+static struct smp_hotplug_thread watchdog_threads = {
+	.store			= &softlockup_watchdog,
+	.thread_should_run	= watchdog_should_run,
+	.thread_fn		= watchdog,
+	.thread_comm		= "watchdog/%u",
+	.setup			= watchdog_enable,
+	.cleanup		= watchdog_cleanup,
+	.park			= watchdog_disable,
+	.unpark			= watchdog_enable,
+};
+
+static int watchdog_enable_all_cpus(void)
 {
-	unsigned int cpu;
+	int err = 0;
 
-	if (watchdog_disabled) {
-		watchdog_disabled = 0;
-		for_each_online_cpu(cpu)
-			kthread_unpark(per_cpu(softlockup_watchdog, cpu));
+	if (!watchdog_running) {
+		err = smpboot_register_percpu_thread(&watchdog_threads);
+		if (err)
+			pr_err("Failed to create watchdog threads, disabled\n");
+		else
+			watchdog_running = 1;
 	}
+
+	return err;
 }
 
+/* prepare/enable/disable routines */
+/* sysctl functions */
+#ifdef CONFIG_SYSCTL
 static void watchdog_disable_all_cpus(void)
 {
-	unsigned int cpu;
-
-	if (!watchdog_disabled) {
-		watchdog_disabled = 1;
-		for_each_online_cpu(cpu)
-			kthread_park(per_cpu(softlockup_watchdog, cpu));
+	if (watchdog_running) {
+		watchdog_running = 0;
+		smpboot_unregister_percpu_thread(&watchdog_threads);
 	}
 }
 
@@ -507,45 +519,48 @@ static void watchdog_disable_all_cpus(void)
 int proc_dowatchdog(struct ctl_table *table, int write,
 		    void __user *buffer, size_t *lenp, loff_t *ppos)
 {
-	int ret;
+	int err, old_thresh, old_enabled;
 
-	if (watchdog_disabled < 0)
-		return -ENODEV;
+	old_thresh = ACCESS_ONCE(watchdog_thresh);
+	old_enabled = ACCESS_ONCE(watchdog_user_enabled);
 
-	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	if (ret || !write)
-		return ret;
+	err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	if (err || !write)
+		return err;
 
 	set_sample_period();
 	/*
 	 * Watchdog threads shouldn't be enabled if they are
-	 * disabled. The 'watchdog_disabled' variable check in
+	 * disabled. The 'watchdog_running' variable check in
 	 * watchdog_*_all_cpus() function takes care of this.
 	 */
-	if (watchdog_enabled && watchdog_thresh)
-		watchdog_enable_all_cpus();
+	if (watchdog_user_enabled && watchdog_thresh)
+		err = watchdog_enable_all_cpus();
 	else
 		watchdog_disable_all_cpus();
 
-	return ret;
+	/* Restore old values on failure */
+	if (err) {
+		watchdog_thresh = old_thresh;
+		watchdog_user_enabled = old_enabled;
+	}
+
+	return err;
 }
 #endif /* CONFIG_SYSCTL */
 
-static struct smp_hotplug_thread watchdog_threads = {
-	.store			= &softlockup_watchdog,
-	.thread_should_run	= watchdog_should_run,
-	.thread_fn		= watchdog,
-	.thread_comm		= "watchdog/%u",
-	.setup			= watchdog_enable,
-	.park			= watchdog_disable,
-	.unpark			= watchdog_enable,
-};
-
 void __init lockup_detector_init(void)
 {
 	set_sample_period();
-	if (smpboot_register_percpu_thread(&watchdog_threads)) {
-		pr_err("Failed to create watchdog threads, disabled\n");
-		watchdog_disabled = -ENODEV;
+
+#ifdef CONFIG_NO_HZ_FULL
+	if (watchdog_user_enabled) {
+		watchdog_user_enabled = 0;
+		pr_warning("Disabled lockup detectors by default for full dynticks\n");
+		pr_warning("You can reactivate it with 'sysctl -w kernel.watchdog=1'\n");
 	}
+#endif
+
+	if (watchdog_user_enabled)
+		watchdog_enable_all_cpus();
 }