Merge Linus master into drm-next

The merge is clean, but the arm build fails afterwards,
due to API changes in the regulator tree.

I've included the patch into the merge to fix the build.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 243 insertions, 74 deletions

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 3174bf8e3538..2316f50b07a4 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -24,8 +24,33 @@
 #include <linux/kvm_para.h>
 #include <linux/perf_event.h>
 
-int watchdog_user_enabled = 1;
+/*
+ * The run state of the lockup detectors is controlled by the content of the
+ * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit -
+ * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector.
+ *
+ * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled'
+ * are variables that are only used as an 'interface' between the parameters
+ * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The
+ * 'watchdog_thresh' variable is handled differently because its value is not
+ * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh'
+ * is equal zero.
+ */
+#define NMI_WATCHDOG_ENABLED_BIT   0
+#define SOFT_WATCHDOG_ENABLED_BIT  1
+#define NMI_WATCHDOG_ENABLED      (1 << NMI_WATCHDOG_ENABLED_BIT)
+#define SOFT_WATCHDOG_ENABLED     (1 << SOFT_WATCHDOG_ENABLED_BIT)
+
+#ifdef CONFIG_HARDLOCKUP_DETECTOR
+static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
+#else
+static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
+#endif
+int __read_mostly nmi_watchdog_enabled;
+int __read_mostly soft_watchdog_enabled;
+int __read_mostly watchdog_user_enabled;
 int __read_mostly watchdog_thresh = 10;
+
 #ifdef CONFIG_SMP
 int __read_mostly sysctl_softlockup_all_cpu_backtrace;
 #else
@@ -58,8 +83,6 @@ static unsigned long soft_lockup_nmi_warn;
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 static int hardlockup_panic =
 			CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
-
-static bool hardlockup_detector_enabled = true;
 /*
  * 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
@@ -68,14 +91,9 @@ static bool hardlockup_detector_enabled = true;
  * kernel command line parameters are parsed, because otherwise it is not
  * possible to override this in hardlockup_panic_setup().
  */
-void watchdog_enable_hardlockup_detector(bool val)
-{
-	hardlockup_detector_enabled = val;
-}
-
-bool watchdog_hardlockup_detector_is_enabled(void)
+void hardlockup_detector_disable(void)
 {
-	return hardlockup_detector_enabled;
+	watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
 }
 
 static int __init hardlockup_panic_setup(char *str)
@@ -85,15 +103,9 @@ static int __init hardlockup_panic_setup(char *str)
 	else if (!strncmp(str, "nopanic", 7))
 		hardlockup_panic = 0;
 	else if (!strncmp(str, "0", 1))
-		watchdog_user_enabled = 0;
-	else if (!strncmp(str, "1", 1) || !strncmp(str, "2", 1)) {
-		/*
-		 * Setting 'nmi_watchdog=1' or 'nmi_watchdog=2' (legacy option)
-		 * has the same effect.
-		 */
-		watchdog_user_enabled = 1;
-		watchdog_enable_hardlockup_detector(true);
-	}
+		watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
+	else if (!strncmp(str, "1", 1))
+		watchdog_enabled |= NMI_WATCHDOG_ENABLED;
 	return 1;
 }
 __setup("nmi_watchdog=", hardlockup_panic_setup);
@@ -112,19 +124,18 @@ __setup("softlockup_panic=", softlockup_panic_setup);
 
 static int __init nowatchdog_setup(char *str)
 {
-	watchdog_user_enabled = 0;
+	watchdog_enabled = 0;
 	return 1;
 }
 __setup("nowatchdog", nowatchdog_setup);
 
-/* deprecated */
 static int __init nosoftlockup_setup(char *str)
 {
-	watchdog_user_enabled = 0;
+	watchdog_enabled &= ~SOFT_WATCHDOG_ENABLED;
 	return 1;
 }
 __setup("nosoftlockup", nosoftlockup_setup);
-/*  */
+
 #ifdef CONFIG_SMP
 static int __init softlockup_all_cpu_backtrace_setup(char *str)
 {
@@ -239,10 +250,11 @@ static int is_softlockup(unsigned long touch_ts)
 {
 	unsigned long now = get_timestamp();
 
-	/* Warn about unreasonable delays: */
-	if (time_after(now, touch_ts + get_softlockup_thresh()))
-		return now - touch_ts;
-
+	if (watchdog_enabled & SOFT_WATCHDOG_ENABLED) {
+		/* Warn about unreasonable delays. */
+		if (time_after(now, touch_ts + get_softlockup_thresh()))
+			return now - touch_ts;
+	}
 	return 0;
 }
 
@@ -477,6 +489,21 @@ static void watchdog(unsigned int cpu)
 	__this_cpu_write(soft_lockup_hrtimer_cnt,
 			 __this_cpu_read(hrtimer_interrupts));
 	__touch_watchdog();
+
+	/*
+	 * watchdog_nmi_enable() clears the NMI_WATCHDOG_ENABLED bit in the
+	 * failure path. Check for failures that can occur asynchronously -
+	 * for example, when CPUs are on-lined - and shut down the hardware
+	 * perf event on each CPU accordingly.
+	 *
+	 * The only non-obvious place this bit can be cleared is through
+	 * watchdog_nmi_enable(), so a pr_info() is placed there.  Placing a
+	 * pr_info here would be too noisy as it would result in a message
+	 * every few seconds if the hardlockup was disabled but the softlockup
+	 * enabled.
+	 */
+	if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
+		watchdog_nmi_disable(cpu);
 }
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
@@ -492,14 +519,9 @@ static int watchdog_nmi_enable(unsigned int cpu)
 	struct perf_event_attr *wd_attr;
 	struct perf_event *event = per_cpu(watchdog_ev, cpu);
 
-	/*
-	 * Some kernels need to default hard lockup detection to
-	 * 'disabled', for example a guest on a hypervisor.
-	 */
-	if (!watchdog_hardlockup_detector_is_enabled()) {
-		event = ERR_PTR(-ENOENT);
-		goto handle_err;
-	}
+	/* nothing to do if the hard lockup detector is disabled */
+	if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
+		goto out;
 
 	/* is it already setup and enabled? */
 	if (event && event->state > PERF_EVENT_STATE_OFF)
@@ -515,7 +537,6 @@ static int watchdog_nmi_enable(unsigned int cpu)
 	/* Try to register using hardware perf events */
 	event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
 
-handle_err:
 	/* save cpu0 error for future comparision */
 	if (cpu == 0 && IS_ERR(event))
 		cpu0_err = PTR_ERR(event);
@@ -527,6 +548,18 @@ handle_err:
 		goto out_save;
 	}
 
+	/*
+	 * Disable the hard lockup detector if _any_ CPU fails to set up
+	 * set up the hardware perf event. The watchdog() function checks
+	 * the NMI_WATCHDOG_ENABLED bit periodically.
+	 *
+	 * The barriers are for syncing up watchdog_enabled across all the
+	 * cpus, as clear_bit() does not use barriers.
+	 */
+	smp_mb__before_atomic();
+	clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled);
+	smp_mb__after_atomic();
+
 	/* skip displaying the same error again */
 	if (cpu > 0 && (PTR_ERR(event) == cpu0_err))
 		return PTR_ERR(event);
@@ -540,6 +573,9 @@ handle_err:
 	else
 		pr_err("disabled (cpu%i): unable to create perf event: %ld\n",
 			cpu, PTR_ERR(event));
+
+	pr_info("Shutting down hard lockup detector on all cpus\n");
+
 	return PTR_ERR(event);
 
 	/* success path */
@@ -567,9 +603,37 @@ static void watchdog_nmi_disable(unsigned int cpu)
 		cpu0_err = 0;
 	}
 }
+
+void watchdog_nmi_enable_all(void)
+{
+	int cpu;
+
+	if (!watchdog_user_enabled)
+		return;
+
+	get_online_cpus();
+	for_each_online_cpu(cpu)
+		watchdog_nmi_enable(cpu);
+	put_online_cpus();
+}
+
+void watchdog_nmi_disable_all(void)
+{
+	int cpu;
+
+	if (!watchdog_running)
+		return;
+
+	get_online_cpus();
+	for_each_online_cpu(cpu)
+		watchdog_nmi_disable(cpu);
+	put_online_cpus();
+}
 #else
 static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
 static void watchdog_nmi_disable(unsigned int cpu) { return; }
+void watchdog_nmi_enable_all(void) {}
+void watchdog_nmi_disable_all(void) {}
 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
 
 static struct smp_hotplug_thread watchdog_threads = {
@@ -600,7 +664,7 @@ static void restart_watchdog_hrtimer(void *info)
 				HRTIMER_MODE_REL_PINNED);
 }
 
-static void update_timers(int cpu)
+static void update_watchdog(int cpu)
 {
 	/*
 	 * Make sure that perf event counter will adopt to a new
@@ -615,17 +679,17 @@ static void update_timers(int cpu)
 	watchdog_nmi_enable(cpu);
 }
 
-static void update_timers_all_cpus(void)
+static void update_watchdog_all_cpus(void)
 {
 	int cpu;
 
 	get_online_cpus();
 	for_each_online_cpu(cpu)
-		update_timers(cpu);
+		update_watchdog(cpu);
 	put_online_cpus();
 }
 
-static int watchdog_enable_all_cpus(bool sample_period_changed)
+static int watchdog_enable_all_cpus(void)
 {
 	int err = 0;
 
@@ -635,8 +699,12 @@ static int watchdog_enable_all_cpus(bool sample_period_changed)
 			pr_err("Failed to create watchdog threads, disabled\n");
 		else
 			watchdog_running = 1;
-	} else if (sample_period_changed) {
-		update_timers_all_cpus();
+	} else {
+		/*
+		 * Enable/disable the lockup detectors or
+		 * change the sample period 'on the fly'.
+		 */
+		update_watchdog_all_cpus();
 	}
 
 	return err;
@@ -654,58 +722,159 @@ static void watchdog_disable_all_cpus(void)
 }
 
 /*
- * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh
+ * Update the run state of the lockup detectors.
  */
+static int proc_watchdog_update(void)
+{
+	int err = 0;
 
-int proc_dowatchdog(struct ctl_table *table, int write,
-		    void __user *buffer, size_t *lenp, loff_t *ppos)
+	/*
+	 * Watchdog threads won't be started if they are already active.
+	 * The 'watchdog_running' variable in watchdog_*_all_cpus() takes
+	 * care of this. If those threads are already active, the sample
+	 * period will be updated and the lockup detectors will be enabled
+	 * or disabled 'on the fly'.
+	 */
+	if (watchdog_enabled && watchdog_thresh)
+		err = watchdog_enable_all_cpus();
+	else
+		watchdog_disable_all_cpus();
+
+	return err;
+
+}
+
+static DEFINE_MUTEX(watchdog_proc_mutex);
+
+/*
+ * common function for watchdog, nmi_watchdog and soft_watchdog parameter
+ *
+ * caller             | table->data points to | 'which' contains the flag(s)
+ * -------------------|-----------------------|-----------------------------
+ * proc_watchdog      | watchdog_user_enabled | NMI_WATCHDOG_ENABLED or'ed
+ *                    |                       | with SOFT_WATCHDOG_ENABLED
+ * -------------------|-----------------------|-----------------------------
+ * proc_nmi_watchdog  | nmi_watchdog_enabled  | NMI_WATCHDOG_ENABLED
+ * -------------------|-----------------------|-----------------------------
+ * proc_soft_watchdog | soft_watchdog_enabled | SOFT_WATCHDOG_ENABLED
+ */
+static int proc_watchdog_common(int which, struct ctl_table *table, int write,
+				void __user *buffer, size_t *lenp, loff_t *ppos)
 {
-	int err, old_thresh, old_enabled;
-	bool old_hardlockup;
-	static DEFINE_MUTEX(watchdog_proc_mutex);
+	int err, old, new;
+	int *watchdog_param = (int *)table->data;
 
 	mutex_lock(&watchdog_proc_mutex);
-	old_thresh = ACCESS_ONCE(watchdog_thresh);
-	old_enabled = ACCESS_ONCE(watchdog_user_enabled);
-	old_hardlockup = watchdog_hardlockup_detector_is_enabled();
 
-	err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	if (err || !write)
-		goto out;
-
-	set_sample_period();
 	/*
-	 * Watchdog threads shouldn't be enabled if they are
-	 * disabled. The 'watchdog_running' variable check in
-	 * watchdog_*_all_cpus() function takes care of this.
+	 * If the parameter is being read return the state of the corresponding
+	 * bit(s) in 'watchdog_enabled', else update 'watchdog_enabled' and the
+	 * run state of the lockup detectors.
 	 */
-	if (watchdog_user_enabled && watchdog_thresh) {
+	if (!write) {
+		*watchdog_param = (watchdog_enabled & which) != 0;
+		err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	} else {
+		err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+		if (err)
+			goto out;
+
 		/*
-		 * Prevent a change in watchdog_thresh accidentally overriding
-		 * the enablement of the hardlockup detector.
+		 * There is a race window between fetching the current value
+		 * from 'watchdog_enabled' and storing the new value. During
+		 * this race window, watchdog_nmi_enable() can sneak in and
+		 * clear the NMI_WATCHDOG_ENABLED bit in 'watchdog_enabled'.
+		 * The 'cmpxchg' detects this race and the loop retries.
 		 */
-		if (watchdog_user_enabled != old_enabled)
-			watchdog_enable_hardlockup_detector(true);
-		err = watchdog_enable_all_cpus(old_thresh != watchdog_thresh);
-	} else
-		watchdog_disable_all_cpus();
+		do {
+			old = watchdog_enabled;
+			/*
+			 * If the parameter value is not zero set the
+			 * corresponding bit(s), else clear it(them).
+			 */
+			if (*watchdog_param)
+				new = old | which;
+			else
+				new = old & ~which;
+		} while (cmpxchg(&watchdog_enabled, old, new) != old);
 
-	/* Restore old values on failure */
-	if (err) {
-		watchdog_thresh = old_thresh;
-		watchdog_user_enabled = old_enabled;
-		watchdog_enable_hardlockup_detector(old_hardlockup);
+		/*
+		 * Update the run state of the lockup detectors.
+		 * Restore 'watchdog_enabled' on failure.
+		 */
+		err = proc_watchdog_update();
+		if (err)
+			watchdog_enabled = old;
 	}
 out:
 	mutex_unlock(&watchdog_proc_mutex);
 	return err;
 }
+
+/*
+ * /proc/sys/kernel/watchdog
+ */
+int proc_watchdog(struct ctl_table *table, int write,
+		  void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED,
+				    table, write, buffer, lenp, ppos);
+}
+
+/*
+ * /proc/sys/kernel/nmi_watchdog
+ */
+int proc_nmi_watchdog(struct ctl_table *table, int write,
+		      void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	return proc_watchdog_common(NMI_WATCHDOG_ENABLED,
+				    table, write, buffer, lenp, ppos);
+}
+
+/*
+ * /proc/sys/kernel/soft_watchdog
+ */
+int proc_soft_watchdog(struct ctl_table *table, int write,
+			void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	return proc_watchdog_common(SOFT_WATCHDOG_ENABLED,
+				    table, write, buffer, lenp, ppos);
+}
+
+/*
+ * /proc/sys/kernel/watchdog_thresh
+ */
+int proc_watchdog_thresh(struct ctl_table *table, int write,
+			 void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	int err, old;
+
+	mutex_lock(&watchdog_proc_mutex);
+
+	old = ACCESS_ONCE(watchdog_thresh);
+	err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+
+	if (err || !write)
+		goto out;
+
+	/*
+	 * Update the sample period.
+	 * Restore 'watchdog_thresh' on failure.
+	 */
+	set_sample_period();
+	err = proc_watchdog_update();
+	if (err)
+		watchdog_thresh = old;
+out:
+	mutex_unlock(&watchdog_proc_mutex);
+	return err;
+}
 #endif /* CONFIG_SYSCTL */
 
 void __init lockup_detector_init(void)
 {
 	set_sample_period();
 
-	if (watchdog_user_enabled)
-		watchdog_enable_all_cpus(false);
+	if (watchdog_enabled)
+		watchdog_enable_all_cpus();
 }