1 files changed, 99 insertions, 86 deletions

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 7f9c3c52ecc1..3d0c56ad4792 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -27,8 +27,8 @@
 #include <asm/irq_regs.h>
 #include <linux/perf_event.h>
 
-int watchdog_enabled;
-int __read_mostly softlockup_thresh = 60;
+int watchdog_enabled = 1;
+int __read_mostly watchdog_thresh = 10;
 
 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
 static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
@@ -43,21 +43,22 @@ static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
 static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
 #endif
 
-static int __read_mostly did_panic;
-static int __initdata no_watchdog;
-
-
 /* boot commands */
 /*
  * Should we panic when a soft-lockup or hard-lockup occurs:
  */
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
-static int hardlockup_panic;
+static int hardlockup_panic =
+                        CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
 
 static int __init hardlockup_panic_setup(char *str)
 {
         if (!strncmp(str, "panic", 5))
                 hardlockup_panic = 1;
+        else if (!strncmp(str, "nopanic", 7))
+                hardlockup_panic = 0;
+        else if (!strncmp(str, "0", 1))
+                watchdog_enabled = 0;
         return 1;
 }
 __setup("nmi_watchdog=", hardlockup_panic_setup);
@@ -76,7 +77,7 @@ __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);
@@ -84,12 +85,23 @@ __setup("nowatchdog", nowatchdog_setup);
 /* deprecated */
 static int __init nosoftlockup_setup(char *str)
 {
-        no_watchdog = 1;
+        watchdog_enabled = 0;
         return 1;
 }
 __setup("nosoftlockup", nosoftlockup_setup);
 /*  */
 
+/*
+ * Hard-lockup warnings should be triggered after just a few seconds. Soft-
+ * lockups can have false positives under extreme conditions. So we generally
+ * want a higher threshold for soft lockups than for hard lockups. So we couple
+ * the thresholds with a factor: we make the soft threshold twice the amount of
+ * time the hard threshold is.
+ */
+static int get_softlockup_thresh(void)
+{
+        return watchdog_thresh * 2;
+}
 
 /*
  * Returns seconds, approximately.  We don't need nanosecond
@@ -104,12 +116,12 @@ static unsigned long get_timestamp(int this_cpu)
 static unsigned long get_sample_period(void)
 {
         /*
-         * convert softlockup_thresh from seconds to ns
+         * convert watchdog_thresh from seconds to ns
          * the divide by 5 is to give hrtimer 5 chances to
          * increment before the hardlockup detector generates
          * a warning
          */
-        return softlockup_thresh / 5 * NSEC_PER_SEC;
+        return get_softlockup_thresh() * (NSEC_PER_SEC / 5);
 }
 
 /* Commands for resetting the watchdog */
@@ -117,12 +129,12 @@ static void __touch_watchdog(void)
 {
         int this_cpu = smp_processor_id();
 
-        __get_cpu_var(watchdog_touch_ts) = get_timestamp(this_cpu);
+        __this_cpu_write(watchdog_touch_ts, get_timestamp(this_cpu));
 }
 
 void touch_softlockup_watchdog(void)
 {
-        __raw_get_cpu_var(watchdog_touch_ts) = 0;
+        __this_cpu_write(watchdog_touch_ts, 0);
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
@@ -166,12 +178,12 @@ void touch_softlockup_watchdog_sync(void)
 /* watchdog detector functions */
 static int is_hardlockup(void)
 {
-        unsigned long hrint = __get_cpu_var(hrtimer_interrupts);
+        unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
 
-        if (__get_cpu_var(hrtimer_interrupts_saved) == hrint)
+        if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
                 return 1;
 
-        __get_cpu_var(hrtimer_interrupts_saved) = hrint;
+        __this_cpu_write(hrtimer_interrupts_saved, hrint);
         return 0;
 }
 #endif
@@ -181,24 +193,12 @@ static int is_softlockup(unsigned long touch_ts)
         unsigned long now = get_timestamp(smp_processor_id());
 
         /* Warn about unreasonable delays: */
-        if (time_after(now, touch_ts + softlockup_thresh))
+        if (time_after(now, touch_ts + get_softlockup_thresh()))
                 return now - touch_ts;
 
         return 0;
 }
 
-static int
-watchdog_panic(struct notifier_block *this, unsigned long event, void *ptr)
-{
-        did_panic = 1;
-
-        return NOTIFY_DONE;
-}
-
-static struct notifier_block panic_block = {
-        .notifier_call = watchdog_panic,
-};
-
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 static struct perf_event_attr wd_hw_attr = {
         .type           = PERF_TYPE_HARDWARE,
@@ -209,15 +209,15 @@ static struct perf_event_attr wd_hw_attr = {
 };
 
 /* Callback function for perf event subsystem */
-void watchdog_overflow_callback(struct perf_event *event, int nmi,
+static void watchdog_overflow_callback(struct perf_event *event, int nmi,
                  struct perf_sample_data *data,
                  struct pt_regs *regs)
 {
         /* Ensure the watchdog never gets throttled */
         event->hw.interrupts = 0;
 
-        if (__get_cpu_var(watchdog_nmi_touch) == true) {
-                __get_cpu_var(watchdog_nmi_touch) = false;
+        if (__this_cpu_read(watchdog_nmi_touch) == true) {
+                __this_cpu_write(watchdog_nmi_touch, false);
                 return;
         }
 
@@ -231,7 +231,7 @@ void watchdog_overflow_callback(struct perf_event *event, int nmi,
                 int this_cpu = smp_processor_id();
 
                 /* only print hardlockups once */
-                if (__get_cpu_var(hard_watchdog_warn) == true)
+                if (__this_cpu_read(hard_watchdog_warn) == true)
                         return;
 
                 if (hardlockup_panic)
@@ -239,16 +239,16 @@ void watchdog_overflow_callback(struct perf_event *event, int nmi,
                 else
                         WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
 
-                __get_cpu_var(hard_watchdog_warn) = true;
+                __this_cpu_write(hard_watchdog_warn, true);
                 return;
         }
 
-        __get_cpu_var(hard_watchdog_warn) = false;
+        __this_cpu_write(hard_watchdog_warn, false);
         return;
 }
 static void watchdog_interrupt_count(void)
 {
-        __get_cpu_var(hrtimer_interrupts)++;
+        __this_cpu_inc(hrtimer_interrupts);
 }
 #else
 static inline void watchdog_interrupt_count(void) { return; }
@@ -257,7 +257,7 @@ static inline void watchdog_interrupt_count(void) { return; }
 /* watchdog kicker functions */
 static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 {
-        unsigned long touch_ts = __get_cpu_var(watchdog_touch_ts);
+        unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts);
         struct pt_regs *regs = get_irq_regs();
         int duration;
 
@@ -265,18 +265,18 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
         watchdog_interrupt_count();
 
         /* kick the softlockup detector */
-        wake_up_process(__get_cpu_var(softlockup_watchdog));
+        wake_up_process(__this_cpu_read(softlockup_watchdog));
 
         /* .. and repeat */
         hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
 
         if (touch_ts == 0) {
-                if (unlikely(__get_cpu_var(softlockup_touch_sync))) {
+                if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
                         /*
                          * If the time stamp was touched atomically
                          * make sure the scheduler tick is up to date.
                          */
-                        __get_cpu_var(softlockup_touch_sync) = false;
+                        __this_cpu_write(softlockup_touch_sync, false);
                         sched_clock_tick();
                 }
                 __touch_watchdog();
@@ -292,7 +292,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
         duration = is_softlockup(touch_ts);
         if (unlikely(duration)) {
                 /* only warn once */
-                if (__get_cpu_var(soft_watchdog_warn) == true)
+                if (__this_cpu_read(soft_watchdog_warn) == true)
                         return HRTIMER_RESTART;
 
                 printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
@@ -307,9 +307,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 
                 if (softlockup_panic)
                         panic("softlockup: hung tasks");
-                __get_cpu_var(soft_watchdog_warn) = true;
+                __this_cpu_write(soft_watchdog_warn, true);
         } else
-                __get_cpu_var(soft_watchdog_warn) = false;
+                __this_cpu_write(soft_watchdog_warn, false);
 
         return HRTIMER_RESTART;
 }
@@ -320,7 +320,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
  */
 static int watchdog(void *unused)
 {
-        struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
+        static struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
         struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
 
         sched_setscheduler(current, SCHED_FIFO, &param);
@@ -370,15 +370,22 @@ static int watchdog_nmi_enable(int cpu)
 
         /* Try to register using hardware perf events */
         wd_attr = &wd_hw_attr;
-        wd_attr->sample_period = hw_nmi_get_sample_period();
-        event = perf_event_create_kernel_counter(wd_attr, cpu, -1, watchdog_overflow_callback);
+        wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
+        event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);
         if (!IS_ERR(event)) {
                 printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
                 goto out_save;
         }
 
-        printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, event);
-        return -1;
+
+        /* vary the KERN level based on the returned errno */
+        if (PTR_ERR(event) == -EOPNOTSUPP)
+                printk(KERN_INFO "NMI watchdog disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
+        else if (PTR_ERR(event) == -ENOENT)
+                printk(KERN_WARNING "NMI watchdog disabled (cpu%i): hardware events not enabled\n", cpu);
+        else
+                printk(KERN_ERR "NMI watchdog disabled (cpu%i): unable to create perf event: %ld\n", cpu, PTR_ERR(event));
+        return PTR_ERR(event);
 
         /* success path */
 out_save:
@@ -408,31 +415,37 @@ static void watchdog_nmi_disable(int cpu) { return; }
 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
 
 /* prepare/enable/disable routines */
-static int watchdog_prepare_cpu(int cpu)
+static void watchdog_prepare_cpu(int cpu)
 {
         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
 
         WARN_ON(per_cpu(softlockup_watchdog, cpu));
         hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
         hrtimer->function = watchdog_timer_fn;
-
-        return 0;
 }
 
 static int watchdog_enable(int cpu)
 {
         struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
+        int err = 0;
 
         /* enable the perf event */
-        if (watchdog_nmi_enable(cpu) != 0)
-                return -1;
+        err = watchdog_nmi_enable(cpu);
+
+        /* Regardless of err above, fall through and start softlockup */
 
         /* create the watchdog thread */
         if (!p) {
                 p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
                 if (IS_ERR(p)) {
                         printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
-                        return -1;
+                        if (!err) {
+                                /* if hardlockup hasn't already set this */
+                                err = PTR_ERR(p);
+                                /* and disable the perf event */
+                                watchdog_nmi_disable(cpu);
+                        }
+                        goto out;
                 }
                 kthread_bind(p, cpu);
                 per_cpu(watchdog_touch_ts, cpu) = 0;
@@ -440,10 +453,8 @@ 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;
+out:
+        return err;
 }
 
 static void watchdog_disable(int cpu)
@@ -470,12 +481,16 @@ 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");
 
 }
@@ -495,26 +510,25 @@ static void watchdog_disable_all_cpus(void)
 /* sysctl functions */
 #ifdef CONFIG_SYSCTL
 /*
- * proc handler for /proc/sys/kernel/nmi_watchdog
+ * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh
  */
 
-int proc_dowatchdog_enabled(struct ctl_table *table, int write,
-                     void __user *buffer, size_t *length, loff_t *ppos)
+int proc_dowatchdog(struct ctl_table *table, int write,
+                    void __user *buffer, size_t *lenp, loff_t *ppos)
 {
-        proc_dointvec(table, write, buffer, length, ppos);
+        int ret;
+
+        ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+        if (ret || !write)
+                goto out;
 
-        if (watchdog_enabled)
+        if (watchdog_enabled && watchdog_thresh)
                 watchdog_enable_all_cpus();
         else
                 watchdog_disable_all_cpus();
-        return 0;
-}
 
-int proc_dowatchdog_thresh(struct ctl_table *table, int write,
-                             void __user *buffer,
-                             size_t *lenp, loff_t *ppos)
-{
-        return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+out:
+        return ret;
 }
 #endif /* CONFIG_SYSCTL */
 
@@ -530,13 +544,12 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
         switch (action) {
         case CPU_UP_PREPARE:
         case CPU_UP_PREPARE_FROZEN:
-                if (watchdog_prepare_cpu(hotcpu))
-                        return NOTIFY_BAD;
+                watchdog_prepare_cpu(hotcpu);
                 break;
         case CPU_ONLINE:
         case CPU_ONLINE_FROZEN:
-                if (watchdog_enable(hotcpu))
-                        return NOTIFY_BAD;
+                if (watchdog_enabled)
+                        watchdog_enable(hotcpu);
                 break;
 #ifdef CONFIG_HOTPLUG_CPU
         case CPU_UP_CANCELED:
@@ -549,6 +562,12 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
                 break;
 #endif /* CONFIG_HOTPLUG_CPU */
         }
+
+        /*
+         * hardlockup and softlockup are not important enough
+         * to block cpu bring up.  Just always succeed and
+         * rely on printk output to flag problems.
+         */
         return NOTIFY_OK;
 }
 
@@ -556,22 +575,16 @@ static struct notifier_block __cpuinitdata cpu_nfb = {
         .notifier_call = cpu_callback
 };
 
-static int __init spawn_watchdog_task(void)
+void __init lockup_detector_init(void)
 {
         void *cpu = (void *)(long)smp_processor_id();
         int err;
 
-        if (no_watchdog)
-                return 0;
-
         err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
-        WARN_ON(err == NOTIFY_BAD);
+        WARN_ON(notifier_to_errno(err));
 
         cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
         register_cpu_notifier(&cpu_nfb);
 
-        atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
-
-        return 0;
+        return;
 }
-early_initcall(spawn_watchdog_task);