1 files changed, 42 insertions, 27 deletions

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 81324d12eb35..4b493f67dcb5 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -22,9 +22,10 @@
 
 static DEFINE_SPINLOCK(print_lock);
 
-static DEFINE_PER_CPU(unsigned long, touch_timestamp);
-static DEFINE_PER_CPU(unsigned long, print_timestamp);
-static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
+static DEFINE_PER_CPU(unsigned long, softlockup_touch_ts); /* touch timestamp */
+static DEFINE_PER_CPU(unsigned long, softlockup_print_ts); /* print timestamp */
+static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
+static DEFINE_PER_CPU(bool, softlock_touch_sync);
 
 static int __read_mostly did_panic;
 int __read_mostly softlockup_thresh = 60;
@@ -70,22 +71,28 @@ static void __touch_softlockup_watchdog(void)
 {
         int this_cpu = raw_smp_processor_id();
 
-        __raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
+        __raw_get_cpu_var(softlockup_touch_ts) = get_timestamp(this_cpu);
 }
 
 void touch_softlockup_watchdog(void)
 {
-        __raw_get_cpu_var(touch_timestamp) = 0;
+        __raw_get_cpu_var(softlockup_touch_ts) = 0;
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
+void touch_softlockup_watchdog_sync(void)
+{
+        __raw_get_cpu_var(softlock_touch_sync) = true;
+        __raw_get_cpu_var(softlockup_touch_ts) = 0;
+}
+
 void touch_all_softlockup_watchdogs(void)
 {
         int cpu;
 
         /* Cause each CPU to re-update its timestamp rather than complain */
         for_each_online_cpu(cpu)
-                per_cpu(touch_timestamp, cpu) = 0;
+                per_cpu(softlockup_touch_ts, cpu) = 0;
 }
 EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
 
@@ -104,28 +111,36 @@ int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
 void softlockup_tick(void)
 {
         int this_cpu = smp_processor_id();
-        unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
-        unsigned long print_timestamp;
+        unsigned long touch_ts = per_cpu(softlockup_touch_ts, this_cpu);
+        unsigned long print_ts;
         struct pt_regs *regs = get_irq_regs();
         unsigned long now;
 
         /* Is detection switched off? */
-        if (!per_cpu(watchdog_task, this_cpu) || softlockup_thresh <= 0) {
+        if (!per_cpu(softlockup_watchdog, this_cpu) || softlockup_thresh <= 0) {
                 /* Be sure we don't false trigger if switched back on */
-                if (touch_timestamp)
-                        per_cpu(touch_timestamp, this_cpu) = 0;
+                if (touch_ts)
+                        per_cpu(softlockup_touch_ts, this_cpu) = 0;
                 return;
         }
 
-        if (touch_timestamp == 0) {
+        if (touch_ts == 0) {
+                if (unlikely(per_cpu(softlock_touch_sync, this_cpu))) {
+                        /*
+                         * If the time stamp was touched atomically
+                         * make sure the scheduler tick is up to date.
+                         */
+                        per_cpu(softlock_touch_sync, this_cpu) = false;
+                        sched_clock_tick();
+                }
                 __touch_softlockup_watchdog();
                 return;
         }
 
-        print_timestamp = per_cpu(print_timestamp, this_cpu);
+        print_ts = per_cpu(softlockup_print_ts, this_cpu);
 
         /* report at most once a second */
-        if (print_timestamp == touch_timestamp || did_panic)
+        if (print_ts == touch_ts || did_panic)
                 return;
 
         /* do not print during early bootup: */
@@ -140,18 +155,18 @@ void softlockup_tick(void)
          * Wake up the high-prio watchdog task twice per
          * threshold timespan.
          */
-        if (now > touch_timestamp + softlockup_thresh/2)
-                wake_up_process(per_cpu(watchdog_task, this_cpu));
+        if (time_after(now - softlockup_thresh/2, touch_ts))
+                wake_up_process(per_cpu(softlockup_watchdog, this_cpu));
 
         /* Warn about unreasonable delays: */
-        if (now <= (touch_timestamp + softlockup_thresh))
+        if (time_before_eq(now - softlockup_thresh, touch_ts))
                 return;
 
-        per_cpu(print_timestamp, this_cpu) = touch_timestamp;
+        per_cpu(softlockup_print_ts, this_cpu) = touch_ts;
 
         spin_lock(&print_lock);
         printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
-                        this_cpu, now - touch_timestamp,
+                        this_cpu, now - touch_ts,
                         current->comm, task_pid_nr(current));
         print_modules();
         print_irqtrace_events(current);
@@ -209,32 +224,32 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
         switch (action) {
         case CPU_UP_PREPARE:
         case CPU_UP_PREPARE_FROZEN:
-                BUG_ON(per_cpu(watchdog_task, hotcpu));
+                BUG_ON(per_cpu(softlockup_watchdog, hotcpu));
                 p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
                 if (IS_ERR(p)) {
                         printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
                         return NOTIFY_BAD;
                 }
-                per_cpu(touch_timestamp, hotcpu) = 0;
-                per_cpu(watchdog_task, hotcpu) = p;
+                per_cpu(softlockup_touch_ts, hotcpu) = 0;
+                per_cpu(softlockup_watchdog, hotcpu) = p;
                 kthread_bind(p, hotcpu);
                 break;
         case CPU_ONLINE:
         case CPU_ONLINE_FROZEN:
-                wake_up_process(per_cpu(watchdog_task, hotcpu));
+                wake_up_process(per_cpu(softlockup_watchdog, hotcpu));
                 break;
 #ifdef CONFIG_HOTPLUG_CPU
         case CPU_UP_CANCELED:
         case CPU_UP_CANCELED_FROZEN:
-                if (!per_cpu(watchdog_task, hotcpu))
+                if (!per_cpu(softlockup_watchdog, hotcpu))
                         break;
                 /* Unbind so it can run.  Fall thru. */
-                kthread_bind(per_cpu(watchdog_task, hotcpu),
+                kthread_bind(per_cpu(softlockup_watchdog, hotcpu),
                              cpumask_any(cpu_online_mask));
         case CPU_DEAD:
         case CPU_DEAD_FROZEN:
-                p = per_cpu(watchdog_task, hotcpu);
-                per_cpu(watchdog_task, hotcpu) = NULL;
+                p = per_cpu(softlockup_watchdog, hotcpu);
+                per_cpu(softlockup_watchdog, hotcpu) = NULL;
                 kthread_stop(p);
                 break;
 #endif /* CONFIG_HOTPLUG_CPU */