fedora core 6 1.2949 + vserver 2.2.0

[linux-2.6.git] / kernel / softlockup.c

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index c67189a..50afeb8 100644 (file)
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -1,12 +1,11 @@
 /*
  * Detect Soft Lockups
  *
- * started by Ingo Molnar, (C) 2005, Red Hat
+ * started by Ingo Molnar, Copyright (C) 2005, 2006 Red Hat, Inc.
  *
  * this code detects soft lockups: incidents in where on a CPU
  * the kernel does not reschedule for 10 seconds or more.
  */
-
 #include <linux/mm.h>
 #include <linux/cpu.h>
 #include <linux/init.h>
@@ -17,13 +16,14 @@
 
 static DEFINE_SPINLOCK(print_lock);
 
-static DEFINE_PER_CPU(unsigned long, timestamp) = 0;
-static DEFINE_PER_CPU(unsigned long, print_timestamp) = 0;
+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 int did_panic = 0;
-static int softlock_panic(struct notifier_block *this, unsigned long event,
-                               void *ptr)
+
+static int
+softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
 {
        did_panic = 1;
 
@@ -36,7 +36,7 @@ static struct notifier_block panic_block = {
 
 void touch_softlockup_watchdog(void)
 {
-       per_cpu(timestamp, raw_smp_processor_id()) = jiffies;
+       __raw_get_cpu_var(touch_timestamp) = jiffies;
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
@@ -44,25 +44,35 @@ EXPORT_SYMBOL(touch_softlockup_watchdog);
  * This callback runs from the timer interrupt, and checks
  * whether the watchdog thread has hung or not:
  */
-void softlockup_tick(struct pt_regs *regs)
+void softlockup_tick(void)
 {
        int this_cpu = smp_processor_id();
-       unsigned long timestamp = per_cpu(timestamp, this_cpu);
+       unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
 
-       if (per_cpu(print_timestamp, this_cpu) == timestamp)
+       /* prevent double reports: */
+       if (per_cpu(print_timestamp, this_cpu) == touch_timestamp ||
+               did_panic ||
+                       !per_cpu(watchdog_task, this_cpu))
                return;
 
-       /* Do not cause a second panic when there already was one */
-       if (did_panic)
+       /* do not print during early bootup: */
+       if (unlikely(system_state != SYSTEM_RUNNING)) {
+               touch_softlockup_watchdog();
                return;
+       }
 
-       if (time_after(jiffies, timestamp + 10*HZ)) {
-               per_cpu(print_timestamp, this_cpu) = timestamp;
+       /* Wake up the high-prio watchdog task every second: */
+       if (time_after(jiffies, touch_timestamp + HZ))
+               wake_up_process(per_cpu(watchdog_task, this_cpu));
+
+       /* Warn about unreasonable 10+ seconds delays: */
+       if (time_after(jiffies, touch_timestamp + 10*HZ)) {
+               per_cpu(print_timestamp, this_cpu) = touch_timestamp;
 
                spin_lock(&print_lock);
                printk(KERN_ERR "BUG: soft lockup detected on CPU#%d!\n",
                        this_cpu);
-               show_regs(regs);
+               dump_stack();
                spin_unlock(&print_lock);
        }
 }
@@ -77,18 +87,16 @@ static int watchdog(void * __bind_cpu)
        sched_setscheduler(current, SCHED_FIFO, &param);
        current->flags |= PF_NOFREEZE;
 
-       set_current_state(TASK_INTERRUPTIBLE);
-
        /*
-        * Run briefly once per second - if this gets delayed for
-        * more than 10 seconds then the debug-printout triggers
-        * in softlockup_tick():
+        * Run briefly once per second to reset the softlockup timestamp.
+        * If this gets delayed for more than 10 seconds then the
+        * debug-printout triggers in softlockup_tick().
         */
        while (!kthread_should_stop()) {
-               msleep_interruptible(1000);
+               set_current_state(TASK_INTERRUPTIBLE);
                touch_softlockup_watchdog();
+               schedule();
        }
-       __set_current_state(TASK_RUNNING);
 
        return 0;
 }
@@ -96,7 +104,7 @@ static int watchdog(void * __bind_cpu)
 /*
  * Create/destroy watchdog threads as CPUs come and go:
  */
-static int __devinit
+static int __cpuinit
 cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
        int hotcpu = (unsigned long)hcpu;
@@ -110,15 +118,17 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
                        printk("watchdog for %i failed\n", hotcpu);
                        return NOTIFY_BAD;
                }
+               per_cpu(touch_timestamp, hotcpu) = jiffies;
                per_cpu(watchdog_task, hotcpu) = p;
                kthread_bind(p, hotcpu);
                break;
        case CPU_ONLINE:
-
                wake_up_process(per_cpu(watchdog_task, hotcpu));
                break;
 #ifdef CONFIG_HOTPLUG_CPU
        case CPU_UP_CANCELED:
+               if (!per_cpu(watchdog_task, hotcpu))
+                       break;
                /* Unbind so it can run.  Fall thru. */
                kthread_bind(per_cpu(watchdog_task, hotcpu),
                             any_online_cpu(cpu_online_map));
@@ -132,18 +142,18 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
        return NOTIFY_OK;
 }
 
-static struct notifier_block __devinitdata cpu_nfb = {
+static struct notifier_block __cpuinitdata cpu_nfb = {
        .notifier_call = cpu_callback
 };
 
 __init void spawn_softlockup_task(void)
 {
        void *cpu = (void *)(long)smp_processor_id();
+       int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
 
-       cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
+       BUG_ON(err == NOTIFY_BAD);
        cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
        register_cpu_notifier(&cpu_nfb);
 
-       notifier_chain_register(&panic_notifier_list, &panic_block);
+       atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
 }
-