doc: move vm/00-INDEX to Documentation/vm

[linux-2.6-omap-h63xx.git] / kernel / softlockup.c

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 50afeb813305d76435e8c6852a80b5b9dc5c8cd9..edeeef3a6a322917b5b2befb95238df5557a9af5 100644 (file)
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -10,17 +10,21 @@
 #include <linux/cpu.h>
 #include <linux/init.h>
 #include <linux/delay.h>
+#include <linux/freezer.h>
 #include <linux/kthread.h>
 #include <linux/notifier.h>
 #include <linux/module.h>
 
+#include <asm/irq_regs.h>
+
 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 int did_panic = 0;
+static int did_panic;
+int softlockup_thresh = 10;
 
 static int
 softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
@@ -34,12 +38,34 @@ static struct notifier_block panic_block = {
        .notifier_call = softlock_panic,
 };
 
+/*
+ * Returns seconds, approximately.  We don't need nanosecond
+ * resolution, and we don't need to waste time with a big divide when
+ * 2^30ns == 1.074s.
+ */
+static unsigned long get_timestamp(int this_cpu)
+{
+       return cpu_clock(this_cpu) >> 30;  /* 2^30 ~= 10^9 */
+}
+
 void touch_softlockup_watchdog(void)
 {
-       __raw_get_cpu_var(touch_timestamp) = jiffies;
+       int this_cpu = raw_smp_processor_id();
+
+       __raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
+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;
+}
+EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
+
 /*
  * This callback runs from the timer interrupt, and checks
  * whether the watchdog thread has hung or not:
@@ -48,12 +74,23 @@ void softlockup_tick(void)
 {
        int this_cpu = smp_processor_id();
        unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
+       unsigned long print_timestamp;
+       struct pt_regs *regs = get_irq_regs();
+       unsigned long now;
+
+       if (touch_timestamp == 0) {
+               touch_softlockup_watchdog();
+               return;
+       }
 
-       /* prevent double reports: */
-       if (per_cpu(print_timestamp, this_cpu) == touch_timestamp ||
-               did_panic ||
-                       !per_cpu(watchdog_task, this_cpu))
+       print_timestamp = per_cpu(print_timestamp, this_cpu);
+
+       /* report at most once a second */
+       if ((print_timestamp >= touch_timestamp &&
+                       print_timestamp < (touch_timestamp + 1)) ||
+                       did_panic || !per_cpu(watchdog_task, this_cpu)) {
                return;
+       }
 
        /* do not print during early bootup: */
        if (unlikely(system_state != SYSTEM_RUNNING)) {
@@ -61,31 +98,40 @@ void softlockup_tick(void)
                return;
        }
 
+       now = get_timestamp(this_cpu);
+
        /* Wake up the high-prio watchdog task every second: */
-       if (time_after(jiffies, touch_timestamp + HZ))
+       if (now > (touch_timestamp + 1))
                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;
+       if (now <= (touch_timestamp + softlockup_thresh))
+               return;
+
+       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);
+       spin_lock(&print_lock);
+       printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
+                       this_cpu, now - touch_timestamp,
+                               current->comm, current->pid);
+       if (regs)
+               show_regs(regs);
+       else
                dump_stack();
-               spin_unlock(&print_lock);
-       }
+       spin_unlock(&print_lock);
 }
 
 /*
  * The watchdog thread - runs every second and touches the timestamp.
  */
-static int watchdog(void * __bind_cpu)
+static int watchdog(void *__bind_cpu)
 {
-       struct sched_param param = { .sched_priority = 99 };
+       struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
 
        sched_setscheduler(current, SCHED_FIFO, &param);
-       current->flags |= PF_NOFREEZE;
+
+       /* initialize timestamp */
+       touch_softlockup_watchdog();
 
        /*
         * Run briefly once per second to reset the softlockup timestamp.
@@ -112,33 +158,37 @@ 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));
                p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
                if (IS_ERR(p)) {
-                       printk("watchdog for %i failed\n", hotcpu);
+                       printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
                        return NOTIFY_BAD;
                }
-               per_cpu(touch_timestamp, hotcpu) = jiffies;
-               per_cpu(watchdog_task, hotcpu) = p;
+               per_cpu(touch_timestamp, hotcpu) = 0;
+               per_cpu(watchdog_task, hotcpu) = p;
                kthread_bind(p, hotcpu);
-               break;
+               break;
        case CPU_ONLINE:
+       case CPU_ONLINE_FROZEN:
                wake_up_process(per_cpu(watchdog_task, hotcpu));
                break;
 #ifdef CONFIG_HOTPLUG_CPU
        case CPU_UP_CANCELED:
+       case CPU_UP_CANCELED_FROZEN:
                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));
        case CPU_DEAD:
+       case CPU_DEAD_FROZEN:
                p = per_cpu(watchdog_task, hotcpu);
                per_cpu(watchdog_task, hotcpu) = NULL;
                kthread_stop(p);
                break;
 #endif /* CONFIG_HOTPLUG_CPU */
-       }
+       }
        return NOTIFY_OK;
 }