Initial import of modified Linux 2.6.28 tree

Original upstream URL:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y

1 files changed, 371 insertions, 0 deletions

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
new file mode 100644
index 0000000..dc0b3be
--- /dev/null
+++ b/kernel/softlockup.c
@@ -0,0 +1,371 @@
+/*
+ * Detect Soft Lockups
+ *
+ * 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/nmi.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/lockdep.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 __read_mostly did_panic;
+int __read_mostly softlockup_thresh = 60;
+
+/*
+ * Should we panic (and reboot, if panic_timeout= is set) when a
+ * soft-lockup occurs:
+ */
+unsigned int __read_mostly softlockup_panic =
+				CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
+
+static int __init softlockup_panic_setup(char *str)
+{
+	softlockup_panic = simple_strtoul(str, NULL, 0);
+
+	return 1;
+}
+__setup("softlockup_panic=", softlockup_panic_setup);
+
+static int
+softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	did_panic = 1;
+
+	return NOTIFY_DONE;
+}
+
+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) >> 30LL;  /* 2^30 ~= 10^9 */
+}
+
+static void __touch_softlockup_watchdog(void)
+{
+	int this_cpu = raw_smp_processor_id();
+
+	__raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
+}
+
+void touch_softlockup_watchdog(void)
+{
+	__raw_get_cpu_var(touch_timestamp) = 0;
+}
+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:
+ */
+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;
+
+	/* Is detection switched off? */
+	if (!per_cpu(watchdog_task, 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;
+		return;
+	}
+
+	if (touch_timestamp == 0) {
+		__touch_softlockup_watchdog();
+		return;
+	}
+
+	print_timestamp = per_cpu(print_timestamp, this_cpu);
+
+	/* report at most once a second */
+	if (print_timestamp == touch_timestamp || did_panic)
+		return;
+
+	/* do not print during early bootup: */
+	if (unlikely(system_state != SYSTEM_RUNNING)) {
+		__touch_softlockup_watchdog();
+		return;
+	}
+
+	now = get_timestamp(this_cpu);
+
+	/*
+	 * 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));
+
+	/* Warn about unreasonable delays: */
+	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 - CPU#%d stuck for %lus! [%s:%d]\n",
+			this_cpu, now - touch_timestamp,
+			current->comm, task_pid_nr(current));
+	print_modules();
+	print_irqtrace_events(current);
+	if (regs)
+		show_regs(regs);
+	else
+		dump_stack();
+	spin_unlock(&print_lock);
+
+	if (softlockup_panic)
+		panic("softlockup: hung tasks");
+}
+
+/*
+ * Have a reasonable limit on the number of tasks checked:
+ */
+unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
+
+/*
+ * Zero means infinite timeout - no checking done:
+ */
+unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
+
+unsigned long __read_mostly sysctl_hung_task_warnings = 10;
+
+/*
+ * Only do the hung-tasks check on one CPU:
+ */
+static int check_cpu __read_mostly = -1;
+
+static void check_hung_task(struct task_struct *t, unsigned long now)
+{
+	unsigned long switch_count = t->nvcsw + t->nivcsw;
+
+	if (t->flags & PF_FROZEN)
+		return;
+
+	if (switch_count != t->last_switch_count || !t->last_switch_timestamp) {
+		t->last_switch_count = switch_count;
+		t->last_switch_timestamp = now;
+		return;
+	}
+	if ((long)(now - t->last_switch_timestamp) <
+					sysctl_hung_task_timeout_secs)
+		return;
+	if (!sysctl_hung_task_warnings)
+		return;
+	sysctl_hung_task_warnings--;
+
+	/*
+	 * Ok, the task did not get scheduled for more than 2 minutes,
+	 * complain:
+	 */
+	printk(KERN_ERR "INFO: task %s:%d blocked for more than "
+			"%ld seconds.\n", t->comm, t->pid,
+			sysctl_hung_task_timeout_secs);
+	printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
+			" disables this message.\n");
+	sched_show_task(t);
+	__debug_show_held_locks(t);
+
+	t->last_switch_timestamp = now;
+	touch_nmi_watchdog();
+
+	if (softlockup_panic)
+		panic("softlockup: blocked tasks");
+}
+
+/*
+ * Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
+ * a really long time (120 seconds). If that happens, print out
+ * a warning.
+ */
+static void check_hung_uninterruptible_tasks(int this_cpu)
+{
+	int max_count = sysctl_hung_task_check_count;
+	unsigned long now = get_timestamp(this_cpu);
+	struct task_struct *g, *t;
+
+	/*
+	 * If the system crashed already then all bets are off,
+	 * do not report extra hung tasks:
+	 */
+	if (test_taint(TAINT_DIE) || did_panic)
+		return;
+
+	read_lock(&tasklist_lock);
+	do_each_thread(g, t) {
+		if (!--max_count)
+			goto unlock;
+		/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
+		if (t->state == TASK_UNINTERRUPTIBLE)
+			check_hung_task(t, now);
+	} while_each_thread(g, t);
+ unlock:
+	read_unlock(&tasklist_lock);
+}
+
+/*
+ * The watchdog thread - runs every second and touches the timestamp.
+ */
+static int watchdog(void *__bind_cpu)
+{
+	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
+	int this_cpu = (long)__bind_cpu;
+
+	sched_setscheduler(current, SCHED_FIFO, &param);
+
+	/* initialize timestamp */
+	__touch_softlockup_watchdog();
+
+	set_current_state(TASK_INTERRUPTIBLE);
+	/*
+	 * Run briefly once per second to reset the softlockup timestamp.
+	 * If this gets delayed for more than 60 seconds then the
+	 * debug-printout triggers in softlockup_tick().
+	 */
+	while (!kthread_should_stop()) {
+		__touch_softlockup_watchdog();
+		schedule();
+
+		if (kthread_should_stop())
+			break;
+
+		if (this_cpu == check_cpu) {
+			if (sysctl_hung_task_timeout_secs)
+				check_hung_uninterruptible_tasks(this_cpu);
+		}
+
+		set_current_state(TASK_INTERRUPTIBLE);
+	}
+	__set_current_state(TASK_RUNNING);
+
+	return 0;
+}
+
+/*
+ * Create/destroy watchdog threads as CPUs come and go:
+ */
+static int __cpuinit
+cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+	int hotcpu = (unsigned long)hcpu;
+	struct task_struct *p;
+
+	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(KERN_ERR "watchdog for %i failed\n", hotcpu);
+			return NOTIFY_BAD;
+		}
+		per_cpu(touch_timestamp, hotcpu) = 0;
+		per_cpu(watchdog_task, hotcpu) = p;
+		kthread_bind(p, hotcpu);
+		break;
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+		check_cpu = any_online_cpu(cpu_online_map);
+		wake_up_process(per_cpu(watchdog_task, hotcpu));
+		break;
+#ifdef CONFIG_HOTPLUG_CPU
+	case CPU_DOWN_PREPARE:
+	case CPU_DOWN_PREPARE_FROZEN:
+		if (hotcpu == check_cpu) {
+			cpumask_t temp_cpu_online_map = cpu_online_map;
+
+			cpu_clear(hotcpu, temp_cpu_online_map);
+			check_cpu = any_online_cpu(temp_cpu_online_map);
+		}
+		break;
+
+	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;
+}
+
+static struct notifier_block __cpuinitdata cpu_nfb = {
+	.notifier_call = cpu_callback
+};
+
+static int __initdata nosoftlockup;
+
+static int __init nosoftlockup_setup(char *str)
+{
+	nosoftlockup = 1;
+	return 1;
+}
+__setup("nosoftlockup", nosoftlockup_setup);
+
+static int __init spawn_softlockup_task(void)
+{
+	void *cpu = (void *)(long)smp_processor_id();
+	int err;
+
+	if (nosoftlockup)
+		return 0;
+
+	err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
+	if (err == NOTIFY_BAD) {
+		BUG();
+		return 1;
+	}
+	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
+	register_cpu_notifier(&cpu_nfb);
+
+	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
+
+	return 0;
+}
+early_initcall(spawn_softlockup_task);