1 files changed, 60 insertions, 10 deletions

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index a272d78185eb..b75b492fbfcf 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -13,6 +13,7 @@
 #include <linux/delay.h>
 #include <linux/freezer.h>
 #include <linux/kthread.h>
+#include <linux/lockdep.h>
 #include <linux/notifier.h>
 #include <linux/module.h>
 
@@ -25,7 +26,22 @@ static DEFINE_PER_CPU(unsigned long, print_timestamp);
 static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
 
 static int __read_mostly did_panic;
-unsigned long __read_mostly softlockup_thresh = 60;
+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)
@@ -84,6 +100,14 @@ void softlockup_tick(void)
 	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;
@@ -92,11 +116,8 @@ void softlockup_tick(void)
 	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)) {
+	if (print_timestamp == touch_timestamp || did_panic)
 		return;
-	}
 
 	/* do not print during early bootup: */
 	if (unlikely(system_state != SYSTEM_RUNNING)) {
@@ -106,8 +127,11 @@ void softlockup_tick(void)
 
 	now = get_timestamp(this_cpu);
 
-	/* Wake up the high-prio watchdog task every second: */
-	if (now > (touch_timestamp + 1))
+	/*
+	 * 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: */
@@ -121,11 +145,15 @@ void softlockup_tick(void)
 			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");
 }
 
 /*
@@ -178,6 +206,9 @@ static void check_hung_task(struct task_struct *t, unsigned long now)
 
 	t->last_switch_timestamp = now;
 	touch_nmi_watchdog();
+
+	if (softlockup_panic)
+		panic("softlockup: blocked tasks");
 }
 
 /*
@@ -307,14 +338,33 @@ static struct notifier_block __cpuinitdata cpu_nfb = {
 	.notifier_call = cpu_callback
 };
 
-__init void spawn_softlockup_task(void)
+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 = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
+	int err;
+
+	if (nosoftlockup)
+		return 0;
 
-	BUG_ON(err == NOTIFY_BAD);
+	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);