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);