Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ed50d6cbc394cd0966469d3e249353c9dd1d38b9
Commit:     ed50d6cbc394cd0966469d3e249353c9dd1d38b9
Parent:     aa6299926950c8dfe2fea638276cad6def092bc9
Author:     Peter Zijlstra <[EMAIL PROTECTED]>
AuthorDate: Sat Feb 2 00:23:08 2008 +0100
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Sat Feb 2 14:27:45 2008 +1100

    debug: softlockup looping fix
    
    Rafael J. Wysocki reported weird, multi-seconds delays during
    suspend/resume and bisected it back to:
    
      commit 82a1fcb90287052aabfa235e7ffc693ea003fe69
      Author: Ingo Molnar <[EMAIL PROTECTED]>
      Date:   Fri Jan 25 21:08:02 2008 +0100
    
          softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks
    
    fix it:
    
     - restore the old wakeup mechanism
     - fix break usage in do_each_thread() { } while_each_thread().
     - fix the hotplug switch stmt, a fall-through case was broken.
    
    Bisected-by: Rafael J. Wysocki <[EMAIL PROTECTED]>
    Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]>
    Tested-by: Rafael J. Wysocki <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
    Acked-by: Rafael J. Wysocki <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 kernel/softlockup.c |   30 ++++++++++++++++++++----------
 1 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index c1d7655..7c2da88 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -101,6 +101,10 @@ 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_process(per_cpu(watchdog_task, this_cpu));
+
        /* Warn about unreasonable delays: */
        if (now <= (touch_timestamp + softlockup_thresh))
                return;
@@ -191,11 +195,11 @@ static void check_hung_uninterruptible_tasks(int this_cpu)
        read_lock(&tasklist_lock);
        do_each_thread(g, t) {
                if (!--max_count)
-                       break;
+                       goto unlock;
                if (t->state & TASK_UNINTERRUPTIBLE)
                        check_hung_task(t, now);
        } while_each_thread(g, t);
-
+ unlock:
        read_unlock(&tasklist_lock);
 }
 
@@ -218,14 +222,19 @@ static int watchdog(void *__bind_cpu)
         * debug-printout triggers in softlockup_tick().
         */
        while (!kthread_should_stop()) {
+               set_current_state(TASK_INTERRUPTIBLE);
                touch_softlockup_watchdog();
-               msleep_interruptible(10000);
+               schedule();
+
+               if (kthread_should_stop())
+                       break;
 
                if (this_cpu != check_cpu)
                        continue;
 
                if (sysctl_hung_task_timeout_secs)
                        check_hung_uninterruptible_tasks(this_cpu);
+
        }
 
        return 0;
@@ -259,13 +268,6 @@ cpu_callback(struct notifier_block *nfb, unsigned long 
action, void *hcpu)
                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_DOWN_PREPARE:
        case CPU_DOWN_PREPARE_FROZEN:
                if (hotcpu == check_cpu) {
@@ -275,6 +277,14 @@ cpu_callback(struct notifier_block *nfb, unsigned long 
action, void *hcpu)
                        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);
-
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