hrtimer_wakeup creates a

  base->lock
    rq->lock

lock dependancy. Avoid this by switching to HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
which doesn't hold base->lock.

This fully untangles hrtimer locks from the scheduler locks, and allows
hrtimer usage in the scheduler proper.

Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]>
---
 kernel/hrtimer.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: linux-2.6/kernel/hrtimer.c
===================================================================
--- linux-2.6.orig/kernel/hrtimer.c
+++ linux-2.6/kernel/hrtimer.c
@@ -1296,7 +1296,7 @@ void hrtimer_init_sleeper(struct hrtimer
        sl->timer.function = hrtimer_wakeup;
        sl->task = task;
 #ifdef CONFIG_HIGH_RES_TIMERS
-       sl->timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_RESTART;
+       sl->timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ;
 #endif
 }
 
@@ -1307,6 +1307,8 @@ static int __sched do_nanosleep(struct h
        do {
                set_current_state(TASK_INTERRUPTIBLE);
                hrtimer_start(&t->timer, t->timer.expires, mode);
+               if (!hrtimer_active(&t->timer))
+                       t->task = NULL;
 
                if (likely(t->task))
                        schedule();

--

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