hrtimer: fix rq->lock inversion (again)

It appears I inadvertly introduced rq->lock recursion to the
hrtimer_start() path when I delegated running already expired
timers to softirq context.

This patch fixes it by introducing a __hrtimer_start_range_ns()
method that will not use raise_softirq_irqoff() but
__raise_softirq_irqoff() which avoids the wakeup.

It then also changes schedule() to check for pending softirqs and
do the wakeup then, I'm not quite sure I like this last bit, nor
am I convinced its really needed.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
LKML-Reference: <20090313112301.096138802@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index bd37078c2d7d..0d2f7c8a33d6 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -336,6 +336,11 @@ extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
                          const enum hrtimer_mode mode);
 extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
                         unsigned long range_ns, const enum hrtimer_mode mode);
+extern int
+__hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
+                         unsigned long delta_ns,
+                         const enum hrtimer_mode mode, int wakeup);
+
 extern int hrtimer_cancel(struct hrtimer *timer);
 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index c68bffd182bb..4528bf70866a 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -294,6 +294,7 @@ extern void softirq_init(void);
 #define __raise_softirq_irqoff(nr) do { or_softirq_pending(1UL << (nr)); } while (0)
 extern void raise_softirq_irqoff(unsigned int nr);
 extern void raise_softirq(unsigned int nr);
+extern void wakeup_softirqd(void);
 
 /* This is the worklist that queues up per-cpu softirq work.
  *