hrtimer, softirq: Fix hrtimer->softirq trampoline
Peter Zijlstra [Wed, 3 Feb 2010 17:08:52 +0000 (18:08 +0100)]
hrtimers callbacks are always done from hardirq context, either the
jiffy tick interrupt or the hrtimer device interrupt.

[ there is currently one exception that can still call a hrtimer
  callback from softirq, but even in that case this will still
  work correctly. ]

Reported-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Yury Polyanskiy <ypolyans@princeton.edu>
Tested-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Acked-by: David S. Miller <davem@davemloft.net>
LKML-Reference: <1265120401.24455.306.camel@laptop>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/softirq.c

index a09502e..7c1a67e 100644 (file)
@@ -500,22 +500,17 @@ EXPORT_SYMBOL(tasklet_kill);
  */
 
 /*
- * The trampoline is called when the hrtimer expires. If this is
- * called from the hrtimer interrupt then we schedule the tasklet as
- * the timer callback function expects to run in softirq context. If
- * it's called in softirq context anyway (i.e. high resolution timers
- * disabled) then the hrtimer callback is called right away.
+ * The trampoline is called when the hrtimer expires. It schedules a tasklet
+ * to run __tasklet_hrtimer_trampoline() which in turn will call the intended
+ * hrtimer callback, but from softirq context.
  */
 static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer)
 {
        struct tasklet_hrtimer *ttimer =
                container_of(timer, struct tasklet_hrtimer, timer);
 
-       if (hrtimer_is_hres_active(timer)) {
-               tasklet_hi_schedule(&ttimer->tasklet);
-               return HRTIMER_NORESTART;
-       }
-       return ttimer->function(timer);
+       tasklet_hi_schedule(&ttimer->tasklet);
+       return HRTIMER_NORESTART;
 }
 
 /*