[tip:timers/urgent] hrtimer, softirq: Fix hrtimer->softirq trampoline

tip-bot for Peter Zijlstra
2010-02-03T17:22:12Z

Commit-ID: b9c3032277f756e73f6c673419dc414155e04e46
Gitweb: http://git.kernel.org/tip/b9c3032277f756e73f6c673419dc414155e04e46
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Wed, 3 Feb 2010 18:08:52 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 3 Feb 2010 18:17:40 +0100

hrtimer, softirq: Fix hrtimer->softirq trampoline

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 | 15 +++++----------
1 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index a09502e..7c1a67e 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -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;
}

/*