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authorPeter Zijlstra <peterz@infradead.org>2013-06-28 11:18:53 +0200
committerIngo Molnar <mingo@kernel.org>2013-07-12 13:52:58 +0200
commit971ee28cbd1ccd87b3164facd9359a534c1d2892 (patch)
treed5d9bcbe6f9c8cb5da70e305b25eefc3e1a25008
parent9903883f1dd6e86f286b7bfa6e4b423f98c1cd9e (diff)
downloadlinux-971ee28cbd1ccd87b3164facd9359a534c1d2892.tar.gz
sched: Fix HRTICK
David reported that the HRTICK sched feature was borken; which was enough motivation for me to finally fix it ;-) We should not allow hrtimer code to do softirq wakeups while holding scheduler locks. The hrtimer code only needs this when we accidentally try to program an expired time. We don't much care about those anyway since we have the regular tick to fall back to. Reported-by: David Ahern <dsahern@gmail.com> Tested-by: David Ahern <dsahern@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20130628091853.GE29209@dyad.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/sched/core.c20
1 files changed, 11 insertions, 9 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9b1f2e533b9..0d8eb4525e7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -370,13 +370,6 @@ static struct rq *this_rq_lock(void)
#ifdef CONFIG_SCHED_HRTICK
/*
* Use HR-timers to deliver accurate preemption points.
- *
- * Its all a bit involved since we cannot program an hrt while holding the
- * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
- * reschedule event.
- *
- * When we get rescheduled we reprogram the hrtick_timer outside of the
- * rq->lock.
*/
static void hrtick_clear(struct rq *rq)
@@ -404,6 +397,15 @@ static enum hrtimer_restart hrtick(struct hrtimer *timer)
}
#ifdef CONFIG_SMP
+
+static int __hrtick_restart(struct rq *rq)
+{
+ struct hrtimer *timer = &rq->hrtick_timer;
+ ktime_t time = hrtimer_get_softexpires(timer);
+
+ return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0);
+}
+
/*
* called from hardirq (IPI) context
*/
@@ -412,7 +414,7 @@ static void __hrtick_start(void *arg)
struct rq *rq = arg;
raw_spin_lock(&rq->lock);
- hrtimer_restart(&rq->hrtick_timer);
+ __hrtick_restart(rq);
rq->hrtick_csd_pending = 0;
raw_spin_unlock(&rq->lock);
}
@@ -430,7 +432,7 @@ void hrtick_start(struct rq *rq, u64 delay)
hrtimer_set_expires(timer, time);
if (rq == this_rq()) {
- hrtimer_restart(timer);
+ __hrtick_restart(rq);
} else if (!rq->hrtick_csd_pending) {
__smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
rq->hrtick_csd_pending = 1;