sched, nohz: Change rq->nr_running to always use wrappers

Sometimes ->nr_running may cross 2 but interrupt is not being
sent to rq's cpu. In this case we don't reenable the timer.
Looks like this may be the reason for rare unexpected effects,
if nohz is enabled.

Patch replaces all places of direct changing of nr_running
and makes add_nr_running() caring about crossing border.

Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140508225830.2469.97461.stgit@localhost
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 26ec6686a00b..f7cac2ba62ea 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3325,7 +3325,7 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
 	}
 
 	if (!se)
-		rq->nr_running -= task_delta;
+		sub_nr_running(rq, task_delta);
 
 	cfs_rq->throttled = 1;
 	cfs_rq->throttled_clock = rq_clock(rq);
@@ -3376,7 +3376,7 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
 	}
 
 	if (!se)
-		rq->nr_running += task_delta;
+		add_nr_running(rq, task_delta);
 
 	/* determine whether we need to wake up potentially idle cpu */
 	if (rq->curr == rq->idle && rq->cfs.nr_running)
@@ -3908,7 +3908,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 
 	if (!se) {
 		update_rq_runnable_avg(rq, rq->nr_running);
-		inc_nr_running(rq);
+		add_nr_running(rq, 1);
 	}
 	hrtick_update(rq);
 }
@@ -3968,7 +3968,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 	}
 
 	if (!se) {
-		dec_nr_running(rq);
+		sub_nr_running(rq, 1);
 		update_rq_runnable_avg(rq, 1);
 	}
 	hrtick_update(rq);