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[PATCH for v3.18.25 5/6] sched,dl: Remove return value from pull_dl_task()

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From: Peter Zijlstra <peterz@infradead.org>

In order to be able to use pull_dl_task() from a callback, we need to
do away with the return value.

Since the return value indicates if we should reschedule, do this
inside the function. Since not all callers currently do this, this can
increase the number of reschedules due rt balancing.

Too many reschedules is not a correctness issues, too few are.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: oleg@redhat.com
Cc: wanpeng.li@linux.intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124742.859398977@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Byungchul Park <byungchul.park@lge.com>

Conflicts:
	kernel/sched/deadline.c
---
 kernel/sched/deadline.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 3bdf558..822b94f 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -252,9 +252,8 @@ static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
 	return false;
 }
 
-static inline int pull_dl_task(struct rq *rq)
+static inline void pull_dl_task(struct rq *rq)
 {
-	return 0;
 }
 
 static inline void queue_push_tasks(struct rq *rq)
@@ -974,7 +973,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
 	resched_curr(rq);
 }
 
-static int pull_dl_task(struct rq *this_rq);
+static void pull_dl_task(struct rq *this_rq);
 
 #endif /* CONFIG_SMP */
 
@@ -1397,15 +1396,16 @@ static void push_dl_tasks(struct rq *rq)
 		;
 }
 
-static int pull_dl_task(struct rq *this_rq)
+static void pull_dl_task(struct rq *this_rq)
 {
-	int this_cpu = this_rq->cpu, ret = 0, cpu;
+	int this_cpu = this_rq->cpu, cpu;
 	struct task_struct *p;
+	bool resched = false;
 	struct rq *src_rq;
 	u64 dmin = LONG_MAX;
 
 	if (likely(!dl_overloaded(this_rq)))
-		return 0;
+		return;
 
 	/*
 	 * Match the barrier from dl_set_overloaded; this guarantees that if we
@@ -1460,7 +1460,7 @@ static int pull_dl_task(struct rq *this_rq)
 					   src_rq->curr->dl.deadline))
 				goto skip;
 
-			ret = 1;
+			resched = true;
 
 			deactivate_task(src_rq, p, 0);
 			set_task_cpu(p, this_cpu);
@@ -1473,7 +1473,8 @@ skip:
 		double_unlock_balance(this_rq, src_rq);
 	}
 
-	return ret;
+	if (resched)
+		resched_curr(this_rq);
 }
 
 /*
-- 
1.9.1

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[STABLE] kernel oops which can be fixed by peterz's patches Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:00 +0100
  [PATCH for v3.14.58 7/7] sched, dl: Convert switched_{from, to}_dl() / prio_changed_dl() to balance callbacks Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:20 +0100
  Re: [STABLE] kernel oops which can be fixed by peterz's patches Peter Zijlstra <peterz@infradead.org> - 2016-01-05 10:20 +0100
    Re: [STABLE] kernel oops which can be fixed by peterz's patches Byungchul Park <byungchul.park@lge.com> - 2016-01-12 09:50 +0100
    Re: [STABLE] kernel oops which can be fixed by peterz's patches Willy Tarreau <w@1wt.eu> - 2016-01-12 11:30 +0100
  [PATCH for v3.14.58 6/7] sched,dl: Remove return value from pull_dl_task() Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:20 +0100
  [PATCH for v3.14.58 1/7] sched: Clean up idle task SMP logic Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:20 +0100
    [PATCH for v3.14.58 4/7] sched,rt: Remove return value from pull_rt_task() Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:20 +0100
    [PATCH for v3.14.58 2/7] sched: Replace post_schedule with a balance callback list Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:20 +0100
    [PATCH for v3.14.58 3/7] sched: Allow balance callbacks for check_class_changed() Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:20 +0100
    [PATCH for v3.14.58 5/7] sched, rt: Convert switched_{from, to}_rt() / prio_changed_rt() to balance callbacks Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:20 +0100
  [PATCH for v3.18.25 1/6] sched: Replace post_schedule with a balance callback list Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:30 +0100
    [PATCH for v3.18.25 3/6] sched,rt: Remove return value from pull_rt_task() Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:30 +0100
    [PATCH for v3.18.25 4/6] sched, rt: Convert switched_{from, to}_rt() / prio_changed_rt() to balance callbacks Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:30 +0100
    [PATCH for v3.18.25 6/6] sched, dl: Convert switched_{from, to}_dl() / prio_changed_dl() to balance callbacks Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:30 +0100
    [PATCH for v3.18.25 5/6] sched,dl: Remove return value from pull_dl_task() Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:30 +0100
    [PATCH for v3.18.25 2/6] sched: Allow balance callbacks for check_class_changed() Byungchul Park <byungchul.park@lge.com> - 2016-01-05 10:30 +0100

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