linux-kernel - [PATCH 2/4] Move the remaining __dl_{sub,add}

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Date:	Mon, 22 Feb 2016 11:57:03 +0100
From:	Luca Abeni <luca.abeni@...tn.it>
To:	Juri Lelli <juri.lelli@....com>
Cc:	rostedt@...dmis.org, linux-kernel@...r.kernel.org,
	peterz@...radead.org, mingo@...hat.com, vincent.guittot@...aro.org,
	wanpeng.li@...mail.com, Luca Abeni <luca.abeni@...tn.it>
Subject: [PATCH 2/4] Move the remaining __dl_{sub,add}_ac() calls from core.c to deadline.c

To move these calls from dl_overflow() to deadline.c, we must change
the meaning of the third parameter of prio_changed_dl().
Instead of passing the "old priority" (which is always equal to the current
one, for SCHED_DEADLINE) we pass the old utilization. An alternative approach
is to change the prototype of the "prio_changed" method of the scheduling
class.
---
 kernel/sched/core.c     | 10 ++++++----
 kernel/sched/deadline.c | 10 +++++++---
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a4f08d1..5dc12db 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2449,9 +2449,7 @@ static int dl_overflow(struct task_struct *p, int policy,
 	} else if (dl_policy(policy) && task_has_dl_policy(p) &&
 		   !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
 		__dl_clear(dl_b, p->dl.dl_bw);
-		__dl_sub_ac(task_rq(p), p->dl.dl_bw);
 		__dl_add(dl_b, new_bw);
-		__dl_add_ac(task_rq(p), new_bw);
 		err = 0;
 	} else if (!dl_policy(policy) && task_has_dl_policy(p)) {
 		__dl_clear(dl_b, p->dl.dl_bw);
@@ -3522,6 +3520,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 		} else
 			p->dl.dl_boosted = 0;
 		p->sched_class = &dl_sched_class;
+		oldprio = 0;
 	} else if (rt_prio(prio)) {
 		if (dl_prio(oldprio))
 			p->dl.dl_boosted = 0;
@@ -3891,7 +3890,7 @@ static int __sched_setscheduler(struct task_struct *p,
 {
 	int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
 		      MAX_RT_PRIO - 1 - attr->sched_priority;
-	int retval, oldprio, oldpolicy = -1, queued, running;
+	int retval, oldprio, oldbw, oldpolicy = -1, queued, running;
 	int new_effective_prio, policy = attr->sched_policy;
 	unsigned long flags;
 	const struct sched_class *prev_class;
@@ -4069,6 +4068,7 @@ change:
 
 	p->sched_reset_on_fork = reset_on_fork;
 	oldprio = p->prio;
+	oldbw = p->dl.dl_bw;
 
 	if (pi) {
 		/*
@@ -4081,6 +4081,8 @@ change:
 		new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
 		if (new_effective_prio == oldprio) {
 			__setscheduler_params(p, attr);
+			if (p->sched_class == &dl_sched_class)
+				p->sched_class->prio_changed(rq, p, oldbw);
 			task_rq_unlock(rq, p, &flags);
 			return 0;
 		}
@@ -4110,7 +4112,7 @@ change:
 		enqueue_task(rq, p, enqueue_flags);
 	}
 
-	check_class_changed(rq, p, prev_class, oldprio);
+	check_class_changed(rq, p, prev_class, ((prev_class == &dl_sched_class) && (p->sched_class == &dl_sched_class)) ? oldbw : oldprio);
 	preempt_disable(); /* avoid rq from going away on us */
 	task_rq_unlock(rq, p, &flags);
 
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 4cc713a..959e7b7 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1757,8 +1757,13 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
  * a push or pull operation might be needed.
  */
 static void prio_changed_dl(struct rq *rq, struct task_struct *p,
-			    int oldprio)
+			    int oldbw)
 {
+	if (oldbw) {
+		__dl_sub_ac(rq, oldbw);
+		__dl_add_ac(rq, p->dl.dl_bw);
+	}
+
 	if (task_on_rq_queued(p) || rq->curr == p) {
 #ifdef CONFIG_SMP
 		/*
@@ -1785,8 +1790,7 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
 		 */
 		resched_curr(rq);
 #endif /* CONFIG_SMP */
-	} else
-		switched_to_dl(rq, p);
+	}
 }
 
 const struct sched_class dl_sched_class = {
-- 
2.5.0