sched: RT-balance, add new methods to sched_class

Dmitry Adamushko found that the current implementation of the RT
balancing code left out changes to the sched_setscheduler and
rt_mutex_setprio.

This patch addresses this issue by adding methods to the schedule classes
to handle being switched out of (switched_from) and being switched into
(switched_to) a sched_class. Also a method for changing of priorities
is also added (prio_changed).

This patch also removes some duplicate logic between rt_mutex_setprio and
sched_setscheduler.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 20 insertions, 22 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 2368a0d..5834c7f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1152,6 +1152,18 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
 #endif
 }
 
+static inline void check_class_changed(struct rq *rq, struct task_struct *p,
+				       const struct sched_class *prev_class,
+				       int oldprio, int running)
+{
+	if (prev_class != p->sched_class) {
+		if (prev_class->switched_from)
+			prev_class->switched_from(rq, p, running);
+		p->sched_class->switched_to(rq, p, running);
+	} else
+		p->sched_class->prio_changed(rq, p, oldprio, running);
+}
+
 #ifdef CONFIG_SMP
 
 /*
@@ -4017,6 +4029,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 	unsigned long flags;
 	int oldprio, on_rq, running;
 	struct rq *rq;
+	const struct sched_class *prev_class = p->sched_class;
 
 	BUG_ON(prio < 0 || prio > MAX_PRIO);
 
@@ -4042,18 +4055,10 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 	if (on_rq) {
 		if (running)
 			p->sched_class->set_curr_task(rq);
+
 		enqueue_task(rq, p, 0);
-		/*
-		 * Reschedule if we are currently running on this runqueue and
-		 * our priority decreased, or if we are not currently running on
-		 * this runqueue and our priority is higher than the current's
-		 */
-		if (running) {
-			if (p->prio > oldprio)
-				resched_task(rq->curr);
-		} else {
-			check_preempt_curr(rq, p);
-		}
+
+		check_class_changed(rq, p, prev_class, oldprio, running);
 	}
 	task_rq_unlock(rq, &flags);
 }
@@ -4253,6 +4258,7 @@ int sched_setscheduler(struct task_struct *p, int policy,
 {
 	int retval, oldprio, oldpolicy = -1, on_rq, running;
 	unsigned long flags;
+	const struct sched_class *prev_class = p->sched_class;
 	struct rq *rq;
 
 	/* may grab non-irq protected spin_locks */
@@ -4346,18 +4352,10 @@ recheck:
 	if (on_rq) {
 		if (running)
 			p->sched_class->set_curr_task(rq);
+
 		activate_task(rq, p, 0);
-		/*
-		 * Reschedule if we are currently running on this runqueue and
-		 * our priority decreased, or if we are not currently running on
-		 * this runqueue and our priority is higher than the current's
-		 */
-		if (running) {
-			if (p->prio > oldprio)
-				resched_task(rq->curr);
-		} else {
-			check_preempt_curr(rq, p);
-		}
+
+		check_class_changed(rq, p, prev_class, oldprio, running);
 	}
 	__task_rq_unlock(rq);
 	spin_unlock_irqrestore(&p->pi_lock, flags);