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Commit 6c37067e authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: Change the sched_class::set_cpus_allowed() calling context 



Change the calling context of sched_class::set_cpus_allowed() such
that we can assume the task is inactive.

This allows us to easily make changes that affect accounting done by
enqueue/dequeue. This does in fact completely remove
set_cpus_allowed_rt() and greatly reduces set_cpus_allowed_dl().

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dedekind1@gmail.com
Cc: juri.lelli@arm.com
Cc: mgorman@suse.de
Cc: riel@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20150515154833.667516139@infradead.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent c5b28038

kernel/sched/core.c

+23 −0
Original line number Diff line number Diff line
@@ -1163,8 +1163,31 @@ void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_ma 


void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)

{

	struct rq *rq = task_rq(p);

	bool queued, running;



	lockdep_assert_held(&p->pi_lock);



	queued = task_on_rq_queued(p);

	running = task_current(rq, p);



	if (queued) {

		/*

		 * Because __kthread_bind() calls this on blocked tasks without

		 * holding rq->lock.

		 */

		lockdep_assert_held(&rq->lock);

		dequeue_task(rq, p, 0);

	}

	if (running)

		put_prev_task(rq, p);



	p->sched_class->set_cpus_allowed(p, new_mask);



	if (running)

		p->sched_class->set_curr_task(rq);

	if (queued)

		enqueue_task(rq, p, 0);

}



/*

kernel/sched/deadline.c

+2 −37
Original line number Diff line number Diff line
@@ -1668,9 +1668,8 @@ static void task_woken_dl(struct rq *rq, struct task_struct *p) 
static void set_cpus_allowed_dl(struct task_struct *p,

				const struct cpumask *new_mask)

{

	struct rq *rq;

	struct root_domain *src_rd;

	int weight;

	struct rq *rq;



	BUG_ON(!dl_task(p));
@@ -1696,41 +1695,7 @@ static void set_cpus_allowed_dl(struct task_struct *p, 
		raw_spin_unlock(&src_dl_b->lock);

	}



	weight = cpumask_weight(new_mask);



	/*

	 * Only update if the process changes its state from whether it

	 * can migrate or not.

	 */

	if ((p->nr_cpus_allowed > 1) == (weight > 1))

		goto done;



	/*

	 * Update only if the task is actually running (i.e.,

	 * it is on the rq AND it is not throttled).

	 */

	if (!on_dl_rq(&p->dl))

		goto done;



	/*

	 * The process used to be able to migrate OR it can now migrate

	 */

	if (weight <= 1) {

		if (!task_current(rq, p))

			dequeue_pushable_dl_task(rq, p);

		BUG_ON(!rq->dl.dl_nr_migratory);

		rq->dl.dl_nr_migratory--;

	} else {

		if (!task_current(rq, p))

			enqueue_pushable_dl_task(rq, p);

		rq->dl.dl_nr_migratory++;

	}



	update_dl_migration(&rq->dl);



done:

	cpumask_copy(&p->cpus_allowed, new_mask);

	p->nr_cpus_allowed = weight;

	set_cpus_allowed_common(p, new_mask);

}



/* Assumes rq->lock is held */

kernel/sched/rt.c

+1 −44
Original line number Diff line number Diff line
@@ -2076,49 +2076,6 @@ static void task_woken_rt(struct rq *rq, struct task_struct *p) 
		push_rt_tasks(rq);

}



static void set_cpus_allowed_rt(struct task_struct *p,

				const struct cpumask *new_mask)

{

	struct rq *rq;

	int weight;



	BUG_ON(!rt_task(p));



	weight = cpumask_weight(new_mask);



	/*

	 * Only update if the process changes its state from whether it

	 * can migrate or not.

	 */

	if ((p->nr_cpus_allowed > 1) == (weight > 1))

		goto done;



	if (!task_on_rq_queued(p))

		goto done;



	rq = task_rq(p);



	/*

	 * The process used to be able to migrate OR it can now migrate

	 */

	if (weight <= 1) {

		if (!task_current(rq, p))

			dequeue_pushable_task(rq, p);

		BUG_ON(!rq->rt.rt_nr_migratory);

		rq->rt.rt_nr_migratory--;

	} else {

		if (!task_current(rq, p))

			enqueue_pushable_task(rq, p);

		rq->rt.rt_nr_migratory++;

	}



	update_rt_migration(&rq->rt);



done:

	cpumask_copy(&p->cpus_allowed, new_mask);

	p->nr_cpus_allowed = weight;

}



/* Assumes rq->lock is held */

static void rq_online_rt(struct rq *rq)

{
@@ -2327,7 +2284,7 @@ const struct sched_class rt_sched_class = { 
#ifdef CONFIG_SMP

	.select_task_rq		= select_task_rq_rt,



	.set_cpus_allowed       = set_cpus_allowed_rt,

	.set_cpus_allowed       = set_cpus_allowed_common,

	.rq_online              = rq_online_rt,

	.rq_offline             = rq_offline_rt,

	.task_woken		= task_woken_rt,