Commit 47efe2dd authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/core: Add assertions to QUEUE_CLASS 



Add some checks to the sched_change pattern to validate assumptions
around changing classes.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/20251127154725.771691954@infradead.org
parent 95a01552

kernel/sched/core.c

+13 −0
Original line number Diff line number Diff line
@@ -10782,6 +10782,7 @@ struct sched_change_ctx *sched_change_begin(struct task_struct *p, unsigned int 


	*ctx = (struct sched_change_ctx){

		.p = p,

		.class = p->sched_class,

		.flags = flags,

		.queued = task_on_rq_queued(p),

		.running = task_current_donor(rq, p),
@@ -10812,6 +10813,11 @@ void sched_change_end(struct sched_change_ctx *ctx) 


	lockdep_assert_rq_held(rq);



	/*

	 * Changing class without *QUEUE_CLASS is bad.

	 */

	WARN_ON_ONCE(p->sched_class != ctx->class && !(ctx->flags & ENQUEUE_CLASS));



	if ((ctx->flags & ENQUEUE_CLASS) && p->sched_class->switching_to)

		p->sched_class->switching_to(rq, p);
@@ -10823,6 +10829,13 @@ void sched_change_end(struct sched_change_ctx *ctx) 
	if (ctx->flags & ENQUEUE_CLASS) {

		if (p->sched_class->switched_to)

			p->sched_class->switched_to(rq, p);



		/*

		 * If this was a degradation in class someone should have set

		 * need_resched by now.

		 */

		WARN_ON_ONCE(sched_class_above(ctx->class, p->sched_class) &&

			     !test_tsk_need_resched(p));

	} else {

		p->sched_class->prio_changed(rq, p, ctx->prio);

	}

kernel/sched/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -3968,6 +3968,7 @@ extern void balance_callbacks(struct rq *rq, struct balance_callback *head); 
struct sched_change_ctx {

	u64			prio;

	struct task_struct	*p;

	const struct sched_class *class;

	int			flags;

	bool			queued;

	bool			running;