Commit 863ccdbb authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched: Allow sched_class::dequeue_task() to fail 



Change the function signature of sched_class::dequeue_task() to return
a boolean, allowing future patches to 'fail' dequeue.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarValentin Schneider <vschneid@redhat.com>
Tested-by: default avatarValentin Schneider <vschneid@redhat.com>
Link: https://lkml.kernel.org/r/20240727105028.864630153@infradead.org
parent 3b3dd89b

kernel/sched/core.c

+5 −2
Original line number Diff line number Diff line
@@ -2001,7 +2001,10 @@ void enqueue_task(struct rq *rq, struct task_struct *p, int flags) 
		sched_core_enqueue(rq, p);

}



void dequeue_task(struct rq *rq, struct task_struct *p, int flags)

/*

 * Must only return false when DEQUEUE_SLEEP.

 */

inline bool dequeue_task(struct rq *rq, struct task_struct *p, int flags)

{

	if (sched_core_enabled(rq))

		sched_core_dequeue(rq, p, flags);
@@ -2015,7 +2018,7 @@ void dequeue_task(struct rq *rq, struct task_struct *p, int flags) 
	}



	uclamp_rq_dec(rq, p);

	p->sched_class->dequeue_task(rq, p, flags);

	return p->sched_class->dequeue_task(rq, p, flags);

}



void activate_task(struct rq *rq, struct task_struct *p, int flags)

kernel/sched/deadline.c

+3 −1
Original line number Diff line number Diff line
@@ -2162,7 +2162,7 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) 
		enqueue_pushable_dl_task(rq, p);

}



static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)

static bool dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)

{

	update_curr_dl(rq);
@@ -2172,6 +2172,8 @@ static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) 
	dequeue_dl_entity(&p->dl, flags);

	if (!p->dl.dl_throttled && !dl_server(&p->dl))

		dequeue_pushable_dl_task(rq, p);



	return true;

}



/*

kernel/sched/fair.c

+3 −1
Original line number Diff line number Diff line
@@ -6865,7 +6865,7 @@ static void set_next_buddy(struct sched_entity *se); 
 * decreased. We remove the task from the rbtree and

 * update the fair scheduling stats:

 */

static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)

static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)

{

	struct cfs_rq *cfs_rq;

	struct sched_entity *se = &p->se;
@@ -6937,6 +6937,8 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
dequeue_throttle:

	util_est_update(&rq->cfs, p, task_sleep);

	hrtick_update(rq);



	return true;

}



#ifdef CONFIG_SMP

kernel/sched/idle.c

+2 −1
Original line number Diff line number Diff line
@@ -482,13 +482,14 @@ struct task_struct *pick_next_task_idle(struct rq *rq) 
 * It is not legal to sleep in the idle task - print a warning

 * message if some code attempts to do it:

 */

static void

static bool

dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)

{

	raw_spin_rq_unlock_irq(rq);

	printk(KERN_ERR "bad: scheduling from the idle thread!\n");

	dump_stack();

	raw_spin_rq_lock_irq(rq);

	return true;

}



/*

kernel/sched/rt.c

+3 −1
Original line number Diff line number Diff line
@@ -1483,7 +1483,7 @@ enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags) 
		enqueue_pushable_task(rq, p);

}



static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)

static bool dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)

{

	struct sched_rt_entity *rt_se = &p->rt;
@@ -1491,6 +1491,8 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags) 
	dequeue_rt_entity(rt_se, flags);



	dequeue_pushable_task(rq, p);



	return true;

}



/*