From nobody Sun Dec 14 06:16:16 2025 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B88CB77113 for ; Sat, 27 Jul 2024 11:02:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722078150; cv=none; b=nQang4pZgNW3Y+VyPMMy/8RT9er4DNyRhgesnhXWQkG12V1XUnETZ/8Y9IEoV/ETzGtxhjl0a8e3boeQy1kj+uDafhACIEHev7LtbVQh+1qDR3MiaNLwLjEvMAVy4/7IVwFITYwWZYAEpnCa4ZCAr7G8robCN67GMFue/rWUBlo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722078150; c=relaxed/simple; bh=nhL59T6elYdLuyB0RjGQo0N9qwu/eI7fAleBo/HW70I=; h=Message-Id:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=OChTs/aLVTFwaKYjDc3+8emYRy+2QLiPJrqvMhTUwdKLR5k6LVi3cPrUsLJ9LSmd9x245zWEJ7ubqbcrpNUjxbJx1UNKXuyp5wupI+EXVBbrdi2Ucb9zOvxss4e4qgoDzOSKu5lzW0E3upIzglBqzml/BrMqObRIHtT+LGDBhPs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=IycGFN9A; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="IycGFN9A" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=FRzZ9IuL6b8fEH7RF9UvkS800H6XvcRuToO64xLZ6Jc=; b=IycGFN9AEvXI5Nmvm/QbZAi7wN 0JRgGNbbT8RilcTR0njK3Iq2TK96dxfNBjyRnM9eghJ8SiaGkbvZpjecLEjl9TT7hPgWfi6RXENIS hXiYkN4BqBLMwXpz8j1uS8mPbzuZNr2jQkSJrfcW9XHZc4irKl75VBvK4E/CHScLxOnl4FfKyGGE/ a0WF5PxlhjakrtX2oI3KPSJu7D/OfIN9tlb1ZPKY/lle9ocytCQMt861cCjlXWE+PO4q6tcAL3khu rvo1P1xFUauTGRdwwcuQWHkKnQFCM9A8+FYLXdLKoBP5wMeju8dOKGtx5mwgomx77Iorsph0RbTZV PkfXJfuQ==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.97.1 #2 (Red Hat Linux)) id 1sXfBg-00000004QMe-0fE9; Sat, 27 Jul 2024 11:02:20 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id A4EB53018AA; Sat, 27 Jul 2024 13:02:06 +0200 (CEST) Message-Id: <20240727105028.864630153@infradead.org> User-Agent: quilt/0.65 Date: Sat, 27 Jul 2024 12:27:38 +0200 From: Peter Zijlstra To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org Cc: kprateek.nayak@amd.com, wuyun.abel@bytedance.com, youssefesmat@chromium.org, tglx@linutronix.de, efault@gmx.de Subject: [PATCH 06/24] sched: Allow sched_class::dequeue_task() to fail References: <20240727102732.960974693@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Change the function signature of sched_class::dequeue_task() to return a boolean, allowing future patches to 'fail' dequeue. Signed-off-by: Peter Zijlstra (Intel) --- kernel/sched/core.c | 7 +++++-- kernel/sched/deadline.c | 4 +++- kernel/sched/fair.c | 4 +++- kernel/sched/idle.c | 3 ++- kernel/sched/rt.c | 4 +++- kernel/sched/sched.h | 4 ++-- kernel/sched/stop_task.c | 3 ++- 7 files changed, 20 insertions(+), 9 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2001,7 +2001,10 @@ void enqueue_task(struct rq *rq, struct sched_core_enqueue(rq, p); } =20 -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 } =20 uclamp_rq_dec(rq, p); - p->sched_class->dequeue_task(rq, p, flags); + return p->sched_class->dequeue_task(rq, p, flags); } =20 void activate_task(struct rq *rq, struct task_struct *p, int flags) --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -2162,7 +2162,7 @@ static void enqueue_task_dl(struct rq *r enqueue_pushable_dl_task(rq, p); } =20 -static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flag= s) +static bool dequeue_task_dl(struct rq *rq, struct task_struct *p, int flag= s) { update_curr_dl(rq); =20 @@ -2172,6 +2172,8 @@ static void dequeue_task_dl(struct rq *r dequeue_dl_entity(&p->dl, flags); if (!p->dl.dl_throttled && !dl_server(&p->dl)) dequeue_pushable_dl_task(rq, p); + + return true; } =20 /* --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6865,7 +6865,7 @@ static void set_next_buddy(struct sched_ * 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 fl= ags) +static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int fl= ags) { struct cfs_rq *cfs_rq; struct sched_entity *se =3D &p->se; @@ -6937,6 +6937,8 @@ static void dequeue_task_fair(struct rq dequeue_throttle: util_est_update(&rq->cfs, p, task_sleep); hrtick_update(rq); + + return true; } =20 #ifdef CONFIG_SMP --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -482,13 +482,14 @@ struct task_struct *pick_next_task_idle( * 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; } =20 /* --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1483,7 +1483,7 @@ enqueue_task_rt(struct rq *rq, struct ta enqueue_pushable_task(rq, p); } =20 -static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flag= s) +static bool dequeue_task_rt(struct rq *rq, struct task_struct *p, int flag= s) { struct sched_rt_entity *rt_se =3D &p->rt; =20 @@ -1491,6 +1491,8 @@ static void dequeue_task_rt(struct rq *r dequeue_rt_entity(rt_se, flags); =20 dequeue_pushable_task(rq, p); + + return true; } =20 /* --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2285,7 +2285,7 @@ struct sched_class { #endif =20 void (*enqueue_task) (struct rq *rq, struct task_struct *p, int flags); - void (*dequeue_task) (struct rq *rq, struct task_struct *p, int flags); + bool (*dequeue_task) (struct rq *rq, struct task_struct *p, int flags); void (*yield_task) (struct rq *rq); bool (*yield_to_task)(struct rq *rq, struct task_struct *p); =20 @@ -3606,7 +3606,7 @@ extern int __sched_setaffinity(struct ta extern void __setscheduler_prio(struct task_struct *p, int prio); extern void set_load_weight(struct task_struct *p, bool update_load); extern void enqueue_task(struct rq *rq, struct task_struct *p, int flags); -extern void dequeue_task(struct rq *rq, struct task_struct *p, int flags); +extern bool dequeue_task(struct rq *rq, struct task_struct *p, int flags); =20 extern void check_class_changed(struct rq *rq, struct task_struct *p, const struct sched_class *prev_class, --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -57,10 +57,11 @@ enqueue_task_stop(struct rq *rq, struct add_nr_running(rq, 1); } =20 -static void +static bool dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags) { sub_nr_running(rq, 1); + return true; } =20 static void yield_task_stop(struct rq *rq)