From mboxrd@z Thu Jan 1 00:00:00 1970 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 A42D916C451 for ; Fri, 5 Apr 2024 11:04:05 +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=1712315047; cv=none; b=nZQw4IFcoKmNK/fWdfvWBoPtkakVXNSFVJBsmUFwkd/LhbgjD75dZ2OJ3abc1gCjIj2PdAo5Kb8X0XQ3dOKpL+l8+KXw6ItviS9RqV1aT3yYmtbbgAnB2MYyOvpBPMkiUPstZgaOqxoF2ch5faWSM1wOKPzo0J0l5nCEemVqyfs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712315047; c=relaxed/simple; bh=nKS2WmuYGE6Nye140v5b3g89kHuVxIHGUJk53tUK2Yg=; h=Message-Id:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=K+76N6Z3alP3E/ZtW2PN8I2f9Ht+l7SkyXdsCXWbJsp2tC0o9L/81Sawo6NQzloGPN68kCmG/+fSgB7XhO3jJ6YjkrQLKALrVi2xJmFkDHXyg3W4D8ecrkKSBgsWUJKsuKTDJ33oPsfu/VB3c5gwBL/iOp93/8OhPfIbjkue+t0= 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=O5UkV30L; 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="O5UkV30L" 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=XqRGGtihCZYBUet+PwKwmohLFDruabUWfUMdx2OINkA=; b=O5UkV30LEO972j+CaiXeaYeWi2 etntYrEu5EVyDaxA4QaqECsLRCCRxXyKPkOzQ/ygkrtSu6kanWoirUtsdHzLvr8B/Otl3PM6bYSEi hsHjEchmuXi122lSdAsqb6iYzoimQWfRevgvadTgoCXualBOHLEA12p4JyQsVYcX84trGiyMWx2Zc YzqdaZZ1KzW4MoSCJLBA/e+xQvlktgfjX82BbijPJrEXxJp5AG9QOB53YnWfVNcmSGcV11q3zoX8t CjRmROtGtrOw/Z1LMjIL1rXT9fNuWdgITxg0lyeoQemDyyrsfkDEWL1rocRMQBCbnayKGfyg9JYZg /C42QNLw==; 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 1rshMH-00000005Z8j-27sk; Fri, 05 Apr 2024 11:03:48 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id 9354F302DA2; Fri, 5 Apr 2024 13:03:44 +0200 (CEST) Message-Id: <20240405110010.381534287@infradead.org> User-Agent: quilt/0.65 Date: Fri, 05 Apr 2024 12:28:00 +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, bristot@redhat.com, vschneid@redhat.com, linux-kernel@vger.kernel.org Cc: kprateek.nayak@amd.com, wuyun.abel@bytedance.com, tglx@linutronix.de, efault@gmx.de Subject: [RFC][PATCH 06/10] sched: Allow sched_class::dequeue_task() to fail References: <20240405102754.435410987@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 | 2 +- kernel/sched/stop_task.c | 3 ++- 7 files changed, 19 insertions(+), 8 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2119,7 +2119,10 @@ static inline void enqueue_task(struct r sched_core_enqueue(rq, p); } -static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags) +/* + * Must only return false when DEQUEUE_SLEEP. + */ +static inline bool dequeue_task(struct rq *rq, struct task_struct *p, int flags) { if (sched_core_enabled(rq)) sched_core_dequeue(rq, p, flags); @@ -2133,7 +2136,7 @@ static inline void dequeue_task(struct r } 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) --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1842,7 +1842,7 @@ static void enqueue_task_dl(struct rq *r 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); @@ -1852,6 +1852,8 @@ 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; } /* --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6828,7 +6828,7 @@ 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 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; @@ -6896,6 +6896,8 @@ static void dequeue_task_fair(struct rq dequeue_throttle: util_est_update(&rq->cfs, p, task_sleep); hrtick_update(rq); + + return true; } #ifdef CONFIG_SMP --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -486,13 +486,14 @@ 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; } /* --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1493,7 +1493,7 @@ enqueue_task_rt(struct rq *rq, struct ta 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; @@ -1501,6 +1501,8 @@ static void dequeue_task_rt(struct rq *r dequeue_rt_entity(rt_se, flags); dequeue_pushable_task(rq, p); + + return true; } /* --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2278,7 +2278,7 @@ struct sched_class { #endif 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); --- 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); } -static void +static bool dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags) { sub_nr_running(rq, 1); + return true; } static void yield_task_stop(struct rq *rq)