From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1A04C433F5 for ; Thu, 2 Dec 2021 00:40:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354762AbhLBAnQ (ORCPT ); Wed, 1 Dec 2021 19:43:16 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:37308 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354672AbhLBAm1 (ORCPT ); Wed, 1 Dec 2021 19:42:27 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D45E9B821A0; Thu, 2 Dec 2021 00:39:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1D1CC58323; Thu, 2 Dec 2021 00:39:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1638405540; bh=BRHANxcsivGosPx0a9A/RcSuNJZDaN1XchfalbMwHgE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=m8YF/fOzUUiUgaIHpowdLrl7SxyQj+zyqBBRJ2Uc74TVqkqSDdgsa03Vssw7W4Ve+ afaBgN1o9CJF2Ujq+zkDYuY/HkcS/bpAt8twqlh29ONB6phHolcpIZq7v8L8u+pwPs 34C6ElfvHmUs446NAG/T2mtzYn63nqigMzRdzoPQRtk+k6jSRp42DxgDYDFX4BwpAN UZpCVizXa0qWF/0aDa3QdZVba3/hRxD2z/Pnl01EbtLx/hdvahlmiKzbMUtmj0otvU zWSqsartL3IC40+/O0LIvr3qpdFvna8nKpjssNcOuYSZhLcvHmX2emzS7MaEmqOFrQ K8BBnr/YV59ZQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 5611E5C12AF; Wed, 1 Dec 2021 16:39:00 -0800 (PST) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" , Martin Lau , Neeraj Upadhyay Subject: [PATCH rcu 10/18] rcu-tasks: Abstract invocations of callbacks Date: Wed, 1 Dec 2021 16:38:50 -0800 Message-Id: <20211202003858.3129628-10-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20211202003826.GA3129369@paulmck-ThinkPad-P17-Gen-1> References: <20211202003826.GA3129369@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This commit adds a rcu_tasks_invoke_cbs() function that invokes all ready callbacks on all of the per-CPU lists that are currently in use. Reported-by: Martin Lau Cc: Neeraj Upadhyay Signed-off-by: Paul E. McKenney --- kernel/rcu/tasks.h | 58 ++++++++++++++++++++++++++++------------------ 1 file changed, 35 insertions(+), 23 deletions(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index bb37d4a4e48de..3bc0edb6a7bb6 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -256,14 +256,43 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp) return needgpcb; } -/* RCU-tasks kthread that detects grace periods and invokes callbacks. */ -static int __noreturn rcu_tasks_kthread(void *arg) +// Advance callbacks and invoke any that are ready. +static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp) { + int cpu; unsigned long flags; int len; - int needgpcb; struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl); struct rcu_head *rhp; + + for (cpu = 0; cpu < rtp->percpu_enqueue_lim; cpu++) { + struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu); + + if (rcu_segcblist_empty(&rtpcp->cblist)) + continue; + raw_spin_lock_irqsave_rcu_node(rtpcp, flags); + smp_mb__after_spinlock(); // Order updates vs. GP. + rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq)); + rcu_segcblist_extract_done_cbs(&rtpcp->cblist, &rcl); + raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); + len = rcl.len; + for (rhp = rcu_cblist_dequeue(&rcl); rhp; rhp = rcu_cblist_dequeue(&rcl)) { + local_bh_disable(); + rhp->func(rhp); + local_bh_enable(); + cond_resched(); + } + raw_spin_lock_irqsave_rcu_node(rtpcp, flags); + rcu_segcblist_add_len(&rtpcp->cblist, -len); + (void)rcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq)); + raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); + } +} + +/* RCU-tasks kthread that detects grace periods and invokes callbacks. */ +static int __noreturn rcu_tasks_kthread(void *arg) +{ + int needgpcb; struct rcu_tasks *rtp = arg; /* Run on housekeeping CPUs by default. Sysadm can move if desired. */ @@ -277,8 +306,6 @@ static int __noreturn rcu_tasks_kthread(void *arg) * This loop is terminated by the system going down. ;-) */ for (;;) { - struct rcu_tasks_percpu *rtpcp; - set_tasks_gp_state(rtp, RTGS_WAIT_CBS); /* If there were none, wait a bit and start over. */ @@ -293,25 +320,10 @@ static int __noreturn rcu_tasks_kthread(void *arg) rcu_seq_end(&rtp->tasks_gp_seq); } - /* Invoke the callbacks. */ + /* Invoke callbacks. */ set_tasks_gp_state(rtp, RTGS_INVOKE_CBS); - rtpcp = per_cpu_ptr(rtp->rtpcpu, 0); - raw_spin_lock_irqsave_rcu_node(rtpcp, flags); - smp_mb__after_spinlock(); // Order updates vs. GP. - rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq)); - rcu_segcblist_extract_done_cbs(&rtpcp->cblist, &rcl); - raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); - len = rcl.len; - for (rhp = rcu_cblist_dequeue(&rcl); rhp; rhp = rcu_cblist_dequeue(&rcl)) { - local_bh_disable(); - rhp->func(rhp); - local_bh_enable(); - cond_resched(); - } - raw_spin_lock_irqsave_rcu_node(rtpcp, flags); - rcu_segcblist_add_len(&rtpcp->cblist, -len); - (void)rcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq)); - raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); + rcu_tasks_invoke_cbs(rtp); + /* Paranoid sleep to keep this from entering a tight loop */ schedule_timeout_idle(rtp->gp_sleep); } -- 2.31.1.189.g2e36527f23