From nobody Tue Feb 10 18:36:53 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1986B1FA844; Wed, 18 Dec 2024 16:50:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734540624; cv=none; b=cmD+kjNTzx/XGEHrwK1mb+w79hNKtHGEQMoAq6K+UXf+4/zgaJUEuDobchLAh3tebYvSDf2oS5f5dyzmQ27NY91C1olpDOLO4DDdKTOzA5+ZpIiW/zXDCBQlYoM9uoZxIa0Kmm9ojKhQQQCD+2zl+JWZkPT7HYe9x4ve7JEqi4E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734540624; c=relaxed/simple; bh=wsSFbaS5gHpFjn7Wfsdir/WXJuDIjV9rXiSlyPWPMQc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gi2k/4oYrsaXDphOzvJz6x6MrYR5ABpBlqe/UWIQGhLqBq02vpb1GtuTiJiS7S/fP/628+x5rlWpTF+DV5oyG2W0CVH7970qHZ1eyNWfNj7x8FQZLLWDyV7QQZuP6out5mQP1bR0JWuAScM/PBK2EqKGBWhAs2OCwDIO9brFSaU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Z6pUHtUW; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Z6pUHtUW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 62F96C4CED0; Wed, 18 Dec 2024 16:50:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734540623; bh=wsSFbaS5gHpFjn7Wfsdir/WXJuDIjV9rXiSlyPWPMQc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Z6pUHtUWCameKpZ4NRaIU4vIuWoERimsAki4k6i1Ijt4tNNLR1XEXTcK3nnW+jyPR Ye7udxzSuydTcufbCs7GvxWaYurgu14Vm1axhtrSRcu9ipj/mLNst8gdC3h+JZnDjH 2j7d/ZAeBGgMQ197/3FX+7m0CE4SyWbxzTHmvY+U+ao7KR7O8uBM58F6oSI+8jupeD iiDXpfSQ/QGJi7hL7R1CUODvj+kY1JbCe8wll2PffppcVReMysaXOZP2i6Hrk9KMpe 5vH1SngktU6IlH1waUGNnG02ve428tLelPYlTatX4C9lGOpEl8C73/lbJZ8Y0uw9NI PtJIBRTRJDCrg== From: Frederic Weisbecker To: Thomas Gleixner Cc: LKML , Frederic Weisbecker , vlad.wing@gmail.com, rcu@vger.kernel.org, boqun.feng@gmail.com, joel@joelfernandes.org, neeraj.upadhyay@amd.com, urezki@gmail.com, qiang.zhang1211@gmail.com, Cheng-Jui.Wang@mediatek.com, leitao@debian.org, kernel-team@meta.com, Usama Arif , paulmck@kernel.org, Anna-Maria Behnsen Subject: [PATCH 2/3] rcu: Remove swake_up_one_online() bandaid Date: Wed, 18 Dec 2024 17:50:07 +0100 Message-ID: <20241218165008.37820-3-frederic@kernel.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20241218165008.37820-1-frederic@kernel.org> References: <20241218165008.37820-1-frederic@kernel.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" It's now ok to perform a wake-up from an offline CPU because the resulting armed scheduler bandwidth hrtimers are now correctly targeted by hrtimer infrastructure. Remove the obsolete hackerry. Signed-off-by: Frederic Weisbecker --- kernel/rcu/tree.c | 34 +--------------------------------- kernel/rcu/tree_exp.h | 2 +- kernel/rcu/tree_nocb.h | 2 +- 3 files changed, 3 insertions(+), 35 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index c160e05dfb7c..576b5c365145 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1060,38 +1060,6 @@ static bool rcu_future_gp_cleanup(struct rcu_node *r= np) return needmore; } =20 -static void swake_up_one_online_ipi(void *arg) -{ - struct swait_queue_head *wqh =3D arg; - - swake_up_one(wqh); -} - -static void swake_up_one_online(struct swait_queue_head *wqh) -{ - int cpu =3D get_cpu(); - - /* - * If called from rcutree_report_cpu_starting(), wake up - * is dangerous that late in the CPU-down hotplug process. The - * scheduler might queue an ignored hrtimer. Defer the wake up - * to an online CPU instead. - */ - if (unlikely(cpu_is_offline(cpu))) { - int target; - - target =3D cpumask_any_and(housekeeping_cpumask(HK_TYPE_RCU), - cpu_online_mask); - - smp_call_function_single(target, swake_up_one_online_ipi, - wqh, 0); - put_cpu(); - } else { - put_cpu(); - swake_up_one(wqh); - } -} - /* * Awaken the grace-period kthread. Don't do a self-awaken (unless in an * interrupt or softirq handler, in which case we just might immediately @@ -1116,7 +1084,7 @@ static void rcu_gp_kthread_wake(void) return; WRITE_ONCE(rcu_state.gp_wake_time, jiffies); WRITE_ONCE(rcu_state.gp_wake_seq, READ_ONCE(rcu_state.gp_seq)); - swake_up_one_online(&rcu_state.gp_wq); + swake_up_one(&rcu_state.gp_wq); } =20 /* diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index fb664d3a01c9..17b1a5e3590c 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -200,7 +200,7 @@ static void __rcu_report_exp_rnp(struct rcu_node *rnp, if (rnp->parent =3D=3D NULL) { raw_spin_unlock_irqrestore_rcu_node(rnp, flags); if (wake) - swake_up_one_online(&rcu_state.expedited_wq); + swake_up_one(&rcu_state.expedited_wq); =20 break; } diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index 2605dd234a13..a43141a1b3a5 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -216,7 +216,7 @@ static bool __wake_nocb_gp(struct rcu_data *rdp_gp, raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags); if (needwake) { trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("DoWake")); - swake_up_one_online(&rdp_gp->nocb_gp_wq); + swake_up_one(&rdp_gp->nocb_gp_wq); } =20 return needwake; --=20 2.46.0