From patchwork Thu Jan 5 00:44:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 13089318 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 15EB3C54E76 for ; Thu, 5 Jan 2023 00:49:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229457AbjAEAt2 (ORCPT ); Wed, 4 Jan 2023 19:49:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51944 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229493AbjAEAsG (ORCPT ); Wed, 4 Jan 2023 19:48:06 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F57630572; Wed, 4 Jan 2023 16:45:05 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id D4116618A0; Thu, 5 Jan 2023 00:45:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34C8EC433EF; Thu, 5 Jan 2023 00:45:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672879503; bh=kVT1HGBSl7LGywi0JFiEDrUmFvLHman/Yt/MTgK22Cc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QZg3Vmw+pnalljHEBPfGidZfVJkNWzTbNxrTJFrdmuXLqMrtlKhIyYsJJGwxSCfVm GyJGL7lJPn4EJ+Q60cntcETE+DTa4JH8nyT4Yl/ED+9N5xeiMWVsaBhKUWsktO3Xlo VMwSNlq3HcA4h8Urxcn0wXUeeb8t5FNXnRWK+WcntYtmyvkq/8O4ALU/nBAMr+sQ3i RwQx2iTPhm7b3GNoxCk4rdJXhUXqC4HJbPZIw7L0Shs1cXWNhwD3+u26B/O+5Kgu9+ zOofsWii/ioo/yezCYFuy+9nIdNSMYHzfq9MgxKK5UB6iCDWFK7ivgbxZRpZ8ROy5l ucIF1h1pRWU1Q== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id E11DC5C149B; Wed, 4 Jan 2023 16:45:02 -0800 (PST) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, Frederic Weisbecker , Boqun Feng , "Paul E . McKenney" , Neeraj Upadhyay , Lai Jiangshan Subject: [PATCH rcu 3/6] rcu-tasks: Remove preemption disablement around srcu_read_[un]lock() calls Date: Wed, 4 Jan 2023 16:44:53 -0800 Message-Id: <20230105004501.1771332-5-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20230105004454.GA1771168@paulmck-ThinkPad-P17-Gen-1> References: <20230105004454.GA1771168@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: Frederic Weisbecker Ever since the following commit: 5a41344a3d83 ("srcu: Simplify __srcu_read_unlock() via this_cpu_dec()") SRCU doesn't rely anymore on preemption to be disabled in order to modify the per-CPU counter. And even then it used to be done from the API itself. Therefore and after checking further, it appears to be safe to remove the preemption disablement around __srcu_read_[un]lock() in exit_tasks_rcu_start() and exit_tasks_rcu_finish() Suggested-by: Boqun Feng Suggested-by: Paul E. McKenney Suggested-by: Neeraj Upadhyay Cc: Lai Jiangshan Signed-off-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney --- kernel/rcu/tasks.h | 4 ---- 1 file changed, 4 deletions(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 50d4c0ec7a89f..fbaed2637a7ff 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1008,9 +1008,7 @@ EXPORT_SYMBOL_GPL(show_rcu_tasks_classic_gp_kthread); */ void exit_tasks_rcu_start(void) __acquires(&tasks_rcu_exit_srcu) { - preempt_disable(); current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu); - preempt_enable(); } /* @@ -1022,9 +1020,7 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu) { struct task_struct *t = current; - preempt_disable(); __srcu_read_unlock(&tasks_rcu_exit_srcu, t->rcu_tasks_idx); - preempt_enable(); exit_tasks_rcu_finish_trace(t); }