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 X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD4C2C433E2 for ; Mon, 31 Aug 2020 18:12:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BA7A2083E for ; Mon, 31 Aug 2020 18:12:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897539; bh=Rv0QZkvfDdaY44ySjZ0q9xWVE/nXdfi0BEhRe/LkNJI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=t4kHlxOcUFpBJaC50MNd63BK7RzCwo4VpFpnXn1fgT/teZQ7RjutmJlwdditAXQ5N yWOyKuCkAjQXSARjNFARC7KDh9Oo66LewsAKqNlfwnVn3VyTakoi6lESAgI4id82J/ qU/IxeymGtJL0HnUbN8v0+aEP6TXayzfbOciw8p0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729395AbgHaSMP (ORCPT ); Mon, 31 Aug 2020 14:12:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:36202 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729214AbgHaSL0 (ORCPT ); Mon, 31 Aug 2020 14:11:26 -0400 Received: from paulmck-ThinkPad-P72.home (unknown [50.45.173.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 89D5021582; Mon, 31 Aug 2020 18:11:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897483; bh=Rv0QZkvfDdaY44ySjZ0q9xWVE/nXdfi0BEhRe/LkNJI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F//kdZpK/us8mF8Zv8ksYtCpbBUxKNMMifuPBJnt9UsxtRgquv3eedgLk+a+ETbCr HgIYRfnGP7+bbtscWsgElFzmgvyH9K0/Vw/7/SdIpERs0aNkbObVRGYvWgJivaATIm TzCVKWMwZFTP/ocDD12LzQcyFATKbRszLvjcHAkE= From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.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" Subject: [PATCH tip/core/rcu 09/13] rcu: IPI all CPUs at GP end for strict GPs Date: Mon, 31 Aug 2020 11:11:16 -0700 Message-Id: <20200831181120.1044-9-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200831181101.GA950@paulmck-ThinkPad-P72> References: <20200831181101.GA950@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" Currently, each CPU discovers the end of a given grace period on its own time, which is again good for efficiency but bad for fast grace periods, given that it is things like kfree() within the RCU callbacks that will cause trouble for pointers leaked from RCU read-side critical sections. This commit therefore uses on_each_cpu() to IPI each CPU after grace-period cleanup in order to inform each CPU of the end of the old grace period in a timely manner, but only in kernels build with CONFIG_RCU_STRICT_GRACE_PERIOD=y. Reported-by Jann Horn Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 88f4fa6..4bbedfc 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2052,6 +2052,10 @@ static void rcu_gp_cleanup(void) rcu_state.gp_flags & RCU_GP_FLAG_INIT); } raw_spin_unlock_irq_rcu_node(rnp); + + // If strict, make all CPUs aware of the end of the old grace period. + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) + on_each_cpu(rcu_strict_gp_boundary, NULL, 0); } /* -- 2.9.5