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=-10.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 D882FC433DF for ; Wed, 13 May 2020 16:47:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B480207C4 for ; Wed, 13 May 2020 16:47:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589388457; bh=DpqSfsq1NEtjbPTH3BFadiNAreRXsV2vPnKorvlK8ws=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rPzoY6FaYJh8MoI9abVhiYJFI2Yn6Y1jbMz68Bt8vzsjhPv2ZvtpFaCJuMWP++4mY VFnkFCau3xPYdicM4zgELErMFOSQMBSgG2Ji4X4mLrihi1K30v5DlIe9jTOp6QVOst tGprcdizcYDAvkv56KGIoWsaEVup0tGiKwbcKZKE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389769AbgEMQrf (ORCPT ); Wed, 13 May 2020 12:47:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:53460 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389749AbgEMQrb (ORCPT ); Wed, 13 May 2020 12:47:31 -0400 Received: from lenoir.home (lfbn-ncy-1-985-231.w90-101.abo.wanadoo.fr [90.101.63.231]) (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 0E1F420794; Wed, 13 May 2020 16:47:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589388451; bh=DpqSfsq1NEtjbPTH3BFadiNAreRXsV2vPnKorvlK8ws=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lhDTh4QdCOE7/RLfFy+shT69iXAxT+qpry12C0XA+kijbcpB1sm+W8KtRYnvU4z8l nW2Opkh8g6IPYxxMTSdpOQwqVNGSEMhDhytKIwwIC89yiiEf+eBeUv1wtSXNFxm8G3 xYyVlTlaQRA0+KbfZH1mB3koT2vLwBZL5yNmOZ+0= From: Frederic Weisbecker To: "Paul E . McKenney" Cc: LKML , Frederic Weisbecker , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , Josh Triplett Subject: [PATCH 06/10] rcu: Make nocb_cb kthread parkable Date: Wed, 13 May 2020 18:47:10 +0200 Message-Id: <20200513164714.22557-7-frederic@kernel.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200513164714.22557-1-frederic@kernel.org> References: <20200513164714.22557-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This will be necessary to correctly implement rdp de-offloading. We don't want rcu_do_batch() in nocb_cb kthread to race with local rcu_do_batch(). Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Josh Triplett Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes --- kernel/rcu/tree_plugin.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 1dd3fdd675a1..43ecc047af26 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2104,7 +2104,9 @@ static void nocb_cb_wait(struct rcu_data *rdp) if (needwake_gp) rcu_gp_kthread_wake(); swait_event_interruptible_exclusive(rdp->nocb_cb_wq, - !READ_ONCE(rdp->nocb_cb_sleep)); + !READ_ONCE(rdp->nocb_cb_sleep) || + kthread_should_park()); + if (!smp_load_acquire(&rdp->nocb_cb_sleep)) { /* VVV */ /* ^^^ Ensure CB invocation follows _sleep test. */ return; @@ -2125,6 +2127,8 @@ static int rcu_nocb_cb_kthread(void *arg) // if there are no more ready callbacks, waits for them. for (;;) { nocb_cb_wait(rdp); + if (kthread_should_park()) + kthread_parkme(); cond_resched_tasks_rcu_qs(); } return 0; -- 2.25.0