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,URIBL_BLOCKED,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 C1E5BC388F7 for ; Fri, 13 Nov 2020 12:14:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D34F2224B for ; Fri, 13 Nov 2020 12:14:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="yHTWZTHs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726854AbgKMMOW (ORCPT ); Fri, 13 Nov 2020 07:14:22 -0500 Received: from mail.kernel.org ([198.145.29.99]:47900 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726789AbgKMMOM (ORCPT ); Fri, 13 Nov 2020 07:14:12 -0500 Received: from localhost.localdomain (unknown [176.167.84.141]) (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 D908622256; Fri, 13 Nov 2020 12:14:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605269651; bh=IjHN6FJZQNuUqJqIsvv8P68KcVqB1SYMXMfYEjj/c5Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yHTWZTHs+SFXiT5zex/ZgHWnqHKcuzen8jAVom2WRksmzln3hhcavIWLaVZrNCicb +ztfT0P+oP/WY0ycwsrke3mKw0YA5HZo88YR85VxzR7nfkEUw9iK5JT01IWLqoy2mB H6zDowpDS9QlOSpTvXg4g3BueVLsRMmXh7/pgp3c= From: Frederic Weisbecker To: "Paul E . McKenney" Cc: LKML , Frederic Weisbecker , Steven Rostedt , Thomas Gleixner , Mathieu Desnoyers , Boqun Feng , Lai Jiangshan , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , rcu@vger.kernel.org Subject: [PATCH 09/19] rcu: Flush bypass before setting SEGCBLIST_SOFTIRQ_ONLY Date: Fri, 13 Nov 2020 13:13:24 +0100 Message-Id: <20201113121334.166723-10-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201113121334.166723-1-frederic@kernel.org> References: <20201113121334.166723-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Make sure to handle the pending bypass queue before we switch to the final de-offload state. We'll have to be careful and later set SEGCBLIST_SOFTIRQ_ONLY before re-enabling again IRQs, or new bypass callbacks could be queued in the meantine. Inspired-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Josh Triplett Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes Cc: Neeraj Upadhyay Cc: Thomas Gleixner Cc: Boqun Feng --- kernel/rcu/tree_plugin.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 44b4ab9b3953..dfb4b62c6b88 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2339,12 +2339,21 @@ static int __rcu_nocb_rdp_deoffload(struct rcu_data *rdp) swait_event_exclusive(rdp->nocb_state_wq, !rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB | SEGCBLIST_KTHREAD_GP)); + rcu_nocb_lock_irqsave(rdp, flags); /* Make sure nocb timer won't stay around */ - rcu_nocb_lock_irqsave(rdp, flags); WRITE_ONCE(rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_OFF); rcu_nocb_unlock_irqrestore(rdp, flags); del_timer_sync(&rdp->nocb_timer); + /* + * Flush bypass. While IRQs are disabled and once we set + * SEGCBLIST_SOFTIRQ_ONLY, no callback is supposed to be + * enqueued on bypass. + */ + rcu_nocb_lock_irqsave(rdp, flags); + rcu_nocb_flush_bypass(rdp, NULL, jiffies); + rcu_nocb_unlock_irqrestore(rdp, flags); + return ret; } -- 2.25.1