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=-10.1 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,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 720BFC35242 for ; Fri, 14 Feb 2020 23:57:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 471B624688 for ; Fri, 14 Feb 2020 23:57:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581724651; bh=Nk4+jqw8EBoCH7Z8k70fREwvdIqjrxQXbTMgrJECdbA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CSyeXh9EQZQ3Zr9CDfmKp3Fi1kD60eV7ZoVIRbH7qIFVCvzbhl21rXiSs5j/1dEOP 0ha1/IKD3Ioc2ECS2+iW7R2DtViazQP2aQBve2elgLB/aY3Y4aYj+cu20cEhRqKHdl lIccRuckTOcTnxspvdsKhTeHo2EeA8CxokjlukHE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728648AbgBNX5a (ORCPT ); Fri, 14 Feb 2020 18:57:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:37330 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728202AbgBNX51 (ORCPT ); Fri, 14 Feb 2020 18:57:27 -0500 Received: from paulmck-ThinkPad-P72.c.hoisthospitality.com (unknown [62.84.152.189]) (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 0BE36222C4; Fri, 14 Feb 2020 23:57:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581724647; bh=Nk4+jqw8EBoCH7Z8k70fREwvdIqjrxQXbTMgrJECdbA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MjQYVybysNAR9bcLqw0RvDjST/uS8p/g4MO7aA6MYSEUlNy8UKby/joVIDwGWXily bDXfSmjyvw0DaPgeFYmX5FPPHnOVY67rqUSPwCGF1wxwC/8xUkcuYIlIQ408or93ih TWCOneMJChVerfWr6FVmTB/8SeHn387z5v6QLlBo= 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, Amol Grover , "Paul E . McKenney" Subject: [PATCH tip/core/rcu 21/30] rculist: Add brackets around cond argument in __list_check_rcu macro Date: Fri, 14 Feb 2020 15:55:58 -0800 Message-Id: <20200214235607.13749-21-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200214235536.GA13364@paulmck-ThinkPad-P72> References: <20200214235536.GA13364@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Amol Grover Passing a complex lockdep condition to __list_check_rcu results in false positive lockdep splat due to incorrect expression evaluation. For example, a lockdep check condition `cond1 || cond2` is evaluated as `!cond1 || cond2 && !rcu_read_lock_any_held()` which, according to operator precedence, evaluates to `!cond1 || (cond2 && !rcu_read_lock_any_held())`. This would result in a lockdep splat when cond1 is false and cond2 is true which is logically incorrect. Signed-off-by: Amol Grover Acked-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- include/linux/rculist.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/rculist.h b/include/linux/rculist.h index 9f313e4..8214cdc 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -60,9 +60,9 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list) #define __list_check_rcu(dummy, cond, extra...) \ ({ \ check_arg_count_one(extra); \ - RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(), \ + RCU_LOCKDEP_WARN(!(cond) && !rcu_read_lock_any_held(), \ "RCU-list traversed in non-reader section!"); \ - }) + }) #else #define __list_check_rcu(dummy, cond, extra...) \ ({ check_arg_count_one(extra); }) -- 2.9.5