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=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 1E513C33CB1 for ; Sat, 18 Jan 2020 16:56:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE95C21D7D for ; Sat, 18 Jan 2020 16:55:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Cuzk/v2r" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726460AbgARQz7 (ORCPT ); Sat, 18 Jan 2020 11:55:59 -0500 Received: from mail-pg1-f195.google.com ([209.85.215.195]:41750 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726413AbgARQz7 (ORCPT ); Sat, 18 Jan 2020 11:55:59 -0500 Received: by mail-pg1-f195.google.com with SMTP id x8so13254295pgk.8; Sat, 18 Jan 2020 08:55:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=pHjwyacvYMGoFpBb1ji3Ywgw20nYhNtNHuaRMfwxOs0=; b=Cuzk/v2rmZxlFbH1iwUh1jcfOyH4GZH0PoB4rDQhzMC2VZ2cGsxXT9sS8GasXDNIrs AlkuBGsxK98YSd2RFM9FbmvQRmcTlP7ka5xpTSFIeeSrSSB66mfDh23S31ELk/vz4em7 Xihf1bM4Akxd0ppex6SP3ivSR/QIiC4evnsYdRjidZDmg3g13H2z9RfxAFCd3QM8WZIS Cq7lun7KzCXChlt7+hGEnCInXMEwtm4YUQ6DjASR/NR4W+yeyH/xYjuSlbzcM6aCIsHe XpqFLy0aLpOkeieWgjx5Pgg1S5JSnNp1SuLaCeskvY7Kiw2ZYUptTRgjfjWB331VY5Ki eluA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=pHjwyacvYMGoFpBb1ji3Ywgw20nYhNtNHuaRMfwxOs0=; b=bvbU63ask1hhNH0MQbOPyHbs8fhhvkCXR6kqVp4dSUo81kS+g2MIsD9QKOQuQKX3n1 2w/uQU9pdawuFX2Dqcbex5/YV9PxRy1sdF12gUCEubInmyl4fYu5X9KBjeIkdtGE0RMJ CQv/to1HRQxC92FjBa+9dZn1uA1VLIG34bQ/ZrAmeKigg6kvddKlGny9RJMjE04n5lCu +8LbJReRiR+MCSwtgkk0oT0vG4XeLdOwuvSeLhVJRo4or7AgjdP3CHZtf3CtrSAfMx/x YCi6oRRWkohDMjvdPJA5OKhVaQo+vv9hWBidkycxfr7gKP/jqYWkiUzRd4sIETkNSxh3 TSRQ== X-Gm-Message-State: APjAAAUt+4RpRfrcuAX/3LfGljpk6u///z55l/HXmoO7xKycSB254scc +tFnmr3/MAGqJRl+gOz9jt6FaxD8 X-Google-Smtp-Source: APXvYqzL3uU0K97mb0rwv+HwRhmmpc3cE2p0938r2jZsWjKwjG8pFWjesMBAZ1rEpZFisR48RYDyNA== X-Received: by 2002:aa7:80c5:: with SMTP id a5mr8989492pfn.53.1579366558488; Sat, 18 Jan 2020 08:55:58 -0800 (PST) Received: from localhost.localdomain ([146.196.37.181]) by smtp.googlemail.com with ESMTPSA id s7sm12389009pjk.22.2020.01.18.08.55.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 18 Jan 2020 08:55:58 -0800 (PST) From: Amol Grover To: "Paul E. McKenney" , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, Madhuparna Bhowmik , Amol Grover Subject: [PATCH] rculist: Add brackets around cond argument in __list_check_rcu macro Date: Sat, 18 Jan 2020 22:24:18 +0530 Message-Id: <20200118165417.12325-1-frextrite@gmail.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org 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 --- 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 4158b7212936..dce491f0b354 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -50,9 +50,9 @@ 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); }) -- 2.24.1