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=-8.9 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_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 E53FBC43219 for ; Sun, 28 Apr 2019 10:41:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B2D1D2075D for ; Sun, 28 Apr 2019 10:41:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Ub76poIb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726659AbfD1KlD (ORCPT ); Sun, 28 Apr 2019 06:41:03 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:40619 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726317AbfD1KlD (ORCPT ); Sun, 28 Apr 2019 06:41:03 -0400 Received: by mail-wr1-f67.google.com with SMTP id h4so11262666wre.7; Sun, 28 Apr 2019 03:41:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=Aq6KZKXYshsYr6wQQa5JDaIk1iwAj4PjtcG2teOpu38=; b=Ub76poIb4dSrREQS7HWOnhTZ6HEAayTxJnVzjnIS8uqYOqdhLvBcSpYWODtq8thFv0 pLQxvKaDxXX6iUB9N0vQBetxFxRDn+Clz9OTWVhgGUaNKe0tTRypRFM59EoxVNqlRlgb woGtSBc1NpXdj+66h+GDuZp25duF27LeiDJBtReycrTR1zvJVLfXNJrVyXFc3BjockLO ys75dGDkt5jt4p7iH+WMDCmNY7s0cV8eLk7uQO0Ds7q3ZfBER5+Fj8e1kCYEKtXG3nI0 c65UfzpwaeDcJTLOUnauf903+m9l+9z+f5Oz5OCkgBfMfCmToAQjPhnsMLZNIzGMLqxO jYNQ== 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; bh=Aq6KZKXYshsYr6wQQa5JDaIk1iwAj4PjtcG2teOpu38=; b=q55wbJy8xRaCJGEGmhnFdz7Y7NxNCc30tGT/g0CrZNnr/Djo5UDqyIbsrdtRSh9Wrc GcgKnXk66As0kPgxVIVT9MEP1hIhLlOA62y9uXbJ2GehfMxkabTUPN8c8XSZDmbNWXN/ jVk7C1vDva/N55M7QNnabHw9eY2myxVpar7Aj6GF0lXZtes5GzFglQ5DCV81UvEsGLdn megga39MTwkiv+YlET42dYvuolj5OH12yz5Hp0bOMG4MfFBfdVSSevCFZWM7bMT9Sbuu joex4LUb+hbufDRpj+CayRrYJT9RgjR3FdL65xUWE7OZluqJlLIiYuyqU0LUDeowx1Zd hC7w== X-Gm-Message-State: APjAAAXwtvO2+JTjCyzx2Wjzouruzcku2RVqjtk3kRR7tQNkGYIIM5zX Q44NzMHcE2dX6M5qM1f+s5Y= X-Google-Smtp-Source: APXvYqzJXCDBMZpSX51c0rY7j9QFCYoCttdhjUVj7uaan2hgh4ct2FFnZAF2xaULbDdPrxWXsp6DBg== X-Received: by 2002:a5d:624d:: with SMTP id m13mr13063359wrv.305.1556448061196; Sun, 28 Apr 2019 03:41:01 -0700 (PDT) Received: from felia.fritz.box ([2001:16b8:2d1d:6500:d144:1911:67c7:5b22]) by smtp.gmail.com with ESMTPSA id e5sm1860032wrh.79.2019.04.28.03.40.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 28 Apr 2019 03:41:00 -0700 (PDT) From: Lukas Bulwahn To: Shaohua Li , Neil Brown , Arnd Bergmann , Himanshu Jha Cc: clang-built-linux@googlegroups.com, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, Lukas Bulwahn Subject: [PATCH] md: properly lock and unlock in rdev_attr_store() Date: Sun, 28 Apr 2019 12:40:41 +0200 Message-Id: <20190428104041.11262-1-lukas.bulwahn@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org rdev_attr_store() should lock and unlock mddev->reconfig_mutex in a balanced way with mddev_lock() and mddev_unlock(). But when rdev->mddev is NULL, rdev_attr_store() would try to unlock without locking before. Resolve this locking issue.. This locking issue was detected with Clang Thread Safety Analyser: drivers/md/md.c:3393:3: warning: releasing mutex 'mddev->reconfig_mutex' that was not held [-Wthread-safety-analysis] mddev_unlock(mddev); ^ This warning was reported after annotating mutex functions and mddev_lock() and mddev_unlock(). Fixes: 27c529bb8e90 ("md: lock access to rdev attributes properly") Link: https://groups.google.com/d/topic/clang-built-linux/CvBiiQLB0H4/discussion Signed-off-by: Lukas Bulwahn --- Arnd, Neil, here a proposal to fix lock and unlocking asymmetry. I quite sure that if mddev is NULL, it should just return. I am still puzzled if the return value from mddev_lock() should be really return by rdev_attr_store() when it is not 0. But that was the behaviour before, so I will keep it that way. drivers/md/md.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 05ffffb8b769..a9735d8f1e70 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -3384,7 +3384,9 @@ rdev_attr_store(struct kobject *kobj, struct attribute *attr, return -EIO; if (!capable(CAP_SYS_ADMIN)) return -EACCES; - rv = mddev ? mddev_lock(mddev): -EBUSY; + if (!mddev) + return -EBUSY; + rv = mddev_lock(mddev); if (!rv) { if (rdev->mddev == NULL) rv = -EBUSY; -- 2.17.1