From patchwork Thu Jul 22 09:29:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Desmond Cheong Zhi Xi X-Patchwork-Id: 12393605 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=-13.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 726B4C6377D for ; Thu, 22 Jul 2021 09:30:14 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 431496120C for ; Thu, 22 Jul 2021 09:30:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 431496120C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id AA8806EE7C; Thu, 22 Jul 2021 09:30:13 +0000 (UTC) Received: from mail-pl1-x62d.google.com (mail-pl1-x62d.google.com [IPv6:2607:f8b0:4864:20::62d]) by gabe.freedesktop.org (Postfix) with ESMTPS id C7A296EE7C; Thu, 22 Jul 2021 09:30:11 +0000 (UTC) Received: by mail-pl1-x62d.google.com with SMTP id n11so3787738plc.2; Thu, 22 Jul 2021 02:30:11 -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:in-reply-to:references :mime-version:content-transfer-encoding; bh=RSgVdB0+HpET8iLINuWOoeOWDDxUJjmmluxZNEz35KA=; b=o6LJ/myMP6JO8ChH8dYoqq21TZnuVfWqQC7aMNZVbEwvgt/wmupSJe5X7mUycZZ1OP wZUOpxPzR0Di4iK476owf2txOnd8aRvZIuWOSyNSQwF8qAfJx1gZjc1rqQNENDcoU4k8 pWfm16Rm2AyVdjC+e3kTofDMg7W/f1X4eU9NPEhv7mUcvN6ebC/kCdQLgGMJIgNOCd38 Z79Cpgk8vmBkJLmcW9tTTfCW8TJv/6nRrpzuj2HycvK3LMZlVo0xpmCpHif6k1kmeqBf /hzT0Pmizi11dqx4L91lE1OKq6ULDL3w/A5pjP58k83vlOPYfDR9I9UDXt06Iw0JzA4O hv7w== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=RSgVdB0+HpET8iLINuWOoeOWDDxUJjmmluxZNEz35KA=; b=ompWVo1nAMaZPZ9ck8m/pAr5jcWYm+23OvsMO0DYy95WPdzNSWicw07M99kOXEjF4I 8RwKS80tqXJFJFN46gg+DdVpPSqvlLOdtM0R2I7fOgiHXbMqKkKIgBRAn2UcFA1ocfj9 aFDyy0xPSNlLV1dUt23h2ip0GsUhCKuJI/bVaBovHscBnAWJoGSlOcyQln9bcBkL5WBh IH070SNaVPVz/2X24dI9J9ZujqL9trlGsupK/JwPVXJsCWS3lzNKkWtqJS5IH7uwGWnx WXp4nE7Sq3crMRkkMxpUgDD/jHEZy1Vi6JZHAC1OIFmJ/lNK4sRgpWUfL61KOru1L6G+ apzA== X-Gm-Message-State: AOAM531cam2O4Ig1PV3/g2ha92gkAMxGn3Z+X55M7O3OIzMoTruvp24f aq3t73qyLe9VGLVTBz9cWgw= X-Google-Smtp-Source: ABdhPJyscK7c550TzHfpDv1WRnYYvoBsSoBWYdMCW0natilUebpT1uRY7os1lbemOjfZnuzWFb0RqA== X-Received: by 2002:a05:6a00:2306:b029:331:ebe8:a4b4 with SMTP id h6-20020a056a002306b0290331ebe8a4b4mr39978184pfh.15.1626946211504; Thu, 22 Jul 2021 02:30:11 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id q5sm1069592pjo.7.2021.07.22.02.30.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jul 2021 02:30:11 -0700 (PDT) From: Desmond Cheong Zhi Xi To: linux-graphics-maintainer@vmware.com, zackr@vmware.com, airlied@linux.ie, daniel@ffwll.ch, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de Subject: [PATCH 1/3] drm: use the lookup lock in drm_is_current_master Date: Thu, 22 Jul 2021 17:29:27 +0800 Message-Id: <20210722092929.244629-2-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210722092929.244629-1-desmondcheongzx@gmail.com> References: <20210722092929.244629-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: gregkh@linuxfoundation.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Daniel Vetter , skhan@linuxfoundation.org, Desmond Cheong Zhi Xi , linux-kernel-mentees@lists.linuxfoundation.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Inside drm_is_current_master, using the outer drm_device.master_mutex to protect reads of drm_file.master makes the function prone to creating lock hierarchy inversions. Instead, we can use the drm_file.master_lookup_lock that sits at the bottom of the lock hierarchy. Reported-by: Daniel Vetter Signed-off-by: Desmond Cheong Zhi Xi Reviewed-by: Daniel Vetter Signed-off-by: Peter Zijlstra (Intel) --- drivers/gpu/drm/drm_auth.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index f00354bec3fb..9c24b8cc8e36 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -63,8 +63,9 @@ static bool drm_is_current_master_locked(struct drm_file *fpriv) { - lockdep_assert_held_once(&fpriv->minor->dev->master_mutex); - + /* Either drm_device.master_mutex or drm_file.master_lookup_lock + * should be held here. + */ return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; } @@ -82,9 +83,9 @@ bool drm_is_current_master(struct drm_file *fpriv) { bool ret; - mutex_lock(&fpriv->minor->dev->master_mutex); + spin_lock(&fpriv->master_lookup_lock); ret = drm_is_current_master_locked(fpriv); - mutex_unlock(&fpriv->minor->dev->master_mutex); + spin_unlock(&fpriv->master_lookup_lock); return ret; }