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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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=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 782D1C432BE for ; Mon, 2 Aug 2021 11:01:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6333660F11 for ; Mon, 2 Aug 2021 11:01:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233422AbhHBLBi (ORCPT ); Mon, 2 Aug 2021 07:01:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233421AbhHBLBa (ORCPT ); Mon, 2 Aug 2021 07:01:30 -0400 Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 832A1C06175F; Mon, 2 Aug 2021 04:01:21 -0700 (PDT) Received: by mail-pl1-x62c.google.com with SMTP id t3so17088590plg.9; Mon, 02 Aug 2021 04:01:21 -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=9wyMs+rwX3ldqcYresSOjD4BweaQ/WnMH4Ky/VQDi2I=; b=Yc4FE9YjAWr9IC8sdF1L1QTKHbzv2l3QIYmiEecRKbBNneolptr9Pi3XzZU6rwfZCT 8O0thjHeEkHK3L1/Txx+ji8Mr513dnL+bfZDMwJt3YYdHu/09mkh0DkeVbUXrIisv81F 7YMYsvks+POltFmWXjm8TqCHeKU721PxvWx25P0sezJAC1cu2Kmi+w494F480GQ/FSHx ZSNFgsT45n6tUDl/ryzLi3U5pAvlm1nCCmxwKgvGjhO5XHayaPGgh8OVwCCgex6V1p10 Isix8qFvOdtIwT36o1vcheb0yZayKW2fHYdpg9VklB8YLMQ+Gj0nlp/wRjfrxfM8ga9f KDHQ== 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=9wyMs+rwX3ldqcYresSOjD4BweaQ/WnMH4Ky/VQDi2I=; b=haq3757bHnC46PBKVQOl1LfZgX2T3bK1FHU/+HHlqjZRE71VcY5XRZ+aDfFjxFty7i 98Rp5pMWcnF5iMjEoFZF1r7zF7ldOvmPSFn7TQG/OHNUroYGXYxdC/HPTg2IE+IGMbdZ Pr8nkEM9QKTAvhgqAprQIaPJ6sFUH1CfFCT1khwdaHYxvVWjWB/NiV6b6pvrLhvIkaHW mcjCYT/AWs+852axmdDLf0QPoxypDd1xjOAYumYQFMRcCB5p6EmFI3m4/pgXWeQr4saq p2m5q8/GbhrGvVUFpEaVeTDBvsTKZGhpk4jxHn9PsTntCSLP6sCIY1NbDKQ8cTpm08Yj KPLA== X-Gm-Message-State: AOAM532El1KyQUG7gvo0MRYm/9SjVvcVTJ/b1qhcnx400A5W80vKW0hN TLu5fWOygg8lpjIYKykn5LQ= X-Google-Smtp-Source: ABdhPJw3Zis0PZJdPsYef4VhN3d7rrLIYlB75L7nQeFiLyBly19H2n3lL4vzH8obKhGcJddjQi2ppw== X-Received: by 2002:a65:6a0a:: with SMTP id m10mr2267519pgu.145.1627902081017; Mon, 02 Aug 2021 04:01:21 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id v30sm9709158pgk.25.2021.08.02.04.01.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Aug 2021 04:01:20 -0700 (PDT) From: Desmond Cheong Zhi Xi To: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@linux.ie, daniel@ffwll.ch, peterz@infradead.org, mingo@redhat.com, will@kernel.org, longman@redhat.com, boqun.feng@gmail.com, sumit.semwal@linaro.org, christian.koenig@amd.com Cc: Desmond Cheong Zhi Xi , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org Subject: [RESEND PATCH v2 2/2] drm: add lockdep assert to drm_is_current_master_locked Date: Mon, 2 Aug 2021 18:59:57 +0800 Message-Id: <20210802105957.77692-3-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210802105957.77692-1-desmondcheongzx@gmail.com> References: <20210802105957.77692-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In drm_is_current_master_locked, accessing drm_file.master should be protected by either drm_file.master_lookup_lock or drm_device.master_mutex. This was previously awkward to assert with lockdep. Following patch ("locking/lockdep: Provide lockdep_assert{,_once}() helpers"), this assertion is now convenient. So we add in the assertion and explain this lock design in the kerneldoc. Signed-off-by: Desmond Cheong Zhi Xi Acked-by: Boqun Feng Acked-by: Waiman Long Acked-by: Peter Zijlstra (Intel) --- drivers/gpu/drm/drm_auth.c | 6 +++--- include/drm/drm_file.h | 4 ++++ 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 9c24b8cc8e36..6f4d7ff23c80 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -63,9 +63,9 @@ static bool drm_is_current_master_locked(struct drm_file *fpriv) { - /* Either drm_device.master_mutex or drm_file.master_lookup_lock - * should be held here. - */ + lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) || + lockdep_is_held(&fpriv->minor->dev->master_mutex)); + return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; } diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h index 726cfe0ff5f5..a3acb7ac3550 100644 --- a/include/drm/drm_file.h +++ b/include/drm/drm_file.h @@ -233,6 +233,10 @@ struct drm_file { * this only matches &drm_device.master if the master is the currently * active one. * + * To update @master, both &drm_device.master_mutex and + * @master_lookup_lock need to be held, therefore holding either of + * them is safe and enough for the read side. + * * When dereferencing this pointer, either hold struct * &drm_device.master_mutex for the duration of the pointer's use, or * use drm_file_get_master() if struct &drm_device.master_mutex is not -- 2.25.1