From patchwork Sat Jul 31 08:24:58 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: 12412381 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,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 2DE1EC4338F for ; Sat, 31 Jul 2021 08:27:07 +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 C641060F39 for ; Sat, 31 Jul 2021 08:27:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org C641060F39 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4AD9F6E7D7; Sat, 31 Jul 2021 08:27:06 +0000 (UTC) Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4306A6E7D7 for ; Sat, 31 Jul 2021 08:27:05 +0000 (UTC) Received: by mail-pj1-x1033.google.com with SMTP id pf12-20020a17090b1d8cb0290175c085e7a5so24236546pjb.0 for ; Sat, 31 Jul 2021 01:27:05 -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=Y7LF0TOJBi8g9oPoxvzY/IMHVXJRvIokqXJgW7n6wWU=; b=RJZ+rGSe9MjdSJpshgn6FdDtxzCLxvmvsad50TODML9WAleAKQiueuhET8/vduh88F S3Xqko1C4QRjj8UG4Wji5ctfC1UfiIV6IuBkUa5GVC4yIbAN60i2NkHaPW4XoZPQFS65 4wCuYy5XdHd1w9ZYa+56L8c2ofiod/VTV1cZEhZYPokwnz/Q2slvJjtd+JnfbTNdC56v P9L35LIukKhPtFZLpaHXBWYCrD5hBpoQ+I7DZnlBVasE9yHb0zuJyTQeLEMrU/wbfaxy baMBSXRZ4aOnXooLgYsykXafJY5MUEZkh5g9EZ+m5U0yN9CCpWoRLru57HYs6wf6U7/E ERrQ== 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=Y7LF0TOJBi8g9oPoxvzY/IMHVXJRvIokqXJgW7n6wWU=; b=cV+3vq4xnKt/f3lt7YCohxSsflLEFRpwZGQUcypL6ANPMDBPMpx6E05mlAuopnyP+y 4yUMmAH/13HCG8+SYdmhTloo0AqSKckGE6uZYYrU56kmRPpsQ3alsXADnKiRDkMgELdP DsAVqACecCujJxlfuWm0D+nopSF3Du+pGk82IFmw5pGF5r7krPWkFr8wjPoSEQ/14aSb bBblnUAbYUm5C3ul5QWv2+J4hfniQQH1tk47cB8m9gx9ZeLaHSUE60Qjg9D9FeuQaxEV 0wjKzL+xZW1MTjALOJni+r0DA0V47zzURYbduXcNr63qPsoaPbMwFjgDBynqzhiiF6RM R8qQ== X-Gm-Message-State: AOAM533JIwi0qb+/VadyZvo4NkxGwfphXn+jTiJth7qXsZpgiZ6Dfe/H kW0MtefZy18BJUVRXrnm1aQ= X-Google-Smtp-Source: ABdhPJzd5bUpeB5fpe0qkJXVTRCMKBesE410MgSb6QJZrGqvamH8Z/gVzFKaP0OmfXbgFlYSkhMzWg== X-Received: by 2002:a17:902:d293:b029:12c:8bb3:7997 with SMTP id t19-20020a170902d293b029012c8bb37997mr6015717plc.36.1627720024937; Sat, 31 Jul 2021 01:27:04 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id mq7sm3182124pjb.50.2021.07.31.01.27.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 31 Jul 2021 01:27:04 -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 Cc: Desmond Cheong Zhi Xi , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org Subject: [PATCH v2 2/2] drm: add lockdep assert to drm_is_current_master_locked Date: Sat, 31 Jul 2021 16:24:58 +0800 Message-Id: <20210731082458.1962043-3-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210731082458.1962043-1-desmondcheongzx@gmail.com> References: <20210731082458.1962043-1-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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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 --- 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