From patchwork Thu Jul 22 09:29:28 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: 12393607 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,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 88AF0C63798 for ; Thu, 22 Jul 2021 09:30:19 +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 560E46120C for ; Thu, 22 Jul 2021 09:30:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 560E46120C 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 AE8E66EEB2; Thu, 22 Jul 2021 09:30:18 +0000 (UTC) Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com [IPv6:2607:f8b0:4864:20::102c]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2D5C76EE80; Thu, 22 Jul 2021 09:30:17 +0000 (UTC) Received: by mail-pj1-x102c.google.com with SMTP id k4-20020a17090a5144b02901731c776526so3405691pjm.4; Thu, 22 Jul 2021 02:30:17 -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=bWqoW1zaypI6FiOc+rFvxYhfwSyGe+LXhfGXUAMjokM=; b=q3mxk07wkguCFJ+lpuERPHN7UiaEpdxTgOavixSsHfPNPXKFiLSITtuEeLIwPZRjU7 s42Q87ZjcaNTrLRJw+tOZoIdFlCwLflimzejiOKT9gyMkMLpthTiHeFKzQnJDsELOScM PtdXIj1ZZXVu3ZM9M3OBzrwO6lugRjWibip1gEsqKagfac6tObLaddc0jIOPyn0rQ/2Q SqIn/SBaRCLr760Fo23EQiVBqg1WabAQZKzLW5+nyHPy0emWxNaaJxxmEC5IAWoOYBMb 2w3ZGx0JEfCUFSrEa95ldc/WJZLAJYcicWU1cZ6niVobKKGPIESb53bReRPgOoJoRBug if1g== 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=bWqoW1zaypI6FiOc+rFvxYhfwSyGe+LXhfGXUAMjokM=; b=kw5N2T3/J8empfEbSpMU8SpjQ82wRZ0ZEJ5bm+AY0qW7UY+TuWtJg3jkGKvNSf7c6N fW0YD+vVNeBkDzsfvzlDPXVEvhtThCzYg3Ncyemab7/F+B3Wi04aMvgNAjqkEgz0rbjt 4iWuLSZiefH9rs/p90dKI126nBORaMZXpvDfm2UNxnvu97y3RlKWtqE5ZXXgADbFX/5b ffPV1ch1S6jGxPS/EvP704wFVlSC/J4jU3LAOHGYJZ616nryd5DK0V/Q1LZM4erqkZFg Xgfiu1uljGbEU/nBNKzeKsM6+8sl3F+ED+1JTu98Hk7OK0ZbF/bmSbz5ZklUwTV1PNSa DVFg== X-Gm-Message-State: AOAM530xJhuOii7FFQxF7Cv/5tGRZKumB2CE2QYmnXfxAdU/f3ohEWVF JHV5PCJ66AJ3SXWwD6Cs88A= X-Google-Smtp-Source: ABdhPJzLwTR8vmDcr35rGyIbAv/nAj71D9TVKb48nTd5YFXyi6D7zffA6NSixOLxJopmOo9LLz5PwA== X-Received: by 2002:a63:cd4b:: with SMTP id a11mr21260014pgj.273.1626946216859; Thu, 22 Jul 2021 02:30:16 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id q5sm1069592pjo.7.2021.07.22.02.30.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jul 2021 02:30:16 -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 2/3] drm: clarify lifetime/locking for drm_master's lease fields Date: Thu, 22 Jul 2021 17:29:28 +0800 Message-Id: <20210722092929.244629-3-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, skhan@linuxfoundation.org, Desmond Cheong Zhi Xi , linux-kernel-mentees@lists.linuxfoundation.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" In particular, we make it clear that &drm_device.mode_config.idr_mutex protects the lease idr and list structures for drm_master. The lessor field itself doesn't need to be protected as it doesn't change after it's set in drm_lease_create. Additionally, we add descriptions for the lifetime of lessors and leases to make it easier to reason about them. Signed-off-by: Desmond Cheong Zhi Xi Reviewed-by: Daniel Vetter --- include/drm/drm_auth.h | 62 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 51 insertions(+), 11 deletions(-) diff --git a/include/drm/drm_auth.h b/include/drm/drm_auth.h index f99d3417f304..c978c85464fa 100644 --- a/include/drm/drm_auth.h +++ b/include/drm/drm_auth.h @@ -58,12 +58,6 @@ struct drm_lock_data { * @refcount: Refcount for this master object. * @dev: Link back to the DRM device * @driver_priv: Pointer to driver-private information. - * @lessor: Lease holder - * @lessee_id: id for lessees. Owners always have id 0 - * @lessee_list: other lessees of the same master - * @lessees: drm_masters leasing from this one - * @leases: Objects leased to this drm_master. - * @lessee_idr: All lessees under this owner (only used where lessor == NULL) * * Note that master structures are only relevant for the legacy/primary device * nodes, hence there can only be one per device, not one per drm_minor. @@ -88,17 +82,63 @@ struct drm_master { struct idr magic_map; void *driver_priv; - /* Tree of display resource leases, each of which is a drm_master struct - * All of these get activated simultaneously, so drm_device master points - * at the top of the tree (for which lessor is NULL). Protected by - * &drm_device.mode_config.idr_mutex. + /** + * @lessor: + * + * Lease holder. The lessor does not change once it's set in + * drm_lease_create(). Each lessee holds a reference to its lessor that + * it releases upon being destroyed in drm_lease_destroy(). + * + * Display resource leases form a tree of &struct drm_master. All of + * these get activated simultaneously, so &drm_device.master + * points at the top of the tree (for which lessor is NULL). */ - struct drm_master *lessor; + + /** + * @lessee_id: + * + * ID for lessees. Owners always have ID 0. Protected by + * &drm_device.mode_config's &drm_mode_config.idr_mutex. + */ int lessee_id; + + /** + * @lessee_list: + * + * List of lessees of the same master. Protected by + * &drm_device.mode_config's &drm_mode_config.idr_mutex. + */ struct list_head lessee_list; + + /** + * @lessees: + * + * List of drm_masters leasing from this one. Protected by + * &drm_device.mode_config's &drm_mode_config.idr_mutex. + * + * This master cannot be destroyed unless this list is empty as lessors + * are referenced by all their lessees. + */ struct list_head lessees; + + /** + * @leases: + * + * Objects leased to this drm_master. Protected by + * &drm_device.mode_config's &drm_mode_config.idr_mutex. + * + * Objects are leased all together in drm_lease_create(), and are + * removed all together when the lease is revoked. + */ struct idr leases; + + /** + * @lessee_idr: + * + * All lessees under this owner (only used where lessor is NULL). + * Protected by &drm_device.mode_config's &drm_mode_config.idr_mutex. + */ struct idr lessee_idr; /* private: */ #if IS_ENABLED(CONFIG_DRM_LEGACY)