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=-12.3 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,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 202ABC63793 for ; Thu, 22 Jul 2021 13:22:01 +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 E3D3860FE7 for ; Thu, 22 Jul 2021 13:22:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E3D3860FE7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 635896EEC4; Thu, 22 Jul 2021 13:22:00 +0000 (UTC) Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8DB486E93C; Thu, 22 Jul 2021 13:03:04 +0000 (UTC) Received: by mail-pj1-x1034.google.com with SMTP id jx7-20020a17090b46c7b02901757deaf2c8so5445579pjb.0; Thu, 22 Jul 2021 06:03:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:cc:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=Ff/8a51zf65javwTWFaQzWRS2rzY3fOngFsjFjhL2pU=; b=QRRSv42l3OKSfAHNwnceLsGisP7k4+dhKuS3ZPP+QH08L8pDuodnXV/ywZIp0mGMV3 Ie4kRVwlk8+RQiyIKSVySxkANpsNy058jZtVjY0OtuEt5O6lohuXIxWHd6YAUxhOeXo0 lX1Vr0t5kSevBOlm0Ojb3WxJrLSkKIsHWzGkPg3NnpU0KyqUPLpTETP/lEa3xjJbo0KG n5lf4h+ao5Aa40NstQ9J44KybIqxo0Kdd+D7K9VtVrDxTlNJFmmDDHAWmJN7+hvjw6cG QBhkDqdXz6X/rIXzRfn/S7OBeNZ54QUTc0rx+GUTCstf46QP9tFuHSULmZOFbR5724ws NhBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Ff/8a51zf65javwTWFaQzWRS2rzY3fOngFsjFjhL2pU=; b=tuxnfxPMZVtRre1CndAzwtP7DY608KaUPnuUUOsxoUtO+oVlzspFUtV9IJDlyyoeBP A2guFEXMlhxl4GNpOLS2bU+vuenHO6QJm0fPfCXc2jpC7O/eqRRDTznyIBIenQf8CXVy 7jWiNLpCij5mu2ZQ3ccKZzmFgYSR41uxkC9zd/frBPdWWNR3CJ+I767OuwSfCHl1I2pe fX/vRcPeKCsgHjocO/8goWY7WI8eUlH6DhaUJ6dUHJnk4mQ/XUpzPw0Q5bvTdyJPU0ww aOKWcSMPyWGf2G44/xmtWj7dQdnMRJuZWNzTRLX18BF7CU5/WTJLRrEwYfDsQ3pqdpy6 3ZUQ== X-Gm-Message-State: AOAM531RHKRa2kaUCovucU3ueiuact3blsuE9BlyaLhp2OYrMyhak//J /Dr+fFiLJdNuIMrfJM0X5xs= X-Google-Smtp-Source: ABdhPJyOCFGS9acfJ60WJxT+N7y/ltJ75utKHHvTo7/YKDME4Kuyaqk+hiaooaaT+vCzYQrSvH2iIQ== X-Received: by 2002:a17:90b:1484:: with SMTP id js4mr40515679pjb.155.1626958983678; Thu, 22 Jul 2021 06:03:03 -0700 (PDT) Received: from [192.168.1.237] ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id m21sm25643502pjz.36.2021.07.22.06.02.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 22 Jul 2021 06:03:02 -0700 (PDT) To: Daniel Vetter References: <20210722092929.244629-1-desmondcheongzx@gmail.com> <20210722092929.244629-3-desmondcheongzx@gmail.com> From: Desmond Cheong Zhi Xi Message-ID: <5b8b3bd5-7519-e383-cb84-f354d898dc81@gmail.com> Date: Thu, 22 Jul 2021 21:02:56 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Mailman-Approved-At: Thu, 22 Jul 2021 13:21:49 +0000 Subject: Re: [Intel-gfx] [PATCH 2/3] drm: clarify lifetime/locking for drm_master's lease fields X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: airlied@linux.ie, gregkh@linuxfoundation.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, mripard@kernel.org, linux-graphics-maintainer@vmware.com, dri-devel@lists.freedesktop.org, tzimmermann@suse.de, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, zackr@vmware.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On 22/7/21 6:35 pm, Daniel Vetter wrote: > On Thu, Jul 22, 2021 at 05:29:28PM +0800, Desmond Cheong Zhi Xi wrote: >> 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 >> --- >> 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 > > Lessor is the lease grantor, lessee is the one receiving the lease. Maybe > clarify this with > > "Lease grantor, only set if this struct drm_master represents a lessee > holding a lease of objects from @lessor. Full owners of the device have > this set to NULL." > >> + * drm_lease_create(). Each lessee holds a reference to its lessor that > > I also figured it'd be a good idea to link to the drm_lease docs here to > explain the concepts, but alas we don't have those :-( Hence at least > define what we mean with lessor, lessee, lease and owner. > Thanks for the suggestions, Daniel. I'll incorporate them in a v2. Regarding the missing drm_lease docs... any reason we can't just add it in? Seems like most of the comments in drm_lease.c are almost correctly formatted too. I could clean them up, define the terms in a preamble, then add it to the v2 patch. >> + * it releases upon being destroyed in drm_lease_destroy(). >> + * >> + * Display resource leases form a tree of &struct drm_master. All of > > For now we've limited the tree to a depth of 1, you can't create another > lease if yourself are a lease. I guess another reason to update the > drm_lease.c docs. > > So maybe add "Currently the lease tree depth is limited to 1." > >> + * 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 > > Maybe clarify to "Owners (i.e. @lessor is NULL) ..." > >> + * &drm_device.mode_config's &drm_mode_config.idr_mutex. >> + */ >> int lessee_id; >> + >> + /** >> + * @lessee_list: >> + * >> + * List of lessees of the same master. Protected by > > We try to distinguis between list entries and the list, even though it's > the same struct. So maybe > > "List entry of lessees of @lessor, where they are linked to @lessee. Not > use for owners." > >> + * &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. > > Maybe add "this list is empty of no leases have been granted." > >> + */ >> 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). > > @lessor so it's highlighted correctly > >> + * Protected by &drm_device.mode_config's &drm_mode_config.idr_mutex. >> + */ >> struct idr lessee_idr; >> /* private: */ > > With the nits addressed: > > Reviewed-by: Daniel Vetter > > Thanks for updating the docs! > -Daniel > >> #if IS_ENABLED(CONFIG_DRM_LEGACY) >> -- >> 2.25.1 >> > _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx