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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35CB4C25B08 for ; Fri, 12 Aug 2022 11:46:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238160AbiHLLqd (ORCPT ); Fri, 12 Aug 2022 07:46:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238127AbiHLLqb (ORCPT ); Fri, 12 Aug 2022 07:46:31 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E47A88DF1; Fri, 12 Aug 2022 04:46:28 -0700 (PDT) Received: from [192.168.2.145] (unknown [109.252.119.13]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dmitry.osipenko) by madras.collabora.co.uk (Postfix) with ESMTPSA id BD19E66016F2; Fri, 12 Aug 2022 12:46:23 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1660304786; bh=C5rdDWAQ0gULbYpYsWO6A2mmdZ/uxYEqrEknr4MoOf8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=f3cXPfNXtZHtoSYE1rfxtQ30MUhUVhGrG/NArO1c7kQB8/Xy+FmlqaaOTXT5gVdlP JQXrT9UtGLSc+oBaf/E/efq95t8eHa3wW8rsdseitQlUvtaI4DwUh/ptuZTZ+7D4oa 7gYb8ygLDMwAttTQiJt/HYS3piyRQe36Z1IpIZJqOFl16YT77Eqw1UGF1vppI4t/Vf GlTMr5So6lTOFJQj6bSYwIN6RamDBXBlbOMkDkPHaJHbuvpX0ALyNVMapf4xI3a4LC uDEbP9wEVI4gkRbHJNZkFWXDO04u0wVdnPFCF2dEImetIe9dBjI0qKFkC2Wjrvs/O9 MpZiQvPIhyRKg== Message-ID: Date: Fri, 12 Aug 2022 14:46:20 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 Subject: Re: [Linaro-mm-sig] [PATCH v2 3/5] dma-buf: Move all dma-bufs to dynamic locking specification Content-Language: en-US To: =?UTF-8?Q?Christian_K=c3=b6nig?= , =?UTF-8?Q?Christian_K=c3=b6nig?= Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Dmitry Osipenko , linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, amd-gfx@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, kernel@collabora.com, virtualization@lists.linux-foundation.org, spice-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-arm-msm@vger.kernel.org, David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Daniel Vetter , Daniel Almeida , Gert Wollny , Gustavo Padovan , Daniel Stone , Tomeu Vizoso , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Rob Clark , Sumit Semwal , "Pan, Xinhui" , Thierry Reding , Tomasz Figa , Marek Szyprowski , Mauro Carvalho Chehab , Alex Deucher , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= References: <20220725151839.31622-1-dmitry.osipenko@collabora.com> <20220725151839.31622-4-dmitry.osipenko@collabora.com> <6c8bded9-1809-608f-749a-5ee28b852d32@gmail.com> <562fbacf-3673-ff3c-23a1-124284b4456c@collabora.com> <87724722-b9f3-a016-c25c-4b0415f2c37f@amd.com> <0863cafa-c252-e194-3d23-ef640941e36e@collabora.com> <93484389-1f79-b364-700f-60769fc5f8a5@gmail.com> From: Dmitry Osipenko In-Reply-To: <93484389-1f79-b364-700f-60769fc5f8a5@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On 8/12/22 14:34, Christian König wrote: > > > Am 10.08.22 um 20:53 schrieb Dmitry Osipenko: >> On 8/10/22 21:25, Christian König wrote: >>> Am 10.08.22 um 19:49 schrieb Dmitry Osipenko: >>>> On 8/10/22 14:30, Christian König wrote: >>>>> Am 25.07.22 um 17:18 schrieb Dmitry Osipenko: >>>>>> This patch moves the non-dynamic dma-buf users over to the dynamic >>>>>> locking specification. The strict locking convention prevents >>>>>> deadlock >>>>>> situation for dma-buf importers and exporters. >>>>>> >>>>>> Previously the "unlocked" versions of the dma-buf API functions >>>>>> weren't >>>>>> taking the reservation lock and this patch makes them to take the >>>>>> lock. >>>>>> >>>>>> Intel and AMD GPU drivers already were mapping imported dma-bufs >>>>>> under >>>>>> the held lock, hence the "locked" variant of the functions are added >>>>>> for them and the drivers are updated to use the "locked" versions. >>>>> In general "Yes, please", but that won't be that easy. >>>>> >>>>> You not only need to change amdgpu and i915, but all drivers >>>>> implementing the map_dma_buf(), unmap_dma_buf() callbacks. >>>>> >>>>> Auditing all that code is a huge bunch of work. >>>> Hm, neither of drivers take the resv lock in map_dma_buf/unmap_dma_buf. >>>> It's easy to audit them all and I did it. So either I'm missing >>>> something or it doesn't take much time to check them all. Am I really >>>> missing something? >>> Ok, so this is only changing map/unmap now? >> It also vmap/vunmap and attach/detach: In the previous patch I added the >> _unlocked postfix to the func names and in this patch I made them all to >> actually take the lock. > > > Take your patch "[PATCH v2 2/5] drm/gem: Take reservation lock for > vmap/vunmap operations" as a blueprint on how to approach it. > > E.g. one callback at a time and then document the result in the end. Yeah, I'll do it for v3. I'm vaguely recalling that there was a problem when I wanted to split this patch in the past, but don't remember what it was.. maybe that problem is gone now, will see :) -- Best regards, Dmitry