Received: by 2002:a05:6358:3188:b0:123:57c1:9b43 with SMTP id q8csp9756541rwd; Wed, 21 Jun 2023 11:23:03 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ7p25PZKu1evD6ZE3fxy63WqLXhI2ajfXRm/jQtbtoipxf+FuVF+9mSqfisq5xo/5mCAquQ X-Received: by 2002:aa7:88d0:0:b0:66a:3eb5:92bb with SMTP id k16-20020aa788d0000000b0066a3eb592bbmr2989803pff.11.1687371783198; Wed, 21 Jun 2023 11:23:03 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1687371783; cv=none; d=google.com; s=arc-20160816; b=Y+nBC4xO+OwdgZSOYLIFNY5SNL8kOUBZzvXur5aE9FF6NoxroR9UwvR/+65LU8P9cE Lk81/zh7cavn0DdXnrA3Igs9yTLs2mO0EuA+j54ie0IM6oVyWBYBo4xnaTFHuHh1dRgp F/L5jmhcj3UzFfnzTqJ0y1VWHZatruJyUnovg+gF4FcCpLF8718qgtPVwH7xblGq2quA bSd3Ib/GDMvZH7Wwljs0YD7dA0szb7+Xq8TF0nHCF6/GABxnAGW56JmKZxzHqqciYoND 4emBL7OO0rIryfeJ8V2mCVQjg2pJHZoqzHp5jDcOlkPgY+jscQLTGI7nURZTkrisraCw 0CoQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:in-reply-to:from :references:cc:to:content-language:subject:user-agent:mime-version :date:message-id:dkim-signature; bh=/smdFPxzKDUWqlXJAZ471X434tSDy7jVr1lXuDmyyP0=; b=FzQ89X+kmlmBQErQe+ZFHwrMNiFC8XozBuBKVzN7oReepDzpNc2KVhY4qnPHg+GcfN iALrk2V85MpCfdePSal/YSq/RAN45uxp4Yz9hKr2f4WRUoegAd27Cnd7gsTZdJuQst8X ovLFRlpkZnQY7Nb2a5LVRw4cJrEZL8G55O4dl1bahQogurJKfIoRKS1QLbp2qaaYoZ7k wz3/OSt2F/RU4c1bapXAHv0qDbe884iSQrL2V+LDt2d+yw+jZXqKHosGPdN71WXJzl2Q LY2PR9AddMfzIYiYR1hvibfSz3hviIsM8V1/D5GQS4SS+XE8waa5/m0u/p6c1MeS8UDO 1glg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@collabora.com header.s=mail header.b=a6uFWwMG; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=collabora.com Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id v15-20020a637a0f000000b0054fd5511053si4439510pgc.377.2023.06.21.11.22.50; Wed, 21 Jun 2023 11:23:03 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@collabora.com header.s=mail header.b=a6uFWwMG; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=collabora.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230382AbjFUSQh (ORCPT + 99 others); Wed, 21 Jun 2023 14:16:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229570AbjFUSQg (ORCPT ); Wed, 21 Jun 2023 14:16:36 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CAA1AFE; Wed, 21 Jun 2023 11:16:35 -0700 (PDT) Received: from [192.168.2.254] (109-252-154-132.dynamic.spd-mgts.ru [109.252.154.132]) (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 61D736606FAC; Wed, 21 Jun 2023 19:16:32 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1687371394; bh=PQA2rc/Gs+XDzpOTYaQqwgwiDRANnpvkFuiUXn6B45A=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=a6uFWwMGM2Wn9oqIqY7w7ZXRsmW9BSZjBsI4Ir5fTcMPux5toiFC6wlyILN77QVfb 0L+ZFaptUWmBOJZm2yvNv0eh15H4wUN+1EiHsUsv63mFz6hu/moMeG3T4oQV6i35F0 sHKIlQJA6GxprALI1nuPl+VQIhbWRMZVczzPnrUz21ntwNTap1H/IueLMyT7eRukEz N3GdhDZdinRaXuMBSFTeA1MUT7KUhYwb+koIItqlM5t/HFmZVenSeMDvjEPNqpSvPr WnQ/f7ngy10rNR4q+TxKWqOltsVMxB7/UwzmOPEST6X3Ell8COhkS5FvW3+wJ2ZV00 b/tPSDkrH1Jtg== Message-ID: <106bc72b-9358-de06-6f3f-06fdfa3859cd@collabora.com> Date: Wed, 21 Jun 2023 21:16:29 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.1 Subject: Re: [PATCH v4 2/6] dma-buf/heaps: Don't assert held reservation lock for dma-buf mmapping Content-Language: en-US To: "T.J. Mercier" Cc: Sumit Semwal , =?UTF-8?Q?Christian_K=c3=b6nig?= , Benjamin Gaignard , Brian Starkey , John Stultz , Gerd Hoffmann , Daniel Vetter , Jani Nikula , Arnd Bergmann , Thomas Zimmermann , Tomi Valkeinen , Thierry Reding , Tomasz Figa , Marek Szyprowski , Mauro Carvalho Chehab , Emil Velikov , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org, kernel@collabora.com, linux-media@vger.kernel.org References: <20230529223935.2672495-1-dmitry.osipenko@collabora.com> <20230529223935.2672495-3-dmitry.osipenko@collabora.com> From: Dmitry Osipenko In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 6/21/23 20:21, T.J. Mercier wrote: > On Mon, May 29, 2023 at 3:46 PM Dmitry Osipenko > wrote: >> >> Don't assert held dma-buf reservation lock on memory mapping of exported >> buffer. >> >> We're going to change dma-buf mmap() locking policy such that exporters >> will have to handle the lock. The previous locking policy caused deadlock >> problem for DRM drivers in a case of self-imported dma-bufs once these >> drivers are moved to use reservation lock universally. The problem >> solved by moving the lock down to exporters. This patch prepares dma-buf >> heaps for the locking policy update. >> > Hi Dmitry, > > I see that in patch 6 of this series calls to > dma_resv_lock/dma_resv_unlock have been added to the > drm_gem_shmem_helper functions and some exporters. But I'm curious why > no dma_resv_lock/dma_resv_unlock calls were added to these two dma-buf > heap exporters for mmap? DMA-buf heaps are exporters, drm_gem_shmem_helper is importer. Locking rules are different for importers and exporters. DMA-heaps use own locking, they can be moved to resv lock in the future. DMA-heaps don't protect internal data in theirs mmap() implementations, nothing to protect there. -- Best regards, Dmitry