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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6177FC4338F for ; Fri, 30 Jul 2021 04:52:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37832600D1 for ; Fri, 30 Jul 2021 04:52:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230148AbhG3Ewi (ORCPT ); Fri, 30 Jul 2021 00:52:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229910AbhG3Ewh (ORCPT ); Fri, 30 Jul 2021 00:52:37 -0400 Received: from mail-lf1-x12b.google.com (mail-lf1-x12b.google.com [IPv6:2a00:1450:4864:20::12b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AAC17C061765 for ; Thu, 29 Jul 2021 21:52:32 -0700 (PDT) Received: by mail-lf1-x12b.google.com with SMTP id h2so15318084lfu.4 for ; Thu, 29 Jul 2021 21:52:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=ngOm50/YMKcUx0bA3+RSYUsPg/JdRRvBdoD4piFXpKk=; b=C8Jp7VhFjs0rnaOQ+PhARQZcXBqL3li1M1opg2ctxUM+UW431Xc6w3HRU9jqMEn9J8 mjRiwwt+tWiXsLMDZKwx5ZLEtcnwodMbSLh35X6Dl8KI5jfLdkHovCiYFvU9yLOXdVzm T56dTYyum/xZim2C5bWj64K+N+jV8WY66Rg5/Bwn91Sn/snbwb/x3RlTxcAU29gmNhjl KgwS2oOAfASo09QS8QxiHdsYQiVobP5e9jTXOpOAtTaaFBAO8bP4tgRSWo5PZXJaTFyV bU5CM0EvtNCO+75RkPo/2Iit3ZJTxAR2kkb3LF3KCQ+AcEjKYyubIAL6gsTqWn2Kh4aO Xr+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=ngOm50/YMKcUx0bA3+RSYUsPg/JdRRvBdoD4piFXpKk=; b=AUIA0GQAHdpbbPLPRNpzDmJzXl0hix5sN9UyMy+Wii2AU4Bn29eLKbqtbI6IG8N5nb i/3e21FthKgmE8mOTochliQ9uRAYn4DdgT8Qis4KyB+cf2y2GbST16y6vCbONMi6HRwi w3zKm4s07x0mX1gx+7FyNMfPhrnBDDmuB8cyxe+z9OREGdgeU3nxc1AZi/fEeIM3j0O3 pZykn//bmqQv3+4i2B7lDH4dixPT/waPIM5lowM1SFOdD0U6jcg06cM8ieoXVZRk7oyr mrQP8WMHvbL6o4cJgoK3JxVg5RsVL1k7prM5StFQBYVo79wSvFWX7H8PG8EGTWLhVidl q1iw== X-Gm-Message-State: AOAM532oYuNcjFS7zl3TzVRShd9cYjemc/ZdXGVWXgYCrXefNBDpeUiV 26R4GVjhk+/5vi6T2ZdEmPLFS5EyNjpPCcmXSDF6rA== X-Google-Smtp-Source: ABdhPJzDU5NmVnsCGCr2QxJh2cy55utwKVijKkr1tTD5MHrq+mqK18bOqc1KLFYSb9qZZ3DlCCOrI4gJHyxXUU4u7Zw= X-Received: by 2002:ac2:4a8d:: with SMTP id l13mr426511lfp.626.1627620751019; Thu, 29 Jul 2021 21:52:31 -0700 (PDT) MIME-Version: 1.0 References: <20210729070330.41443-1-christian.koenig@amd.com> <20210729070330.41443-3-christian.koenig@amd.com> In-Reply-To: From: John Stultz Date: Thu, 29 Jul 2021 21:52:19 -0700 Message-ID: Subject: Re: [PATCH 3/3] dma-buf: nuke SW_SYNC debugfs files To: Daniel Vetter Cc: =?UTF-8?Q?Christian_K=C3=B6nig?= , Gustavo Padovan , dri-devel , "moderated list:DMA BUFFER SHARING FRAMEWORK" , linux-media , Alistair Delva , Hridya Valsaraju , Sandeep Patil Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Thu, Jul 29, 2021 at 12:24 AM Daniel Vetter wrote: > > On Thu, Jul 29, 2021 at 09:03:30AM +0200, Christian K=C3=B6nig wrote: > > As we now knew controlling dma_fence synchronization from userspace is > > extremely dangerous and can not only deadlock drivers but trivially als= o the > > whole kernel memory management. > > > > Entirely remove this option. We now have in kernel unit tests to exerci= se the > > dma_fence framework and it's containers. > > > > Signed-off-by: Christian K=C3=B6nig > > There's also igts for this, and Android heavily uses this. So I'm not sur= e > we can just nuke it. Eeeeh... I don't think that's actually the case anymore. As of android12-5.10 CONFIG_SW_SYNC is not turned on. Further, Android is disabling debugfs in their kernels as it exposes too much to userland. That said, there still are some references to it: https://cs.android.com/android/platform/superproject/+/master:system/core= /libsync/sync.c;l=3D416 But it looks like the actual users are only kselftest and igt? Adding Alistair, Hridya and Sandeep in case they have more context. thanks -john 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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 A94B4C4320A for ; Fri, 30 Jul 2021 04:52:35 +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 6C8DB600D1 for ; Fri, 30 Jul 2021 04:52:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 6C8DB600D1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org 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 D439A6EC62; Fri, 30 Jul 2021 04:52:34 +0000 (UTC) Received: from mail-lf1-x12b.google.com (mail-lf1-x12b.google.com [IPv6:2a00:1450:4864:20::12b]) by gabe.freedesktop.org (Postfix) with ESMTPS id ACA456EC62 for ; Fri, 30 Jul 2021 04:52:32 +0000 (UTC) Received: by mail-lf1-x12b.google.com with SMTP id a26so15226195lfr.11 for ; Thu, 29 Jul 2021 21:52:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=ngOm50/YMKcUx0bA3+RSYUsPg/JdRRvBdoD4piFXpKk=; b=C8Jp7VhFjs0rnaOQ+PhARQZcXBqL3li1M1opg2ctxUM+UW431Xc6w3HRU9jqMEn9J8 mjRiwwt+tWiXsLMDZKwx5ZLEtcnwodMbSLh35X6Dl8KI5jfLdkHovCiYFvU9yLOXdVzm T56dTYyum/xZim2C5bWj64K+N+jV8WY66Rg5/Bwn91Sn/snbwb/x3RlTxcAU29gmNhjl KgwS2oOAfASo09QS8QxiHdsYQiVobP5e9jTXOpOAtTaaFBAO8bP4tgRSWo5PZXJaTFyV bU5CM0EvtNCO+75RkPo/2Iit3ZJTxAR2kkb3LF3KCQ+AcEjKYyubIAL6gsTqWn2Kh4aO Xr+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=ngOm50/YMKcUx0bA3+RSYUsPg/JdRRvBdoD4piFXpKk=; b=aiiNgt7ra6RKrPFLSZsMKiNYrM6E79knjjJIPG8evZL+IGvkNbVO/KO56MsV+aK03O 6Q+n/x+QSqz6W/5p2SfMjmwR/6UfMFEHTYKjSGNOPvZbQOfIxj4FmxxuWKKURHm+wMaQ W0vuMLQangPs4pzmutwIbojxuH21uTPEEIkjWsGiImvE0R3a4xD+eTzLZC5cXFahzg3H UFRv9cnuaYx7QaGcdfknRzaforVW5XNznVV3xxWnURtaUdmt7fnsduJVlrBcwJ5K4yU3 wFfD3fQeWv3/fL4QgZjhW6ecpWpLYhrBy6jfTXqHYPL/O9fw0TBArzIPZNj4NgiOLk7H 3SrQ== X-Gm-Message-State: AOAM531QB1ajiE1gwpGiZ+HXBDeINuOVOIwLYBFrm4av937hBe/tNPGs w/mxkSp37859JzH5rKElnvK7rOetlkQ5yF1p+wamcA== X-Google-Smtp-Source: ABdhPJzDU5NmVnsCGCr2QxJh2cy55utwKVijKkr1tTD5MHrq+mqK18bOqc1KLFYSb9qZZ3DlCCOrI4gJHyxXUU4u7Zw= X-Received: by 2002:ac2:4a8d:: with SMTP id l13mr426511lfp.626.1627620751019; Thu, 29 Jul 2021 21:52:31 -0700 (PDT) MIME-Version: 1.0 References: <20210729070330.41443-1-christian.koenig@amd.com> <20210729070330.41443-3-christian.koenig@amd.com> In-Reply-To: From: John Stultz Date: Thu, 29 Jul 2021 21:52:19 -0700 Message-ID: Subject: Re: [PATCH 3/3] dma-buf: nuke SW_SYNC debugfs files To: Daniel Vetter Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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: Alistair Delva , Sandeep Patil , =?UTF-8?Q?Christian_K=C3=B6nig?= , dri-devel , "moderated list:DMA BUFFER SHARING FRAMEWORK" , Gustavo Padovan , Hridya Valsaraju , linux-media Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Thu, Jul 29, 2021 at 12:24 AM Daniel Vetter wrote: > > On Thu, Jul 29, 2021 at 09:03:30AM +0200, Christian K=C3=B6nig wrote: > > As we now knew controlling dma_fence synchronization from userspace is > > extremely dangerous and can not only deadlock drivers but trivially als= o the > > whole kernel memory management. > > > > Entirely remove this option. We now have in kernel unit tests to exerci= se the > > dma_fence framework and it's containers. > > > > Signed-off-by: Christian K=C3=B6nig > > There's also igts for this, and Android heavily uses this. So I'm not sur= e > we can just nuke it. Eeeeh... I don't think that's actually the case anymore. As of android12-5.10 CONFIG_SW_SYNC is not turned on. Further, Android is disabling debugfs in their kernels as it exposes too much to userland. That said, there still are some references to it: https://cs.android.com/android/platform/superproject/+/master:system/core= /libsync/sync.c;l=3D416 But it looks like the actual users are only kselftest and igt? Adding Alistair, Hridya and Sandeep in case they have more context. thanks -john