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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id D0343C433F5 for ; Thu, 31 Mar 2022 19:11:35 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1BF8910EC1A; Thu, 31 Mar 2022 19:11:35 +0000 (UTC) Received: from mail-wm1-x342.google.com (mail-wm1-x342.google.com [IPv6:2a00:1450:4864:20::342]) by gabe.freedesktop.org (Postfix) with ESMTPS id C637810EC1A for ; Thu, 31 Mar 2022 19:11:33 +0000 (UTC) Received: by mail-wm1-x342.google.com with SMTP id bi13-20020a05600c3d8d00b0038c2c33d8f3so2226056wmb.4 for ; Thu, 31 Mar 2022 12:11:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=RYIGJmB33fF+/pgFvO9mxz22cWndqAj0H0/t408XR54=; b=P982/t+9cFEzEXcNEGG5uEW2hYSl+z2KjjZi3atzzMtuTQW2uw3NXipQGlr7miTzAe ql6h+Jz6baMykbxiAwaUgEBzeaB+49EaOfMsT5ddEGKKgY/Y5Q9nHcGLdPkervWcARdX AKNgJmX29VeHHYfwW41FaRbOrbVMjgHBLXqtE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=RYIGJmB33fF+/pgFvO9mxz22cWndqAj0H0/t408XR54=; b=ftcJi5SpFdJflsxgDTleNr3b2bHFHvHA8DmpRsbjCFHAidVFFl5CLC9xGDuJVWhuLh xkkWecq4tB8ecr8oCBs++/I6jt5ca+VHmVaxpwN8cyNxE8+DjlSPX2Vkadvn2VYPBZ1U By9RegioJKlN+7y0mJYq/9L56FbdsZx2+rebbvcOoYUkQ1kPhMiOvLnCh/1wSPhxpaEI d80wypzsxgemMOPerR7czI5G4wq1UB6B4TYQm8Xp1Kbb6u2EzgJk+GGX9Gh7SrgRtehi 9rQJCS9dTEloBBElHGBX7Twbb394/KygLx9e/leLQWhc7OjoHpzjLR67/qXTjqGIC3vn O8Bg== X-Gm-Message-State: AOAM533afVbTAz7pS2/AX7zoBn3RczuMVlPmLsB9EFq5cujEl/h97XyH Z6t9rMbSkI5QNkdDSc6Qqih/AA== X-Google-Smtp-Source: ABdhPJwjpCdJJGJ5L1W7v/23fuJuNb9eO/ZsPvhLM6kJHb5m/7AKtlviGneMJQJC15SeDjgGxclF0Q== X-Received: by 2002:a7b:cc12:0:b0:37c:1ae:100a with SMTP id f18-20020a7bcc12000000b0037c01ae100amr5743177wmh.54.1648753892300; Thu, 31 Mar 2022 12:11:32 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id v14-20020a7bcb4e000000b0034492fa24c6sm97647wmj.34.2022.03.31.12.11.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 31 Mar 2022 12:11:31 -0700 (PDT) Date: Thu, 31 Mar 2022 21:11:29 +0200 From: Daniel Vetter To: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= Subject: Re: [PATCH v4] drm/atomic-helpers: remove legacy_cursor_update hacks Message-ID: References: <20220331130545.625721-1-maxime@cerno.tech> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Operating-System: Linux phenom 5.10.0-8-amd64 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: Dom Cobley , Tim Gover , Dave Stevenson , Daniel Vetter , Michel =?iso-8859-1?Q?D=E4nzer?= , dri-devel@lists.freedesktop.org, "Kazlauskas, Nicholas" , Maxime Ripard , Daniel Vetter , mikita.lipski@amd.com, Phil Elwell Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Thu, Mar 31, 2022 at 06:48:43PM +0300, Ville Syrjälä wrote: > On Thu, Mar 31, 2022 at 05:14:29PM +0200, Daniel Vetter wrote: > > On Thu, Mar 31, 2022 at 04:25:13PM +0300, Ville Syrjälä wrote: > > > On Thu, Mar 31, 2022 at 03:05:45PM +0200, Maxime Ripard wrote: > > > > From: Daniel Vetter > > > > > > > > The stuff never really worked, and leads to lots of fun because it > > > > out-of-order frees atomic states. Which upsets KASAN, among other > > > > things. > > > > > > > > For async updates we now have a more solid solution with the > > > > ->atomic_async_check and ->atomic_async_commit hooks. Support for that > > > > for msm and vc4 landed. nouveau and i915 have their own commit > > > > routines, doing something similar. > > > > > > > > For everyone else it's probably better to remove the use-after-free > > > > bug, and encourage folks to use the async support instead. The > > > > affected drivers which register a legacy cursor plane and don't either > > > > use the new async stuff or their own commit routine are: amdgpu, > > > > atmel, mediatek, qxl, rockchip, sti, sun4i, tegra, virtio, and vmwgfx. > > > > > > > > Inspired by an amdgpu bug report. > > > > > > > > v2: Drop RFC, I think with amdgpu converted over to use > > > > atomic_async_check/commit done in > > > > > > > > commit 674e78acae0dfb4beb56132e41cbae5b60f7d662 > > > > Author: Nicholas Kazlauskas > > > > Date: Wed Dec 5 14:59:07 2018 -0500 > > > > > > > > drm/amd/display: Add fast path for cursor plane updates > > > > > > > > we don't have any driver anymore where we have userspace expecting > > > > solid legacy cursor support _and_ they are using the atomic helpers in > > > > their fully glory. So we can retire this. > > > > > > > > v3: Paper over msm and i915 regression. The complete_all is the only > > > > thing missing afaict. > > > > > > > > v4: Rebased on recent kernel, added extra link for vc4 bug. > > > > > > > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=199425 > > > > Link: https://lore.kernel.org/all/20220221134155.125447-9-maxime@cerno.tech/ > > > > Cc: mikita.lipski@amd.com > > > > Cc: Michel Dänzer > > > > Cc: harry.wentland@amd.com > > > > Cc: Rob Clark > > > > Cc: "Kazlauskas, Nicholas" > > > > Tested-by: Maxime Ripard > > > > Signed-off-by: Daniel Vetter > > > > Signed-off-by: Maxime Ripard > > > > --- > > > > drivers/gpu/drm/drm_atomic_helper.c | 13 ------------- > > > > drivers/gpu/drm/i915/display/intel_display.c | 13 +++++++++++++ > > > > drivers/gpu/drm/msm/msm_atomic.c | 2 ++ > > > > 3 files changed, 15 insertions(+), 13 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > > > > index 9603193d2fa1..a2899af82b4a 100644 > > > > --- a/drivers/gpu/drm/drm_atomic_helper.c > > > > +++ b/drivers/gpu/drm/drm_atomic_helper.c > > > > @@ -1498,13 +1498,6 @@ drm_atomic_helper_wait_for_vblanks(struct drm_device *dev, > > > > int i, ret; > > > > unsigned int crtc_mask = 0; > > > > > > > > - /* > > > > - * Legacy cursor ioctls are completely unsynced, and userspace > > > > - * relies on that (by doing tons of cursor updates). > > > > - */ > > > > - if (old_state->legacy_cursor_update) > > > > - return; > > > > - > > > > for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, new_crtc_state, i) { > > > > if (!new_crtc_state->active) > > > > continue; > > > > @@ -2135,12 +2128,6 @@ int drm_atomic_helper_setup_commit(struct drm_atomic_state *state, > > > > continue; > > > > } > > > > > > > > - /* Legacy cursor updates are fully unsynced. */ > > > > - if (state->legacy_cursor_update) { > > > > - complete_all(&commit->flip_done); > > > > - continue; > > > > - } > > > > - > > > > if (!new_crtc_state->event) { > > > > commit->event = kzalloc(sizeof(*commit->event), > > > > GFP_KERNEL); > > > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c > > > > index bf7ce684dd8e..bde32f5a33cb 100644 > > > > --- a/drivers/gpu/drm/i915/display/intel_display.c > > > > +++ b/drivers/gpu/drm/i915/display/intel_display.c > > > > @@ -8855,6 +8855,19 @@ static int intel_atomic_commit(struct drm_device *dev, > > > > state->base.legacy_cursor_update = false; > > > > } > > > > > > > > + /* > > > > + * FIXME: Cut over to (async) commit helpers instead of hand-rolling > > > > + * everything. > > > > + */ > > > > > > Intel cursors can't even do async updates so this is rather > > > nonsensical. What we need is some kind of reasonable mailbox > > > support. > > > > This is not the async plane update you're thinking of. i915 really should > > switch over more to atomic helpers. > > The comment should be clarified then. As is I have no real idea > what it's trying to say. Use drm_atomic_commit and only overwrite atomic_commit_tail. But I'm not really clear why the comment isn't clear - i915 is the only driver not using them, maybe should start to take a look when they're so unfamiliar :-P -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch