On Thu, Mar 31, 2022 at 05:20:21PM +0200, Daniel Vetter wrote:
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 nicholas.kazlauskas@amd.com Date: Wed Dec 5 14:59:07 2018 -0500
drm/amd/display: Add fast path for cursor plane updateswe 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: Fixup i915 fixup ...
References: https://bugzilla.kernel.org/show_bug.cgi?id=199425 References: https://lore.kernel.org/all/20220221134155.125447-9-maxime@cerno.tech/ References: https://bugzilla.kernel.org/show_bug.cgi?id=199425 Cc: Maxime Ripard maxime@cerno.tech Tested-by: Maxime Ripard maxime@cerno.tech Cc: mikita.lipski@amd.com Cc: Michel Dänzer michel@daenzer.net Cc: harry.wentland@amd.com Cc: Rob Clark robdclark@gmail.com Cc: "Kazlauskas, Nicholas" nicholas.kazlauskas@amd.com Cc: Dmitry Osipenko dmitry.osipenko@collabora.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com
Acked-by: Maxime Ripard maxime@cerno.tech
Maxime