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 <[email protected]> > > > > > > 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 <[email protected]> > > > 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/[email protected]/ > > > Cc: [email protected] > > > Cc: Michel Dänzer <[email protected]> > > > Cc: [email protected] > > > Cc: Rob Clark <[email protected]> > > > Cc: "Kazlauskas, Nicholas" <[email protected]> > > > Tested-by: Maxime Ripard <[email protected]> > > > Signed-off-by: Daniel Vetter <[email protected]> > > > Signed-off-by: Maxime Ripard <[email protected]> > > > --- > > > 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. -- Ville Syrjälä Intel
