On Thu, Apr 07, 2022 at 09:49:49AM +0200, Thomas Zimmermann wrote: > Hi Daniel > > Am 31.03.22 um 17:20 schrieb 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. > > A while ago, I received a patch for a bug in ast. Cursor movement interfered > with modesetting. [1] I didn't really knew what to make of it. Could this be > related to the problem you're describing here? Maybe. > I guess the correct fix would be to implement async operations for cursor > planes? ast doesn't do this yet. Yeah the async ops are the new attempt (since a few years) to make this work and suck less. -Daniel > > Best regards > Thomas > > [1] https://lore.kernel.org/dri-devel/20210917072226.17357-1-kuohsiang_chou@xxxxxxxxxxxxxx/ > > > > > 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@xxxxxxx> > > 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: Fixup i915 fixup ... > > > > References: https://bugzilla.kernel.org/show_bug.cgi?id=199425 > > References: https://lore.kernel.org/all/20220221134155.125447-9-maxime@xxxxxxxxxx/ > > References: https://bugzilla.kernel.org/show_bug.cgi?id=199425 > > Cc: Maxime Ripard <maxime@xxxxxxxxxx> > > Tested-by: Maxime Ripard <maxime@xxxxxxxxxx> > > Cc: mikita.lipski@xxxxxxx > > Cc: Michel Dänzer <michel@xxxxxxxxxxx> > > Cc: harry.wentland@xxxxxxx > > Cc: Rob Clark <robdclark@xxxxxxxxx> > > Cc: "Kazlauskas, Nicholas" <nicholas.kazlauskas@xxxxxxx> > > Cc: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx> > > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> > > --- > > drivers/gpu/drm/drm_atomic_helper.c | 13 ------------- > > drivers/gpu/drm/i915/display/intel_display.c | 14 ++++++++++++++ > > drivers/gpu/drm/msm/msm_atomic.c | 2 ++ > > 3 files changed, 16 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 d2abe0e430bf..6ca5a6e7703b 100644 > > --- a/drivers/gpu/drm/i915/display/intel_display.c > > +++ b/drivers/gpu/drm/i915/display/intel_display.c > > @@ -8799,6 +8799,20 @@ static int intel_atomic_commit(struct drm_device *dev, > > intel_runtime_pm_put(&dev_priv->runtime_pm, state->wakeref); > > return ret; > > } > > + > > + /* > > + * FIXME: Cut over to (async) commit helpers instead of hand-rolling > > + * everything. > > + */ > > + if (state->base.legacy_cursor_update) { > > + struct intel_crtc_state *new_crtc_state; > > + struct intel_crtc *crtc; > > + int i; > > + > > + for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) > > + complete_all(&new_crtc_state->uapi.commit->flip_done); > > + } > > + > > intel_shared_dpll_swap_state(state); > > intel_atomic_track_fbs(state); > > diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c > > index 1686fbb611fd..b3cfabebe5d6 100644 > > --- a/drivers/gpu/drm/msm/msm_atomic.c > > +++ b/drivers/gpu/drm/msm/msm_atomic.c > > @@ -222,6 +222,8 @@ void msm_atomic_commit_tail(struct drm_atomic_state *state) > > /* async updates are limited to single-crtc updates: */ > > WARN_ON(crtc_mask != drm_crtc_mask(async_crtc)); > > + complete_all(&async_crtc->state->commit->flip_done); > > + > > /* > > * Start timer if we don't already have an update pending > > * on this crtc: > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5, 90409 Nürnberg, Germany > (HRB 36809, AG Nürnberg) > Geschäftsführer: Ivo Totev -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
