On Thu, Mar 31, 2022 at 03:05:45PM +0200, Maxime Ripard wrote: > From: Daniel Vetter <daniel.vetter@xxxxxxxx> > > 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@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: 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@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> > Tested-by: Maxime Ripard <maxime@xxxxxxxxxx> > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> > Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx> > --- > 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. > + 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); > + } You can complete what doesn't yet exist. Missing cc: intel-gfx for fireworks. > + > ret = intel_atomic_prepare_commit(state); > if (ret) { > drm_dbg_atomic(&dev_priv->drm, > diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c > index 27c9ae563f2f..6ed14fafa40c 100644 > --- a/drivers/gpu/drm/msm/msm_atomic.c > +++ b/drivers/gpu/drm/msm/msm_atomic.c > @@ -237,6 +237,8 @@ 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: > -- > 2.35.1 -- Ville Syrjälä Intel
