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?
I guess the correct fix would be to implement async operations for cursor planes? ast doesn't do this yet.
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.cindex 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
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