target/linux/bcm27xx/patches-5.15/950-0806-drm-atomic-helpers-remove-legacy_cursor_update-hacks.patch

   1 From 41a635c959507290ba41afa56ac143d648a69958 Mon Sep 17 00:00:00 2001
   2 From: Daniel Vetter <daniel.vetter@ffwll.ch>
   3 Date: Fri, 23 Oct 2020 14:39:23 +0200
   4 Subject: [PATCH] drm/atomic-helpers: remove legacy_cursor_update hacks
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   8
   9 The stuff never really worked, and leads to lots of fun because it
  10 out-of-order frees atomic states. Which upsets KASAN, among other
  11 things.
  12
  13 For async updates we now have a more solid solution with the
  14 ->atomic_async_check and ->atomic_async_commit hooks. Support for that
  15 for msm and vc4 landed. nouveau and i915 have their own commit
  16 routines, doing something similar.
  17
  18 For everyone else it's probably better to remove the use-after-free
  19 bug, and encourage folks to use the async support instead. The
  20 affected drivers which register a legacy cursor plane and don't either
  21 use the new async stuff or their own commit routine are: amdgpu,
  22 atmel, mediatek, qxl, rockchip, sti, sun4i, tegra, virtio, and vmwgfx.
  23
  24 Inspired by an amdgpu bug report.
  25
  26 v2: Drop RFC, I think with amdgpu converted over to use
  27 atomic_async_check/commit done in
  28
  29 commit 674e78acae0dfb4beb56132e41cbae5b60f7d662
  30 Author: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
  31 Date:   Wed Dec 5 14:59:07 2018 -0500
  32
  33     drm/amd/display: Add fast path for cursor plane updates
  34
  35 we don't have any driver anymore where we have userspace expecting
  36 solid legacy cursor support _and_ they are using the atomic helpers in
  37 their fully glory. So we can retire this.
  38
  39 v3: Paper over msm and i915 regression. The complete_all is the only
  40 thing missing afaict.
  41
  42 v4: Rebased on recent kernel, added extra link for vc4 bug.
  43
  44 Link: https://bugzilla.kernel.org/show_bug.cgi?id=199425
  45 Link: https://lore.kernel.org/all/20220221134155.125447-9-maxime@cerno.tech/
  46 Cc: mikita.lipski@amd.com
  47 Cc: Michel Dänzer <michel@daenzer.net>
  48 Cc: harry.wentland@amd.com
  49 Cc: Rob Clark <robdclark@gmail.com>
  50 Cc: "Kazlauskas, Nicholas" <nicholas.kazlauskas@amd.com>
  51 Tested-by: Maxime Ripard <maxime@cerno.tech>
  52 Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
  53 Signed-off-by: Maxime Ripard <maxime@cerno.tech>
  54 ---
  55  drivers/gpu/drm/drm_atomic_helper.c          | 13 -------------
  56  drivers/gpu/drm/i915/display/intel_display.c | 13 +++++++++++++
  57  drivers/gpu/drm/msm/msm_atomic.c             |  2 ++
  58  3 files changed, 15 insertions(+), 13 deletions(-)
  59
  60 --- a/drivers/gpu/drm/drm_atomic_helper.c
  61 +++ b/drivers/gpu/drm/drm_atomic_helper.c
  62 @@ -1498,13 +1498,6 @@ drm_atomic_helper_wait_for_vblanks(struc
  63         int i, ret;
  64         unsigned int crtc_mask = 0;
  65
  66 -        /*
  67 -         * Legacy cursor ioctls are completely unsynced, and userspace
  68 -         * relies on that (by doing tons of cursor updates).
  69 -         */
  70 -       if (old_state->legacy_cursor_update)
  71 -               return;
  72 -
  73         for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, new_crtc_state, i) {
  74                 if (!new_crtc_state->active)
  75                         continue;
  76 @@ -2132,12 +2125,6 @@ int drm_atomic_helper_setup_commit(struc
  77                         complete_all(&commit->flip_done);
  78                         continue;
  79                 }
  80 -
  81 -               /* Legacy cursor updates are fully unsynced. */
  82 -               if (state->legacy_cursor_update) {
  83 -                       complete_all(&commit->flip_done);
  84 -                       continue;
  85 -               }
  86
  87                 if (!new_crtc_state->event) {
  88                         commit->event = kzalloc(sizeof(*commit->event),
  89 --- a/drivers/gpu/drm/i915/display/intel_display.c
  90 +++ b/drivers/gpu/drm/i915/display/intel_display.c
  91 @@ -10821,6 +10821,19 @@ static int intel_atomic_commit(struct dr
  92                                 state->base.legacy_cursor_update = false;
  93         }
  94
  95 +       /*
  96 +        * FIXME: Cut over to (async) commit helpers instead of hand-rolling
  97 +        * everything.
  98 +        */
  99 +       if (state->base.legacy_cursor_update) {
 100 +               struct intel_crtc_state *new_crtc_state;
 101 +               struct intel_crtc *crtc;
 102 +               int i;
 103 +
 104 +               for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i)
 105 +                       complete_all(&new_crtc_state->uapi.commit->flip_done);
 106 +       }
 107 +
 108         ret = intel_atomic_prepare_commit(state);
 109         if (ret) {
 110                 drm_dbg_atomic(&dev_priv->drm,
 111 --- a/drivers/gpu/drm/msm/msm_atomic.c
 112 +++ b/drivers/gpu/drm/msm/msm_atomic.c
 113 @@ -246,6 +246,8 @@ void msm_atomic_commit_tail(struct drm_a
 114                 /* async updates are limited to single-crtc updates: */
 115                 WARN_ON(crtc_mask != drm_crtc_mask(async_crtc));
 116
 117 +               complete_all(&async_crtc->state->commit->flip_done);
 118 +
 119                 /*
 120                  * Start timer if we don't already have an update pending
 121                  * on this crtc: