[PATCH] drm/atomic-helpers: remove legacy_cursor_update hacks
Jessica Zhang
quic_jesszhan at quicinc.com
Thu Apr 7 01:27:00 UTC 2022
On 3/31/2022 8:20 AM, Daniel Vetter wrote:
> 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 at amd.com>
> 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@cerno.tech/
> References: https://bugzilla.kernel.org/show_bug.cgi?id=199425
> Cc: Maxime Ripard <maxime at cerno.tech>
> Tested-by: Maxime Ripard <maxime at cerno.tech>
> Cc: mikita.lipski at amd.com
> Cc: Michel Dänzer <michel at daenzer.net>
> Cc: harry.wentland at amd.com
> Cc: Rob Clark <robdclark at gmail.com>
Hey Rob,
I saw your tested-by and reviewed-by tags on Patchwork. Just curious,
what device did you test on?
I'm hitting several instances of this error when doing a start/stop ui
on Lazor Chromebook with this patch:
[ 3092.608322] CPU: 2 PID: 18579 Comm: DrmThread Tainted: G W
5.17.0-rc2-lockdep-00089-g7f17ab7bf567 #155
e5912cd286513b064a82a38938b3fdef86b079aa
[ 3092.622880] Hardware name: Google Lazor Limozeen without Touchscreen
(rev4) (DT)
[ 3092.630492] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS
BTYPE=--)
[ 3092.637664] pc : dpu_crtc_atomic_flush+0x9c/0x144
[ 3092.642523] lr : dpu_crtc_atomic_flush+0x60/0x144
[ 3092.647379] sp : ffffffc00c1e3760
[ 3092.650805] x29: ffffffc00c1e3760 x28: ffffff80985dd800 x27:
0000000000000425
[ 3092.658164] x26: ffffff80985dc500 x25: ffffff80985ddc00 x24:
ffffffdf8ae3b6f0
[ 3092.665522] x23: 0000000000000000 x22: 0000000000000000 x21:
ffffff809b82da00
[ 3092.672890] x20: ffffff80840e1000 x19: ffffff80840e2000 x18:
0000000000001000
[ 3092.680255] x17: 0000000000000400 x16: 0000000000000100 x15:
000000000000003b
[ 3092.687622] x14: 0000000000000000 x13: 0000000000000002 x12:
0000000000000003
[ 3092.694979] x11: ffffff8084009000 x10: 0000000000000040 x9 :
0000000000000040
[ 3092.702340] x8 : 0000000000000300 x7 : 000000000000000c x6 :
0000000000000004
[ 3092.709698] x5 : 0000000000000320 x4 : 0000000000000018 x3 :
0000000000000000
[ 3092.717056] x2 : 0000000000000000 x1 : 7bfb38b2a3a89800 x0 :
ffffff809a1eb300
[ 3092.724424] Call trace:
[ 3092.726958] dpu_crtc_atomic_flush+0x9c/0x144
[ 3092.731463] drm_atomic_helper_commit_planes+0x1bc/0x1c4
[ 3092.736944] msm_atomic_commit_tail+0x23c/0x3e0
[ 3092.741627] commit_tail+0x7c/0xfc
[ 3092.745145] drm_atomic_helper_commit+0x158/0x15c
[ 3092.749998] drm_atomic_commit+0x60/0x74
[ 3092.754055] drm_atomic_helper_update_plane+0x100/0x110
[ 3092.759449] __setplane_atomic+0x11c/0x120
[ 3092.763685] drm_mode_cursor_universal+0x188/0x22c
[ 3092.768633] drm_mode_cursor_common+0x120/0x1f8
[ 3092.773310] drm_mode_cursor_ioctl+0x68/0x8c
[ 3092.777721] drm_ioctl_kernel+0xe8/0x168
[ 3092.781770] drm_ioctl+0x320/0x370
[ 3092.785289] drm_compat_ioctl+0x40/0xdc
[ 3092.789257] __arm64_compat_sys_ioctl+0xe0/0x150
[ 3092.794030] invoke_syscall+0x80/0x114
[ 3092.797905] el0_svc_common.constprop.3+0xc4/0xf8
[ 3092.802765] do_el0_svc_compat+0x2c/0x54
[ 3092.806811] el0_svc_compat+0x4c/0xe4
[ 3092.810598] el0t_32_sync_handler+0xc4/0xf4
[ 3092.814914] el0t_32_sync+0x174/0x178
[ 3092.818701] irq event stamp: 55940
[ 3092.822217] hardirqs last enabled at (55939): [<ffffffdf8ad617a4>]
exit_to_kernel_mode+0x10c/0x11c
[ 3092.831523] hardirqs last disabled at (55940): [<ffffffdf8ad62728>]
el1_dbg+0x28/0x70
[ 3092.839577] softirqs last enabled at (55938): [<ffffffdf8a2103a8>]
__do_softirq+0x1e8/0x480
[ 3092.848256] softirqs last disabled at (55923): [<ffffffdf8a28d668>]
__irq_exit_rcu+0xdc/0x140
[ 3092.857022] ---[ end trace 0000000000000000 ]---
Thanks,
Jessica Zhang
> Cc: "Kazlauskas, Nicholas" <nicholas.kazlauskas at amd.com>
> Cc: Dmitry Osipenko <dmitry.osipenko at collabora.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
> 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:
> --
> 2.34.1
>
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