[PATCH] drm/atomic-helpers: remove legacy_cursor_update hacks
Abhinav Kumar
quic_abhinavk at quicinc.com
Thu Apr 7 22:59:19 UTC 2022
Hi Rob and Daniel
On 4/7/2022 3:51 PM, Rob Clark wrote:
> On Wed, Apr 6, 2022 at 6:27 PM Jessica Zhang <quic_jesszhan at quicinc.com> wrote:
>>
>>
>>
>> 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 was testing on strongbad.. v5.18-rc1 + patches (notably, revert
> 80253168dbfd ("drm: of: Lookup if child node has panel or bridge")
>
> I think the display setup shouldn't be significantly different than
> limozeen (ie. it's an eDP panel). But I didn't do much start/stop
> ui.. I was mostly looking to make sure cursor movements weren't
> causing fps drops ;-)
>
> BR,
> -R
start ui/ stop ui is a basic operation for us to use IGT on msm-next.
So we cannot let that break.
I think we need to check whats causing this splat.
Can we hold back this change till then?
Thanks
Abhinav
>
>> 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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