[PATCH] drm/atomic-helpers: remove legacy_cursor_update hacks
Abhinav Kumar
quic_abhinavk at quicinc.com
Sat Apr 9 04:04:33 UTC 2022
On 4/7/2022 4:12 PM, Rob Clark wrote:
> On Thu, Apr 7, 2022 at 3:59 PM Abhinav Kumar <quic_abhinavk at quicinc.com> wrote:
>>
>> 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?
>
> Can you reproduce on v5.18-rc1 (plus 80253168dbfd)? I'm running a
> loop of stop ui / start ui and hasn't triggered a splat yet.
>
> Otherwise maybe you can addr2line to figure out where it crashed?
>
> BR,
> -R
So this is not a crash. Its a warning splat coming from
https://gitlab.freedesktop.org/drm/msm/-/blob/msm-next/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c#L785
Looks like the complete_commit() which should signal the event has not
happened before the next cursor commit.
Somehow this change is affecting the flow to miss the event signaling
that the event is done.
We tried a couple of approaches but couldnt still fix the warning.
Will continue to check further next week.
>
>> 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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