Op 01-11-2019 om 21:06 schreef Sean Paul:
> On Fri, Nov 1, 2019 at 2:09 PM Rob Clark <robdclark@xxxxxxxxx> wrote:
>> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>>
>> drm_self_refresh_helper_update_avg_times() was incorrectly accessing the
>> new incoming state after drm_atomic_helper_commit_hw_done(). But this
>> state might have already been superceeded by an !nonblock atomic update
>> resulting in dereferencing an already free'd crtc_state.
>>
>> Fixes: d4da4e33341c ("drm: Measure Self Refresh Entry/Exit times to avoid thrashing")
>> Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
>> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
>> ---
>> TODO I *think* this will more or less do the right thing.. althought I'm
>> not 100% sure if, for example, we enter psr in a nonblock commit, and
>> then leave psr in a !nonblock commit that overtakes the completion of
>> the nonblock commit. Not sure if this sort of scenario can happen in
>> practice. But not crashing is better than crashing, so I guess we
>> should either take this patch or rever the self-refresh helpers until
>> Sean can figure out a better solution.
>>
>> drivers/gpu/drm/drm_atomic_helper.c | 2 ++
>> drivers/gpu/drm/drm_self_refresh_helper.c | 11 ++++++-----
>> include/drm/drm_atomic.h | 8 ++++++++
>> 3 files changed, 16 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
>> index 3ef2ac52ce94..732bd0ce9241 100644
>> --- a/drivers/gpu/drm/drm_atomic_helper.c
>> +++ b/drivers/gpu/drm/drm_atomic_helper.c
>> @@ -2240,6 +2240,8 @@ void drm_atomic_helper_commit_hw_done(struct drm_atomic_state *old_state)
>> int i;
>>
>> for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, new_crtc_state, i) {
>> + old_state->crtcs[i].new_self_refresh_active = new_crtc_state->self_refresh_active;
>> +
>> commit = new_crtc_state->commit;
>> if (!commit)
>> continue;
>> diff --git a/drivers/gpu/drm/drm_self_refresh_helper.c b/drivers/gpu/drm/drm_self_refresh_helper.c
>> index 68f4765a5896..77b9079fa578 100644
>> --- a/drivers/gpu/drm/drm_self_refresh_helper.c
>> +++ b/drivers/gpu/drm/drm_self_refresh_helper.c
>> @@ -143,19 +143,20 @@ void drm_self_refresh_helper_update_avg_times(struct drm_atomic_state *state,
>> unsigned int commit_time_ms)
>> {
>> struct drm_crtc *crtc;
>> - struct drm_crtc_state *old_crtc_state, *new_crtc_state;
>> + struct drm_crtc_state *old_crtc_state;
>> int i;
>>
>> - for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state,
>> - new_crtc_state, i) {
>> + for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
>> + bool new_self_refresh_active =
>> + state->crtcs[i].new_self_refresh_active;
>> struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
>> struct ewma_psr_time *time;
>>
>> if (old_crtc_state->self_refresh_active ==
>> - new_crtc_state->self_refresh_active)
>> + new_self_refresh_active)
>> continue;
>>
>> - if (new_crtc_state->self_refresh_active)
>> + if (new_self_refresh_active)
>> time = &sr_data->entry_avg_ms;
>> else
>> time = &sr_data->exit_avg_ms;
>> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
>> index 927e1205d7aa..86baf2b38bb3 100644
>> --- a/include/drm/drm_atomic.h
>> +++ b/include/drm/drm_atomic.h
>> @@ -155,6 +155,14 @@ struct __drm_crtcs_state {
>> struct drm_crtc *ptr;
>> struct drm_crtc_state *state, *old_state, *new_state;
>>
>> + /**
>> + * @new_self_refresh_active:
>> + *
>> + * drm_atomic_helper_commit_hw_done() stashes new_crtc_state->self_refresh_active
>> + * so that it can be accessed late in drm_self_refresh_helper_update_avg_times().
>> + */
>> + bool new_self_refresh_active;
>> +
> Instead of stashing this in crtc, we could generate a bitmask local to
> commit_tail and pass that to calc_avg_times? That way we don't have to
> worry about someone using this when they shouldn't
Yeah would make sense to have a bitmask, instead of making the property special. :)
Current solution seems a bit ugly.
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