On 2021-09-07 10:10 a.m., Nicholas Kazlauskas wrote: > [Why] > If we're running a headless config with 0 links then the vblank > workqueue will be NULL - causing a NULL pointer exception during > any commit. > > [How] > Guard access to the workqueue if it's NULL and don't queue or flush > work if it is. > > Cc: Roman Li <Roman.Li@xxxxxxx> > Cc: Wayne Lin <Wayne.Lin@xxxxxxx> > Cc: Harry Wentland <Harry.Wentland@xxxxxxx> > Reported-by: Mike Lothian <mike@xxxxxxxxxxxxxx> > BugLink: https://gitlab.freedesktop.org/drm/amd/-/issues/1700 > Fixes: 91f86d4cce2 ("drm/amd/display: Use vblank control events for PSR enable/disable") > Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx> Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx> Harry > --- > .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 32 +++++++++++-------- > 1 file changed, 18 insertions(+), 14 deletions(-) > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > index 8837259215d..46e08736f94 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -6185,21 +6185,23 @@ static inline int dm_set_vblank(struct drm_crtc *crtc, bool enable) > return 0; > > #if defined(CONFIG_DRM_AMD_DC_DCN) > - work = kzalloc(sizeof(*work), GFP_ATOMIC); > - if (!work) > - return -ENOMEM; > + if (dm->vblank_control_workqueue) { > + work = kzalloc(sizeof(*work), GFP_ATOMIC); > + if (!work) > + return -ENOMEM; > > - INIT_WORK(&work->work, vblank_control_worker); > - work->dm = dm; > - work->acrtc = acrtc; > - work->enable = enable; > + INIT_WORK(&work->work, vblank_control_worker); > + work->dm = dm; > + work->acrtc = acrtc; > + work->enable = enable; > > - if (acrtc_state->stream) { > - dc_stream_retain(acrtc_state->stream); > - work->stream = acrtc_state->stream; > - } > + if (acrtc_state->stream) { > + dc_stream_retain(acrtc_state->stream); > + work->stream = acrtc_state->stream; > + } > > - queue_work(dm->vblank_control_workqueue, &work->work); > + queue_work(dm->vblank_control_workqueue, &work->work); > + } > #endif > > return 0; > @@ -8809,7 +8811,8 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state, > * If PSR or idle optimizations are enabled then flush out > * any pending work before hardware programming. > */ > - flush_workqueue(dm->vblank_control_workqueue); > + if (dm->vblank_control_workqueue) > + flush_workqueue(dm->vblank_control_workqueue); > #endif > > bundle->stream_update.stream = acrtc_state->stream; > @@ -9144,7 +9147,8 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state) > /* if there mode set or reset, disable eDP PSR */ > if (mode_set_reset_required) { > #if defined(CONFIG_DRM_AMD_DC_DCN) > - flush_workqueue(dm->vblank_control_workqueue); > + if (dm->vblank_control_workqueue) > + flush_workqueue(dm->vblank_control_workqueue); > #endif > amdgpu_dm_psr_disable_all(dm); > } >
