[Intel-xe] [PATCH 2/3] drm/vblank: Warn when silently cancelling vblank works

[Lyude Paul]

Good point!

Reviewed-by: Lyude Paul <lyude at redhat.com>

On Wed, 2023-09-20 at 17:03 +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Silently cancelling vblank works is a bit rude, especially
> if said works do any resource management (eg. free memory).
> WARN if we ever hit this.
> 
> TODO: Maybe drm_crtc_vblank_off() should wait for any
> pending work to reach its target vblank before actually
> doing anything drastic?
> 
> Cc: Lyude Paul <lyude at redhat.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/drm_vblank_work.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_vblank_work.c b/drivers/gpu/drm/drm_vblank_work.c
> index bd481fdd6b87..43cd5c0f4f6f 100644
> --- a/drivers/gpu/drm/drm_vblank_work.c
> +++ b/drivers/gpu/drm/drm_vblank_work.c
> @@ -73,6 +73,9 @@ void drm_vblank_cancel_pending_works(struct drm_vblank_crtc *vblank)
>  
>  	assert_spin_locked(&vblank->dev->event_lock);
>  
> +	drm_WARN_ONCE(vblank->dev, !list_empty(&vblank->pending_work),
> +		      "Cancelling pending vblank works!\n");
> +
>  	list_for_each_entry_safe(work, next, &vblank->pending_work, node) {
>  		list_del_init(&work->node);
>  		drm_vblank_put(vblank->dev, vblank->pipe);

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat