Re: [PATCH 06/10] drm/vkms: flush crc workers earlier in commit flow

[Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>]

On Thu, Jun 6, 2019 at 7:28 PM Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>
> Currently we flush pending crc workers very late in the commit flow,
> when we destry all the old crtc states. Unfortunately at that point

destry -> destroy

> the framebuffers are already unpinned (and our vaddr possible gone),
> so this isn't good. Also, the plane_states we need might also already
> be cleaned up, since cleanup order of state structures isn't well
> defined.
>
> Fix this by waiting for all crc workers of the old state to complete
> before we start any of the cleanup work.
>
> Note that this is not yet race-free, because the hrtimer and crc
> worker look at the wrong state pointers, but that will be fixed in
> subsequent patches.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
> Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> ---
>  drivers/gpu/drm/vkms/vkms_crtc.c |  2 +-
>  drivers/gpu/drm/vkms/vkms_drv.c  | 10 ++++++++++
>  2 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
> index 55b16d545fe7..b6987d90805f 100644
> --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> @@ -125,7 +125,7 @@ static void vkms_atomic_crtc_destroy_state(struct drm_crtc *crtc,
>         __drm_atomic_helper_crtc_destroy_state(state);
>
>         if (vkms_state) {
> -               flush_work(&vkms_state->crc_work);
> +               WARN_ON(work_pending(&vkms_state->crc_work));
>                 kfree(vkms_state);
>         }
>  }
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> index f677ab1d0094..cc53ef88a331 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -62,6 +62,9 @@ static void vkms_release(struct drm_device *dev)
>  static void vkms_atomic_commit_tail(struct drm_atomic_state *old_state)
>  {
>         struct drm_device *dev = old_state->dev;
> +       struct drm_crtc *crtc;
> +       struct drm_crtc_state *old_crtc_state;
> +       int i;
>
>         drm_atomic_helper_commit_modeset_disables(dev, old_state);
>
> @@ -75,6 +78,13 @@ static void vkms_atomic_commit_tail(struct drm_atomic_state *old_state)
>
>         drm_atomic_helper_wait_for_vblanks(dev, old_state);
>
> +       for_each_old_crtc_in_state(old_state, crtc, old_crtc_state, i) {
> +               struct vkms_crtc_state *vkms_state =
> +                       to_vkms_crtc_state(old_crtc_state);
> +
> +               flush_work(&vkms_state->crc_work);
> +       }
> +
>         drm_atomic_helper_cleanup_planes(dev, old_state);
>  }

why not use drm_atomic_helper_commit_tail() here? I mean:

for_each_old_crtc_in_state(old_state, crtc, old_crtc_state, i) {
…
}

drm_atomic_helper_commit_tail(old_state);

After looking at drm_atomic_helper_cleanup_planes() it sounds safe for
me to use the above code; I just test it with two tests from
crc_cursor. Maybe I missed something, could you help me here?

Finally, IMHO, I think that Patch 05, 06 and 07 could be squashed in a
single patch to make it easier to understand the change.

> --
> 2.20.1
>


-- 

Rodrigo Siqueira
https://siqueira.tech
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