On Wed, Jan 10, 2018 at 6:00 AM, Maarten Lankhorst
<maarten.lankhorst@xxxxxxxxxxxxxxx> wrote:
> From: "Leo (Sunpeng) Li" <sunpeng.li@xxxxxxx>
>
> During a non-blocking commit, it is possible to return before the
> commit_tail work is queued (-ERESTARTSYS, for example).
>
> Since a reference on the crtc commit object is obtained for the pending
> vblank event when preparing the commit, the above situation will leave
> us with an extra reference.
>
> Therefore, if the commit_tail worker has not consumed the event at the
> end of a commit, release it's reference.
>
> Changes since v1:
> - Also check for state->event->base.completion being set, to
> handle the case where stall_checks() fails in setup_crtc_commit().
>
> Fixes: 24835e442f28 ("drm: reference count event->completion")
Thanks for fixing this up. You mentioned on IRC that this version
still caused problems. What were those?
Thanks,
Alex
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.11+
> Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@xxxxxxx>
> Acked-by: Harry Wentland <harry.wentland@xxxxxxx> #v1
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_atomic_helper.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index b16f1d69a0bb..1d43f3e85a7d 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -3327,6 +3327,15 @@ EXPORT_SYMBOL(drm_atomic_helper_crtc_duplicate_state);
> void __drm_atomic_helper_crtc_destroy_state(struct drm_crtc_state *state)
> {
> if (state->commit) {
> + /*
> + * In the event that a non-blocking commit returns
> + * -ERESTARTSYS before the commit_tail work is queued, we will
> + * have an extra reference to the commit object. Release it, if
> + * the event has not been consumed by the worker.
> + */
> + if (state->event && state->event->base.completion)
> + drm_crtc_commit_put(state->commit);
> +
> kfree(state->commit->event);
> state->commit->event = NULL;
> drm_crtc_commit_put(state->commit);
> --
> 2.15.1
>
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