[PATCH] drm/atomic: Fix memleak on ERESTARTSYS during non-blocking commits

[Harry Wentland]

On 2018-01-04 02:47 PM, sunpeng.li at amd.com wrote:
> From: "Leo (Sunpeng) Li" <sunpeng.li at amd.com>
> 
> 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.
> 
> Signed-off-by: Leo (Sunpeng) Li <sunpeng.li at amd.com>

No expert on this but looks sane to me.

Acked-by: Harry Wentland <harry.wentland at amd.com>

Harry

> ---
>  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 ab40321..4253f57 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -3421,6 +3421,15 @@ 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)
> +			drm_crtc_commit_put(state->commit);
> +
>  		kfree(state->commit->event);
>  		state->commit->event = NULL;
>  		drm_crtc_commit_put(state->commit);
>