Re: [PATCH v1 2/2] drm: Clear the fence pointer when writeback job signaled

From: Brian Starkey
Date: Mon Aug 05 2019 - 09:12:21 EST


Hi Lowry,

Based on Daniel's input, this patch looks fine:

Reviewed-by: Brian Starkey <brian.starkey@xxxxxxx>

I think there's some opportunity for improvement around
prepare_signaling/complete_signaling, but that can be treated as
separate from fixing this bug.

Thanks,
-Brian

On Wed, Jul 31, 2019 at 11:04:45AM +0000, Lowry Li (Arm Technology China) wrote:
> During it signals the completion of a writeback job, after releasing
> the out_fence, we'd clear the pointer.
>
> Check if fence left over in drm_writeback_cleanup_job(), release it.
>
> Signed-off-by: Lowry Li (Arm Technology China) <lowry.li@xxxxxxx>
> ---
> drivers/gpu/drm/drm_writeback.c | 23 +++++++++++++++--------
> 1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
> index ff138b6..43d9e3b 100644
> --- a/drivers/gpu/drm/drm_writeback.c
> +++ b/drivers/gpu/drm/drm_writeback.c
> @@ -324,6 +324,9 @@ void drm_writeback_cleanup_job(struct drm_writeback_job *job)
> if (job->fb)
> drm_framebuffer_put(job->fb);
>
> + if (job->out_fence)
> + dma_fence_put(job->out_fence);
> +
> kfree(job);
> }
> EXPORT_SYMBOL(drm_writeback_cleanup_job);
> @@ -366,25 +369,29 @@ static void cleanup_work(struct work_struct *work)
> {
> unsigned long flags;
> struct drm_writeback_job *job;
> + struct dma_fence *out_fence;
>
> spin_lock_irqsave(&wb_connector->job_lock, flags);
> job = list_first_entry_or_null(&wb_connector->job_queue,
> struct drm_writeback_job,
> list_entry);
> - if (job) {
> + if (job)
> list_del(&job->list_entry);
> - if (job->out_fence) {
> - if (status)
> - dma_fence_set_error(job->out_fence, status);
> - dma_fence_signal(job->out_fence);
> - dma_fence_put(job->out_fence);
> - }
> - }
> +
> spin_unlock_irqrestore(&wb_connector->job_lock, flags);
>
> if (WARN_ON(!job))
> return;
>
> + out_fence = job->out_fence;
> + if (out_fence) {
> + if (status)
> + dma_fence_set_error(out_fence, status);
> + dma_fence_signal(out_fence);
> + dma_fence_put(out_fence);
> + job->out_fence = NULL;
> + }
> +
> INIT_WORK(&job->cleanup_work, cleanup_work);
> queue_work(system_long_wq, &job->cleanup_work);
> }
> --
> 1.9.1
>