[Intel-gfx] [PATCH 06/10] drm/syncobj: use the timeline point in drm_syncobj_find_fence v3

[Chris Wilson]

Quoting Chunming Zhou (2018-12-11 10:34:45)
> From: Christian König <ckoenig.leichtzumerken at gmail.com>
> 
> Implement finding the right timeline point in drm_syncobj_find_fence.
> 
> v2: return -EINVAL when the point is not submitted yet.
> v3: fix reference counting bug, add flags handling as well
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>  drivers/gpu/drm/drm_syncobj.c | 43 ++++++++++++++++++++++++++++++++---
>  1 file changed, 40 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index 76ce13dafc4d..d964b348ecba 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -231,16 +231,53 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
>                            struct dma_fence **fence)
>  {
>         struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
> -       int ret = 0;
> +       struct syncobj_wait_entry wait;
> +       int ret;
>  
>         if (!syncobj)
>                 return -ENOENT;
>  
>         *fence = drm_syncobj_fence_get(syncobj);
> -       if (!*fence) {
> +       drm_syncobj_put(syncobj);
> +
> +       if (*fence) {
> +               ret = dma_fence_chain_find_seqno(fence, point);
> +               if (!ret)
> +                       return 0;
> +               dma_fence_put(*fence);
> +       } else {
>                 ret = -EINVAL;
>         }
> -       drm_syncobj_put(syncobj);
> +
> +       if (!(flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT))
> +               return ret;
> +
> +       memset(&wait, 0, sizeof(wait));
> +       wait.task = current;
> +       wait.point = point;
> +       drm_syncobj_fence_add_wait(syncobj, &wait);

> +
> +       do {
> +               set_current_state(TASK_INTERRUPTIBLE);
> +               if (wait.fence) {
> +                       ret = 0;
> +                       break;
> +               }
> +
> +               if (signal_pending(current)) {
> +                       ret = -ERESTARTSYS;
> +                       break;
> +               }
> +
> +               schedule();
> +       } while (1);

I've previously used a dma_fence_proxy so that we could do nonblocking
waits on future submits. That would be preferrable (a requirement for
our stupid BKL-driven code).
-Chris