Re: [Intel-gfx] [PATCH 20/26] drm: use new iterator in drm_gem_fence_array_add_implicit v2

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Sep 17, 2021 at 02:35:07PM +0200, Christian König wrote:
> Simplifying the code a bit.
> 
> v2: add missing rcu_read_lock()/unlock()
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

This will be gone as soon as I can land the last conversion patches. Plus
it's always called with dma_resv_lock held.

I wouldn't bother tbh.
-Daniel

> ---
>  drivers/gpu/drm/drm_gem.c | 34 ++++++++++++----------------------
>  1 file changed, 12 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index 09c820045859..c2c41b668f40 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -1340,31 +1340,21 @@ int drm_gem_fence_array_add_implicit(struct xarray *fence_array,
>  				     struct drm_gem_object *obj,
>  				     bool write)
>  {
> -	int ret;
> -	struct dma_fence **fences;
> -	unsigned int i, fence_count;
> -
> -	if (!write) {
> -		struct dma_fence *fence =
> -			dma_resv_get_excl_unlocked(obj->resv);
> -
> -		return drm_gem_fence_array_add(fence_array, fence);
> -	}
> -
> -	ret = dma_resv_get_fences(obj->resv, NULL,
> -						&fence_count, &fences);
> -	if (ret || !fence_count)
> -		return ret;
> -
> -	for (i = 0; i < fence_count; i++) {
> -		ret = drm_gem_fence_array_add(fence_array, fences[i]);
> +	struct dma_resv_iter cursor;
> +	struct dma_fence *fence;
> +	int ret = 0;
> +
> +	rcu_read_lock();
> +	dma_resv_iter_begin(&cursor, obj->resv, write);
> +	dma_resv_for_each_fence_unlocked(&cursor, fence) {
> +		rcu_read_unlock();
> +		ret = drm_gem_fence_array_add(fence_array, fence);
> +		rcu_read_lock();
>  		if (ret)
>  			break;
>  	}
> -
> -	for (; i < fence_count; i++)
> -		dma_fence_put(fences[i]);
> -	kfree(fences);
> +	dma_resv_iter_end(&cursor);
> +	rcu_read_unlock();
>  	return ret;
>  }
>  EXPORT_SYMBOL(drm_gem_fence_array_add_implicit);
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch