Re: [Intel-gfx] [PATCH 13/28] drm/amdgpu: use new iterator in amdgpu_vm_prt_fini

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Oct 05, 2021 at 01:37:27PM +0200, Christian König wrote:
> No need to actually allocate an array of fences here.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 26 +++++---------------------
>  1 file changed, 5 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index 6b15cad78de9..e42dd79ed6f4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -2090,30 +2090,14 @@ static void amdgpu_vm_free_mapping(struct amdgpu_device *adev,
>  static void amdgpu_vm_prt_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
>  {
>  	struct dma_resv *resv = vm->root.bo->tbo.base.resv;
> -	struct dma_fence *excl, **shared;
> -	unsigned i, shared_count;
> -	int r;
> +	struct dma_resv_iter cursor;
> +	struct dma_fence *fence;
>  
> -	r = dma_resv_get_fences(resv, &excl, &shared_count, &shared);
> -	if (r) {
> -		/* Not enough memory to grab the fence list, as last resort
> -		 * block for all the fences to complete.
> -		 */
> -		dma_resv_wait_timeout(resv, true, false,
> -						    MAX_SCHEDULE_TIMEOUT);
> -		return;
> -	}
> -
> -	/* Add a callback for each fence in the reservation object */
> -	amdgpu_vm_prt_get(adev);

I was confused for a bit why the old code wouldn't leak a refcount for
!excl case, but it's all handled.

Not sure amdgpu_vm_add_prt_cb still needs to handle the !fence case, it's
a bit a gotcha but I guess can happen?

Either way, looks correct.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> -	amdgpu_vm_add_prt_cb(adev, excl);
> -
> -	for (i = 0; i < shared_count; ++i) {
> +	dma_resv_for_each_fence(&cursor, resv, true, fence) {
> +		/* Add a callback for each fence in the reservation object */
>  		amdgpu_vm_prt_get(adev);
> -		amdgpu_vm_add_prt_cb(adev, shared[i]);
> +		amdgpu_vm_add_prt_cb(adev, fence);
>  	}
> -
> -	kfree(shared);
>  }
>  
>  /**
> -- 
> 2.25.1
> 

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