Re: [PATCH] usb: gadget: f_fs: Remove deprecated dma_fence->ops

[Paul Cercueil <paul@crapouillou.net>]

Hi Philipp,

Le jeudi 29 octobre 2026 à 13:51 +0100, Philipp Stanner a écrit :
> The dma_fence_ops function ops->release() has been deprecated because it
> prevents drivers from unloading. f_fs's implementation merely frees the
> fence. The dma_fence backend performs this deallocation automatically in
> the correct manner if ops->release() is not implemented.
> 
> The backend simultaneously correctly frees struct ffs_dma_fence since
> struct dma_fence is its base class.

For context, this .release() callback was added to avoid the implicit free of
the base class, which IIRC was a request I got during the review process of this
change set.

I'm personally fine with the change, but do we need a "keep this field at the
top" comment for the base class in the ffs_dma_fence struct? Or what's the
policy here?

Cheers,
-Paul

> 
> Remove ops->release().
> 
> Signed-off-by: Philipp Stanner <phasta@kernel.org>
> ---
>  drivers/usb/gadget/function/f_fs.c | 9 ---------
>  1 file changed, 9 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/f_fs.c
> b/drivers/usb/gadget/function/f_fs.c
> index c64a268e98a4..e8672b37e890 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -1479,18 +1479,9 @@ static const char *ffs_dmabuf_get_timeline_name(struct
> dma_fence *fence)
>  	return "";
>  }
>  
> -static void ffs_dmabuf_fence_release(struct dma_fence *fence)
> -{
> -	struct ffs_dma_fence *dma_fence =
> -		container_of(fence, struct ffs_dma_fence, base);
> -
> -	kfree(dma_fence);
> -}
> -
>  static const struct dma_fence_ops ffs_dmabuf_fence_ops = {
>  	.get_driver_name	= ffs_dmabuf_get_driver_name,
>  	.get_timeline_name	= ffs_dmabuf_get_timeline_name,
> -	.release		= ffs_dmabuf_fence_release,
>  };
>  
>  static int ffs_dma_resv_lock(struct dma_buf *dmabuf, bool nonblock)