Re: [PATCH RFC v2 1/3] io_uring: use an enumeration for io_uring_register(2) opcodes

[Pavel Begunkov <asml.silence@gmail.com>]

On 16/07/2020 15:48, Stefano Garzarella wrote:
> The enumeration allows us to keep track of the last
> io_uring_register(2) opcode available.
> 
> Behaviour and opcodes names don't change.
> 
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>  include/uapi/linux/io_uring.h | 27 ++++++++++++++++-----------
>  1 file changed, 16 insertions(+), 11 deletions(-)
> 
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index 7843742b8b74..efc50bd0af34 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -253,17 +253,22 @@ struct io_uring_params {
>  /*
>   * io_uring_register(2) opcodes and arguments
>   */
> -#define IORING_REGISTER_BUFFERS		0
> -#define IORING_UNREGISTER_BUFFERS	1
> -#define IORING_REGISTER_FILES		2
> -#define IORING_UNREGISTER_FILES		3
> -#define IORING_REGISTER_EVENTFD		4
> -#define IORING_UNREGISTER_EVENTFD	5
> -#define IORING_REGISTER_FILES_UPDATE	6
> -#define IORING_REGISTER_EVENTFD_ASYNC	7
> -#define IORING_REGISTER_PROBE		8
> -#define IORING_REGISTER_PERSONALITY	9
> -#define IORING_UNREGISTER_PERSONALITY	10
> +enum {
> +	IORING_REGISTER_BUFFERS,
> +	IORING_UNREGISTER_BUFFERS,
> +	IORING_REGISTER_FILES,
> +	IORING_UNREGISTER_FILES,
> +	IORING_REGISTER_EVENTFD,
> +	IORING_UNREGISTER_EVENTFD,
> +	IORING_REGISTER_FILES_UPDATE,
> +	IORING_REGISTER_EVENTFD_ASYNC,
> +	IORING_REGISTER_PROBE,
> +	IORING_REGISTER_PERSONALITY,
> +	IORING_UNREGISTER_PERSONALITY,
> +
> +	/* this goes last */
> +	IORING_REGISTER_LAST
> +};

It breaks userspace API. E.g.

#ifdef IORING_REGISTER_BUFFERS

>  
>  struct io_uring_files_update {
>  	__u32 offset;
> 

-- 
Pavel Begunkov