[PATCH 3/3] /dev/null: add IORING_OP_URING_CMD support

[Greg Kroah-Hartman]

On Mon, Aug 22, 2022 at 05:21:19PM -0400, Paul Moore wrote:
> This patch adds support for the io_uring command pass through, aka
> IORING_OP_URING_CMD, to the /dev/null driver.  As with all of the
> /dev/null functionality, the implementation is just a simple sink
> where commands go to die, but it should be useful for developers who
> need a simple IORING_OP_URING_CMD test device that doesn't require
> any special hardware.
> 
> Cc: Arnd Bergmann <arnd at arndb.de>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Signed-off-by: Paul Moore <paul at paul-moore.com>
> ---
>  drivers/char/mem.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/char/mem.c b/drivers/char/mem.c
> index 84ca98ed1dad..32a932a065a6 100644
> --- a/drivers/char/mem.c
> +++ b/drivers/char/mem.c
> @@ -480,6 +480,11 @@ static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
>  	return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
>  }
>  
> +static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
> +{
> +	return 0;

If a callback just returns 0, that implies it is not needed at all and
can be removed and then you are back at the original file before your
commit :)

thanks,

greg k-h