Re: [PATCH 1/1] uapi: cdc.h: cleanly provide for more interfaces and countries

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Oct 28, 2025 at 01:32:22PM +0100, Oliver Neukum wrote:
> The spec requires at least one interface respectively country.
> It allows multiple ones. This needs to be clearly said in the UAPI.
> 
> Signed-off-by: Oliver Neukum <oneukum@suse.com>
> ---
>  include/uapi/linux/usb/cdc.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/uapi/linux/usb/cdc.h b/include/uapi/linux/usb/cdc.h
> index 1924cf665448..5fcbce0be133 100644
> --- a/include/uapi/linux/usb/cdc.h
> +++ b/include/uapi/linux/usb/cdc.h
> @@ -105,7 +105,7 @@ struct usb_cdc_union_desc {
>  
>  	__u8	bMasterInterface0;
>  	__u8	bSlaveInterface0;
> -	/* ... and there could be other slave interfaces */
> +	__u8	bSlaveInterfaces[];

Can this be combined with bSlaveInterface0?  Feels odd to have 0 and
then "more".

Also, what determines how many, the overall length?

>  } __attribute__ ((packed));
>  
>  /* "Country Selection Functional Descriptor" from CDC spec 5.2.3.9 */
> @@ -116,7 +116,7 @@ struct usb_cdc_country_functional_desc {
>  
>  	__u8	iCountryCodeRelDate;
>  	__le16	wCountyCode0;
> -	/* ... and there can be a lot of country codes */
> +	__le16	wCountyCodes[];

same here.

thanks,

greg k-h