Subject: Re: [PATCH net-next v2] netlink: split up copies in the ack construction

From: David Ahern <[email-masked]>
Date: Sun, 13 Nov 2022 19:39:27 -0700

On Thu, Oct 27, 2022 at 02:25:53PM -0700, Jakub Kicinski wrote:
> diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
> index e2ae82e3f9f7..5da0da59bf01 100644
> --- a/include/uapi/linux/netlink.h
> +++ b/include/uapi/linux/netlink.h
> @@ -48,6 +48,7 @@ struct sockaddr_nl {
>   * @nlmsg_flags: Additional flags
>   * @nlmsg_seq:   Sequence number
>   * @nlmsg_pid:   Sending process port ID
> + * @nlmsg_data:  Message payload
>   */
>  struct nlmsghdr {
>  	__u32		nlmsg_len;
> @@ -55,6 +56,7 @@ struct nlmsghdr {
>  	__u16		nlmsg_flags;
>  	__u32		nlmsg_seq;
>  	__u32		nlmsg_pid;
> +	__u8		nlmsg_data[];

This breaks compile of iproute2 with clang. It does not like the
variable length array in the middle of a struct. While I could re-do the
structs in iproute2, I doubt it is alone in being affected by this
change.