Re: [PATCH v6 net-next 1/7] netlink: Add a macro to set policy message with format string

[Paolo Abeni <pabeni@redhat.com>]

On Mon, 2023-03-20 at 15:25 +0200, Shay Agroskin wrote:
> Similar to NL_SET_ERR_MSG_FMT, add a macro which sets netlink policy
> error message with a format string.
> 
> Signed-off-by: Shay Agroskin <shayagr@amazon.com>
> ---
>  include/linux/netlink.h | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/include/linux/netlink.h b/include/linux/netlink.h
> index 3e8743252167..2ca76ec1fc33 100644
> --- a/include/linux/netlink.h
> +++ b/include/linux/netlink.h
> @@ -161,9 +161,22 @@ struct netlink_ext_ack {
>  	}							\
>  } while (0)
>  
> +#define NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, pol, fmt, args...) do {	\
> +	struct netlink_ext_ack *__extack = (extack);				\
> +										\
> +	if (__extack) {								\
> +		NL_SET_ERR_MSG_FMT(extack, fmt, ##args);			\

You should use '__extack' even above, to avoid multiple evaluation of
the 'extack' expression.

Side note: you dropped the acked-by/revied-by tags collected on
previous iterations, you could and should have retained them for the
unmodified patches.

Thanks,

Paolo