From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Ahern <dsahern@gmail.com>
Subject: Re: [RFC 2/5] netlink: set extack error message in nla_validate()
Date: Tue, 18 Sep 2018 10:18:05 -0700
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References: <20180918131212.20266-1-johannes@sipsolutions.net>
 <20180918131212.20266-2-johannes@sipsolutions.net>
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Cc: Johannes Berg <johannes.berg@intel.com>
To: Johannes Berg <johannes@sipsolutions.net>, netdev@vger.kernel.org
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On 9/18/18 6:12 AM, Johannes Berg wrote:
> diff --git a/lib/nlattr.c b/lib/nlattr.c
> index 120ad569e13d..efbd6c1aff29 100644
> --- a/lib/nlattr.c
> +++ b/lib/nlattr.c
> @@ -181,9 +181,13 @@ int nla_validate(const struct nlattr *head, int len, int maxtype,
>  	int rem;
>  
>  	nla_for_each_attr(nla, head, len, rem) {
> -		int err = validate_nla(nla, maxtype, policy, NULL);
> +		static const char _msg[] = "Attribute failed policy validation";
> +		const char *msg = _msg;
> +		int err = validate_nla(nla, maxtype, policy, &msg);
>  
>  		if (err < 0) {
> +			if (extack)
> +				extack->_msg = msg;
>  			NL_SET_BAD_ATTR(extack, nla);
>  			return err;
>  		}
> 

I take it this set is on top of another set - the NLA_REJECT?