[RFC 2/5] netlink: set extack error message in nla_validate()

[Johannes Berg <johannes@sipsolutions.net>]

From: Johannes Berg <johannes.berg@intel.com>

In nla_parse() we already set this, but it makes sense to
also do it in nla_validate() which already also sets the
bad attribute pointer.

CC: David Ahern <dsahern@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 lib/nlattr.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

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;
 		}
-- 
2.14.4