Re: [PATCH v4] net: ipv6: seg6: report lwtunnel setup errors via extack

On Mon,  5 Oct 2026 16:06:34 +0200
Gabriel Goller [off-list ref] wrote:

Hi Gabriel,

thanks for the v4. +1 to Jakub on _MISS. I also have two comments on
the message text.

[snip]
 	switch (tuninfo->mode) {
 	case SEG6_IPTUN_MODE_INLINE:
-		if (family != AF_INET6)
+		if (family != AF_INET6) {
+			NL_SET_ERR_MSG_ATTR(extack, tb[SEG6_IPTUNNEL_SRH],
+					    "inline mode requires an IPv6 route");
 			return -EINVAL;
+		}

This message is also returned for an IPv4 nexthop object, where there
is no route, for example:

  ip -4 nexthop add id 1 encap seg6 mode inline segs fc00::1 dev dummy0

What about "inline mode requires the IPv6 address family"?

[snip]
 	/* verify that SRH is consistent */
-	if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo), false))
+	if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo),
+			       false)) {
+		NL_SET_ERR_MSG_ATTR(extack, tb[SEG6_IPTUNNEL_SRH],
+				    "invalid SRv6 segment routing header");
 		return -EINVAL;
+	}

A nit: the same header is "SRv6 segment routing header" here and
"SRv6 SRH" in the other messages of seg6_build_state(). What about
using the name from the title of RFC 8754 in the extack messages,
for example:

  "invalid SRv6 segment routing header"
    -> "invalid IPv6 Segment Routing Header"

Thanks,
Andrea