[PATCH net-next 1/2] ipv6: report why a route was deleted in RTM_DELROUTE

[Yuyang Huang <sigefriedhyy@gmail.com>]

Add RTA_DEL_REASON (u8) to RTM_DELROUTE notifications to report the
cause of kernel-initiated IPv6 route deletions, so user space can tell
routes that expired from routes explicitly withdrawn by Router
Advertisements.

The two causes call for different treatment in user space. An expired
RA route means the router failed to refresh it before its lifetime ran
out, which points at a misconfigured or unreliable router; user space
may want to react, for example by disabling IPv6 on that network
entirely. An RA withdrawal (zero lifetime) is valid, RFC-compliant
operation and needs no such recovery. Today both surface as an
identical RTM_DELROUTE.

Plumb the deletion reason through the IPv6 FIB and notification paths:
- Update `fib6_del`, `fib6_del_route`, and `inet6_rt_notify` signatures
  to explicitly pass the `del_reason` (u8) down the call chain.
- Update `rt6_fill_node()` to emit `RTA_DEL_REASON` attribute when the
  reason is not UNSPEC.
- Record the cause in the kernel-initiated IPv6 deletion paths:
  - RTA_DEL_REASON_EXPIRED: for routes cleaned up by the FIB6 garbage
    collector.
  - RTA_DEL_REASON_RA_WITHDRAWN: for default routes, prefix routes, or
    route information option routes withdrawn by Router Advertisements.
- Update the `rt-route` Netlink YAML spec to define the new attribute,
  notifications, and multicast groups.

Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
---
 Documentation/netlink/specs/rt-route.yaml | 33 ++++++++++++
 include/net/ip6_fib.h                     |  4 +-
 include/net/ip6_route.h                   |  2 +
 include/uapi/linux/rtnetlink.h            | 17 ++++++
 net/ipv6/addrconf.c                       |  3 +-
 net/ipv6/ip6_fib.c                        | 19 ++++---
 net/ipv6/ndisc.c                          |  7 ++-
 net/ipv6/route.c                          | 66 +++++++++++++++--------
 8 files changed, 116 insertions(+), 35 deletions(-)

diff --git a/Documentation/netlink/specs/rt-route.yaml b/Documentation/netlink/specs/rt-route.yaml
index 33195db96746..d5f6824127c2 100644
--- a/Documentation/netlink/specs/rt-route.yaml
+++ b/Documentation/netlink/specs/rt-route.yaml
@@ -78,6 +78,15 @@ definitions:
       -
         name: rta-used
         type: u32
+  -
+    name: del-reason
+    type: enum
+    name-prefix: rta-del-reason-
+    enum-name: rta-del-reason
+    entries:
+      - unspec
+      - expired
+      - ra-withdrawn
 
 attribute-sets:
   -
@@ -185,6 +194,10 @@ attribute-sets:
         type: u32
         byte-order: big-endian
         display-hint: hex
+      -
+        name: del-reason
+        type: u8
+        enum: del-reason
   -
     name: metrics
     name-prefix: rtax-
@@ -299,6 +312,7 @@ operations:
             - dport
             - nh-id
             - flowlabel
+            - del-reason
       dump:
         request:
           value: 26
@@ -322,3 +336,22 @@ operations:
         request:
           value: 25
           attributes: *all-route-attrs
+    -
+      name: newroute-ntf
+      doc: Notification about a created route.
+      value: 24
+      notify: getroute
+    -
+      name: delroute-ntf
+      doc: Notification about a deleted route.
+      value: 25
+      notify: getroute
+
+mcast-groups:
+  list:
+    -
+      name: rtnlgrp-ipv4-route
+      value: 7
+    -
+      name: rtnlgrp-ipv6-route
+      value: 11
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 9cd27e1b9b69..c93a997bb41e 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -468,7 +468,7 @@ void fib6_clean_all_skip_notify(struct net *net,
 
 int fib6_add(struct fib6_node *root, struct fib6_info *rt,
 	     struct nl_info *info, struct netlink_ext_ack *extack);
-int fib6_del(struct fib6_info *rt, struct nl_info *info);
+int fib6_del(struct fib6_info *rt, struct nl_info *info, u8 del_reason);
 
 static inline
 void rt6_get_prefsrc(const struct rt6_info *rt, struct in6_addr *addr)
@@ -531,7 +531,7 @@ static inline void fib6_rt_update(struct net *net, struct fib6_info *rt,
 }
 #endif
 void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
-		     unsigned int flags);
+		     unsigned int flags, u8 del_reason);
 
 void fib6_age_exceptions(struct fib6_info *rt, struct fib6_gc_args *gc_args,
 			 unsigned long now);
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 09ffe0f13ce7..bf6b39eaaa20 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -128,6 +128,8 @@ int ip6_route_add(struct fib6_config *cfg, gfp_t gfp_flags,
 int ip6_ins_rt(struct net *net, struct fib6_info *f6i);
 #if IS_ENABLED(CONFIG_IPV6)
 int ip6_del_rt(struct net *net, struct fib6_info *f6i, bool skip_notify);
+int ip6_del_rt_reason(struct net *net, struct fib6_info *f6i, bool skip_notify,
+		      u8 del_reason);
 #else
 static inline int ip6_del_rt(struct net *net, struct fib6_info *f6i,
 			     bool skip_notify)
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index 27265fd31e5f..86b407bef4ce 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -399,6 +399,7 @@ enum rtattr_type_t {
 	RTA_DPORT,
 	RTA_NH_ID,
 	RTA_FLOWLABEL,
+	RTA_DEL_REASON,
 	__RTA_MAX
 };
 
@@ -407,6 +408,22 @@ enum rtattr_type_t {
 #define RTM_RTA(r)  ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct rtmsg))))
 #define RTM_PAYLOAD(n) NLMSG_PAYLOAD(n,sizeof(struct rtmsg))
 
+/* RTA_DEL_REASON: why the kernel deleted the route. u8.
+ * Emitted only on RTM_DELROUTE notifications, and only when the deletion
+ * path records a cause. Absence means either an older kernel or a
+ * deletion path that does not (yet) record its cause - consumers must
+ * treat "absent" and "unspec" identically. New causes may be appended.
+ * Currently only IPv6 deletion paths record a cause.
+ */
+enum rta_del_reason {
+	RTA_DEL_REASON_UNSPEC,		/* cause not recorded */
+	RTA_DEL_REASON_EXPIRED,		/* RTF_EXPIRES lifetime ran out (GC) */
+	RTA_DEL_REASON_RA_WITHDRAWN,	/* zero-lifetime RA / PIO / RIO */
+	__RTA_DEL_REASON_MAX
+};
+
+#define RTA_DEL_REASON_MAX (__RTA_DEL_REASON_MAX - 1)
+
 /* RTM_MULTIPATH --- array of struct rtnexthop.
  *
  * "struct rtnexthop" describes all necessary nexthop information,
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index f1fe9ede1edb..1ca9d82b5721 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2874,7 +2874,8 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
 		if (rt) {
 			/* Autoconf prefix route */
 			if (valid_lft == 0) {
-				ip6_del_rt(net, rt, false);
+				ip6_del_rt_reason(net, rt, false,
+						  RTA_DEL_REASON_RA_WITHDRAWN);
 				rt = NULL;
 			} else {
 				table = rt->fib6_table;
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index a130cdfaebfb..2c9bce3213b7 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1286,7 +1286,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
 		rcu_assign_pointer(rt->fib6_node, fn);
 		rcu_assign_pointer(*ins, rt);
 		if (!info->skip_notify)
-			inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
+			inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags,
+					RTA_DEL_REASON_UNSPEC);
 		info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
 
 		if (!(fn->fn_flags & RTN_RTINFO)) {
@@ -1317,7 +1318,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
 		rt->fib6_next = iter->fib6_next;
 		rcu_assign_pointer(*ins, rt);
 		if (!info->skip_notify)
-			inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
+			inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE,
+					RTA_DEL_REASON_UNSPEC);
 		if (!(fn->fn_flags & RTN_RTINFO)) {
 			info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
 			fn->fn_flags |= RTN_RTINFO;
@@ -1966,7 +1968,8 @@ static struct fib6_node *fib6_repair_tree(struct net *net,
 }
 
 static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
-			   struct fib6_info __rcu **rtp, struct nl_info *info)
+			   struct fib6_info __rcu **rtp, struct nl_info *info,
+			   u8 del_reason)
 {
 	struct fib6_info *leaf, *replace_rt = NULL;
 	struct fib6_walker *w;
@@ -2055,13 +2058,13 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
 			call_fib6_entry_notifiers_replace(net, replace_rt);
 	}
 	if (!info->skip_notify)
-		inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
+		inet6_rt_notify(RTM_DELROUTE, rt, info, 0, del_reason);
 
 	fib6_info_release(rt);
 }
 
 /* Need to own table->tb6_lock */
-int fib6_del(struct fib6_info *rt, struct nl_info *info)
+int fib6_del(struct fib6_info *rt, struct nl_info *info, u8 del_reason)
 {
 	struct net *net = info->nl_net;
 	struct fib6_info __rcu **rtp;
@@ -2090,7 +2093,7 @@ int fib6_del(struct fib6_info *rt, struct nl_info *info)
 		if (rt == cur) {
 			if (fib6_requires_src(cur))
 				fib6_routes_require_src_dec(info->nl_net);
-			fib6_del_route(table, fn, rtp, info);
+			fib6_del_route(table, fn, rtp, info, del_reason);
 			return 0;
 		}
 		rtp_next = &cur->fib6_next;
@@ -2252,7 +2255,7 @@ static int fib6_clean_node(struct fib6_walker *w)
 		res = c->func(rt, c->arg);
 		if (res == -1) {
 			w->leaf = rt;
-			res = fib6_del(rt, &info);
+			res = fib6_del(rt, &info, RTA_DEL_REASON_UNSPEC);
 			if (res) {
 #if RT6_DEBUG >= 2
 				pr_debug("%s: del failed: rt=%p@%p err=%d\n",
@@ -2400,7 +2403,7 @@ static void fib6_gc_table(struct net *net,
 
 	hlist_for_each_entry_safe(rt, n, &tb6->tb6_gc_hlist, gc_link)
 		if (fib6_age(rt, gc_args) == -1)
-			fib6_del(rt, &info);
+			fib6_del(rt, &info, RTA_DEL_REASON_EXPIRED);
 }
 
 static void fib6_gc_all(struct net *net, struct fib6_gc_args *gc_args)
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index f867ec8d3d90..c3537fc0ec63 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1361,7 +1361,9 @@ static enum skb_drop_reason ndisc_router_discovery(struct sk_buff *skb)
 	defrtr_usr_metric = in6_dev->cnf.ra_defrtr_metric;
 	/* delete the route if lifetime is 0 or if metric needs change */
 	if (rt && (lifetime == 0 || rt->fib6_metric != defrtr_usr_metric)) {
-		ip6_del_rt(net, rt, false);
+		ip6_del_rt_reason(net, rt, false,
+				  lifetime == 0 ? RTA_DEL_REASON_RA_WITHDRAWN :
+						  RTA_DEL_REASON_UNSPEC);
 		rt = NULL;
 	}
 
@@ -1396,7 +1398,8 @@ static enum skb_drop_reason ndisc_router_discovery(struct sk_buff *skb)
 			.nl_net = net,
 		};
 		rt->fib6_flags = (rt->fib6_flags & ~RTF_PREF_MASK) | RTF_PREF(pref);
-		inet6_rt_notify(RTM_NEWROUTE, rt, &nlinfo, NLM_F_REPLACE);
+		inet6_rt_notify(RTM_NEWROUTE, rt, &nlinfo, NLM_F_REPLACE,
+				RTA_DEL_REASON_UNSPEC);
 	}
 
 	if (rt) {
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index a1301334da48..ee7ba58e83c7 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -111,7 +111,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			 struct fib6_info *rt, struct dst_entry *dst,
 			 struct in6_addr *dest, struct in6_addr *src,
 			 int iif, int type, u32 portid, u32 seq,
-			 unsigned int flags);
+			 unsigned int flags, u8 del_reason);
 static struct rt6_info *rt6_find_cached_rt(const struct fib6_result *res,
 					   const struct in6_addr *daddr,
 					   const struct in6_addr *saddr);
@@ -1020,7 +1020,7 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
 					gwaddr, dev);
 
 	if (rt && !lifetime) {
-		ip6_del_rt(net, rt, false);
+		ip6_del_rt_reason(net, rt, false, RTA_DEL_REASON_RA_WITHDRAWN);
 		rt = NULL;
 	}
 
@@ -3973,7 +3973,8 @@ int ip6_route_add(struct fib6_config *cfg, gfp_t gfp_flags,
 	return err;
 }
 
-static int __ip6_del_rt(struct fib6_info *rt, struct nl_info *info)
+static int __ip6_del_rt(struct fib6_info *rt, struct nl_info *info,
+			u8 del_reason)
 {
 	struct net *net = info->nl_net;
 	struct fib6_table *table;
@@ -3986,7 +3987,7 @@ static int __ip6_del_rt(struct fib6_info *rt, struct nl_info *info)
 
 	table = rt->fib6_table;
 	spin_lock_bh(&table->tb6_lock);
-	err = fib6_del(rt, info);
+	err = fib6_del(rt, info, del_reason);
 	spin_unlock_bh(&table->tb6_lock);
 
 out:
@@ -3994,14 +3995,20 @@ static int __ip6_del_rt(struct fib6_info *rt, struct nl_info *info)
 	return err;
 }
 
-int ip6_del_rt(struct net *net, struct fib6_info *rt, bool skip_notify)
+int ip6_del_rt_reason(struct net *net, struct fib6_info *rt, bool skip_notify,
+		      u8 del_reason)
 {
 	struct nl_info info = {
 		.nl_net = net,
-		.skip_notify = skip_notify
+		.skip_notify = skip_notify,
 	};
 
-	return __ip6_del_rt(rt, &info);
+	return __ip6_del_rt(rt, &info, del_reason);
+}
+
+int ip6_del_rt(struct net *net, struct fib6_info *rt, bool skip_notify)
+{
+	return ip6_del_rt_reason(net, rt, skip_notify, RTA_DEL_REASON_UNSPEC);
 }
 
 static int __ip6_del_rt_siblings(struct fib6_info *rt, struct fib6_config *cfg)
@@ -4028,7 +4035,8 @@ static int __ip6_del_rt_siblings(struct fib6_info *rt, struct fib6_config *cfg)
 
 			if (rt6_fill_node(net, skb, rt, NULL,
 					  NULL, NULL, 0, RTM_DELROUTE,
-					  info->portid, seq, 0) < 0) {
+					  info->portid, seq, 0,
+					  RTA_DEL_REASON_UNSPEC) < 0) {
 				kfree_skb(skb);
 				skb = NULL;
 			} else
@@ -4064,13 +4072,13 @@ static int __ip6_del_rt_siblings(struct fib6_info *rt, struct fib6_config *cfg)
 		list_for_each_entry_safe(sibling, next_sibling,
 					 &rt->fib6_siblings,
 					 fib6_siblings) {
-			err = fib6_del(sibling, info);
+			err = fib6_del(sibling, info, RTA_DEL_REASON_UNSPEC);
 			if (err)
 				goto out_unlock;
 		}
 	}
 
-	err = fib6_del(rt, info);
+	err = fib6_del(rt, info, RTA_DEL_REASON_UNSPEC);
 out_unlock:
 	spin_unlock_bh(&table->tb6_lock);
 out_put:
@@ -4196,7 +4204,8 @@ static int ip6_route_del(struct fib6_config *cfg,
 				if (!fib6_info_hold_safe(rt))
 					continue;
 
-				err =  __ip6_del_rt(rt, &cfg->fc_nlinfo);
+				err = __ip6_del_rt(rt, &cfg->fc_nlinfo,
+						   RTA_DEL_REASON_UNSPEC);
 				break;
 			}
 			if (cfg->fc_nh_id)
@@ -4215,7 +4224,8 @@ static int ip6_route_del(struct fib6_config *cfg,
 
 			/* if gateway was specified only delete the one hop */
 			if (cfg->fc_flags & RTF_GATEWAY)
-				err = __ip6_del_rt(rt, &cfg->fc_nlinfo);
+				err = __ip6_del_rt(rt, &cfg->fc_nlinfo,
+						   RTA_DEL_REASON_UNSPEC);
 			else
 				err = __ip6_del_rt_siblings(rt, cfg);
 			break;
@@ -5381,7 +5391,8 @@ static void ip6_route_mpath_notify(struct fib6_info *rt,
 	}
 
 	if (rt)
-		inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
+		inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags,
+				RTA_DEL_REASON_UNSPEC);
 
 	rcu_read_unlock();
 }
@@ -5739,6 +5750,7 @@ static size_t rt6_nlmsg_size(struct fib6_info *f6i)
 	       + nla_total_size(sizeof(struct rta_cacheinfo))
 	       + nla_total_size(TCP_CA_NAME_MAX) /* RTAX_CC_ALGO */
 	       + nla_total_size(1) /* RTA_PREF */
+	       + nla_total_size(1) /* RTA_DEL_REASON */
 	       + nexthop_len;
 }
 
@@ -5775,7 +5787,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			 struct fib6_info *rt, struct dst_entry *dst,
 			 struct in6_addr *dest, struct in6_addr *src,
 			 int iif, int type, u32 portid, u32 seq,
-			 unsigned int flags)
+			 unsigned int flags, u8 del_reason)
 {
 	struct rt6_info *rt6 = dst_rt6_info(dst);
 	struct rt6key *rt6_dst, *rt6_src;
@@ -5954,6 +5966,10 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 	if (rtnl_put_cacheinfo(skb, dst, 0, expires, dst ? dst->error : 0) < 0)
 		goto nla_put_failure;
 
+	if (type == RTM_DELROUTE && del_reason != RTA_DEL_REASON_UNSPEC &&
+	    nla_put_u8(skb, RTA_DEL_REASON, del_reason))
+		goto nla_put_failure;
+
 	if (nla_put_u8(skb, RTA_PREF, IPV6_EXTRACT_PREF(rt6_flags)))
 		goto nla_put_failure;
 
@@ -6055,7 +6071,8 @@ static int rt6_nh_dump_exceptions(struct fib6_nh *nh, void *arg)
 					    &rt6_ex->rt6i->dst, NULL, NULL, 0,
 					    RTM_NEWROUTE,
 					    NETLINK_CB(dump->cb->skb).portid,
-					    dump->cb->nlh->nlmsg_seq, w->flags);
+					    dump->cb->nlh->nlmsg_seq, w->flags,
+					    RTA_DEL_REASON_UNSPEC);
 			if (err)
 				return err;
 
@@ -6103,7 +6120,8 @@ int rt6_dump_route(struct fib6_info *rt, void *p_arg, unsigned int skip)
 			if (rt6_fill_node(net, arg->skb, rt, NULL, NULL, NULL,
 					  0, RTM_NEWROUTE,
 					  NETLINK_CB(arg->cb->skb).portid,
-					  arg->cb->nlh->nlmsg_seq, flags)) {
+					  arg->cb->nlh->nlmsg_seq, flags,
+					  RTA_DEL_REASON_UNSPEC)) {
 				return 0;
 			}
 			count++;
@@ -6336,12 +6354,14 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 			err = rt6_fill_node(net, skb, from, NULL, NULL, NULL,
 					    iif, RTM_NEWROUTE,
 					    NETLINK_CB(in_skb).portid,
-					    nlh->nlmsg_seq, 0);
+					    nlh->nlmsg_seq, 0,
+					    RTA_DEL_REASON_UNSPEC);
 		else
 			err = rt6_fill_node(net, skb, from, dst, &fl6.daddr,
 					    &fl6.saddr, iif, RTM_NEWROUTE,
 					    NETLINK_CB(in_skb).portid,
-					    nlh->nlmsg_seq, 0);
+					    nlh->nlmsg_seq, 0,
+					    RTA_DEL_REASON_UNSPEC);
 	} else {
 		err = -ENETUNREACH;
 	}
@@ -6358,7 +6378,7 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 }
 
 void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
-		     unsigned int nlm_flags)
+		     unsigned int nlm_flags, u8 del_reason)
 {
 	struct net *net = info->nl_net;
 	struct sk_buff *skb;
@@ -6377,7 +6397,8 @@ void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
 		goto errout;
 
 	err = rt6_fill_node(net, skb, rt, NULL, NULL, NULL, 0,
-			    event, info->portid, seq, nlm_flags);
+			    event, info->portid, seq, nlm_flags,
+			    del_reason);
 	if (err < 0) {
 		kfree_skb(skb);
 		/* -EMSGSIZE implies needed space grew under us. */
@@ -6410,7 +6431,8 @@ void fib6_rt_update(struct net *net, struct fib6_info *rt,
 		goto errout;
 
 	err = rt6_fill_node(net, skb, rt, NULL, NULL, NULL, 0,
-			    RTM_NEWROUTE, info->portid, seq, NLM_F_REPLACE);
+			    RTM_NEWROUTE, info->portid, seq, NLM_F_REPLACE,
+			    RTA_DEL_REASON_UNSPEC);
 	if (err < 0) {
 		/* -EMSGSIZE implies BUG in rt6_nlmsg_size() */
 		WARN_ON(err == -EMSGSIZE);
@@ -6463,7 +6485,7 @@ void fib6_info_hw_flags_set(struct net *net, struct fib6_info *f6i,
 	}
 
 	err = rt6_fill_node(net, skb, f6i, NULL, NULL, NULL, 0, RTM_NEWROUTE, 0,
-			    0, 0);
+			    0, 0, RTA_DEL_REASON_UNSPEC);
 	if (err < 0) {
 		/* -EMSGSIZE implies BUG in rt6_nlmsg_size() */
 		WARN_ON(err == -EMSGSIZE);
-- 
2.43.0