From: Ido Schimmel <idosch@mellanox.com>
Date: Sat, 14 Dec 2019 17:53:09 +0200
Subject: ipv4: Notify route if replacing currently offloaded one
Patch-mainline: v5.6-rc1
Git-commit: ee3936d658821d26de9039c64c90750ba240989d
References: bsc#1176774

When replacing a route, its replacement should only be notified in case
the replaced route is of any interest to listeners. In other words, if
the replaced route is currently used in the data path, which means it is
the first route in the FIB alias list with the given {prefix, prefix
length, table ID}.

v2:
* Convert to use fib_find_alias() instead of fib_find_first_alias()

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/ipv4/fib_trie.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1222,6 +1222,17 @@ int fib_table_insert(struct net *net, st
 			new_fa->tb_id = tb->tb_id;
 			new_fa->fa_default = -1;
 
+			if (fib_find_alias(&l->leaf, fa->fa_slen, 0, 0,
+					   tb->tb_id, true) == fa) {
+				enum fib_event_type fib_event;
+
+				fib_event = FIB_EVENT_ENTRY_REPLACE_TMP;
+				err = call_fib_entry_notifiers(net, fib_event,
+							       key, plen,
+							       new_fa, extack);
+				if (err)
+					goto out_free_new_fa;
+			}
 			err = call_fib_entry_notifiers(net,
 						       FIB_EVENT_ENTRY_REPLACE,
 						       key, plen, new_fa,