Subject: Re: [RFC PATCH net-next 07/15] ipv4: Only Replay routes of interest to new listeners

From: Ido Schimmel <[email-masked]>
Date: Thu, 3 Oct 2019 16:04:27 +0300

On Wed, Oct 02, 2019 at 07:44:02PM +0200, Jiri Pirko wrote:
> Wed, Oct 02, 2019 at 10:40:55AM CEST, [email-masked] wrote:
> >From: Ido Schimmel <[email-masked]>
> >
> >When a new listener is registered to the FIB notification chain it
> >receives a dump of all the available routes in the system. Instead, make
> >sure to only replay the IPv4 routes that are actually used in the data
> >path and are of any interest to the new listener.
> >
> >Signed-off-by: Ido Schimmel <[email-masked]>
> >---
> > net/ipv4/fib_trie.c | 10 ++++++++++
> > 1 file changed, 10 insertions(+)
> >
> >diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> >index dc4c4e2cb0b3..4937a3503f4f 100644
> >--- a/net/ipv4/fib_trie.c
> >+++ b/net/ipv4/fib_trie.c
> >@@ -2096,6 +2096,7 @@ static int fib_leaf_notify(struct key_vector *l, struct fib_table *tb,
> > 			   struct netlink_ext_ack *extack)
> > {
> > 	struct fib_alias *fa;
> >+	int last_slen = -1;
> > 	int err;
> > 
> > 	hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
> >@@ -2110,6 +2111,15 @@ static int fib_leaf_notify(struct key_vector *l, struct fib_table *tb,
> > 		if (tb->tb_id != fa->tb_id)
> > 			continue;
> > 
> >+		if (fa->fa_slen == last_slen)
> >+			continue;
> 
> Hmm, I wonder, don't you want to continue only for FIB_EVENT_ENTRY_REPLACE_TMP
> and keep the notifier call for FIB_EVENT_ENTRY_ADD?

Yea, I think you're right. As-is this introduces a small regression
until later in the series. Will fix. Thanks!

> 
> 
> >+
> >+		last_slen = fa->fa_slen;
> >+		err = call_fib_entry_notifier(nb, FIB_EVENT_ENTRY_REPLACE_TMP,
> >+					      l->key, KEYLENGTH - fa->fa_slen,
> >+					      fa, extack);
> >+		if (err)
> >+			return err;
> > 		err = call_fib_entry_notifier(nb, FIB_EVENT_ENTRY_ADD, l->key,
> > 					      KEYLENGTH - fa->fa_slen,
> > 					      fa, extack);
> >-- 
> >2.21.0
> >