Re: [PATCH net-next] ipv4/fib: send RTM_DELROUTE notify when flush fib

[Hangbin Liu <liuhangbin@gmail.com>]

On Thu, Jul 20, 2023 at 10:01:06PM -0600, David Ahern wrote:
> >>> How about ignore route deletion for link down? e.g.
> >>>
> >>> diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> >>> index 74d403dbd2b4..11c0f325e887 100644
> >>> --- a/net/ipv4/fib_trie.c
> >>> +++ b/net/ipv4/fib_trie.c
> >>> @@ -2026,6 +2026,7 @@ void fib_table_flush_external(struct fib_table *tb)
> >>>  int fib_table_flush(struct net *net, struct fib_table *tb, bool flush_all)
> >>>  {
> >>>         struct trie *t = (struct trie *)tb->tb_data;
> >>> +       struct nl_info info = { .nl_net = net };
> >>>         struct key_vector *pn = t->kv;
> >>>         unsigned long cindex = 1;
> >>>         struct hlist_node *tmp;
> >>> @@ -2088,6 +2089,11 @@ int fib_table_flush(struct net *net, struct fib_table *tb, bool flush_all)
> >>>
> >>>                         fib_notify_alias_delete(net, n->key, &n->leaf, fa,
> >>>                                                 NULL);
> >>> +                       if (!(fi->fib_flags & RTNH_F_LINKDOWN)) {
> >>> +                               rtmsg_fib(RTM_DELROUTE, htonl(n->key), fa,
> >>> +                                         KEYLENGTH - fa->fa_slen, tb->tb_id, &info, 0);
> >>> +                       }
> >>
> >> Will you get a notification in this case for 198.51.100.0/24?
> > 
> > No. Do you think it is expected with this patch or not?
> 
> The intent is that notifications are sent for link events but not route
> events which are easily deduced from the link events.

Sorry, I didn't get what you mean. The link events should be notified to user
via rtmsg_ifinfo_event()? So I think here we ignore the route events caused by
link down looks reasonable.

Thanks
Hangbin