netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Ido Schimmel <idosch@idosch.org>
To: Jonas Gorski <jonas.gorski@gmail.com>
Cc: Network Development <netdev@vger.kernel.org>,
	David Ahern <dsahern@kernel.org>
Subject: Re: RTM_DELROUTE not sent anymore when deleting (last) nexthop of routes in 6.1
Date: Thu, 24 Nov 2022 14:41:31 +0200	[thread overview]
Message-ID: <Y39me56NhhPYewYK@shredder> (raw)
In-Reply-To: <CAOiHx==ddZr6mvvbzgoAwwhJW76qGNVOcNsTG-6m79Ch+=aA5Q@mail.gmail.com>

On Thu, Nov 24, 2022 at 10:20:00AM +0100, Jonas Gorski wrote:
> Hello,
> 
> when an IPv4 route gets removed because its nexthop was deleted, the
> kernel does not send a RTM_DELROUTE netlink notifications anymore in
> 6.1. A bisect lead me to 61b91eb33a69 ("ipv4: Handle attempt to delete
> multipath route when fib_info contains an nh reference"), and
> reverting it makes it work again.
> 
> It can be reproduced by doing the following and listening to netlink
> (e.g. via ip monitor)
> 
> ip a a 172.16.1.1/24 dev veth1
> ip nexthop add id 100 via 172.16.1.2 dev veth1
> ip route add 172.16.101.0/24 nhid 100
> ip nexthop del id 100
> 
> where the nexthop del will trigger a RTM_DELNEXTHOP message, but no
> RTM_DELROUTE, but the route is gone afterwards anyways.

I tried the reproducer and I get the same notifications in ip monitor
regardless of whether 61b91eb33a69 is reverted or not.

Looking at the code and thinking about it, I don't think we ever
generated RTM_DELROUTE notifications when IPv4 routes were flushed (to
avoid a notification storm).

Are you running an upstream kernel?

Thanks

> 
> Doing the same thing with IPv6 still works as expected
> 
> ip a a 2001:db8:91::1/64 dev veth1
> ip nexthop add id 100 via 2001:db8:91::2 dev veth1
> ip route add 2001:db8:101::/64 nhid 100
> ip nexthop del id 100
> 
> Here the kernel will send out both the RTM_DELNEXTHOP and the
> RTM_DELROUTE netlink messages.
> 
> Unfortunately my net-foo is not good enough to propose a fix.
> 
> Best regards
> Jonas

  reply	other threads:[~2022-11-24 12:42 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-24  9:20 RTM_DELROUTE not sent anymore when deleting (last) nexthop of routes in 6.1 Jonas Gorski
2022-11-24 12:41 ` Ido Schimmel [this message]
2022-11-24 14:15   ` Jonas Gorski
2022-11-24 14:40     ` Jonas Gorski
2022-11-24 14:50       ` Ido Schimmel
2022-11-24 15:20         ` Jonas Gorski
2022-11-24 16:04           ` Ido Schimmel
2022-11-24 16:58             ` Jonas Gorski
2022-11-25  3:53   ` David Ahern
2022-11-25  8:36 ` RTM_DELROUTE not sent anymore when deleting (last) nexthop of routes in 6.1 #forregzbot Thorsten Leemhuis
2022-11-27 12:08   ` Thorsten Leemhuis
2022-11-29  8:50     ` Thorsten Leemhuis

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=Y39me56NhhPYewYK@shredder \
    --to=idosch@idosch.org \
    --cc=dsahern@kernel.org \
    --cc=jonas.gorski@gmail.com \
    --cc=netdev@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).