[Babel-users] [PATCH] Flush ipv4 addresses and routes when ipv6 link layer addr is lost

[Dave Taht]

On Fri, Feb 24, 2017 at 12:19 PM, Juliusz Chroboczek <jch at irif.fr> wrote:
> Applied, thanks, although you're just fixing the symptom, not the cause.
>
> I'm really not happy with this part of the code, it's one of the most
> fragile bits in babeld.  Plus it's racy (if the interface goes down and
> back up before we notice, bad things may happen).  I suspect it's
> unavoidable, the kernel interfaces we're using are intrinsically racy.

I have a patch for recognizing errors better pending here, but it
still needs some work and stress testing.

https://github.com/dtaht/rabeld/blob/master/kernel_netlink.c#L470

These were all errnos that I saw in my stress testing in the past few
weeks, and why they happened.

We could get away from having a single netlink socket for all messages
and instead have one per logical group
(routes,interfaces,addresses,rules), and have one per each - doing an
interface check when ENETDOWN hits, for example.

I too have now seen the kernel return EAGAIN indefinitely - in my case
wpa_supplicant or the wifi driver had crashed beyond recovery - and I
haven't the foggiest idea what to do about it... (closing/reopening
the socket crashed things harder)

The new noprefixroute stuff helps a little on separating interface
changes from automatic kernel flushes.

> If anyone competent wants to rework this code, I'll be grateful.

I'll try in the coming weeks. Assuming you think I'm competent.

>
> -- Juliusz



-- 
Dave Täht
Let's go make home routers and wifi faster! With better software!
http://blog.cerowrt.org