Re: [EVL] Kernel WARNING: notifier callback netevent_handler already registered

[Philippe Gerum <rpm@xenomai.org>]

Hannes Diethelm <hannes.diethelm@gmail.com> writes:

> Hello
>
> There is a Kernel WARNING: "notifier callback netevent_handler already registered right after boot". It is repeated 5 times.
>
> Config:
> Debian Trixie with xfce4 Desktop
> libevl: r56
> linux-evl: v6.12.67-evl2-rebase
>
> I traced the issue already trough the following code:
> net/core/net_namespace.c:355
> kernel/evl/net/net.c:35
> kernel/evl/net/ipv4/ipv4.c:41
> kernel/evl/net/ipv4/arp.c:323
>
> However, I lack the knowledge to do a proper fix. One way would be to just check in evl_net_init_arp() if it is already
> registered and don't do it more than once but that doesn't feel right.

It looks like the system is instantiating multiple network namespaces,
for each of which we set up an ARP front cache by calling
evl_net_init_arp(). Bad idea to hook a system-wide handler there as
well. Could you confirm this fix [1] works for you?

Thanks for reporting this.

[1] https://gitlab.com/Xenomai/xenomai4/linux-evl/-/commit/569beef061321c2c00d775b13ad0aec1a1d2a416

-- 
Philippe.