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

[Hannes Diethelm <hannes.diethelm@gmail.com>]

Am 25.04.26 um 20:50 schrieb Philippe Gerum:
> 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
> 

Thanks, that was fast. The WARNING is gone now.

But now after just updating to the kernel including your fix, I have a different behavior on
incoming packages. It seams that the default when no filter is set has changed from EVL_RX_SKIP to EVL_RX_ACCEPT.

linux-evl: v6.12.67-evl2-rebase
-After evl net -ei enp7s0, I can ping another host.
-oob-net-icmp does only receive packages when I use an eBPF filter with EVL_RX_ACCEPT
-After that, ping doesn't work any more

linux-evl: v6.12.y-cip-evl-rebase
-After evl net -ei enp7s0, I can NOT ping another host.
-oob-net-icmp does receive packages
-If I use an eBPF filter returning EVL_RX_SKIP, I can ping again

I am not using VLAN's.

Was that changed on purpose?