Networking panic on 12 - found the cause

[Pete French]

Thanks guys! That was fast....

On 12/02/2019 20:13, Kristof Provost wrote:
> On 2019-02-12 13:54:21 (-0600), Eric van Gyzen <eric at vangyzen.net> wrote:
>  > I see the same behavior on head (and stable/12).
>  >
>  > (kgdb) f
>  > #16 0xffffffff80ce5331 in ether_output_frame (ifp=0xfffff80003672800,
>  > m=0xfffff8000c88b100) at /usr/src/sys/net/if_ethersubr.c:468
>  > 468 switch (pfil_run_hooks(V_link_pfil_head, &m, ifp, PFIL_OUT,
>  >
>  > 0xffffffff80ce5321 <+81>: mov %gs:0x0,%rax
>  > 0xffffffff80ce532a <+90>: mov 0x500(%rax),%rax
>  > => 0xffffffff80ce5331 <+97>: mov 0x28(%rax),%rax
>  >
>  > I think this is part of the V_link_pfil_head. I'm not very familiar
>  > with vnet. Does this need a CURVNET_SET(), maybe in garp_rexmit()?
>  >
> Yes. I posted a proposed patch in
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=235699 
> 
> Basically we get called through a timer, so there's no vnet context. It
> needs to be set, and then we can safely use any V_ variables.
> 
> Regards,
> Kristof