Possible solutions for PR #46587

[Roger Pau Monne <roger.pau%citrix.com@localhost>]

Hello,

I've submitted this PR some time ago, and I would like to fix it, since
it's very annoying to get a panic every time I shut down the system.
I've dug a little bit into this, and it is caused by rev 1.180 of
sys/arch/amd64/amd64/machdep.c, which adds the detach of devices
(config_detach_all) in the cpu_reboot function. This causes the bnx, and
other network cards to call it's detach function.

If bridges are configured, and network card is UP, when we unset the
IFF_PROMISC flag we will call bnx_init (or fxp_init as reported by
another user) after destroying the callout (it is destroyed in
bnx_detach), which leads us to the panic.

I think the solution should be to remove the callout destroy or to mark
the interface as DOWN (calling if_down at some point before ether_ifdetach).

Thanks, Roger.