cvs commit: src/sys/dev/re if_re.c

[M. Warner Losh]

In message: <20050916091928.GG88456 at ip.net.ua>
            Ruslan Ermilov <ru at FreeBSD.org> writes:
: On Thu, Sep 15, 2005 at 11:56:39PM +0300, Ruslan Ermilov wrote:
: > The first is the BPF detach bad interaction with foo_detach(),
: > as described in re_detach().  This panic is real with (I think)
: > all drivers.  And testing IFF_DRV_RUNNING here doesn't seem to
: > be able to prevent the panic.  Perhaps the fix would be to
: > move ether_ifdetach() before foo_stop() in foo_detach(), I'm
: > not yet sure.
: > 
: I tried with rl(4) PCCARD, by moving ether_ifdetach() before
: rl_stop() in rl_detach().  It fixes the panic when you eject
: the card, but doesn't fix it when kldunloading the module.
: The difference is that rl_detach() is called already after
: miibus0 and rlphy0 has been detached when kldunloading the
: module.  When ejecting the card, rl_detach() is called first.
: What happens when you kldunload the module with BPF listener
: attached, is that bpfdetach() calls rl_ioctl() to reset
: promisc, that calls rl_init_locked(), and that results in
: 
: 	mii = device_get_softc(sc->rl_miibus);
: 
: being NULL (remember the miibus has already been detached),
: and that panics later here:
: 
: 	mii_mediachg(mii);
: 
: When we reset IFF_UP, rl_ioctl(SIOCSIFFLAGS) silently exits
: and no harm is done.  So the question is: how do we prevent
: this from happening without resetting IFF_UP.  One possible
: solution would be to add sc->detaching, similar to
: sc->suspended, abd check it in rl_ioctl().

Ugg.  In ed, we check to make sure that we still have a child before
doing things with mii bus.  A similar fix could be made.

Warner