kern/63772: tap device / exclusive open problem

Brooks Davis brooks at one-eyed-alien.net
Fri Mar 5 10:55:46 PST 2004


On Fri, Mar 05, 2004 at 07:18:52PM +0100, Stefan `Sec` Zehl wrote:
> On Thu, Mar 04, 2004 at 11:20 -0800, FreeBSD-gnats-submit at FreeBSD.org wrote:
> > Thank you very much for your problem report.
> > It has the internal identification `kern/63772'.
> 
> I have checked the if_tap.c in the current and stable branches, and was
> thus able to come up with an easy fix:
> 
> --- if_tap.c    Tue Feb 24 05:35:44 2004
> +++ if_tap.c.neu        Fri Mar  5 19:09:12 2004
> @@ -323,6 +323,9 @@
>         KASSERT(!(tp->tap_flags & TAP_OPEN), 
>                 ("%s flags is out of sync", tp->tap_if.if_xname));
>  
> +       if (tp->tap_flags & TAP_OPEN)
> +               return (EBUSY);
> +
>         bcopy(tp->arpcom.ac_enaddr, tp->ether_addr, sizeof(tp->ether_addr));
>  
>         tp->tap_pid = td->td_proc->p_pid;
> 
> 
> After this simple change, openvpn works with multiple tunnels again.

There's obviously something complicated going on since with INVARIANTS
enabled this would either return EBUSY or panic.  This should definitely
not be committed as is.

-- Brooks


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