kern/63772: tap device / exclusive open problem

Brooks Davis brooks at one-eyed-alien.net
Fri Mar 5 11:00:26 PST 2004


The following reply was made to PR kern/63772; it has been noted by GNATS.

From: Brooks Davis <brooks at one-eyed-alien.net>
To: Stefan `Sec` Zehl <sec at 42.org>
Cc: FreeBSD-gnats-submit at freebsd.org, freebsd-bugs at freebsd.org
Subject: Re: kern/63772: tap device / exclusive open problem
Date: Fri, 5 Mar 2004 10:55:30 -0800

 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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