LOR + panic in scope6.c

Robert Watson rwatson at FreeBSD.org
Tue Aug 9 21:53:27 GMT 2005

On Tue, 9 Aug 2005, John Baldwin wrote:

>> Could it be a problem of ether_ifattach and ether_ifdetach being run 
>> without the driver locks?  UP machine btw.
> I don't think it is a locking problem.  I think that the inet6 code is 
> simply not taking into account some edge case.  In theory I don't think 
> that if_afdata[AF_INET6] should be NULL since ether_ifattach() has 
> called inet6's domain attach routine.  Are you sure that you have called 
> ether_ifattach() btw?

At one point there existed a set of races where event timeouts for IPv6 
would fire during the attaching of a network interface, and since the IPv6 
init routines hadn't been called for the interface yet, pointers that were 
otherwise always non-NULL would be NULL.  I wouldn't be surprised if this 
is one of those.  The initialization/construction ordering for ifnets is 
probably not right yet, although it's getting better.

Robert N M Watson

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