IPv6 route mutex recursion (crash) and fix

[Bruce M Simpson]

On Tue, Sep 21, 2004 at 10:53:20PM -0400, Brian Fundakowski Feldman wrote:
> Sorry, I should have provided a higher number of lines of context.
> It prevents a call to nd6_lookup() and reentry into the route table
> when entered via RTM_RESOLVE.  I.e. nd6_rtrequest(), nd6_is_addr_neighbor(),
> nd6_lookup().

I haven't tested your patch but the rationale for this sounds fine. Recursive
locking attempts via the lookup code by way of neighbour discovery is a Bad
Thing, and it would be useful to keep these semantics working for IPv6. So
it looks good to me.

BMS