On Wed, Feb 25, 2009 at 08:18:47AM +0100, Patrick McHardy wrote:

Unfortunately its more complicated than I thought because of
device renames, where the sysctl pointer is reused after
unregistration and the rename/unregistration/re-registration
should be atomic. Deferring unregistration means we can't perform
the new registration immediately unless we allow multiple
registrations for a single device to be active simulaneously,
which introduces a whole new set of problems.

Good point.

Simply ignoring the request during unregistration doesn't seem
so bad after all, the main problem is that it intoduces a different
race on renames where a write to the "forwarding" file returns
success, but the change doesn't take effect. We could return
-ENOENT, but that seems a bit strange after open() returned success.
Maybe -EBUSY, although I would prefer to make this transparent
to userspace.

I'd like to avoid that for the rename case just because shell
scripts know how to deal with echo foo > /nonexist/file but not
necessarily a failed echo on write/close.

I think I'm stuck. Will rethink it after some coffee :)

Yes we need more coffee :)

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt