Re: 2.6.17-rc6-mm1/pktcdvd - BUG: possible circular locking

Arjan van de Ven
2006-07-14T22:29:19Z

>
> In the first call chain, do_open -> pkt_open, the bd_mutex object that
> is being locked corresponds to a pktcdvd block device, because those
> are the only devices that have their open method set to pkt_open.
>
> In the second call chain, pkt_ctl_ioctl -> pkt_new_dev -> do_open, the
> bd_mutex object that is being locked *does not* correspond to a
> pktcdvd block device, because pkt_new_dev will bail out with a "Can't
> chain pktcdvd devices" error if you call it with "dev" set to a
> pktcdvd device.
>
> Therefore, there is no AB-BA deadlock possibility. The locking
> dependencies are A -> B and B -> A', where it is known that A, B and
> A' are all different.
>
> So the claim from the lockdep code, "BUG: possible circular locking
> deadlock detected!", is a false alarm.

ok I'll try to find a annotation for that that works