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Re: unregister_netdevice: waiting for lo to become free. Usage count = 8

To: Hans Schillstrom <hans@xxxxxxxxxxxxxxx>
Subject: Re: unregister_netdevice: waiting for lo to become free. Usage count = 8
Cc: Simon Horman <horms@xxxxxxxxxxxx>, netdev@xxxxxxxxxxxxxxx, lvs-devel@xxxxxxxxxxxxxxx, "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
From: Julian Anastasov <ja@xxxxxx>
Date: Tue, 19 Apr 2011 01:23:17 +0300 (EEST)
        Hello,

On Mon, 18 Apr 2011, Hans Schillstrom wrote:

> On Monday, April 18, 2011 23:12:27 Julian Anastasov wrote:
> > 
> >     Hello,
> > 
> > On Mon, 18 Apr 2011, Hans Schillstrom wrote:
> > 
> > > Actually I forgot to tell there is a need for a
> > > ip_vs_service_cleanup() due to above.
> > > Do you see any drawbacks with it ?
> > 
> >     May be ip_vs_service_cleanup() should call only
> > ip_vs_flush(), under __ip_vs_mutex.
> 
> Hmm,  
> I'm not sure if the IP_VS_WAIT_WHILE() in ip_vs_flush is a good idea in this 
> case...
> That was why I wrote ip_vs_service_cleanup()

        IP_VS_WAIT_WHILE should be called because some
schedulers do not use locks for ->schedule, eg. WLC.
They rely on svc->usecnt reference to hold the virtual
service. Nothing changes now with netns. It is currently the
only way to modify or delete virtual service or scheduler.
Of course, __ip_vs_svc_lock is now global but we do not
have a choice.

> > _cleanup_net. Now there are many register_pernet_subsys()
> > calls and I'm not sure we preserve the needed order for
> > cleanup. Are the ->exit methods called in reverse order?
> 
> Yes

        You mean, only in the planned patch, yes?

> > I don't see it in ops_exit_list() and we can not rely
> > on such registration order. I think, ip_vs_init() should
> > call global functions as now but __ip_vs_init() and
> > __ip_vs_cleanup() should call the _net methods in right
> > order.
> 
> Exactly,
> I have already done that in my next patch,  and some other small changes :-)
> For the ip_vs.ko there is only one register/unregister now, the schedulers 
> still have their own.
> Hopefully the patch is ready to morrow

        OK, very good.

Regards

--
Julian Anastasov <ja@xxxxxx>
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