Re: [PATCH] [NETNS45] network namespace locking rules

["Denis V. Lunev" <dlunev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Eric W. Biederman wrote:
> "Denis V. Lunev" <den-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org> writes:
> 
>> Current locking for network namespace list/initialization is broken.
>> for_each_net is called under single rtnl_lock in
>> register_netdevice_notifier.
> 
> As of  984e617a3e1974022b8f671427a76ffbe886f75b this issue has
> been addressed in net-2.6.24
> 
> The only remaining part to address is rtnl_unlock().
> 
> My current hypothesis is that rtnl_unlock() only needs to process
> the packets that are queued while we had the rtnl_lock held,
> to maintain the current semantics.
> 
> So the retry may not be necessary as it may be possible to prove
> that the only extra packets that could come in come from another
> thread taking the rtnl_lock and they will those packets in their
> rtnl_unlock() if we don't.
> 
> I will review this later today, and add the retry if necessary.
> 
> One way or another I think we agree on how to get the locking correct.
> The other details are a bit tricky but look usable.
> 
> Eric
> 

Unfortunately, the answer is 'no'. data_ready callback takes rtnl
inside, so we can have new packets from other namespaces during the
processing.

No way, but restart :(

Regards,
	Den