[Devel] [PATCH 06/16] net: Add a network namespace parameter to struct sock

[Daniel Lezcano]

Denis V. Lunev wrote:
> Eric W. Biederman wrote:
>> Sockets need to get a reference to their network namespace,
>> or possibly a simple hold if someone registers on the network
>> namespace notifier and will free the sockets when the namespace
>> is going to be destroyed.
>>
>> Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
>> ---
>>  include/net/inet_timewait_sock.h |    1 +
>>  include/net/sock.h               |    3 +++
>>  2 files changed, 4 insertions(+), 0 deletions(-)
>>
>> diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
>> index 47d52b2..abaff05 100644
>> --- a/include/net/inet_timewait_sock.h
>> +++ b/include/net/inet_timewait_sock.h
>> @@ -115,6 +115,7 @@ struct inet_timewait_sock {
>>  #define tw_refcnt		__tw_common.skc_refcnt
>>  #define tw_hash			__tw_common.skc_hash
>>  #define tw_prot			__tw_common.skc_prot
>> +#define tw_net			__tw_common.skc_net
> 
> 
> This place is a very tricky, indeed. If we keep the namespace until
> timewait bucket death - we'll keep the namespace alive at least 5
> _minutes_ after all process death.

Yes, that's right. And for me that makes totally sense. The namespace 
should not be destroyed until it is referenced somewhere.

> If we stop a VE (in terms of OpenVz) and restart it, we'll 100% have an
> _OLD_ namespace with all buckets shown :( 
> So, in OpenVz we use a number
> of VE instead of pointer to a VE. Additionally, on VE death we can wipe
> all TW buckets. VE start stop from outside world looks very much like a
> computer power on/off.

That makes sense too. But if you wipe out the sockets when stopping the 
VE where is the problem with the restart ?