[Devel] Re: [patch -mm 08/17] nsproxy: add hashtable

[Eric W. Biederman]

"Serge E. Hallyn" <serue at us.ibm.com> writes:

> Quoting Eric W. Biederman (ebiederm at xmission.com):
>> clg at fr.ibm.com writes:
>> 
>> > From: Cedric Le Goater <clg at fr.ibm.com>
>> >
>> > This patch adds a hashtable of nsproxy using the nsproxy as a key. 
>> > init_nsproxy is hashed at init with key 0. This is considered to be 
>> > the 'host' nsproxy.
>> 
>> NAK.  Which namespace do these ids live in?
>> 
>> It sounds like you are setting up to make the 'host' nsproxy special
>> and have special rules.  That also sounds wrong.
>> 
>> Even letting the concept of nsproxy escape to user space sounds wrong.
>> nsproxy is an internal space optimization.  It's not struct container
>> and I don't think we want it to become that.
>> 
>> Eric
>
> So would you advocate referring to containers just by the pid of a
> process containing the nsproxy, and letting userspace maintain a mapping
> of id's to containers through container create/enter commands?  Or is
> there some other way you were thinking of doing this?

There are two possible ways.
1) Just use a process using the namespace.
   This is easiest to implement.

2) Have a struct pid reference in the namespace itself, and probably
   an extra pointer in struct pid to find it.
   This is the most stable, because fork/exit won't affect which pid you need
   to use.

Beyond that yes it seems to make sense to let user space maintain any mapping
of containers to ids.

Eric
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