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

[Eric W. Biederman]

Cedric Le Goater <clg at fr.ibm.com> writes:

>>> Let me try : you would add a 'struct pid pid' field to all namespaces and
>>> assign that 'pid' field  with the struct pid of the task creating the
>>> namespace ?
>> 
>> Yes a struct pid *pid field, that we did the proper reference counting
>> on.
>
> sure.
>  
>> As for which pid to assign, that is a little trickier.  The struct pid
>> of the task creating the namespace is the obvious choice and that will
>> always work for clone.  For unshare that would only work if we added
>> the restriction you can't unshare if someone already has used that pid
>> for that kind of namespace.
>
> clone will also be an issue if more than one namespace is unshared. Do 
> you use the same 'struct pid*' for each namespace ? hmm, it feels also 
> wrong.
>
> having an id field in the namespace and using a bind_ns like syscall
> to let the user assign whatever id he wants to, doesn't seem to be
> such a bad idea.

I think I would probably have suggested simply taking the next
available id in that case in practice.  Partly it depends on exactly
what we are trying to do with these.

But I do agree getting that last little details right so some corner
case doesn't feel wrong is hard.  That is why I try and put off
this kind of things until as much is known about how we are going
to use it as possible.  So we can make a good decision and solve
practical problems, and not theoretical ones.

Eric
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