[Devel] Re: [PATCH 4/6] cr: checkpoint and restore task credentials

[Oren Laadan]

Serge E. Hallyn wrote:
> Quoting Oren Laadan (orenl at cs.columbia.edu):
>> Serge -
>>
>> The 'creator' makes the 'struct user' recursive because to save
>> an object you need to first save its creator etc. However the
>> implementation may not call checkpoint_obj() recursively, if
>> the depth isn't bound a-priory. You probably need to convert
>> checkpoint_write_user() to do an iterative (loop) implementation
>> of the recursion...
> 
> It's not done recursively, though.  checkpoint_write_userns() will
> only be called by checkpoint_write_user().   checkpoint_write_user()
> will make sure there are only 5 levels deep of unwritten creator
> user namespace (else bail), then start at the oldest creator, and
> write it.  That checkpoint_write_user will cause a write of its
> user_ns, then write the user, then return to the original
> checkpoint_write_user() which will now write the next-oldest
> user_struct
> 
> So the max recursion depth we get is:
> 
> 	checkpoint_task_struct -> checkpoint_write_cred ->
> 	checkpoint_write_user -> checkpoint_write_user ->
> 	checkpoint_write_userns (END)

Ok. Let's not restrict to 5 levels :)

Oren.

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