[Devel] Re: [RFC][PATCH 0/4] Object creation with a specified id

[Nadia Derbey]

Pavel Emelyanov wrote:
> Oren Laadan wrote:
> 
>>Nadia Derbey wrote:
>>
>>>Oren Laadan wrote:
>>>
>>>>Nadia.Derbey at bull.net wrote:
>>>>
>>>>
>>>>>A couple of weeks ago, a discussion has started after Pierre's 
>>>>>proposal for
>>>>>a new syscall to change an ipc id (see thread
>>>>>http://lkml.org/lkml/2008/1/29/209).
>>>>>
>>>>>
>>>>>Oren's suggestion was to force an object's id during its creation, 
>>>>>rather
>>>>>than 1. create it, 2. change its id.
>>>>>
>>>>>So here is an implementation of what Oren has suggested.
>>>>>
>>>>>2 new files are defined under /proc/self:
>>>>>  . next_ipcid --> next id to use for ipc object creation
>>>>>  . next_pids --> next upid nr(s) to use for next task to be forked
>>>>>                  (see patch #2 for more details).
>>>>
>>>>Generally looks good. One meta-comment, though:
>>>>
>>>>I wonder why you use separate files for separate resources, 
>>>
>>>That would be needed in a situation wheere we don't care about next, 
>>>say, ipc id to be created but we need a predefined pid. But I must admit 
>>>I don't see any pratical application to it.
>>
>>exactly; why set the next-ipc value so far in advance ?  I think it's
>>better (and less confusing) if we require that setting the next-id value
>>be done right before the respective syscall.
> 
> 
> And race with some other syscall caller? This will only work if the next-ipc-id
> and the next-pid are on a task_struct. Are they (at least supposed to be such)?
> 
> 

Yes they are.

Regards,
Nadia
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