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

[Oren Laadan]

Nadia Derbey wrote:
> Nick Andrew wrote:
> > On Fri, Apr 04, 2008 at 04:51:29PM +0200, Nadia.Derbey@xxxxxxxx wrote:
> >
> > >   . echo "LONG XX" > /proc/self/next_id
> > >     next object to be created will have an id set to XX
> > >   . echo "LONG<n> X0 ... X<n-1>" > /proc/self/next_id
> > >     next object to be created will have its ids set to XX0, ... X<n-1>
> > >     This is particularly useful for processes that may have several 
> > > ids if
> > >     they belong to nested namespaces.
> >
> >
> > How do you handle race conditions, i.e. you specify the ID for the
> > next object to be created, and then some other thread goes and creates
> > an object before your thread creates one?
> >
> > Nick.
>
>
> Sorry for not answering earlier, I just saw your e-mail!

[I too managed to miss that message].

> It's true that the way I've done things, the "create_with_id" doesn't 
> take into account multi-threaded apps, since "self" is related to the 
> thread group leader.
>
> May be using something like /proc/self/task/<my_tid>/next_id would be 
> better, but I have to think more about it...

That /proc/self links to /proc/TGID slipped my mind. Definitely must
be done on a per-thread basis (and /proc/<TGID>/task/<PID>/next_id
will do the trick).

Oren.

> Regards,
> Nadia
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