[RFC] Transactional CGroup task attachment

Paul Menage menage at google.com
Fri Jul 11 08:23:22 PDT 2008


On Fri, Jul 11, 2008 at 7:27 AM, Serge E. Hallyn <serue at us.ibm.com> wrote:
>
> It does feel like it may be too much designed for one particular user
> (i.e. is there a reason not to expect a future cgroup to need a check
> under a spinlock before a check under a mutex - say an i_sem - in the
> can_attach sequence?),

It would be fine as long as the code didn't want to *keep* holding the
spinlock after the first check, while taking the mutex - and since
that style of code is invalid under the existing locking rules, I
don't see that as a problem. There's nothing to stop a
prepare_attach_sleep() method from taking a spinlock as long as it
releases it before it returns.

Paul


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