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    SubjectRe: [patch 0/6] rcu head debugobjects
    * Paul E. McKenney (paulmck@linux.vnet.ibm.com) wrote:
    > On Mon, Mar 29, 2010 at 09:39:33AM -0400, Mathieu Desnoyers wrote:
    > > Hi Paul,
    > >
    > > Thinking about the rcu head init topic, we might be able to drop the
    > > init_rcu_head() initializer. The idea is the following:
    > >
    > > - We need init_rcu_head_on_stack()/destroy_rcu_head_on_stack().
    > > - call_rcu() populates the rcu_head and normally does not care about it being
    > > pre-initialized.
    > > - The activation fixup can detect if a non-initialized rcu head is being
    > > activated and just perform the fixup without complaining.
    > > - If we have two call_rcu() in a row in the same GP on the same rcu_head, the
    > > activation check will detect it.
    > >
    > > So either we remove all the init_rcu_head(), as was originally proposed, or we
    > > use one that is a no-op on !DEBUG configs and initialize the object with DEBUG
    > > configs.
    > >
    > > That removes the dependency on object_is_static().
    >
    > If I understand correctly, this does sound good. Here is what I think
    > you are proposing:
    >
    > o call_rcu() and friends only complain if handed an rcu_head
    > structure that is still queued awaiting a grace period.
    > They don't care otherwise.
    >
    > o rcu_do_batch() complains unless the rcu_head structure has
    > most recently been enqueued by call_rcu() or one if its friends.
    >
    > Did I get it right?

    Exactly.

    Thanks,

    Mathieu

    >
    > Thanx, Paul

    --
    Mathieu Desnoyers
    Operating System Efficiency R&D Consultant
    EfficiOS Inc.
    http://www.efficios.com


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