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    SubjectRe: [RFC][PATCH 2/6] x86, nmi: create new NMI handler routines
    On Mon, Aug 22, 2011 at 04:16:20PM +0200, Peter Zijlstra wrote:
    > On Fri, 2011-08-19 at 16:37 -0400, Don Zickus wrote:
    > > +static struct nmiaction *__free_nmi(unsigned int type, const char *name)
    > > +{
    > > + struct nmi_desc *desc = nmi_to_desc(type);
    > > + struct nmiaction *n, **np = &(desc->head);
    > > + unsigned long flags;
    > > +
    > > + spin_lock_irqsave(&desc->lock, flags);
    > > +
    > ...
    > > +
    > > + spin_unlock_irqrestore(&desc->lock, flags);
    > > + synchronize_rcu();
    > > + return *np;
    > > +}
    >
    > > +void unregister_nmi_handler(unsigned int type, const char *name)
    > > +{
    > > + kfree(__free_nmi(type, name));
    > > +}
    >
    > This code is weird.. why not have the kfree() in __free_nmi(), also why
    > use sync_rcu() and not use kfree_rcu()?

    It's a mixture of copying the notifier code and not fully understanding
    the rcu options out there. I'll look into kfree_rcu and try to clean this
    up.

    >
    > > +EXPORT_SYMBOL_GPL(unregister_nmi_handler);
    >
    > *g*, so binary modules can register an NMI handler, but can't unregister
    > it..?

    heh. I suck. Sorry about that.

    Cheers,
    Don



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