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    SubjectRe: [RFC][PATCH 2/9] perf: core, remove hw_perf_event_init
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    On Mon, 2010-05-10 at 14:27 +0200, Frederic Weisbecker wrote:
    > On Mon, May 10, 2010 at 12:19:29PM +0200, Peter Zijlstra wrote:
    > > On Mon, 2010-05-10 at 18:17 +0800, Lin Ming wrote:
    > > > On Mon, 2010-05-10 at 17:40 +0800, Peter Zijlstra wrote:
    > > > > On Mon, 2010-05-10 at 17:26 +0800, Lin Ming wrote:
    > > > > > +static struct pmu *perf_event_lookup_pmu(struct perf_event *event)
    > > > > > +{
    > > > > > + struct pmu *pmu;
    > > > > > + int pmu_id = event->attr.pmu_id;
    > > > > > +
    > > > > > + list_for_each_entry(pmu, &pmus, entry) {
    > > > > > + if (pmu->id == pmu_id)
    > > > > > + return pmu;
    > > > > > + }
    > > > > > +
    > > > > > + return NULL;
    > > > > > +}
    > > > >
    > > > > > +void perf_event_register_pmu(struct pmu *pmu)
    > > > > > +{
    > > > > > + pmu->id = pmu_id_curr++;
    > > > > > + list_add_tail(&pmu->entry, &pmus);
    > > > > > +}
    > > > >
    > > > > That will be wanting some sort of synchronization
    > > >
    > > > Will add a mutex to protect the list of pmus.
    > >
    > > I'm thinking RCU might be better suited, a mutex for lookup doesn't
    > > sound ideal.
    >
    >
    > Is it really needed? I expect this function to be called on boot
    > only.
    >
    > In fact I would even suggest to tag it as __init.

    Loadable modules as well as PCI-Hotplug need supporting.


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