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    Subject[patch 2/3] perf/x86/intel/uncore: Cleanup hotplug conversion fallout
    The recent conversion to the hotplug state machine kept two mechanisms from
    the original code:

    1) The first_init logic which adds the number of online CPUs in a package
    to the refcount. That's wrong because the callbacks are executed for
    all online CPUs.

    Remove it so the refcounting is correct.

    2) The on_each_cpu() call to undo box->init() in the error handling
    path. That's bogus because when the prepare callback fails no box has
    been initialized yet.

    Remove it.

    Fixes: 1a246b9f58c6 ("perf/x86/intel/uncore: Convert to hotplug state machine")
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    arch/x86/events/intel/uncore.c | 44 +++--------------------------------------
    1 file changed, 4 insertions(+), 40 deletions(-)

    --- a/arch/x86/events/intel/uncore.c
    +++ b/arch/x86/events/intel/uncore.c
    @@ -764,30 +764,6 @@ static void uncore_pmu_unregister(struct
    pmu->registered = false;
    }

    -static void __uncore_exit_boxes(struct intel_uncore_type *type, int cpu)
    -{
    - struct intel_uncore_pmu *pmu = type->pmus;
    - struct intel_uncore_box *box;
    - int i, pkg;
    -
    - if (pmu) {
    - pkg = topology_physical_package_id(cpu);
    - for (i = 0; i < type->num_boxes; i++, pmu++) {
    - box = pmu->boxes[pkg];
    - if (box)
    - uncore_box_exit(box);
    - }
    - }
    -}
    -
    -static void uncore_exit_boxes(void *dummy)
    -{
    - struct intel_uncore_type **types;
    -
    - for (types = uncore_msr_uncores; *types; types++)
    - __uncore_exit_boxes(*types++, smp_processor_id());
    -}
    -
    static void uncore_free_boxes(struct intel_uncore_pmu *pmu)
    {
    int pkg;
    @@ -1078,22 +1054,12 @@ static int uncore_cpu_dying(unsigned int
    return 0;
    }

    -static int first_init;
    -
    static int uncore_cpu_starting(unsigned int cpu)
    {
    struct intel_uncore_type *type, **types = uncore_msr_uncores;
    struct intel_uncore_pmu *pmu;
    struct intel_uncore_box *box;
    - int i, pkg, ncpus = 1;
    -
    - if (first_init) {
    - /*
    - * On init we get the number of online cpus in the package
    - * and set refcount for all of them.
    - */
    - ncpus = cpumask_weight(topology_core_cpumask(cpu));
    - }
    + int i, pkg;

    pkg = topology_logical_package_id(cpu);
    for (; *types; types++) {
    @@ -1104,7 +1070,7 @@ static int uncore_cpu_starting(unsigned
    if (!box)
    continue;
    /* The first cpu on a package activates the box */
    - if (atomic_add_return(ncpus, &box->refcnt) == ncpus)
    + if (atomic_inc_return(&box->refcnt) == 1)
    uncore_box_init(box);
    }
    }
    @@ -1408,19 +1374,17 @@ static int __init intel_uncore_init(void
    "perf/x86/intel/uncore:prepare",
    uncore_cpu_prepare, NULL);
    }
    - first_init = 1;
    +
    cpuhp_setup_state(CPUHP_AP_PERF_X86_UNCORE_STARTING,
    "perf/x86/uncore:starting",
    uncore_cpu_starting, uncore_cpu_dying);
    - first_init = 0;
    +
    cpuhp_setup_state(CPUHP_AP_PERF_X86_UNCORE_ONLINE,
    "perf/x86/uncore:online",
    uncore_event_cpu_online, uncore_event_cpu_offline);
    return 0;

    err:
    - /* Undo box->init_box() */
    - on_each_cpu_mask(&uncore_cpu_mask, uncore_exit_boxes, NULL, 1);
    uncore_types_exit(uncore_msr_uncores);
    uncore_pci_exit();
    return ret;

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