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    Subject[patch V2 14/67] perf/x86/intel/rapl: Convert to hotplug state machine
    From: Richard Cochran <rcochran@linutronix.de>

    Install the callbacks via the state machine and let the core invoke
    the callbacks on the already online CPUs.

    Signed-off-by: Richard Cochran <rcochran@linutronix.de>
    Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: Huang Rui <ray.huang@amd.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Vince Weaver <vincent.weaver@maine.edu>
    Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
    ---
    arch/x86/events/intel/rapl.c | 84 +++++++++++++-------------------------------
    include/linux/cpuhotplug.h | 2 ++
    2 files changed, 27 insertions(+), 59 deletions(-)

    diff --git a/arch/x86/events/intel/rapl.c b/arch/x86/events/intel/rapl.c
    index e30eef4..6255ede 100644
    --- a/arch/x86/events/intel/rapl.c
    +++ b/arch/x86/events/intel/rapl.c
    @@ -555,14 +555,14 @@ const struct attribute_group *rapl_attr_groups[] = {
    NULL,
    };

    -static void rapl_cpu_exit(int cpu)
    +static int rapl_cpu_offline(unsigned int cpu)
    {
    struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);
    int target;

    /* Check if exiting cpu is used for collecting rapl events */
    if (!cpumask_test_and_clear_cpu(cpu, &rapl_cpu_mask))
    - return;
    + return 0;

    pmu->cpu = -1;
    /* Find a new cpu to collect rapl events */
    @@ -574,9 +574,10 @@ static void rapl_cpu_exit(int cpu)
    pmu->cpu = target;
    perf_pmu_migrate_context(pmu->pmu, cpu, target);
    }
    + return 0;
    }

    -static void rapl_cpu_init(int cpu)
    +static int rapl_cpu_online(unsigned int cpu)
    {
    struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);
    int target;
    @@ -587,13 +588,14 @@ static void rapl_cpu_init(int cpu)
    */
    target = cpumask_any_and(&rapl_cpu_mask, topology_core_cpumask(cpu));
    if (target < nr_cpu_ids)
    - return;
    + return 0;

    cpumask_set_cpu(cpu, &rapl_cpu_mask);
    pmu->cpu = cpu;
    + return 0;
    }

    -static int rapl_cpu_prepare(int cpu)
    +static int rapl_cpu_prepare(unsigned int cpu)
    {
    struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);

    @@ -614,33 +616,6 @@ static int rapl_cpu_prepare(int cpu)
    return 0;
    }

    -static int rapl_cpu_notifier(struct notifier_block *self,
    - unsigned long action, void *hcpu)
    -{
    - unsigned int cpu = (long)hcpu;
    -
    - switch (action & ~CPU_TASKS_FROZEN) {
    - case CPU_UP_PREPARE:
    - rapl_cpu_prepare(cpu);
    - break;
    -
    - case CPU_DOWN_FAILED:
    - case CPU_ONLINE:
    - rapl_cpu_init(cpu);
    - break;
    -
    - case CPU_DOWN_PREPARE:
    - rapl_cpu_exit(cpu);
    - break;
    - }
    - return NOTIFY_OK;
    -}
    -
    -static struct notifier_block rapl_cpu_nb = {
    - .notifier_call = rapl_cpu_notifier,
    - .priority = CPU_PRI_PERF + 1,
    -};
    -
    static int rapl_check_hw_unit(bool apply_quirk)
    {
    u64 msr_rapl_power_unit_bits;
    @@ -691,24 +666,6 @@ static void __init rapl_advertise(void)
    }
    }

    -static int __init rapl_prepare_cpus(void)
    -{
    - unsigned int cpu, pkg;
    - int ret;
    -
    - for_each_online_cpu(cpu) {
    - pkg = topology_logical_package_id(cpu);
    - if (rapl_pmus->pmus[pkg])
    - continue;
    -
    - ret = rapl_cpu_prepare(cpu);
    - if (ret)
    - return ret;
    - rapl_cpu_init(cpu);
    - }
    - return 0;
    -}
    -
    static void cleanup_rapl_pmus(void)
    {
    int i;
    @@ -835,35 +792,44 @@ static int __init rapl_pmu_init(void)
    if (ret)
    return ret;

    - cpu_notifier_register_begin();
    + /*
    + * Install callbacks. Core will call them for each online cpu.
    + */

    - ret = rapl_prepare_cpus();
    + ret = cpuhp_setup_state(CPUHP_PERF_X86_RAPL_PREP, "PERF_X86_RAPL_PREP",
    + rapl_cpu_prepare, NULL);
    if (ret)
    goto out;

    + ret = cpuhp_setup_state(CPUHP_AP_PERF_X86_RAPL_ONLINE,
    + "AP_PERF_X86_RAPL_ONLINE",
    + rapl_cpu_online, rapl_cpu_offline);
    + if (ret)
    + goto out1;
    +
    ret = perf_pmu_register(&rapl_pmus->pmu, "power", -1);
    if (ret)
    - goto out;
    + goto out2;

    - __register_cpu_notifier(&rapl_cpu_nb);
    - cpu_notifier_register_done();
    rapl_advertise();
    return 0;

    +out2:
    + cpuhp_remove_state(CPUHP_AP_PERF_X86_RAPL_ONLINE);
    +out1:
    + cpuhp_remove_state(CPUHP_PERF_X86_RAPL_PREP);
    out:
    pr_warn("Initialization failed (%d), disabled\n", ret);
    cleanup_rapl_pmus();
    - cpu_notifier_register_done();
    return ret;
    }
    module_init(rapl_pmu_init);

    static void __exit intel_rapl_exit(void)
    {
    - cpu_notifier_register_begin();
    - __unregister_cpu_notifier(&rapl_cpu_nb);
    + cpuhp_remove_state_nocalls(CPUHP_AP_PERF_X86_RAPL_ONLINE);
    + cpuhp_remove_state_nocalls(CPUHP_PERF_X86_RAPL_PREP);
    perf_pmu_unregister(&rapl_pmus->pmu);
    cleanup_rapl_pmus();
    - cpu_notifier_register_done();
    }
    module_exit(intel_rapl_exit);
    diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
    index 4672019..06d77fd 100644
    --- a/include/linux/cpuhotplug.h
    +++ b/include/linux/cpuhotplug.h
    @@ -8,6 +8,7 @@ enum cpuhp_state {
    CPUHP_PERF_X86_PREPARE,
    CPUHP_PERF_X86_UNCORE_PREP,
    CPUHP_PERF_X86_AMD_UNCORE_PREP,
    + CPUHP_PERF_X86_RAPL_PREP,
    CPUHP_NOTIFY_PREPARE,
    CPUHP_BRINGUP_CPU,
    CPUHP_AP_IDLE_DEAD,
    @@ -34,6 +35,7 @@ enum cpuhp_state {
    CPUHP_AP_PERF_X86_ONLINE,
    CPUHP_AP_PERF_X86_UNCORE_ONLINE,
    CPUHP_AP_PERF_X86_AMD_UNCORE_ONLINE,
    + CPUHP_AP_PERF_X86_RAPL_ONLINE,
    CPUHP_AP_NOTIFY_ONLINE,
    CPUHP_AP_ONLINE_DYN,
    CPUHP_AP_ONLINE_DYN_END = CPUHP_AP_ONLINE_DYN + 30,
    --
    2.8.1


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