From: Richard Cochran <rcoch...@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 <rcoch...@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <a...@kernel.org>
Cc: James Hogan <james.ho...@imgtec.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: linux-me...@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-ma...@linutronix.de>
---
 arch/metag/kernel/perf/perf_event.c | 26 +++++++-------------------
 include/linux/cpuhotplug.h          |  1 +
 2 files changed, 8 insertions(+), 19 deletions(-)

diff --git a/arch/metag/kernel/perf/perf_event.c 
b/arch/metag/kernel/perf/perf_event.c
index 33a365f..052cba2 100644
--- a/arch/metag/kernel/perf/perf_event.c
+++ b/arch/metag/kernel/perf/perf_event.c
@@ -806,25 +806,16 @@ static struct metag_pmu _metag_pmu = {
 };
 
 /* PMU CPU hotplug notifier */
-static int metag_pmu_cpu_notify(struct notifier_block *b, unsigned long action,
-                               void *hcpu)
+static int metag_pmu_starting_cpu(unsigned int cpu)
 {
-       unsigned int cpu = (unsigned int)hcpu;
        struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
 
-       if ((action & ~CPU_TASKS_FROZEN) != CPU_STARTING)
-               return NOTIFY_DONE;
-
        memset(cpuc, 0, sizeof(struct cpu_hw_events));
        raw_spin_lock_init(&cpuc->pmu_lock);
 
-       return NOTIFY_OK;
+       return 0;
 }
 
-static struct notifier_block metag_pmu_notifier = {
-       .notifier_call = metag_pmu_cpu_notify,
-};
-
 /* PMU Initialisation */
 static int __init init_hw_perf_events(void)
 {
@@ -876,16 +867,13 @@ static int __init init_hw_perf_events(void)
        metag_out32(0, PERF_COUNT(0));
        metag_out32(0, PERF_COUNT(1));
 
-       for_each_possible_cpu(cpu) {
-               struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
+       cpuhp_setup_state(CPUHP_AP_PERF_METAG_STARTING,
+                         "AP_PERF_METAG_STARTING", metag_pmu_starting_cpu,
+                         NULL);
 
-               memset(cpuc, 0, sizeof(struct cpu_hw_events));
-               raw_spin_lock_init(&cpuc->pmu_lock);
-       }
-
-       register_cpu_notifier(&metag_pmu_notifier);
        ret = perf_pmu_register(&pmu, metag_pmu->name, PERF_TYPE_RAW);
-out:
+       if (ret)
+               cpuhp_remove_state_nocalls(CPUHP_AP_PERF_METAG_STARTING);
        return ret;
 }
 early_initcall(init_hw_perf_events);
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 0a36e61..5c66102 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -35,6 +35,7 @@ enum cpuhp_state {
        CPUHP_AP_PERF_X86_CQM_STARTING,
        CPUHP_AP_PERF_X86_CSTATE_STARTING,
        CPUHP_AP_PERF_XTENSA_STARTING,
+       CPUHP_AP_PERF_METAG_STARTING,
        CPUHP_AP_ARM_VFP_STARTING,
        CPUHP_AP_PERF_ARM_STARTING,
        CPUHP_AP_ARM_ARCH_TIMER_STARTING,
-- 
2.8.1



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