s390/perf: Convert the hotplug notifier to state machine callbacks (Sampling)

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

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-s390@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153334.518084858@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 20 insertions, 26 deletions

diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index a8e832166417..f4a4c118f8b4 100644
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -1506,37 +1506,28 @@ static void cpumf_measurement_alert(struct ext_code ext_code,
                 sf_disable();
         }
 }
-
-static int cpumf_pmu_notifier(struct notifier_block *self,
-                              unsigned long action, void *hcpu)
+static int cpusf_pmu_setup(unsigned int cpu, int flags)
 {
-        int flags;
-
         /* Ignore the notification if no events are scheduled on the PMU.
          * This might be racy...
          */
         if (!atomic_read(&num_events))
-                return NOTIFY_OK;
-
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_ONLINE:
-        case CPU_DOWN_FAILED:
-                flags = PMC_INIT;
-                local_irq_disable();
-                setup_pmc_cpu(&flags);
-                local_irq_enable();
-                break;
-        case CPU_DOWN_PREPARE:
-                flags = PMC_RELEASE;
-                local_irq_disable();
-                setup_pmc_cpu(&flags);
-                local_irq_enable();
-                break;
-        default:
-                break;
-        }
+                return 0;
 
-        return NOTIFY_OK;
+        local_irq_disable();
+        setup_pmc_cpu(&flags);
+        local_irq_enable();
+        return 0;
+}
+
+static int s390_pmu_sf_online_cpu(unsigned int cpu)
+{
+        return cpusf_pmu_setup(cpu, PMC_INIT);
+}
+
+static int s390_pmu_sf_offline_cpu(unsigned int cpu)
+{
+        return cpusf_pmu_setup(cpu, PMC_RELEASE);
 }
 
 static int param_get_sfb_size(char *buffer, const struct kernel_param *kp)
@@ -1636,7 +1627,9 @@ static int __init init_cpum_sampling_pmu(void)
                                         cpumf_measurement_alert);
                 goto out;
         }
-        perf_cpu_notifier(cpumf_pmu_notifier);
+
+        cpuhp_setup_state(CPUHP_AP_PERF_S390_SF_ONLINE, "AP_PERF_S390_SF_ONLINE",
+                          s390_pmu_sf_online_cpu, s390_pmu_sf_offline_cpu);
 out:
         return err;
 }
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index d4e09cb0c100..fea66667d190 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -43,6 +43,7 @@ enum cpuhp_state {
         CPUHP_AP_PERF_X86_CQM_ONLINE,
         CPUHP_AP_PERF_X86_CSTATE_ONLINE,
         CPUHP_AP_PERF_S390_CF_ONLINE,
+        CPUHP_AP_PERF_S390_SF_ONLINE,
         CPUHP_AP_NOTIFY_ONLINE,
         CPUHP_AP_ONLINE_DYN,
         CPUHP_AP_ONLINE_DYN_END         = CPUHP_AP_ONLINE_DYN + 30,