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Subject[patch V2 20/67] s390/perf: Convert the hotplug notifier to state machine callbacks (Sampling)
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

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>
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-kernel@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
arch/s390/kernel/perf_cpum_sf.c | 45 +++++++++++++++++------------------------
include/linux/cpuhotplug.h | 1 +
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 a8e8321..f4a4c11 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 d4e09cb..fea6666 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,
--
2.8.1


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