xtensa/perf: Convert the hotplug notifier to state machine callbacks

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: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-xtensa@linux-xtensa.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153334.852575891@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 10 insertions, 17 deletions

diff --git a/arch/xtensa/kernel/perf_event.c b/arch/xtensa/kernel/perf_event.c
index ef90479e0397..0fecc8a2c0b5 100644
--- a/arch/xtensa/kernel/perf_event.c
+++ b/arch/xtensa/kernel/perf_event.c
@@ -404,7 +404,7 @@ static struct pmu xtensa_pmu = {
         .read = xtensa_pmu_read,
 };
 
-static void xtensa_pmu_setup(void)
+static int xtensa_pmu_setup(int cpu)
 {
         unsigned i;
 
@@ -413,21 +413,7 @@ static void xtensa_pmu_setup(void)
                 set_er(0, XTENSA_PMU_PMCTRL(i));
                 set_er(get_er(XTENSA_PMU_PMSTAT(i)), XTENSA_PMU_PMSTAT(i));
         }
-}
-
-static int xtensa_pmu_notifier(struct notifier_block *self,
-                               unsigned long action, void *data)
-{
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_STARTING:
-                xtensa_pmu_setup();
-                break;
-
-        default:
-                break;
-        }
-
-        return NOTIFY_OK;
+        return 0;
 }
 
 static int __init xtensa_pmu_init(void)
@@ -435,7 +421,13 @@ static int __init xtensa_pmu_init(void)
         int ret;
         int irq = irq_create_mapping(NULL, XCHAL_PROFILING_INTERRUPT);
 
-        perf_cpu_notifier(xtensa_pmu_notifier);
+        ret = cpuhp_setup_state(CPUHP_AP_PERF_XTENSA_STARTING,
+                                "AP_PERF_XTENSA_STARTING", xtensa_pmu_setup,
+                                NULL);
+        if (ret) {
+                pr_err("xtensa_pmu: failed to register CPU-hotplug.\n");
+                return ret;
+        }
 #if XTENSA_FAKE_NMI
         enable_irq(irq);
 #else
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 2ee3c0edcc2d..f187c46eb7a1 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -30,6 +30,7 @@ enum cpuhp_state {
         CPUHP_AP_PERF_X86_AMD_IBS_STARTING,
         CPUHP_AP_PERF_X86_CQM_STARTING,
         CPUHP_AP_PERF_X86_CSTATE_STARTING,
+        CPUHP_AP_PERF_XTENSA_STARTING,
         CPUHP_AP_NOTIFY_STARTING,
         CPUHP_AP_ONLINE,
         CPUHP_TEARDOWN_CPU,