x86/hpet: Convert to hotplug state machine

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: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153335.279718463@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 36 insertions, 35 deletions

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index f112af7aa62e..3d747070fe67 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -710,31 +710,29 @@ static void hpet_work(struct work_struct *w)
         complete(&hpet_work->complete);
 }
 
-static int hpet_cpuhp_notify(struct notifier_block *n,
-                unsigned long action, void *hcpu)
+static int hpet_cpuhp_online(unsigned int cpu)
 {
-        unsigned long cpu = (unsigned long)hcpu;
         struct hpet_work_struct work;
+
+        INIT_DELAYED_WORK_ONSTACK(&work.work, hpet_work);
+        init_completion(&work.complete);
+        /* FIXME: add schedule_work_on() */
+        schedule_delayed_work_on(cpu, &work.work, 0);
+        wait_for_completion(&work.complete);
+        destroy_delayed_work_on_stack(&work.work);
+        return 0;
+}
+
+static int hpet_cpuhp_dead(unsigned int cpu)
+{
         struct hpet_dev *hdev = per_cpu(cpu_hpet_dev, cpu);
 
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_ONLINE:
-                INIT_DELAYED_WORK_ONSTACK(&work.work, hpet_work);
-                init_completion(&work.complete);
-                /* FIXME: add schedule_work_on() */
-                schedule_delayed_work_on(cpu, &work.work, 0);
-                wait_for_completion(&work.complete);
-                destroy_delayed_work_on_stack(&work.work);
-                break;
-        case CPU_DEAD:
-                if (hdev) {
-                        free_irq(hdev->irq, hdev);
-                        hdev->flags &= ~HPET_DEV_USED;
-                        per_cpu(cpu_hpet_dev, cpu) = NULL;
-                }
-                break;
-        }
-        return NOTIFY_OK;
+        if (!hdev)
+                return 0;
+        free_irq(hdev->irq, hdev);
+        hdev->flags &= ~HPET_DEV_USED;
+        per_cpu(cpu_hpet_dev, cpu) = NULL;
+        return 0;
 }
 #else
 
@@ -750,11 +748,8 @@ static void hpet_reserve_msi_timers(struct hpet_data *hd)
 }
 #endif
 
-static int hpet_cpuhp_notify(struct notifier_block *n,
-                unsigned long action, void *hcpu)
-{
-        return NOTIFY_OK;
-}
+#define hpet_cpuhp_online       NULL
+#define hpet_cpuhp_dead         NULL
 
 #endif
 
@@ -931,7 +926,7 @@ out_nohpet:
  */
 static __init int hpet_late_init(void)
 {
-        int cpu;
+        int ret;
 
         if (boot_hpet_disable)
                 return -ENODEV;
@@ -961,16 +956,20 @@ static __init int hpet_late_init(void)
         if (boot_cpu_has(X86_FEATURE_ARAT))
                 return 0;
 
-        cpu_notifier_register_begin();
-        for_each_online_cpu(cpu) {
-                hpet_cpuhp_notify(NULL, CPU_ONLINE, (void *)(long)cpu);
-        }
-
         /* This notifier should be called after workqueue is ready */
-        __hotcpu_notifier(hpet_cpuhp_notify, -20);
-        cpu_notifier_register_done();
-
+        ret = cpuhp_setup_state(CPUHP_AP_X86_HPET_ONLINE, "AP_X86_HPET_ONLINE",
+                                hpet_cpuhp_online, NULL);
+        if (ret)
+                return ret;
+        ret = cpuhp_setup_state(CPUHP_X86_HPET_DEAD, "X86_HPET_DEAD", NULL,
+                                hpet_cpuhp_dead);
+        if (ret)
+                goto err_cpuhp;
         return 0;
+
+err_cpuhp:
+        cpuhp_remove_state(CPUHP_AP_X86_HPET_ONLINE);
+        return ret;
 }
 fs_initcall(hpet_late_init);
 
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 60557a9e783d..7449081ff412 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -12,6 +12,7 @@ enum cpuhp_state {
         CPUHP_PERF_BFIN,
         CPUHP_PERF_POWER,
         CPUHP_PERF_SUPERH,
+        CPUHP_X86_HPET_DEAD,
         CPUHP_WORKQUEUE_PREP,
         CPUHP_NOTIFY_PREPARE,
         CPUHP_BRINGUP_CPU,
@@ -54,6 +55,7 @@ enum cpuhp_state {
         CPUHP_AP_NOTIFY_ONLINE,
         CPUHP_AP_ONLINE_DYN,
         CPUHP_AP_ONLINE_DYN_END         = CPUHP_AP_ONLINE_DYN + 30,
+        CPUHP_AP_X86_HPET_ONLINE,
         CPUHP_AP_ACTIVE,
         CPUHP_ONLINE,
 };