drivers base/topology: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs. No functional change

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161103145021.28528-14-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 6 insertions, 37 deletions

diff --git a/drivers/base/topology.c b/drivers/base/topology.c
index df3c97cb4c99..d6ec1c546f5b 100644
--- a/drivers/base/topology.c
+++ b/drivers/base/topology.c
@@ -118,51 +118,19 @@ static int topology_add_dev(unsigned int cpu)
         return sysfs_create_group(&dev->kobj, &topology_attr_group);
 }
 
-static void topology_remove_dev(unsigned int cpu)
+static int topology_remove_dev(unsigned int cpu)
 {
         struct device *dev = get_cpu_device(cpu);
 
         sysfs_remove_group(&dev->kobj, &topology_attr_group);
-}
-
-static int topology_cpu_callback(struct notifier_block *nfb,
-                                 unsigned long action, void *hcpu)
-{
-        unsigned int cpu = (unsigned long)hcpu;
-        int rc = 0;
-
-        switch (action) {
-        case CPU_UP_PREPARE:
-        case CPU_UP_PREPARE_FROZEN:
-                rc = topology_add_dev(cpu);
-                break;
-        case CPU_UP_CANCELED:
-        case CPU_UP_CANCELED_FROZEN:
-        case CPU_DEAD:
-        case CPU_DEAD_FROZEN:
-                topology_remove_dev(cpu);
-                break;
-        }
-        return notifier_from_errno(rc);
+        return 0;
 }
 
 static int topology_sysfs_init(void)
 {
-        int cpu;
-        int rc = 0;
-
-        cpu_notifier_register_begin();
-
-        for_each_online_cpu(cpu) {
-                rc = topology_add_dev(cpu);
-                if (rc)
-                        goto out;
-        }
-        __hotcpu_notifier(topology_cpu_callback, 0);
-
-out:
-        cpu_notifier_register_done();
-        return rc;
+        return cpuhp_setup_state(CPUHP_TOPOLOGY_PREPARE,
+                                 "base/topology:prepare", topology_add_dev,
+                                 topology_remove_dev);
 }
 
 device_initcall(topology_sysfs_init);
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 86b940f19df8..3410d83cc2e2 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -57,6 +57,7 @@ enum cpuhp_state {
         CPUHP_SH_SH3X_PREPARE,
         CPUHP_BLK_MQ_PREPARE,
         CPUHP_NET_FLOW_PREPARE,
+        CPUHP_TOPOLOGY_PREPARE,
         CPUHP_TIMERS_DEAD,
         CPUHP_NOTF_ERR_INJ_PREPARE,
         CPUHP_MIPS_SOC_PREPARE,