cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()

Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights the
refcount semantics in these operations.

The new API guarantees protection against the cpu-hotplug operation, but
it doesn't guarantee serialized access to any of the local data
structures. Hence the changes needs to be reviewed.

In case of pseries_add_processor/pseries_remove_processor, use
cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the
cpu_present_map there.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/s390/char/sclp_config.c b/drivers/s390/char/sclp_config.c
index 5322e5e54a98..9dc77f14fa52 100644
--- a/drivers/s390/char/sclp_config.c
+++ b/drivers/s390/char/sclp_config.c
@@ -29,12 +29,12 @@ static void sclp_cpu_capability_notify(struct work_struct *work)
         struct sys_device *sysdev;
 
         printk(KERN_WARNING TAG "cpu capability changed.\n");
-        lock_cpu_hotplug();
+        get_online_cpus();
         for_each_online_cpu(cpu) {
                 sysdev = get_cpu_sysdev(cpu);
                 kobject_uevent(&sysdev->kobj, KOBJ_CHANGE);
         }
-        unlock_cpu_hotplug();
+        put_online_cpus();
 }
 
 static void sclp_conf_receiver_fn(struct evbuf_header *evbuf)