hotplug, powerpc, x86: Remove cpu_hotplug_driver_lock()

cpu_hotplug_driver_lock() serializes CPU online/offline operations
when ARCH_CPU_PROBE_RELEASE is set.  This lock interface is no longer
necessary with the following reason:

 - lock_device_hotplug() now protects CPU online/offline operations,
   including the probe & release interfaces enabled by
   ARCH_CPU_PROBE_RELEASE.  The use of cpu_hotplug_driver_lock() is
   redundant.
 - cpu_hotplug_driver_lock() is only valid when ARCH_CPU_PROBE_RELEASE
   is defined, which is misleading and is only enabled on powerpc.

This patch removes the cpu_hotplug_driver_lock() interface.  As
a result, ARCH_CPU_PROBE_RELEASE only enables / disables the cpu
probe & release interface as intended.  There is no functional change
in this patch.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 3 insertions, 12 deletions

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 51f5d7fe2f0b..f48370dfc908 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -44,13 +44,11 @@ static int __ref cpu_subsys_online(struct device *dev)
         struct cpu *cpu = container_of(dev, struct cpu, dev);
         int cpuid = dev->id;
         int from_nid, to_nid;
-        int ret = -ENODEV;
-
-        cpu_hotplug_driver_lock();
+        int ret;
 
         from_nid = cpu_to_node(cpuid);
         if (from_nid == NUMA_NO_NODE)
-                goto out;
+                return -ENODEV;
 
         ret = cpu_up(cpuid);
         /*
@@ -61,19 +59,12 @@ static int __ref cpu_subsys_online(struct device *dev)
         if (from_nid != to_nid)
                 change_cpu_under_node(cpu, from_nid, to_nid);
 
- out:
-        cpu_hotplug_driver_unlock();
         return ret;
 }
 
 static int cpu_subsys_offline(struct device *dev)
 {
-        int ret;
-
-        cpu_hotplug_driver_lock();
-        ret = cpu_down(dev->id);
-        cpu_hotplug_driver_unlock();
-        return ret;
+        return cpu_down(dev->id);
 }
 
 void unregister_cpu(struct cpu *cpu)