hotplug / x86: Add hotplug lock to missing places

lock_device_hotplug[_sysfs]() serializes CPU & Memory online/offline
and hotplug operations.  However, this lock is not held in the debug
interfaces below that initiate CPU online/offline operations.

 - _debug_hotplug_cpu(), cpu0 hotplug test interface enabled by
   CONFIG_DEBUG_HOTPLUG_CPU0.
 - cpu_probe_store() and cpu_release_store(), cpu hotplug test interface
   enabled by CONFIG_ARCH_CPU_PROBE_RELEASE.

This patch changes the above interfaces to hold lock_device_hotplug().

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
index 5823bbd668f4..a3f35ebb3b52 100644
--- a/arch/x86/kernel/topology.c
+++ b/arch/x86/kernel/topology.c
@@ -65,6 +65,7 @@ int __ref _debug_hotplug_cpu(int cpu, int action)
         if (!cpu_is_hotpluggable(cpu))
                 return -EINVAL;
 
+        lock_device_hotplug();
         cpu_hotplug_driver_lock();
 
         switch (action) {
@@ -91,6 +92,7 @@ int __ref _debug_hotplug_cpu(int cpu, int action)
         }
 
         cpu_hotplug_driver_unlock();
+        unlock_device_hotplug();
 
         return ret;
 }