From: Vitaly Kuznetsov <vkuznets@redhat.com>

Well require to call add_memory()/add_memory_resource() with
device_hotplug_lock held, to avoid a lock inversion. Allow external modules
(e.g. hv_balloon) that make use of add_memory()/add_memory_resource() to
lock device hotplug.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
[modify patch description]
Signed-off-by: David Hildenbrand <redacted>
---
 drivers/base/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 04bbcd779e11..9010b9e942b5 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c

@@ -700,11 +700,13 @@ void lock_device_hotplug(void)
 {
 	mutex_lock(&device_hotplug_lock);
 }
+EXPORT_SYMBOL_GPL(lock_device_hotplug);
 
 void unlock_device_hotplug(void)
 {
 	mutex_unlock(&device_hotplug_lock);
 }
+EXPORT_SYMBOL_GPL(unlock_device_hotplug);
 
 int lock_device_hotplug_sysfs(void)
 {

-- 
2.17.1