[RFC v5 5/6] powerpc/mobility: Add lock/unlock device hotplug

powerpc/mobility: Add device lock/unlock to PowerPC 'mobility' operation
to delay the operation of CPU DLPAR work queue operations by the 'readd'
activity until after any changes to the corresponding device-tree
properties have been written.

Signed-off-by: Michael Bringmann <redacted>
---
 arch/powerpc/platforms/pseries/mobility.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 8a8033a..6d98f84 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c

@@ -283,6 +283,8 @@ int pseries_devicetree_update(s32 scope)
 	if (!rtas_buf)
 		return -ENOMEM;
 
+	lock_device_hotplug();
+
 	do {
 		rc = mobility_rtas_call(update_nodes_token, rtas_buf, scope);
 		if (rc && rc != 1)

@@ -321,6 +323,7 @@ int pseries_devicetree_update(s32 scope)
 	} while (rc == 1);
 
 	kfree(rtas_buf);
+	unlock_device_hotplug();
 	return rc;
 }