Drivers: hv: vmbus: incorrect device name is printed when child device is unregistered

commit 84672369 upstream.

Whenever a device is unregistered in vmbus_device_unregister (drivers/hv/vmbus_drv.c), the device name in the log message may contain garbage as the memory has already been freed by the time pr_info is called. Log example:
 [ 3149.170475] hv_vmbus: child device àõsèè0_5 unregistered

By logging the message just before calling device_unregister, the correct device name is printed:
[ 3145.034652] hv_vmbus: child device vmbus_0_5 unregistered

Also changing register & unregister messages to debug to avoid unnecessarily cluttering the kernel log.
Signed-off-by: Fernando M Soto <fsoto@bluecatnetworks.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joseph Salisbury <joseph.salisbury@canonical.com>
Signed-off-by: Zefan Li <lizefan@huawei.com>

drivers/hv/vmbus_drv.c

@@ -681,7 +681,7 @@ int vmbus_device_register(struct hv_device *child_device_obj)
 	if (ret)
 		pr_err("Unable to register child device\n");
 	else
-		pr_info("child device %s registered\n",
+		pr_debug("child device %s registered\n",
 			dev_name(&child_device_obj->device));
 
 	return ret;
@@ -693,14 +693,14 @@ int vmbus_device_register(struct hv_device *child_device_obj)
  */
 void vmbus_device_unregister(struct hv_device *device_obj)
 {
+	pr_debug("child device %s unregistered\n",
+		dev_name(&device_obj->device));
+
 	/*
 	 * Kick off the process of unregistering the device.
 	 * This will call vmbus_remove() and eventually vmbus_device_release()
 	 */
 	device_unregister(&device_obj->device);
-
-	pr_info("child device %s unregistered\n",
-		dev_name(&device_obj->device));
 }