memory-hotplug: fix store_mem_state() return value

If store_mem_state() is called to online memory which is already online,
it will return 1, the value it got from device_online().

This is wrong because store_mem_state() is a device_attribute .store
function.  Thus a non-negative return value represents input bytes read.

Set the return value to -EINVAL in this case.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Reza Arbab <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Vitaly Kuznetsov <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Yaowei Bai <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Xishi Qiu <[email protected]>
Cc: David Vrabel <[email protected]>
Cc: Chen Yucong <[email protected]>
Cc: Andrew Banman <[email protected]>
Cc: Seth Jennings <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

drivers/base/memory.c

@@ -361,8 +361,11 @@ store_mem_state(struct device *dev,
 err:
 	unlock_device_hotplug();
 
-	if (ret)
+	if (ret < 0)
 		return ret;
+	if (ret)
+		return -EINVAL;
+
 	return count;
 }