percpu: add test module for various percpu operations

Tests various percpu operations.

Enable with CONFIG_PERCPU_TEST=m.

Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/Makefile b/lib/Makefile
index f3bb2cb..bb016e1 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -157,6 +157,8 @@
 
 interval_tree_test-objs := interval_tree_test_main.o interval_tree.o
 
+obj-$(CONFIG_PERCPU_TEST) += percpu_test.o
+
 obj-$(CONFIG_ASN1) += asn1_decoder.o
 
 obj-$(CONFIG_FONT_SUPPORT) += fonts/