blackhole_dev: add a selftest

Since this is not really a device with all capabilities, this test
ensures that it has *enough* to make it through the data path
without causing unwanted side-effects (read crash!).

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/lib/Makefile b/lib/Makefile
index dcb558c..6ac44fe 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -91,6 +91,7 @@
 obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o
 obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o
 obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o
+obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o
 
 obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/