lib: add module support to atomic64 tests

Allow to compile the atomic64 test code either to a loadable module, or
builtin into the kernel.

Link: http://lkml.kernel.org/r/1483470276-10517-3-git-send-email-geert@linux-m68k.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/Kconfig.debug

@@ -1790,9 +1790,10 @@ config PERCPU_TEST
 	  If unsure, say N.
 
 config ATOMIC64_SELFTEST
-	bool "Perform an atomic64_t self-test at boot"
+	tristate "Perform an atomic64_t self-test"
 	help
-	  Enable this option to test the atomic64_t functions at boot.
+	  Enable this option to test the atomic64_t functions at boot or
+	  at module load time.
 
 	  If unsure, say N.
 

lib/atomic64_test.c

@@ -15,6 +15,7 @@
 #include <linux/bug.h>
 #include <linux/kernel.h>
 #include <linux/atomic.h>
+#include <linux/module.h>
 
 #ifdef CONFIG_X86
 #include <asm/cpufeature.h>	/* for boot_cpu_has below */
@@ -241,7 +242,7 @@ static __init void test_atomic64(void)
 	BUG_ON(v.counter != r);
 }
 
-static __init int test_atomics(void)
+static __init int test_atomics_init(void)
 {
 	test_atomic();
 	test_atomic64();
@@ -264,4 +265,9 @@ static __init int test_atomics(void)
 	return 0;
 }
 
-core_initcall(test_atomics);
+static __exit void test_atomics_exit(void) {}
+
+module_init(test_atomics_init);
+module_exit(test_atomics_exit);
+
+MODULE_LICENSE("GPL");