ida: Start new test_ida module

Start transitioning the IDA tests into kernel space.  Framework heavily
cribbed from test_xarray.c.

Signed-off-by: Matthew Wilcox <willy@infradead.org>

lib/test_ida.c

@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * test_ida.c: Test the IDA API
+ * Copyright (c) 2016-2018 Microsoft Corporation
+ * Copyright (c) 2018 Oracle Corporation
+ * Author: Matthew Wilcox <willy@infradead.org>
+ */
+
+#include <linux/idr.h>
+#include <linux/module.h>
+
+static unsigned int tests_run;
+static unsigned int tests_passed;
+
+#ifdef __KERNEL__
+void ida_dump(struct ida *ida) { }
+#endif
+#define IDA_BUG_ON(ida, x) do {						\
+	tests_run++;							\
+	if (x) {							\
+		ida_dump(ida);						\
+		dump_stack();						\
+	} else {							\
+		tests_passed++;						\
+	}								\
+} while (0)
+
+static int ida_checks(void)
+{
+	DEFINE_IDA(ida);
+
+	IDA_BUG_ON(&ida, !ida_is_empty(&ida));
+
+	printk("IDA: %u of %u tests passed\n", tests_passed, tests_run);
+	return (tests_run != tests_passed) ? 0 : -EINVAL;
+}
+
+static void ida_exit(void)
+{
+}
+
+module_init(ida_checks);
+module_exit(ida_exit);
+MODULE_AUTHOR("Matthew Wilcox <willy@infradead.org>");
+MODULE_LICENSE("GPL");