lib/test_bitmap.c: add optimisation tests

Patch series "Bitmap optimisations", v2.

These three bitmap patches use more efficient specialisations when the
compiler can figure out that it's safe to do so.  Thanks to Rasmus's
eagle eyes, a nasty bug in v1 was avoided, and I've added a test case
which would have caught it.

This patch (of 4):

This version of the test is actually a no-op; the next patch will enable
it.

Link: http://lkml.kernel.org/r/20170628153221.11322-2-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

lib/test_bitmap.c

@@ -333,10 +333,42 @@ static void __init test_bitmap_u32_array_conversions(void)
 	}
 }
 
+#define __bitmap_set(a, b, c)	bitmap_set(a, b, c)
+#define __bitmap_clear(a, b, c)	bitmap_clear(a, b, c)
+
+static void noinline __init test_mem_optimisations(void)
+{
+	DECLARE_BITMAP(bmap1, 1024);
+	DECLARE_BITMAP(bmap2, 1024);
+	unsigned int start, nbits;
+
+	for (start = 0; start < 1024; start += 8) {
+		memset(bmap1, 0x5a, sizeof(bmap1));
+		memset(bmap2, 0x5a, sizeof(bmap2));
+		for (nbits = 0; nbits < 1024 - start; nbits += 8) {
+			bitmap_set(bmap1, start, nbits);
+			__bitmap_set(bmap2, start, nbits);
+			if (!bitmap_equal(bmap1, bmap2, 1024))
+				printk("set not equal %d %d\n", start, nbits);
+			if (!__bitmap_equal(bmap1, bmap2, 1024))
+				printk("set not __equal %d %d\n", start, nbits);
+
+			bitmap_clear(bmap1, start, nbits);
+			__bitmap_clear(bmap2, start, nbits);
+			if (!bitmap_equal(bmap1, bmap2, 1024))
+				printk("clear not equal %d %d\n", start, nbits);
+			if (!__bitmap_equal(bmap1, bmap2, 1024))
+				printk("clear not __equal %d %d\n", start,
+									nbits);
+		}
+	}
+}
+
 static int __init test_bitmap_init(void)
 {
 	test_zero_fill_copy();
 	test_bitmap_u32_array_conversions();
+	test_mem_optimisations();
 
 	if (failed_tests == 0)
 		pr_info("all %u tests passed\n", total_tests);