powerpc/msi: Fix the msi bitmap alignment tests

When we added the alignment tests recently we failed to check they were
actually passing - oops.

They weren't passing, because the bitmap was full. We should also be a
bit more careful when checking the return code, a negative error return
could by divisible by our alignment value.

Fixes: b0345bbc ("powerpc/msi: Improve IRQ bitmap allocator")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/sysdev/msi_bitmap.c

@@ -151,7 +151,7 @@ void msi_bitmap_free(struct msi_bitmap *bmp)
 static void __init test_basics(void)
 {
 	struct msi_bitmap bmp;
-	int i, size = 512;
+	int rc, i, size = 512;
 
 	/* Can't allocate a bitmap of 0 irqs */
 	check(msi_bitmap_alloc(&bmp, 0, NULL) != 0);
@@ -185,14 +185,24 @@ static void __init test_basics(void)
 	msi_bitmap_free_hwirqs(&bmp, size / 2, 1);
 	check(msi_bitmap_alloc_hwirqs(&bmp, 1) == size / 2);
 
+	/* Free most of them for the alignment tests */
+	msi_bitmap_free_hwirqs(&bmp, 3, size - 3);
+
 	/* Check we get a naturally aligned offset */
-	check(msi_bitmap_alloc_hwirqs(&bmp, 2) % 2 == 0);
-	check(msi_bitmap_alloc_hwirqs(&bmp, 4) % 4 == 0);
-	check(msi_bitmap_alloc_hwirqs(&bmp, 8) % 8 == 0);
-	check(msi_bitmap_alloc_hwirqs(&bmp, 9) % 16 == 0);
-	check(msi_bitmap_alloc_hwirqs(&bmp, 3) % 4 == 0);
-	check(msi_bitmap_alloc_hwirqs(&bmp, 7) % 8 == 0);
-	check(msi_bitmap_alloc_hwirqs(&bmp, 121) % 128 == 0);
+	rc = msi_bitmap_alloc_hwirqs(&bmp, 2);
+	check(rc >= 0 && rc % 2 == 0);
+	rc = msi_bitmap_alloc_hwirqs(&bmp, 4);
+	check(rc >= 0 && rc % 4 == 0);
+	rc = msi_bitmap_alloc_hwirqs(&bmp, 8);
+	check(rc >= 0 && rc % 8 == 0);
+	rc = msi_bitmap_alloc_hwirqs(&bmp, 9);
+	check(rc >= 0 && rc % 16 == 0);
+	rc = msi_bitmap_alloc_hwirqs(&bmp, 3);
+	check(rc >= 0 && rc % 4 == 0);
+	rc = msi_bitmap_alloc_hwirqs(&bmp, 7);
+	check(rc >= 0 && rc % 8 == 0);
+	rc = msi_bitmap_alloc_hwirqs(&bmp, 121);
+	check(rc >= 0 && rc % 128 == 0);
 
 	msi_bitmap_free(&bmp);