Commit 25bbe844 authored by David Gow's avatar David Gow Committed by Christian König
Browse files

drm: test: Fix 32-bit issue in drm_buddy_test 



The drm_buddy_test KUnit tests verify that returned blocks have sizes
which are powers of two using is_power_of_2(). However, is_power_of_2()
operations on a 'long', but the block size is a u64. So on systems where
long is 32-bit, this can sometimes fail even on correctly sized blocks.

This only reproduces randomly, as the parameters passed to the buddy
allocator in this test are random. The seed 0xb2e06022 reproduced it
fine here.

For now, just hardcode an is_power_of_2() implementation using
x & (x - 1).

Signed-off-by: default avatarDavid Gow <davidgow@google.com>
Acked-by: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarMaíra Canal <mcanal@igalia.com>
Reviewed-by: default avatarArunpravin Paneer Selvam <arunpravin.paneerselvam@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230329065532.2122295-2-davidgow@google.com


Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
parent 4453545b

drivers/gpu/drm/tests/drm_buddy_test.c

+2 −1
Original line number Diff line number Diff line
@@ -89,7 +89,8 @@ static int check_block(struct kunit *test, struct drm_buddy *mm, 
		err = -EINVAL;

	}



	if (!is_power_of_2(block_size)) {

	/* We can't use is_power_of_2() for a u64 on 32-bit systems. */

	if (block_size & (block_size - 1)) {

		kunit_err(test, "block size not power of two\n");

		err = -EINVAL;

	}