From: David Gow davidgow@google.com
[ Upstream commit 25bbe844ef5c4fb4d7d8dcaa0080f922b7cd3a16 ]
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: David Gow davidgow@google.com Acked-by: Christian König christian.koenig@amd.com Reviewed-by: Maíra Canal mcanal@igalia.com Reviewed-by: Arunpravin Paneer Selvam arunpravin.paneerselvam@amd.com Link: https://patchwork.freedesktop.org/patch/msgid/20230329065532.2122295-2-david... Signed-off-by: Christian König christian.koenig@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/tests/drm_buddy_test.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c b/drivers/gpu/drm/tests/drm_buddy_test.c index f8ee714df3967..09ee6f6af896b 100644 --- a/drivers/gpu/drm/tests/drm_buddy_test.c +++ b/drivers/gpu/drm/tests/drm_buddy_test.c @@ -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; }