From 4218f6383cb4a6106caeee3983c1cec62a1d13fe Mon Sep 17 00:00:00 2001 From: David Gow Date: Wed, 29 Mar 2023 14:55:34 +0800 Subject: [PATCH] drm: test: Fix 32-bit issue in drm_buddy_test MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ 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 Acked-by: Christian König Reviewed-by: Maíra Canal Reviewed-by: Arunpravin Paneer Selvam Link: https://patchwork.freedesktop.org/patch/msgid/20230329065532.2122295-2-davidgow@google.com Signed-off-by: Christian König Signed-off-by: Sasha Levin --- 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 f8ee714df396..09ee6f6af896 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; }