Re: [PATCH 1/2] selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));"

[Zi Yan]

On 17 Jul 2025, at 9:18, wang lian wrote:

> Several mm selftests use the `asm volatile("" : "+r" (variable));`
> construct to force a read of a variable, preventing the compiler from
> optimizing away the memory access. This idiom is cryptic and duplicated
> across multiple test files.
>
> Following a suggestion from David[1], this patch refactors this
> common pattern into a FORCE_READ() macro
>
> [1] https://lore.kernel.org/lkml/4a3e0759-caa1-4cfa-bc3f-402593f1eee3@xxxxxxxxxx/
>
> Signed-off-by: wang lian <lianux.mm@xxxxxxxxx>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
> ---
>  tools/testing/selftests/mm/cow.c              | 30 +++++++++----------
>  tools/testing/selftests/mm/guard-regions.c    |  7 -----
>  tools/testing/selftests/mm/hugetlb-madvise.c  |  5 +---
>  tools/testing/selftests/mm/migration.c        | 13 ++++----
>  tools/testing/selftests/mm/pagemap_ioctl.c    |  4 +--
>  .../selftests/mm/split_huge_page_test.c       |  4 +--
>  tools/testing/selftests/mm/vm_util.h          |  7 +++++
>  7 files changed, 31 insertions(+), 39 deletions(-)

Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Best Regards,
Yan, Zi