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

[Andrew Morton]

On Wed, 16 Jul 2025 20:31:26 +0800 wang lian <lianux.mm@xxxxxxxxx> 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
> 
>  tools/testing/selftests/mm/cow.c              | 30 +++++++++----------
>  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 +--
>  5 files changed, 24 insertions(+), 32 deletions(-)

The patch forgot to move the FORCE_READ definition into a header?