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

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Message-ID: <42db9f05-11cc-453b-8259-39cee70f137d@redhat.com>
Date: Thu, 17 Jul 2025 16:49:19 +0200
From: David Hildenbrand <david@...hat.com>
To: wang lian <lianux.mm@...il.com>, akpm@...ux-foundation.org,
 broonie@...nel.org, lorenzo.stoakes@...cle.com, sj@...nel.org,
 ziy@...dia.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: brauner@...nel.org, gkwang@...x-info.com, jannh@...gle.com,
 Liam.Howlett@...cle.com, ludovico.zy.wu@...il.com, p1ucky0923@...il.com,
 richard.weiyang@...il.com, ryncsn@...il.com, shuah@...nel.org,
 vbabka@...e.cz, zijing.zhang@...ton.me
Subject: Re: [PATCH 1/2] selftests/mm: reuse FORCE_READ to replace "asm
 volatile("" : "+r" (XXX));"

On 17.07.25 15:18, 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@redhat.com/
> 
> Signed-off-by: wang lian <lianux.mm@...il.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> ---

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb