linux-kernel - Re: [PATCH v3 4/7] x86: switch atomic.h to use atomic-instrumented.h

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Date:   Fri, 16 Jun 2017 18:54:03 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Dmitry Vyukov <dvyukov@...gle.com>, mark.rutland@....com,
        peterz@...radead.org, mingo@...hat.com, will.deacon@....com,
        hpa@...or.com
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH v3 4/7] x86: switch atomic.h to use atomic-instrumented.h

On 06/06/2017 01:11 PM, Dmitry Vyukov wrote:
> Add arch_ prefix to all atomic operations and include
> <asm-generic/atomic-instrumented.h>. This will allow
> to add KASAN instrumentation to all atomic ops.
> 
> Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Will Deacon <will.deacon@....com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: kasan-dev@...glegroups.com
> Cc: linux-mm@...ck.org
> Cc: linux-kernel@...r.kernel.org
> Cc: x86@...nel.org
> 
> ---




> -static __always_inline void atomic_set(atomic_t *v, int i)
> +static __always_inline void arch_atomic_set(atomic_t *v, int i)
>  {
> +	/*
> +	 * We could use WRITE_ONCE_NOCHECK() if it exists, similar to
> +	 * READ_ONCE_NOCHECK() in arch_atomic_read(). But there is no such
> +	 * thing at the moment, and introducing it for this case does not
> +	 * worth it.
> +	 */


I'd rather remove this comment. I woudn't say that WRITE_ONCE() here looks confusing
and needs comment. Also there is no READ_ONCE_NOCHECK() in arch_atomic_read() anymore.

Otherwise,
	Reviewed-by: Andrey Ryabinin <aryabinin@...tuozzo.com>

>  	WRITE_ONCE(v->counter, i);
>  }
>