linux-kernel - Re: [PATCH] x86: remove unused atomic_inc

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Date:   Wed, 22 Mar 2017 19:13:31 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Dmitry Vyukov <dvyukov@...gle.com>, <x86@...nel.org>,
        <akpm@...ux-foundation.org>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        <linux-kernel@...r.kernel.org>, Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH] x86: remove unused atomic_inc_short()



On 03/22/2017 05:10 PM, Dmitry Vyukov wrote:
> It is completely unused and implemented only on x86.
> Remove it.
> 
> Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
> Suggested-by: Andrey Ryabinin <aryabinin@...tuozzo.com>

Not me, it was Mark Rutland <mark.rutland@....com>

> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: linux-kernel@...r.kernel.org
> Cc: x86@...nel.org
> 
> ---
> 
> Andrew, I think it needs to go into mm as
> the atomic-instrumented.h patch is in mm.
> ---
>  arch/tile/lib/atomic_asm_32.S             |  3 +--
>  arch/x86/include/asm/atomic.h             | 13 -------------
>  include/asm-generic/atomic-instrumented.h |  6 ------
>  3 files changed, 1 insertion(+), 21 deletions(-)
> 
> diff --git a/arch/tile/lib/atomic_asm_32.S b/arch/tile/lib/atomic_asm_32.S
> index 1a70e6c0f259..94709ab41ed8 100644
> --- a/arch/tile/lib/atomic_asm_32.S
> +++ b/arch/tile/lib/atomic_asm_32.S
> @@ -24,8 +24,7 @@
>   * has an opportunity to return -EFAULT to the user if needed.
>   * The 64-bit routines just return a "long long" with the value,
>   * since they are only used from kernel space and don't expect to fault.
> - * Support for 16-bit ops is included in the framework but we don't provide
> - * any (x86_64 has an atomic_inc_short(), so we might want to some day).
> + * Support for 16-bit ops is included in the framework but we don't provide any.
>   *
>   * Note that the caller is advised to issue a suitable L1 or L2
>   * prefetch on the address being manipulated to avoid extra stalls.
> diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
> index 0cde164f058a..9ff8738103eb 100644
> --- a/arch/x86/include/asm/atomic.h
> +++ b/arch/x86/include/asm/atomic.h
> @@ -237,19 +237,6 @@ ATOMIC_OPS(xor, ^)
>  
>  int __arch_atomic_add_unless(atomic_t *v, int a, int u);
>  
> -/**
> - * arch_atomic_inc_short - increment of a short integer
> - * @v: pointer to type int
> - *
> - * Atomically adds 1 to @v
> - * Returns the new value of @u
> - */
> -static __always_inline short int arch_atomic_inc_short(short int *v)
> -{
> -	asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
> -	return *v;
> -}
> -
>  #ifdef CONFIG_X86_32
>  # include <asm/atomic64_32.h>
>  #else
> diff --git a/include/asm-generic/atomic-instrumented.h b/include/asm-generic/atomic-instrumented.h
> index 951bcd083925..70742da13087 100644
> --- a/include/asm-generic/atomic-instrumented.h
> +++ b/include/asm-generic/atomic-instrumented.h
> @@ -78,12 +78,6 @@ static __always_inline bool atomic64_add_unless(atomic64_t *v, long long a,
>  	return arch_atomic64_add_unless(v, a, u);
>  }
>  
> -static __always_inline short int atomic_inc_short(short int *v)
> -{
> -	kasan_check_write(v, sizeof(*v));
> -	return arch_atomic_inc_short(v);
> -}
> -
>  #define __INSTR_VOID1(op, sz)						\
>  static __always_inline void atomic##sz##_##op(atomic##sz##_t *v)	\
>  {									\
>