linux-kernel - Re: [PATCH] arm/arm64: remove atomic_clear

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Message-ID: <CAFLxGvwsx2YfNHiGtjWsANfVW74PT3KneLA-T6SpY4NEp_OSUA@mail.gmail.com>
Date:	Fri, 11 Oct 2013 14:08:17 +0200
From:	Richard Weinberger <richard.weinberger@...il.com>
To:	Chen Gang <gang.chen@...anux.com>
Cc:	Will Deacon <will.deacon@....com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"linux390@...ibm.com" <linux390@...ibm.com>,
	"linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm/arm64: remove atomic_clear_mask() in "include/asm/atomic.h"

On Fri, Oct 11, 2013 at 1:47 PM, Chen Gang <gang.chen@...anux.com> wrote:
> In current kernel wide source code, except other architectures, only
> s390 scsi drivers use atomic_clear_mask(), and arm/arm64 need not
> support s390 drivers.
>
> So remove atomic_clear_mask() from "arm[64]/include/asm/atomic.h".

Is it really worth removing such a primitive?
If someone needs it later he has to implement it from scratch and
introduces bugs...

>
> Signed-off-by: Chen Gang <gang.chen@...anux.com>
> ---
>  arch/arm/include/asm/atomic.h   |   24 ------------------------
>  arch/arm64/include/asm/atomic.h |   14 --------------
>  2 files changed, 0 insertions(+), 38 deletions(-)
>
> diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
> index da1c77d..3b3ae49fa 100644
> --- a/arch/arm/include/asm/atomic.h
> +++ b/arch/arm/include/asm/atomic.h
> @@ -134,21 +134,6 @@ static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
>         return oldval;
>  }
>
> -static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
> -{
> -       unsigned long tmp, tmp2;
> -
> -       __asm__ __volatile__("@ atomic_clear_mask\n"
> -"1:    ldrex   %0, [%3]\n"
> -"      bic     %0, %0, %4\n"
> -"      strex   %1, %0, [%3]\n"
> -"      teq     %1, #0\n"
> -"      bne     1b"
> -       : "=&r" (tmp), "=&r" (tmp2), "+Qo" (*addr)
> -       : "r" (addr), "Ir" (mask)
> -       : "cc");
> -}
> -
>  #else /* ARM_ARCH_6 */
>
>  #ifdef CONFIG_SMP
> @@ -197,15 +182,6 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
>         return ret;
>  }
>
> -static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
> -{
> -       unsigned long flags;
> -
> -       raw_local_irq_save(flags);
> -       *addr &= ~mask;
> -       raw_local_irq_restore(flags);
> -}
> -
>  #endif /* __LINUX_ARM_ARCH__ */
>
>  #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
> diff --git a/arch/arm64/include/asm/atomic.h b/arch/arm64/include/asm/atomic.h
> index 8363644..01de5aa 100644
> --- a/arch/arm64/include/asm/atomic.h
> +++ b/arch/arm64/include/asm/atomic.h
> @@ -126,20 +126,6 @@ static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
>         return oldval;
>  }
>
> -static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
> -{
> -       unsigned long tmp, tmp2;
> -
> -       asm volatile("// atomic_clear_mask\n"
> -"1:    ldxr    %0, %2\n"
> -"      bic     %0, %0, %3\n"
> -"      stxr    %w1, %0, %2\n"
> -"      cbnz    %w1, 1b"
> -       : "=&r" (tmp), "=&r" (tmp2), "+Q" (*addr)
> -       : "Ir" (mask)
> -       : "cc");
> -}
> -
>  #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
>
>  static inline int __atomic_add_unless(atomic_t *v, int a, int u)
> --
> 1.7.7.6
> --
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-- 
Thanks,
//richard
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