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SubjectRe: [PATCH 2/3] arm: include: asm: atomic.h: use 'unsigned int' and 'atomic' instead of 'unsigned long' for atomic_clear_mask()
On Thu, Oct 10, 2013 at 03:34:02AM +0100, Chen Gang wrote:
> In current kernel wide source, for arm, only s390 scsi drivers use
> atomic_clear_mask(), now, s390 itself need use 'unsigned int' and
> 'atomic_t', so need match s390's atomic_clear_mask().
>
>
> Signed-off-by: Chen Gang <gang.chen@asianux.com>
> ---
> arch/arm/include/asm/atomic.h | 13 +++++++------
> 1 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
> index da1c77d..0832a7f 100644
> --- a/arch/arm/include/asm/atomic.h
> +++ b/arch/arm/include/asm/atomic.h
> @@ -134,9 +134,10 @@ 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)
> +static inline void atomic_clear_mask(unsigned int mask, atomic_t *ptr)
> {
> - unsigned long tmp, tmp2;
> + unsigned int tmp;

I reckon this should be int (the mask parameter is unsigned, but
atomic_t.counter is signed).

> + unsigned long tmp2;
>
> __asm__ __volatile__("@ atomic_clear_mask\n"
> "1: ldrex %0, [%3]\n"
> @@ -144,8 +145,8 @@ static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
> " strex %1, %0, [%3]\n"
> " teq %1, #0\n"
> " bne 1b"
> - : "=&r" (tmp), "=&r" (tmp2), "+Qo" (*addr)
> - : "r" (addr), "Ir" (mask)
> + : "=&r" (tmp), "=&r" (tmp2), "+Qo" (ptr->counter)
> + : "r" (&ptr->counter), "Ir" (mask)
> : "cc");
> }
>
> @@ -197,12 +198,12 @@ 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)
> +static inline void atomic_clear_mask(unsigned int mask, atomic_t *v)
> {
> unsigned long flags;
>
> raw_local_irq_save(flags);
> - *addr &= ~mask;
> + v->counter &= ~mask;
> raw_local_irq_restore(flags);
> }

This is now identical to asm-generic/atomic.h. I wonder whether we could
just #include that file for the ARMv6 case? You'd need to check the
differences carefully.

Finally, I still question the need for the clear_mask function anyway. We
don't implement set_mask, and these functions are only used by either other
arch code or in drivers that don't work on ARM anyway.

Will


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