linux-kernel - Re: [PATCH 1/8] sparc32: make __cmpxchg

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Date: Tue, 2 Apr 2024 13:03:13 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: linux-kernel@...r.kernel.org, kernel-team@...a.com,
	"David S. Miller" <davem@...emloft.net>,
	Andreas Larsson <andreas@...sler.com>,
	Palmer Dabbelt <palmer@...osinc.com>, Arnd Bergmann <arnd@...db.de>,
	Marco Elver <elver@...gle.com>
Subject: Re: [PATCH 1/8] sparc32: make __cmpxchg_u32() return u32

On Tue, Apr 02, 2024 at 12:28:28AM -0400, Al Viro wrote:
> Conversion between u32 and unsigned long is tautological there,
> and the only use of return value is to return it from
> __cmpxchg() (which return unsigned long).
> 
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>

I have pulled these in as replacements for my patches in the meantime.

Thank you!

							Thanx, Paul

> ---
>  arch/sparc/include/asm/cmpxchg_32.h | 2 +-
>  arch/sparc/lib/atomic32.c           | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/sparc/include/asm/cmpxchg_32.h b/arch/sparc/include/asm/cmpxchg_32.h
> index d0af82c240b7..112bfaa28729 100644
> --- a/arch/sparc/include/asm/cmpxchg_32.h
> +++ b/arch/sparc/include/asm/cmpxchg_32.h
> @@ -39,7 +39,7 @@ static __always_inline unsigned long __arch_xchg(unsigned long x, __volatile__ v
>  /* bug catcher for when unsupported size is used - won't link */
>  void __cmpxchg_called_with_bad_pointer(void);
>  /* we only need to support cmpxchg of a u32 on sparc */
> -unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
> +u32 __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
>  
>  /* don't worry...optimizer will get rid of most of this */
>  static inline unsigned long
> diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c
> index cf80d1ae352b..d90d756123d8 100644
> --- a/arch/sparc/lib/atomic32.c
> +++ b/arch/sparc/lib/atomic32.c
> @@ -159,7 +159,7 @@ unsigned long sp32___change_bit(unsigned long *addr, unsigned long mask)
>  }
>  EXPORT_SYMBOL(sp32___change_bit);
>  
> -unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
> +u32 __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
>  {
>  	unsigned long flags;
>  	u32 prev;
> @@ -169,7 +169,7 @@ unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
>  		*ptr = new;
>  	spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);
>  
> -	return (unsigned long)prev;
> +	return prev;
>  }
>  EXPORT_SYMBOL(__cmpxchg_u32);
>  
> -- 
> 2.39.2
>