Re: [PATCH] locking/atomic: Add acquire and release fence for atomic(64)_read(set)

[Peter Zijlstra]

On Fri, Nov 24, 2023 at 11:25:08AM -0500, guoren@xxxxxxxxxx wrote:
> From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> 
> The definitions of atomic(64)_read(set) are relax version, so
> add acquire and release fence for them.
> 
> Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Guo Ren <guoren@xxxxxxxxxx>
> ---

You lost the script change?

>  include/linux/atomic/atomic-arch-fallback.h | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/atomic/atomic-arch-fallback.h b/include/linux/atomic/atomic-arch-fallback.h
> index 18f5744dfb5d..9775900eeefd 100644
> --- a/include/linux/atomic/atomic-arch-fallback.h
> +++ b/include/linux/atomic/atomic-arch-fallback.h
> @@ -460,7 +460,10 @@ raw_atomic_read_acquire(const atomic_t *v)
>  #if defined(arch_atomic_read_acquire)
>  	return arch_atomic_read_acquire(v);
>  #elif defined(arch_atomic_read)
> -	return arch_atomic_read(v);
> +	int ret;
> +	ret = arch_atomic_read(v);
> +	__atomic_acquire_fence();
> +	return ret;
>  #else
>  	int ret;
>  
> @@ -509,6 +512,7 @@ raw_atomic_set_release(atomic_t *v, int i)
>  #if defined(arch_atomic_set_release)
>  	arch_atomic_set_release(v, i);
>  #elif defined(arch_atomic_set)
> +	__atomic_release_fence();
>  	arch_atomic_set(v, i);
>  #else
>  	if (__native_word(atomic_t)) {
> @@ -2576,7 +2580,10 @@ raw_atomic64_read_acquire(const atomic64_t *v)
>  #if defined(arch_atomic64_read_acquire)
>  	return arch_atomic64_read_acquire(v);
>  #elif defined(arch_atomic64_read)
> -	return arch_atomic64_read(v);
> +	s64 ret;
> +	ret = arch_atomic64_read(v);
> +	__atomic_acquire_fence();
> +	return ret;
>  #else
>  	s64 ret;
>  
> @@ -2625,6 +2632,7 @@ raw_atomic64_set_release(atomic64_t *v, s64 i)
>  #if defined(arch_atomic64_set_release)
>  	arch_atomic64_set_release(v, i);
>  #elif defined(arch_atomic64_set)
> +	__atomic_release_fence();
>  	arch_atomic64_set(v, i);
>  #else
>  	if (__native_word(atomic64_t)) {
> @@ -4657,4 +4665,4 @@ raw_atomic64_dec_if_positive(atomic64_t *v)
>  }
>  
>  #endif /* _LINUX_ATOMIC_FALLBACK_H */
> -// 202b45c7db600ce36198eb1f1fc2c2d5268ace2d
> +// 3135f55051cf62b76664e528bf04337c44a14e72
> -- 
> 2.36.1
>