2023-11-24 16:25:37

by Guo Ren

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

From: Guo Ren <[email protected]>

The definitions of atomic(64)_read(set) are relax version, so
add acquire and release fence for them.

Signed-off-by: Guo Ren <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
---
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

2023-11-24 16:33:11

by Peter Zijlstra

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

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

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
>

2023-11-25 01:35:53

by Guo Ren

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

On Sat, Nov 25, 2023 at 12:32 AM Peter Zijlstra <[email protected]> wrote:
>
> On Fri, Nov 24, 2023 at 11:25:08AM -0500, [email protected] wrote:
> > From: Guo Ren <[email protected]>
> >
> > The definitions of atomic(64)_read(set) are relax version, so
> > add acquire and release fence for them.
> >
> > Signed-off-by: Guo Ren <[email protected]>
> > Signed-off-by: Guo Ren <[email protected]>
> > ---
>
> You lost the script change?
Sorry, it's my fault. I shouldn't have modify header file directly.
Here is the v2:
https://lore.kernel.org/all/[email protected]/

>
> > 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
> >



--
Best Regards
Guo Ren