Re: [patch V2 2/4] atomics: Provide atomic_add_and_negative() variants

From: Mark Rutland
Date: Wed Mar 22 2023 - 09:21:30 EST

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On Tue, Mar 07, 2023 at 01:57:43PM +0100, Thomas Gleixner wrote:
> atomic_add_and_negative() does not provide the relaxed/acquire/release
^^^^

Spurious 'and_' above.

> variants.
>
> Provide them in preparation for a new scalable reference count algorithm.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

Other than the typo, this looks reasonable to me, so FWIW:

Acked-by: Mark Rutland <mark.rutland@xxxxxxx>

Mark.

> ---
> V2: New patch
> ---
> include/linux/atomic/atomic-arch-fallback.h | 200 +++++++++++++++++++++++++++-
> include/linux/atomic/atomic-instrumented.h | 68 +++++++++
> include/linux/atomic/atomic-long.h | 38 +++++
> scripts/atomic/atomics.tbl | 2
> scripts/atomic/fallbacks/add_negative | 4
> 5 files changed, 306 insertions(+), 6 deletions(-)
>
> --- a/include/linux/atomic/atomic-arch-fallback.h
> +++ b/include/linux/atomic/atomic-arch-fallback.h
> @@ -1208,6 +1208,13 @@ arch_atomic_inc_and_test(atomic_t *v)
> #define arch_atomic_inc_and_test arch_atomic_inc_and_test
> #endif
>
> +#ifndef arch_atomic_add_negative_relaxed
> +#ifdef arch_atomic_add_negative
> +#define arch_atomic_add_negative_acquire arch_atomic_add_negative
> +#define arch_atomic_add_negative_release arch_atomic_add_negative
> +#define arch_atomic_add_negative_relaxed arch_atomic_add_negative
> +#endif /* arch_atomic_add_negative */
> +
> #ifndef arch_atomic_add_negative
> /**
> * arch_atomic_add_negative - add and test if negative
> @@ -1226,6 +1233,98 @@ arch_atomic_add_negative(int i, atomic_t
> #define arch_atomic_add_negative arch_atomic_add_negative
> #endif
>
> +#ifndef arch_atomic_add_negative_acquire
> +/**
> + * arch_atomic_add_negative - add and test if negative
> + * @i: integer value to add
> + * @v: pointer of type atomic_t
> + *
> + * Atomically adds @i to @v and returns true
> + * if the result is negative, or false when
> + * result is greater than or equal to zero.
> + */
> +static __always_inline bool
> +arch_atomic_add_negative_acquire(int i, atomic_t *v)
> +{
> + return arch_atomic_add_return_acquire(i, v) < 0;
> +}
> +#define arch_atomic_add_negative_acquire arch_atomic_add_negative_acquire
> +#endif
> +
> +#ifndef arch_atomic_add_negative_release
> +/**
> + * arch_atomic_add_negative - add and test if negative
> + * @i: integer value to add
> + * @v: pointer of type atomic_t
> + *
> + * Atomically adds @i to @v and returns true
> + * if the result is negative, or false when
> + * result is greater than or equal to zero.
> + */
> +static __always_inline bool
> +arch_atomic_add_negative_release(int i, atomic_t *v)
> +{
> + return arch_atomic_add_return_release(i, v) < 0;
> +}
> +#define arch_atomic_add_negative_release arch_atomic_add_negative_release
> +#endif
> +
> +#ifndef arch_atomic_add_negative_relaxed
> +/**
> + * arch_atomic_add_negative - add and test if negative
> + * @i: integer value to add
> + * @v: pointer of type atomic_t
> + *
> + * Atomically adds @i to @v and returns true
> + * if the result is negative, or false when
> + * result is greater than or equal to zero.
> + */
> +static __always_inline bool
> +arch_atomic_add_negative_relaxed(int i, atomic_t *v)
> +{
> + return arch_atomic_add_return_relaxed(i, v) < 0;
> +}
> +#define arch_atomic_add_negative_relaxed arch_atomic_add_negative_relaxed
> +#endif
> +
> +#else /* arch_atomic_add_negative_relaxed */
> +
> +#ifndef arch_atomic_add_negative_acquire
> +static __always_inline bool
> +arch_atomic_add_negative_acquire(int i, atomic_t *v)
> +{
> + bool ret = arch_atomic_add_negative_relaxed(i, v);
> + __atomic_acquire_fence();
> + return ret;
> +}
> +#define arch_atomic_add_negative_acquire arch_atomic_add_negative_acquire
> +#endif
> +
> +#ifndef arch_atomic_add_negative_release
> +static __always_inline bool
> +arch_atomic_add_negative_release(int i, atomic_t *v)
> +{
> + __atomic_release_fence();
> + return arch_atomic_add_negative_relaxed(i, v);
> +}
> +#define arch_atomic_add_negative_release arch_atomic_add_negative_release
> +#endif
> +
> +#ifndef arch_atomic_add_negative
> +static __always_inline bool
> +arch_atomic_add_negative(int i, atomic_t *v)
> +{
> + bool ret;
> + __atomic_pre_full_fence();
> + ret = arch_atomic_add_negative_relaxed(i, v);
> + __atomic_post_full_fence();
> + return ret;
> +}
> +#define arch_atomic_add_negative arch_atomic_add_negative
> +#endif
> +
> +#endif /* arch_atomic_add_negative_relaxed */
> +
> #ifndef arch_atomic_fetch_add_unless
> /**
> * arch_atomic_fetch_add_unless - add unless the number is already a given value
> @@ -2329,6 +2428,13 @@ arch_atomic64_inc_and_test(atomic64_t *v
> #define arch_atomic64_inc_and_test arch_atomic64_inc_and_test
> #endif
>
> +#ifndef arch_atomic64_add_negative_relaxed
> +#ifdef arch_atomic64_add_negative
> +#define arch_atomic64_add_negative_acquire arch_atomic64_add_negative
> +#define arch_atomic64_add_negative_release arch_atomic64_add_negative
> +#define arch_atomic64_add_negative_relaxed arch_atomic64_add_negative
> +#endif /* arch_atomic64_add_negative */
> +
> #ifndef arch_atomic64_add_negative
> /**
> * arch_atomic64_add_negative - add and test if negative
> @@ -2347,6 +2453,98 @@ arch_atomic64_add_negative(s64 i, atomic
> #define arch_atomic64_add_negative arch_atomic64_add_negative
> #endif
>
> +#ifndef arch_atomic64_add_negative_acquire
> +/**
> + * arch_atomic64_add_negative - add and test if negative
> + * @i: integer value to add
> + * @v: pointer of type atomic64_t
> + *
> + * Atomically adds @i to @v and returns true
> + * if the result is negative, or false when
> + * result is greater than or equal to zero.
> + */
> +static __always_inline bool
> +arch_atomic64_add_negative_acquire(s64 i, atomic64_t *v)
> +{
> + return arch_atomic64_add_return_acquire(i, v) < 0;
> +}
> +#define arch_atomic64_add_negative_acquire arch_atomic64_add_negative_acquire
> +#endif
> +
> +#ifndef arch_atomic64_add_negative_release
> +/**
> + * arch_atomic64_add_negative - add and test if negative
> + * @i: integer value to add
> + * @v: pointer of type atomic64_t
> + *
> + * Atomically adds @i to @v and returns true
> + * if the result is negative, or false when
> + * result is greater than or equal to zero.
> + */
> +static __always_inline bool
> +arch_atomic64_add_negative_release(s64 i, atomic64_t *v)
> +{
> + return arch_atomic64_add_return_release(i, v) < 0;
> +}
> +#define arch_atomic64_add_negative_release arch_atomic64_add_negative_release
> +#endif
> +
> +#ifndef arch_atomic64_add_negative_relaxed
> +/**
> + * arch_atomic64_add_negative - add and test if negative
> + * @i: integer value to add
> + * @v: pointer of type atomic64_t
> + *
> + * Atomically adds @i to @v and returns true
> + * if the result is negative, or false when
> + * result is greater than or equal to zero.
> + */
> +static __always_inline bool
> +arch_atomic64_add_negative_relaxed(s64 i, atomic64_t *v)
> +{
> + return arch_atomic64_add_return_relaxed(i, v) < 0;
> +}
> +#define arch_atomic64_add_negative_relaxed arch_atomic64_add_negative_relaxed
> +#endif
> +
> +#else /* arch_atomic64_add_negative_relaxed */
> +
> +#ifndef arch_atomic64_add_negative_acquire
> +static __always_inline bool
> +arch_atomic64_add_negative_acquire(s64 i, atomic64_t *v)
> +{
> + bool ret = arch_atomic64_add_negative_relaxed(i, v);
> + __atomic_acquire_fence();
> + return ret;
> +}
> +#define arch_atomic64_add_negative_acquire arch_atomic64_add_negative_acquire
> +#endif
> +
> +#ifndef arch_atomic64_add_negative_release
> +static __always_inline bool
> +arch_atomic64_add_negative_release(s64 i, atomic64_t *v)
> +{
> + __atomic_release_fence();
> + return arch_atomic64_add_negative_relaxed(i, v);
> +}
> +#define arch_atomic64_add_negative_release arch_atomic64_add_negative_release
> +#endif
> +
> +#ifndef arch_atomic64_add_negative
> +static __always_inline bool
> +arch_atomic64_add_negative(s64 i, atomic64_t *v)
> +{
> + bool ret;
> + __atomic_pre_full_fence();
> + ret = arch_atomic64_add_negative_relaxed(i, v);
> + __atomic_post_full_fence();
> + return ret;
> +}
> +#define arch_atomic64_add_negative arch_atomic64_add_negative
> +#endif
> +
> +#endif /* arch_atomic64_add_negative_relaxed */
> +
> #ifndef arch_atomic64_fetch_add_unless
> /**
> * arch_atomic64_fetch_add_unless - add unless the number is already a given value
> @@ -2456,4 +2654,4 @@ arch_atomic64_dec_if_positive(atomic64_t
> #endif
>
> #endif /* _LINUX_ATOMIC_FALLBACK_H */
> -// b5e87bdd5ede61470c29f7a7e4de781af3770f09
> +// 63bcc1a53125d4eca5e659892e10615f00f9abf8
> --- a/include/linux/atomic/atomic-instrumented.h
> +++ b/include/linux/atomic/atomic-instrumented.h
> @@ -592,6 +592,28 @@ atomic_add_negative(int i, atomic_t *v)
> return arch_atomic_add_negative(i, v);
> }
>
> +static __always_inline bool
> +atomic_add_negative_acquire(int i, atomic_t *v)
> +{
> + instrument_atomic_read_write(v, sizeof(*v));
> + return arch_atomic_add_negative_acquire(i, v);
> +}
> +
> +static __always_inline bool
> +atomic_add_negative_release(int i, atomic_t *v)
> +{
> + kcsan_release();
> + instrument_atomic_read_write(v, sizeof(*v));
> + return arch_atomic_add_negative_release(i, v);
> +}
> +
> +static __always_inline bool
> +atomic_add_negative_relaxed(int i, atomic_t *v)
> +{
> + instrument_atomic_read_write(v, sizeof(*v));
> + return arch_atomic_add_negative_relaxed(i, v);
> +}
> +
> static __always_inline int
> atomic_fetch_add_unless(atomic_t *v, int a, int u)
> {
> @@ -1211,6 +1233,28 @@ atomic64_add_negative(s64 i, atomic64_t
> return arch_atomic64_add_negative(i, v);
> }
>
> +static __always_inline bool
> +atomic64_add_negative_acquire(s64 i, atomic64_t *v)
> +{
> + instrument_atomic_read_write(v, sizeof(*v));
> + return arch_atomic64_add_negative_acquire(i, v);
> +}
> +
> +static __always_inline bool
> +atomic64_add_negative_release(s64 i, atomic64_t *v)
> +{
> + kcsan_release();
> + instrument_atomic_read_write(v, sizeof(*v));
> + return arch_atomic64_add_negative_release(i, v);
> +}
> +
> +static __always_inline bool
> +atomic64_add_negative_relaxed(s64 i, atomic64_t *v)
> +{
> + instrument_atomic_read_write(v, sizeof(*v));
> + return arch_atomic64_add_negative_relaxed(i, v);
> +}
> +
> static __always_inline s64
> atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u)
> {
> @@ -1830,6 +1874,28 @@ atomic_long_add_negative(long i, atomic_
> return arch_atomic_long_add_negative(i, v);
> }
>
> +static __always_inline bool
> +atomic_long_add_negative_acquire(long i, atomic_long_t *v)
> +{
> + instrument_atomic_read_write(v, sizeof(*v));
> + return arch_atomic_long_add_negative_acquire(i, v);
> +}
> +
> +static __always_inline bool
> +atomic_long_add_negative_release(long i, atomic_long_t *v)
> +{
> + kcsan_release();
> + instrument_atomic_read_write(v, sizeof(*v));
> + return arch_atomic_long_add_negative_release(i, v);
> +}
> +
> +static __always_inline bool
> +atomic_long_add_negative_relaxed(long i, atomic_long_t *v)
> +{
> + instrument_atomic_read_write(v, sizeof(*v));
> + return arch_atomic_long_add_negative_relaxed(i, v);
> +}
> +
> static __always_inline long
> atomic_long_fetch_add_unless(atomic_long_t *v, long a, long u)
> {
> @@ -2083,4 +2149,4 @@ atomic_long_dec_if_positive(atomic_long_
> })
>
> #endif /* _LINUX_ATOMIC_INSTRUMENTED_H */
> -// 764f741eb77a7ad565dc8d99ce2837d5542e8aee
> +// 1b485de9cbaa4900de59e14ee2084357eaeb1c3a
> --- a/include/linux/atomic/atomic-long.h
> +++ b/include/linux/atomic/atomic-long.h
> @@ -479,6 +479,24 @@ arch_atomic_long_add_negative(long i, at
> return arch_atomic64_add_negative(i, v);
> }
>
> +static __always_inline bool
> +arch_atomic_long_add_negative_acquire(long i, atomic_long_t *v)
> +{
> + return arch_atomic64_add_negative_acquire(i, v);
> +}
> +
> +static __always_inline bool
> +arch_atomic_long_add_negative_release(long i, atomic_long_t *v)
> +{
> + return arch_atomic64_add_negative_release(i, v);
> +}
> +
> +static __always_inline bool
> +arch_atomic_long_add_negative_relaxed(long i, atomic_long_t *v)
> +{
> + return arch_atomic64_add_negative_relaxed(i, v);
> +}
> +
> static __always_inline long
> arch_atomic_long_fetch_add_unless(atomic_long_t *v, long a, long u)
> {
> @@ -973,6 +991,24 @@ arch_atomic_long_add_negative(long i, at
> return arch_atomic_add_negative(i, v);
> }
>
> +static __always_inline bool
> +arch_atomic_long_add_negative_acquire(long i, atomic_long_t *v)
> +{
> + return arch_atomic_add_negative_acquire(i, v);
> +}
> +
> +static __always_inline bool
> +arch_atomic_long_add_negative_release(long i, atomic_long_t *v)
> +{
> + return arch_atomic_add_negative_release(i, v);
> +}
> +
> +static __always_inline bool
> +arch_atomic_long_add_negative_relaxed(long i, atomic_long_t *v)
> +{
> + return arch_atomic_add_negative_relaxed(i, v);
> +}
> +
> static __always_inline long
> arch_atomic_long_fetch_add_unless(atomic_long_t *v, long a, long u)
> {
> @@ -1011,4 +1047,4 @@ arch_atomic_long_dec_if_positive(atomic_
>
> #endif /* CONFIG_64BIT */
> #endif /* _LINUX_ATOMIC_LONG_H */
> -// e8f0e08ff072b74d180eabe2ad001282b38c2c88
> +// a194c07d7d2f4b0e178d3c118c919775d5d65f50
> --- a/scripts/atomic/atomics.tbl
> +++ b/scripts/atomic/atomics.tbl
> @@ -33,7 +33,7 @@ try_cmpxchg B v p:old i:new
> sub_and_test b i v
> dec_and_test b v
> inc_and_test b v
> -add_negative b i v
> +add_negative B i v
> add_unless fb v i:a i:u
> inc_not_zero b v
> inc_unless_negative b v
> --- a/scripts/atomic/fallbacks/add_negative
> +++ b/scripts/atomic/fallbacks/add_negative
> @@ -9,8 +9,8 @@ cat <<EOF
> * result is greater than or equal to zero.
> */
> static __always_inline bool
> -arch_${atomic}_add_negative(${int} i, ${atomic}_t *v)
> +arch_${atomic}_add_negative${order}(${int} i, ${atomic}_t *v)
> {
> - return arch_${atomic}_add_return(i, v) < 0;
> + return arch_${atomic}_add_return${order}(i, v) < 0;
> }
> EOF
>

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