> This operation can be used for non-blocking algorithms, such as a non-blocking
> stack or ring.
>
> Signed-off-by: Gage Eads <gage.e...@intel.com>
> ---
> .../common/include/arch/x86/rte_atomic_64.h | 33 ++++++++++++
> lib/librte_eal/common/include/generic/rte_atomic.h | 59
> ++++++++++++++++++++++
> 2 files changed, 92 insertions(+)
>
> diff --git a/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> b/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> index fd2ec9c53..413e5361b 100644
> --- a/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> +++ b/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> @@ -34,6 +34,7 @@
> /*
> * Inspired from FreeBSD src/sys/amd64/include/atomic.h
> * Copyright (c) 1998 Doug Rabson
> + * Copyright (c) 2019 Intel Corporation
> * All rights reserved.
> */
>
> @@ -46,6 +47,7 @@
>
> #include <stdint.h>
> #include <rte_common.h>
> +#include <rte_compat.h>
> #include <rte_atomic.h>
>
> /*------------------------- 64 bit atomic operations
> -------------------------*/ @@ -
> 208,4 +210,35 @@ static inline void rte_atomic64_clear(rte_atomic64_t *v) }
> #endif
>
> +static inline int __rte_experimental
> +rte_atomic128_cmpxchg(rte_int128_t *dst,
> + rte_int128_t *exp,
> + const rte_int128_t *src,
> + unsigned int weak,
> + int success,
> + int failure)
> +{
> + RTE_SET_USED(weak);
> + RTE_SET_USED(success);
> + RTE_SET_USED(failure);
> + uint8_t res;
> +
> + asm volatile (
> + MPLOCKED
> + "cmpxchg16b %[dst];"
> + " sete %[res]"
> + : [dst] "=m" (dst->val[0]),
> + "=a" (exp->val[0]),
> + "=d" (exp->val[1]),
> + [res] "=r" (res)
> + : "b" (src->val[0]),
> + "c" (src->val[1]),
> + "a" (exp->val[0]),
> + "d" (exp->val[1]),
> + "m" (dst->val[0])
> + : "memory");
> +
> + return res;
> +}
> +
> #endif /* _RTE_ATOMIC_X86_64_H_ */
> diff --git a/lib/librte_eal/common/include/generic/rte_atomic.h
> b/lib/librte_eal/common/include/generic/rte_atomic.h
> index 4afd1acc3..7c43896e9 100644
> --- a/lib/librte_eal/common/include/generic/rte_atomic.h
> +++ b/lib/librte_eal/common/include/generic/rte_atomic.h
> @@ -14,6 +14,7 @@
>
> #include <stdint.h>
> #include <rte_common.h>
> +#include <rte_compat.h>
>
> #ifdef __DOXYGEN__
>
> @@ -1082,4 +1083,62 @@ static inline void
> rte_atomic64_clear(rte_atomic64_t *v) } #endif
>
> +/*------------------------ 128 bit atomic operations
> +-------------------------*/
> +
> +#if defined(RTE_ARCH_X86_64)
> +/**
> + * 128-bit integer structure.
> + */
> +RTE_STD_C11
> +typedef struct {
> + RTE_STD_C11
> + union {
> + uint64_t val[2];
> + __int128 int128;
> + };
> +} __rte_aligned(16) rte_int128_t;
> +
> +/**
> + * An atomic compare and set function used by the mutex functions.
> + * (Atomically) Equivalent to:
> + * if (*dst == exp)
Should be, "if (*dst == *exp)"
> + * *dst = src
Should be "*dst = *src"
> + * else
> + * *exp = *dst
> + *
> + * @note The success and failure arguments must be one of the
> +__ATOMIC_* values
> + * defined in the C++11 standard. For details on their behavior, refer
> +to the
> + * standard.
> + *
> + * @param dst
> + * The destination into which the value will be written.
> + * @param exp
> + * Pointer to the expected value. If the operation fails, this memory is
> + * updated with the actual value.
> + * @param src
> + * Pointer to the new value.
> + * @param weak
> + * A value of true allows the comparison to spuriously fail and allows the
> + * 'exp' update to occur non-atomically (i.e. a torn read may occur).
> + * Implementations may ignore this argument and only implement the strong
> + * variant.
> + * @param success
> + * If successful, the operation's memory behavior conforms to this (or a
> + * stronger) model.
> + * @param failure
> + * If unsuccessful, the operation's memory behavior conforms to this (or a
> + * stronger) model. This argument cannot be __ATOMIC_RELEASE,
> + * __ATOMIC_ACQ_REL, or a stronger model than success.
> + * @return
> + * Non-zero on success; 0 on failure.
> + */
> +static inline int __rte_experimental
> +rte_atomic128_cmpxchg(rte_int128_t *dst,
Name could be more neutral. May be rte_atomic128_compare/cmp_exchange?
> + rte_int128_t *exp,
> + const rte_int128_t *src,
> + unsigned int weak,
> + int success,
> + int failure);
> +#endif
> +
> #endif /* _RTE_ATOMIC_H_ */
> --
> 2.13.6
Few minor comments.
I have not reviewed the x86 implementation.
Otherwise,
Reviewed-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
