On Fri, 2019-03-08 at 15:56 +0800, Gavin Hu wrote:
> -------------------------------------------------------------------
> ---
> The __sync builtin based implementation generates full memory
> barriers
> ('dmb ish') on Arm platforms. Using C11 atomic builtins to generate
> one way
> barriers.
>
>
> lib/librte_eal/common/include/generic/rte_spinlock.h | 18
> +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/lib/librte_eal/common/include/generic/rte_spinlock.h
> b/lib/librte_eal/common/include/generic/rte_spinlock.h
> index c4c3fc3..87ae7a4 100644
> --- a/lib/librte_eal/common/include/generic/rte_spinlock.h
> +++ b/lib/librte_eal/common/include/generic/rte_spinlock.h
> @@ -61,9 +61,14 @@ rte_spinlock_lock(rte_spinlock_t *sl);
> static inline void
> rte_spinlock_lock(rte_spinlock_t *sl)
> {
> - while (__sync_lock_test_and_set(&sl->locked, 1))
> - while(sl->locked)
> + int exp = 0;
> +
> + while (!__atomic_compare_exchange_n(&sl->locked, &exp, 1, 0,
> + __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)) {
Would it be clean to use __atomic_test_and_set()
to avoid explicit exp =
0.
> + while (__atomic_load_n(&sl->locked, __ATOMIC_RELAXED))
> rte_pause();
> + exp = 0;
> + }
> }
> #endif
>
> @@ -80,7 +85,7 @@ rte_spinlock_unlock (rte_spinlock_t *sl);
> static inline void
> rte_spinlock_unlock (rte_spinlock_t *sl)
> {
> - __sync_lock_release(&sl->locked);
> + __atomic_store_n(&sl->locked, 0, __ATOMIC_RELEASE);
__atomic_clear(.., __ATOMIC_RELEASE) looks more clean to me.
> }
> #endif
>
> @@ -99,7 +104,10 @@ rte_spinlock_trylock (rte_spinlock_t *sl);
> static inline int
> rte_spinlock_trylock (rte_spinlock_t *sl)
> {
> - return __sync_lock_test_and_set(&sl->locked,1) == 0;
> + int exp = 0;
> + return __atomic_compare_exchange_n(&sl->locked, &exp, 1,
> + 0, /* disallow spurious failure */
> + __ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
return (__atomic_test_and_set(.., __ATOMIC_ACQUIRE) == 0) will be more
clean version.
> }
> #endif
>
> @@ -113,7 +121,7 @@ rte_spinlock_trylock (rte_spinlock_t *sl)
> */
> static inline int rte_spinlock_is_locked (rte_spinlock_t *sl)
> {
> - return sl->locked;
> + return __atomic_load_n(&sl->locked, __ATOMIC_ACQUIRE);
Does __ATOMIC_RELAXED will be sufficient?
> }
>
> /**
