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Make various fixes to <stdatomic.h>.

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- According to the standard, memory_order is a type. Use a typedef.

- atomic_*_fence() and atomic_flag_*() are described by the standard as
  functions. Use inline functions to implement them.

- Only expose the atomic_*_explicit() functions in kernel space. We
  should not use the short-hand functions, as they will always use
  memory_order_seq_cst.
This commit is contained in:
ed 2013-06-30 08:54:41 +00:00
parent c3008dddb1
commit 69fe417f6e
1 changed files with 68 additions and 22 deletions
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90
sys/sys/stdatomic.h
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@ -122,33 +122,44 @@
* atomic operations.
*/
enum memory_order {
typedef enum {
memory_order_relaxed = __ATOMIC_RELAXED,
memory_order_consume = __ATOMIC_CONSUME,
memory_order_acquire = __ATOMIC_ACQUIRE,
memory_order_release = __ATOMIC_RELEASE,
memory_order_acq_rel = __ATOMIC_ACQ_REL,
memory_order_seq_cst = __ATOMIC_SEQ_CST
};
} memory_order;
/*
* 7.17.4 Fences.
*/
static __inline void
atomic_thread_fence(memory_order __order __unused)
{
#ifdef __CLANG_ATOMICS
#define atomic_thread_fence(order) __c11_atomic_thread_fence(order)
#define atomic_signal_fence(order) __c11_atomic_signal_fence(order)
__c11_atomic_thread_fence(__order);
#elif defined(__GNUC_ATOMICS)
#define atomic_thread_fence(order) __atomic_thread_fence(order)
#define atomic_signal_fence(order) __atomic_signal_fence(order)
__atomic_thread_fence(__order);
#else
#define atomic_thread_fence(order) ((void)(order), __sync_synchronize())
#define atomic_signal_fence(order) __extension__ ({ \
(void)(order); \
__asm volatile ("" ::: "memory"); \
(void)0; \
})
__sync_synchronize();
#endif
}
static __inline void
atomic_signal_fence(memory_order __order __unused)
{
#ifdef __CLANG_ATOMICS
__c11_atomic_signal_fence(__order);
#elif defined(__GNUC_ATOMICS)
__atomic_signal_fence(__order);
#else
__asm volatile ("" ::: "memory");
#endif
}
/*
* 7.17.5 Lock-free property.
@ -319,8 +330,12 @@ __extension__ ({ \
/*
* Convenience functions.
*
* Don't provide these in kernel space. In kernel space, we should be
* disciplined enough to always provide explicit barriers.
*/
#ifndef _KERNEL
#define atomic_compare_exchange_strong(object, expected, desired) \
atomic_compare_exchange_strong_explicit(object, expected, \
desired, memory_order_seq_cst, memory_order_seq_cst)
@ -343,23 +358,54 @@ __extension__ ({ \
atomic_load_explicit(object, memory_order_seq_cst)
#define atomic_store(object, desired) \
atomic_store_explicit(object, desired, memory_order_seq_cst)
#endif /* !_KERNEL */
/*
* 7.17.8 Atomic flag type and operations.
*
* XXX: Assume atomic_bool can be used as an atomic_flag. Is there some
* kind of compiler built-in type we could use?
*/
typedef atomic_bool atomic_flag;
typedef struct {
atomic_bool __flag;
} atomic_flag;
#define ATOMIC_FLAG_INIT ATOMIC_VAR_INIT(0)
#define ATOMIC_FLAG_INIT { ATOMIC_VAR_INIT(0) }
#define atomic_flag_clear_explicit(object, order) \
atomic_store_explicit(object, 0, order)
#define atomic_flag_test_and_set_explicit(object, order) \
atomic_compare_exchange_strong_explicit(object, 0, 1, order, order)
static __inline _Bool
atomic_flag_test_and_set_explicit(volatile atomic_flag *__object,
memory_order __order)
{
_Bool __expected;
#define atomic_flag_clear(object) \
atomic_flag_clear_explicit(object, memory_order_seq_cst)
#define atomic_flag_test_and_set(object) \
atomic_flag_test_and_set_explicit(object, memory_order_seq_cst)
__expected = 0;
return (atomic_compare_exchange_strong_explicit(&__object->__flag,
&__expected, 1, __order, __order));
}
static __inline void
atomic_flag_clear_explicit(volatile atomic_flag *__object, memory_order __order)
{
atomic_store_explicit(&__object->__flag, 0, __order);
}
#ifndef _KERNEL
static __inline _Bool
atomic_flag_test_and_set(volatile atomic_flag *__object)
{
return (atomic_flag_test_and_set_explicit(__object,
memory_order_seq_cst));
}
static __inline void
atomic_flag_clear(volatile atomic_flag *__object)
{
atomic_flag_clear_explicit(__object, memory_order_seq_cst);
}
#endif /* !_KERNEL */
#endif /* !_STDATOMIC_H_ */