Author: ed
Date: Sun Jun 30 08:54:41 2013
New Revision: 252411
URL: http://svnweb.freebsd.org/changeset/base/252411
Log:
Make various fixes to <stdatomic.h>.
- 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.
Modified:
head/sys/sys/stdatomic.h
Modified: head/sys/sys/stdatomic.h
==============================================================================
--- head/sys/sys/stdatomic.h Sun Jun 30 08:36:19 2013 (r252410)
+++ head/sys/sys/stdatomic.h Sun Jun 30 08:54:41 2013 (r252411)
@@ -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;
-
-#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)
-
-#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)
+typedef struct {
+ atomic_bool __flag;
+} atomic_flag;
+
+#define ATOMIC_FLAG_INIT { ATOMIC_VAR_INIT(0) }
+
+static __inline _Bool
+atomic_flag_test_and_set_explicit(volatile atomic_flag *__object,
+ memory_order __order)
+{
+ _Bool __expected;
+
+ __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_ */
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