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/*
* Copyright (c) 2013, 2014 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* This header implements atomic operation primitives on GCC 4.x. */
#ifndef IN_OVS_ATOMIC_H
#error "This header should only be included indirectly via ovs-atomic.h."
#endif
#include "ovs-atomic-locked.h"
#define OVS_ATOMIC_GCC4P_IMPL 1
#define ATOMIC(TYPE) TYPE
#define ATOMIC_BOOL_LOCK_FREE 2
#define ATOMIC_CHAR_LOCK_FREE 2
#define ATOMIC_SHORT_LOCK_FREE 2
#define ATOMIC_INT_LOCK_FREE 2
#define ATOMIC_LONG_LOCK_FREE (ULONG_MAX <= UINTPTR_MAX ? 2 : 0)
#define ATOMIC_LLONG_LOCK_FREE (ULLONG_MAX <= UINTPTR_MAX ? 2 : 0)
#define ATOMIC_POINTER_LOCK_FREE 2
typedef enum {
memory_order_relaxed,
memory_order_consume,
memory_order_acquire,
memory_order_release,
memory_order_acq_rel,
memory_order_seq_cst
} memory_order;
#define IS_LOCKLESS_ATOMIC(OBJECT) (sizeof(OBJECT) <= sizeof(void *))
#define atomic_init(OBJECT, VALUE) (*(OBJECT) = (VALUE), (void) 0)
static inline void
atomic_thread_fence(memory_order order)
{
if (order != memory_order_relaxed) {
__sync_synchronize();
}
}
static inline void
atomic_thread_fence_if_seq_cst(memory_order order)
{
if (order == memory_order_seq_cst) {
__sync_synchronize();
}
}
static inline void
atomic_signal_fence(memory_order order)
{
if (order != memory_order_relaxed) {
asm volatile("" : : : "memory");
}
}
#define atomic_is_lock_free(OBJ) \
((void) *(OBJ), \
IS_LOCKLESS_ATOMIC(*(OBJ)) ? 2 : 0)
#define atomic_store(DST, SRC) \
atomic_store_explicit(DST, SRC, memory_order_seq_cst)
#define atomic_store_explicit(DST, SRC, ORDER) \
({ \
typeof(DST) dst__ = (DST); \
typeof(SRC) src__ = (SRC); \
\
if (IS_LOCKLESS_ATOMIC(*dst__)) { \
atomic_thread_fence(ORDER); \
*(typeof(*(DST)) volatile *)dst__ = src__; \
atomic_thread_fence_if_seq_cst(ORDER); \
} else { \
atomic_store_locked(dst__, src__); \
} \
(void) 0; \
})
#define atomic_read(SRC, DST) \
atomic_read_explicit(SRC, DST, memory_order_seq_cst)
#define atomic_read_explicit(SRC, DST, ORDER) \
({ \
typeof(DST) dst__ = (DST); \
typeof(SRC) src__ = (SRC); \
\
if (IS_LOCKLESS_ATOMIC(*src__)) { \
atomic_thread_fence_if_seq_cst(ORDER); \
*dst__ = *(typeof(*(SRC)) volatile *)src__; \
} else { \
atomic_read_locked(src__, dst__); \
} \
(void) 0; \
})
#define atomic_compare_exchange_strong(DST, EXP, SRC) \
({ \
typeof(DST) dst__ = (DST); \
typeof(EXP) expp__ = (EXP); \
typeof(SRC) src__ = (SRC); \
typeof(SRC) exp__ = *expp__; \
typeof(SRC) ret__; \
\
ret__ = __sync_val_compare_and_swap(dst__, exp__, src__); \
if (ret__ != exp__) { \
*expp__ = ret__; \
} \
ret__ == exp__; \
})
#define atomic_compare_exchange_strong_explicit(DST, EXP, SRC, ORD1, ORD2) \
((void) (ORD1), (void) (ORD2), \
atomic_compare_exchange_strong(DST, EXP, SRC))
#define atomic_compare_exchange_weak \
atomic_compare_exchange_strong
#define atomic_compare_exchange_weak_explicit \
atomic_compare_exchange_strong_explicit
#define atomic_exchange_explicit(DST, SRC, ORDER) \
__sync_lock_test_and_set(DST, SRC)
#define atomic_exchange(DST, SRC) \
atomic_exchange_explicit(DST, SRC, memory_order_seq_cst)
#define atomic_op__(RMW, OP, ARG, ORIG) \
({ \
typeof(RMW) rmw__ = (RMW); \
typeof(ARG) arg__ = (ARG); \
typeof(ORIG) orig__ = (ORIG); \
\
if (IS_LOCKLESS_ATOMIC(*rmw__)) { \
*orig__ = __sync_fetch_and_##OP(rmw__, arg__); \
} else { \
atomic_op_locked(rmw__, OP, arg__, orig__); \
} \
(void) 0; \
})
#define atomic_add(RMW, ARG, ORIG) atomic_op__(RMW, add, ARG, ORIG)
#define atomic_sub(RMW, ARG, ORIG) atomic_op__(RMW, sub, ARG, ORIG)
#define atomic_or(RMW, ARG, ORIG) atomic_op__(RMW, or, ARG, ORIG)
#define atomic_xor(RMW, ARG, ORIG) atomic_op__(RMW, xor, ARG, ORIG)
#define atomic_and(RMW, ARG, ORIG) atomic_op__(RMW, and, ARG, ORIG)
#define atomic_add_explicit(RMW, OPERAND, ORIG, ORDER) \
((void) (ORDER), atomic_add(RMW, OPERAND, ORIG))
#define atomic_sub_explicit(RMW, OPERAND, ORIG, ORDER) \
((void) (ORDER), atomic_sub(RMW, OPERAND, ORIG))
#define atomic_or_explicit(RMW, OPERAND, ORIG, ORDER) \
((void) (ORDER), atomic_or(RMW, OPERAND, ORIG))
#define atomic_xor_explicit(RMW, OPERAND, ORIG, ORDER) \
((void) (ORDER), atomic_xor(RMW, OPERAND, ORIG))
#define atomic_and_explicit(RMW, OPERAND, ORIG, ORDER) \
((void) (ORDER), atomic_and(RMW, OPERAND, ORIG))
/* atomic_flag */
typedef struct {
int b;
} atomic_flag;
#define ATOMIC_FLAG_INIT { false }
static inline bool
atomic_flag_test_and_set_explicit(volatile atomic_flag *object,
memory_order order)
{
bool old;
/* __sync_lock_test_and_set() by itself is an acquire barrier.
* For anything higher additional barriers are needed. */
if (order > memory_order_acquire) {
atomic_thread_fence(order);
}
old = __sync_lock_test_and_set(&object->b, 1);
atomic_thread_fence_if_seq_cst(order);
return old;
}
#define atomic_flag_test_and_set(FLAG) \
atomic_flag_test_and_set_explicit(FLAG, memory_order_seq_cst)
static inline void
atomic_flag_clear_explicit(volatile atomic_flag *object,
memory_order order)
{
/* __sync_lock_release() by itself is a release barrier. For
* anything else additional barrier may be needed. */
if (order != memory_order_release) {
atomic_thread_fence(order);
}
__sync_lock_release(&object->b);
atomic_thread_fence_if_seq_cst(order);
}
#define atomic_flag_clear(FLAG) \
atomic_flag_clear_explicit(FLAG, memory_order_seq_cst)
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