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Diffstat (limited to 'src/dpdk_lib18/librte_eal/common/include/rte_rwlock.h')
| -rwxr-xr-x | src/dpdk_lib18/librte_eal/common/include/rte_rwlock.h | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/src/dpdk_lib18/librte_eal/common/include/rte_rwlock.h b/src/dpdk_lib18/librte_eal/common/include/rte_rwlock.h new file mode 100755 index 00000000..115731de --- /dev/null +++ b/src/dpdk_lib18/librte_eal/common/include/rte_rwlock.h @@ -0,0 +1,158 @@ +/*- + * BSD LICENSE + * + * Copyright(c) 2010-2014 Intel Corporation. All rights reserved. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * * Neither the name of Intel Corporation nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef _RTE_RWLOCK_H_ +#define _RTE_RWLOCK_H_ + +/** + * @file + * + * RTE Read-Write Locks + * + * This file defines an API for read-write locks. The lock is used to + * protect data that allows multiple readers in parallel, but only + * one writer. All readers are blocked until the writer is finished + * writing. + * + */ + +#ifdef __cplusplus +extern "C" { +#endif + +#include <rte_common.h> +#include <rte_atomic.h> + +/** + * The rte_rwlock_t type. + * + * cnt is -1 when write lock is held, and > 0 when read locks are held. + */ +typedef struct { + volatile int32_t cnt; /**< -1 when W lock held, > 0 when R locks held. */ +} rte_rwlock_t; + +/** + * A static rwlock initializer. + */ +#define RTE_RWLOCK_INITIALIZER { 0 } + +/** + * Initialize the rwlock to an unlocked state. + * + * @param rwl + * A pointer to the rwlock structure. + */ +static inline void +rte_rwlock_init(rte_rwlock_t *rwl) +{ + rwl->cnt = 0; +} + +/** + * Take a read lock. Loop until the lock is held. + * + * @param rwl + * A pointer to a rwlock structure. + */ +static inline void +rte_rwlock_read_lock(rte_rwlock_t *rwl) +{ + int32_t x; + int success = 0; + + while (success == 0) { + x = rwl->cnt; + /* write lock is held */ + if (x < 0) { + rte_pause(); + continue; + } + success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt, + x, x + 1); + } +} + +/** + * Release a read lock. + * + * @param rwl + * A pointer to the rwlock structure. + */ +static inline void +rte_rwlock_read_unlock(rte_rwlock_t *rwl) +{ + rte_atomic32_dec((rte_atomic32_t *)(intptr_t)&rwl->cnt); +} + +/** + * Take a write lock. Loop until the lock is held. + * + * @param rwl + * A pointer to a rwlock structure. + */ +static inline void +rte_rwlock_write_lock(rte_rwlock_t *rwl) +{ + int32_t x; + int success = 0; + + while (success == 0) { + x = rwl->cnt; + /* a lock is held */ + if (x != 0) { + rte_pause(); + continue; + } + success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt, + 0, -1); + } +} + +/** + * Release a write lock. + * + * @param rwl + * A pointer to a rwlock structure. + */ +static inline void +rte_rwlock_write_unlock(rte_rwlock_t *rwl) +{ + rte_atomic32_inc((rte_atomic32_t *)(intptr_t)&rwl->cnt); +} + +#ifdef __cplusplus +} +#endif + +#endif /* _RTE_RWLOCK_H_ */ |