1 /* SPDX-License-Identifier: BSD-3-Clause
2 * Copyright(c) 2010-2014 Intel Corporation
11 * RTE Read-Write Locks
13 * This file defines an API for read-write locks. The lock is used to
14 * protect data that allows multiple readers in parallel, but only
15 * one writer. All readers are blocked until the writer is finished
24 #include <rte_common.h>
25 #include <rte_atomic.h>
26 #include <rte_pause.h>
29 * The rte_rwlock_t type.
31 * cnt is -1 when write lock is held, and > 0 when read locks are held.
34 volatile int32_t cnt; /**< -1 when W lock held, > 0 when R locks held. */
38 * A static rwlock initializer.
40 #define RTE_RWLOCK_INITIALIZER { 0 }
43 * Initialize the rwlock to an unlocked state.
46 * A pointer to the rwlock structure.
49 rte_rwlock_init(rte_rwlock_t *rwl)
55 * Take a read lock. Loop until the lock is held.
58 * A pointer to a rwlock structure.
61 rte_rwlock_read_lock(rte_rwlock_t *rwl)
66 while (success == 0) {
68 /* write lock is held */
73 success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
79 * Release a read lock.
82 * A pointer to the rwlock structure.
85 rte_rwlock_read_unlock(rte_rwlock_t *rwl)
87 rte_atomic32_dec((rte_atomic32_t *)(intptr_t)&rwl->cnt);
91 * Take a write lock. Loop until the lock is held.
94 * A pointer to a rwlock structure.
97 rte_rwlock_write_lock(rte_rwlock_t *rwl)
102 while (success == 0) {
109 success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
115 * Release a write lock.
118 * A pointer to a rwlock structure.
121 rte_rwlock_write_unlock(rte_rwlock_t *rwl)
123 rte_atomic32_inc((rte_atomic32_t *)(intptr_t)&rwl->cnt);
127 * Try to execute critical section in a hardware memory transaction, if it
128 * fails or not available take a read lock
130 * NOTE: An attempt to perform a HW I/O operation inside a hardware memory
131 * transaction always aborts the transaction since the CPU is not able to
132 * roll-back should the transaction fail. Therefore, hardware transactional
133 * locks are not advised to be used around rte_eth_rx_burst() and
134 * rte_eth_tx_burst() calls.
137 * A pointer to a rwlock structure.
140 rte_rwlock_read_lock_tm(rte_rwlock_t *rwl);
143 * Commit hardware memory transaction or release the read lock if the lock is used as a fall-back
146 * A pointer to the rwlock structure.
149 rte_rwlock_read_unlock_tm(rte_rwlock_t *rwl);
152 * Try to execute critical section in a hardware memory transaction, if it
153 * fails or not available take a write lock
155 * NOTE: An attempt to perform a HW I/O operation inside a hardware memory
156 * transaction always aborts the transaction since the CPU is not able to
157 * roll-back should the transaction fail. Therefore, hardware transactional
158 * locks are not advised to be used around rte_eth_rx_burst() and
159 * rte_eth_tx_burst() calls.
162 * A pointer to a rwlock structure.
165 rte_rwlock_write_lock_tm(rte_rwlock_t *rwl);
168 * Commit hardware memory transaction or release the write lock if the lock is used as a fall-back
171 * A pointer to a rwlock structure.
174 rte_rwlock_write_unlock_tm(rte_rwlock_t *rwl);
180 #endif /* _RTE_RWLOCK_H_ */