-/*-
- * 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.
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2010-2014 Intel Corporation
*/
#ifndef _RTE_RWLOCK_H_
#include <rte_common.h>
#include <rte_atomic.h>
+#include <rte_pause.h>
/**
* The rte_rwlock_t type.
int success = 0;
while (success == 0) {
- x = rwl->cnt;
+ x = __atomic_load_n(&rwl->cnt, __ATOMIC_RELAXED);
/* write lock is held */
if (x < 0) {
rte_pause();
continue;
}
- success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
- x, x + 1);
+ success = __atomic_compare_exchange_n(&rwl->cnt, &x, x + 1, 1,
+ __ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
}
}
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * try to take a read lock.
+ *
+ * @param rwl
+ * A pointer to a rwlock structure.
+ * @return
+ * - zero if the lock is successfully taken
+ * - -EBUSY if lock could not be acquired for reading because a
+ * writer holds the lock
+ */
+__rte_experimental
+static inline int
+rte_rwlock_read_trylock(rte_rwlock_t *rwl)
+{
+ int32_t x;
+ int success = 0;
+
+ while (success == 0) {
+ x = __atomic_load_n(&rwl->cnt, __ATOMIC_RELAXED);
+ /* write lock is held */
+ if (x < 0)
+ return -EBUSY;
+ success = __atomic_compare_exchange_n(&rwl->cnt, &x, x + 1, 1,
+ __ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
+ }
+
+ return 0;
+}
+
/**
* Release a read lock.
*
static inline void
rte_rwlock_read_unlock(rte_rwlock_t *rwl)
{
- rte_atomic32_dec((rte_atomic32_t *)(intptr_t)&rwl->cnt);
+ __atomic_fetch_sub(&rwl->cnt, 1, __ATOMIC_RELEASE);
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * try to take a write lock.
+ *
+ * @param rwl
+ * A pointer to a rwlock structure.
+ * @return
+ * - zero if the lock is successfully taken
+ * - -EBUSY if lock could not be acquired for writing because
+ * it was already locked for reading or writing
+ */
+__rte_experimental
+static inline int
+rte_rwlock_write_trylock(rte_rwlock_t *rwl)
+{
+ int32_t x;
+
+ x = __atomic_load_n(&rwl->cnt, __ATOMIC_RELAXED);
+ if (x != 0 || __atomic_compare_exchange_n(&rwl->cnt, &x, -1, 1,
+ __ATOMIC_ACQUIRE, __ATOMIC_RELAXED) == 0)
+ return -EBUSY;
+
+ return 0;
}
/**
int success = 0;
while (success == 0) {
- x = rwl->cnt;
+ x = __atomic_load_n(&rwl->cnt, __ATOMIC_RELAXED);
/* a lock is held */
if (x != 0) {
rte_pause();
continue;
}
- success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
- 0, -1);
+ success = __atomic_compare_exchange_n(&rwl->cnt, &x, -1, 1,
+ __ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
}
}
static inline void
rte_rwlock_write_unlock(rte_rwlock_t *rwl)
{
- rte_atomic32_inc((rte_atomic32_t *)(intptr_t)&rwl->cnt);
+ __atomic_store_n(&rwl->cnt, 0, __ATOMIC_RELEASE);
}
/**