rte_rwlock.h

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/*-
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 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
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 *       notice, this list of conditions and the following disclaimer.
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#ifndef _RTE_RWLOCK_H_
#define _RTE_RWLOCK_H_

#ifdef __cplusplus
extern "C" {
#endif

#include <rte_common.h>
#include <rte_atomic.h>
#include <rte_pause.h>

typedef struct {
    volatile int32_t cnt; 
} rte_rwlock_t;

#define RTE_RWLOCK_INITIALIZER { 0 }

static inline void
rte_rwlock_init(rte_rwlock_t *rwl)
{
    rwl->cnt = 0;
}

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,
                          (uint32_t)x, (uint32_t)(x + 1));
    }
}

static inline void
rte_rwlock_read_unlock(rte_rwlock_t *rwl)
{
    rte_atomic32_dec((rte_atomic32_t *)(intptr_t)&rwl->cnt);
}

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, (uint32_t)-1);
    }
}

static inline void
rte_rwlock_write_unlock(rte_rwlock_t *rwl)
{
    rte_atomic32_inc((rte_atomic32_t *)(intptr_t)&rwl->cnt);
}

static inline void
rte_rwlock_read_lock_tm(rte_rwlock_t *rwl);

static inline void
rte_rwlock_read_unlock_tm(rte_rwlock_t *rwl);

static inline void
rte_rwlock_write_lock_tm(rte_rwlock_t *rwl);

static inline void
rte_rwlock_write_unlock_tm(rte_rwlock_t *rwl);

#ifdef __cplusplus
}
#endif

#endif /* _RTE_RWLOCK_H_ */