DPDK  20.11.3
examples/performance-thread/common/lthread_mutex.c
/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2015 Intel Corporation
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stddef.h>
#include <limits.h>
#include <inttypes.h>
#include <unistd.h>
#include <pthread.h>
#include <fcntl.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <rte_per_lcore.h>
#include <rte_log.h>
#include <rte_spinlock.h>
#include <rte_common.h>
#include "lthread_api.h"
#include "lthread_int.h"
#include "lthread_mutex.h"
#include "lthread_sched.h"
#include "lthread_queue.h"
#include "lthread_objcache.h"
#include "lthread_diag.h"
/*
* Create a mutex
*/
int
lthread_mutex_init(char *name, struct lthread_mutex **mutex,
__rte_unused const struct lthread_mutexattr *attr)
{
struct lthread_mutex *m;
if (mutex == NULL)
return POSIX_ERRNO(EINVAL);
m = _lthread_objcache_alloc((THIS_SCHED)->mutex_cache);
if (m == NULL)
return POSIX_ERRNO(EAGAIN);
m->blocked = _lthread_queue_create("blocked queue");
if (m->blocked == NULL) {
_lthread_objcache_free((THIS_SCHED)->mutex_cache, m);
return POSIX_ERRNO(EAGAIN);
}
if (name == NULL)
strncpy(m->name, "no name", sizeof(m->name));
else
strncpy(m->name, name, sizeof(m->name));
m->name[sizeof(m->name)-1] = 0;
m->root_sched = THIS_SCHED;
m->owner = NULL;
rte_atomic64_init(&m->count);
DIAG_CREATE_EVENT(m, LT_DIAG_MUTEX_CREATE);
/* success */
(*mutex) = m;
return 0;
}
/*
* Destroy a mutex
*/
int lthread_mutex_destroy(struct lthread_mutex *m)
{
if ((m == NULL) || (m->blocked == NULL)) {
DIAG_EVENT(m, LT_DIAG_MUTEX_DESTROY, m, POSIX_ERRNO(EINVAL));
return POSIX_ERRNO(EINVAL);
}
if (m->owner == NULL) {
/* try to delete the blocked queue */
if (_lthread_queue_destroy(m->blocked) < 0) {
DIAG_EVENT(m, LT_DIAG_MUTEX_DESTROY,
m, POSIX_ERRNO(EBUSY));
return POSIX_ERRNO(EBUSY);
}
/* free the mutex to cache */
_lthread_objcache_free(m->root_sched->mutex_cache, m);
DIAG_EVENT(m, LT_DIAG_MUTEX_DESTROY, m, 0);
return 0;
}
/* can't do its still in use */
DIAG_EVENT(m, LT_DIAG_MUTEX_DESTROY, m, POSIX_ERRNO(EBUSY));
return POSIX_ERRNO(EBUSY);
}
/*
* Try to obtain a mutex
*/
int lthread_mutex_lock(struct lthread_mutex *m)
{
struct lthread *lt = THIS_LTHREAD;
if ((m == NULL) || (m->blocked == NULL)) {
DIAG_EVENT(m, LT_DIAG_MUTEX_LOCK, m, POSIX_ERRNO(EINVAL));
return POSIX_ERRNO(EINVAL);
}
/* allow no recursion */
if (m->owner == lt) {
DIAG_EVENT(m, LT_DIAG_MUTEX_LOCK, m, POSIX_ERRNO(EDEADLK));
return POSIX_ERRNO(EDEADLK);
}
for (;;) {
rte_atomic64_inc(&m->count);
do {
((uint64_t *) &m->owner, 0, (uint64_t) lt)) {
/* happy days, we got the lock */
DIAG_EVENT(m, LT_DIAG_MUTEX_LOCK, m, 0);
return 0;
}
/* spin due to race with unlock when
* nothing was blocked
*/
} while ((rte_atomic64_read(&m->count) == 1) &&
(m->owner == NULL));
/* queue the current thread in the blocked queue
* we defer this to after we return to the scheduler
* to ensure that the current thread context is saved
* before unlock could result in it being dequeued and
* resumed
*/
DIAG_EVENT(m, LT_DIAG_MUTEX_BLOCKED, m, lt);
lt->pending_wr_queue = m->blocked;
/* now relinquish cpu */
_suspend();
/* resumed, must loop and compete for the lock again */
}
return 0;
}
/* try to lock a mutex but don't block */
int lthread_mutex_trylock(struct lthread_mutex *m)
{
struct lthread *lt = THIS_LTHREAD;
if ((m == NULL) || (m->blocked == NULL)) {
DIAG_EVENT(m, LT_DIAG_MUTEX_TRYLOCK, m, POSIX_ERRNO(EINVAL));
return POSIX_ERRNO(EINVAL);
}
if (m->owner == lt) {
/* no recursion */
DIAG_EVENT(m, LT_DIAG_MUTEX_TRYLOCK, m, POSIX_ERRNO(EDEADLK));
return POSIX_ERRNO(EDEADLK);
}
rte_atomic64_inc(&m->count);
((uint64_t *) &m->owner, (uint64_t) NULL, (uint64_t) lt)) {
/* got the lock */
DIAG_EVENT(m, LT_DIAG_MUTEX_TRYLOCK, m, 0);
return 0;
}
/* failed so return busy */
rte_atomic64_dec(&m->count);
DIAG_EVENT(m, LT_DIAG_MUTEX_TRYLOCK, m, POSIX_ERRNO(EBUSY));
return POSIX_ERRNO(EBUSY);
}
/*
* Unlock a mutex
*/
int lthread_mutex_unlock(struct lthread_mutex *m)
{
struct lthread *lt = THIS_LTHREAD;
struct lthread *unblocked;
if ((m == NULL) || (m->blocked == NULL)) {
DIAG_EVENT(m, LT_DIAG_MUTEX_UNLOCKED, m, POSIX_ERRNO(EINVAL));
return POSIX_ERRNO(EINVAL);
}
/* fail if its owned */
if (m->owner != lt || m->owner == NULL) {
DIAG_EVENT(m, LT_DIAG_MUTEX_UNLOCKED, m, POSIX_ERRNO(EPERM));
return POSIX_ERRNO(EPERM);
}
rte_atomic64_dec(&m->count);
/* if there are blocked threads then make one ready */
while (rte_atomic64_read(&m->count) > 0) {
unblocked = _lthread_queue_remove(m->blocked);
if (unblocked != NULL) {
rte_atomic64_dec(&m->count);
DIAG_EVENT(m, LT_DIAG_MUTEX_UNLOCKED, m, unblocked);
RTE_ASSERT(unblocked->sched != NULL);
_ready_queue_insert((struct lthread_sched *)
unblocked->sched, unblocked);
break;
}
}
/* release the lock */
m->owner = NULL;
return 0;
}
/*
* return the diagnostic ref val stored in a mutex
*/
uint64_t
lthread_mutex_diag_ref(struct lthread_mutex *m)
{
if (m == NULL)
return 0;
return m->diag_ref;
}