Function timer_set_config_state

dpdk/lib/timer/rte_timer.c:221–266

* if timer is pending or stopped (or running on the same core than * us), mark timer as configuring, and on success return the previous * status of the timer */

 * status of the timer
 */
static int
timer_set_config_state(struct rte_timer *tim,
		       union rte_timer_status *ret_prev_status,
		       struct priv_timer *priv_timer)
{
	union rte_timer_status prev_status, status;
	int success = 0;
	unsigned lcore_id;

	lcore_id = rte_lcore_id();

	/* wait that the timer is in correct status before update,
	 * and mark it as being configured */
	prev_status.u32 = rte_atomic_load_explicit(&tim->status.u32, rte_memory_order_relaxed);

	while (success == 0) {
		/* timer is running on another core
		 * or ready to run on local core, exit
		 */
		if (prev_status.state == RTE_TIMER_RUNNING &&
		    (prev_status.owner != (uint16_t)lcore_id ||
		     tim != priv_timer[lcore_id].running_tim))
			return -1;

		/* timer is being configured on another core */
		if (prev_status.state == RTE_TIMER_CONFIG)
			return -1;

		/* here, we know that timer is stopped or pending,
		 * mark it atomically as being configured */
		status.state = RTE_TIMER_CONFIG;
		status.owner = (int16_t)lcore_id;
		/* CONFIG states are acting as locked states. If the
		 * timer is in CONFIG state, the state cannot be changed
		 * by other threads. So, we should use ACQUIRE here.
		 */
		success = rte_atomic_compare_exchange_strong_explicit(&tim->status.u32,
					      (uint32_t *)(uintptr_t)&prev_status.u32,
					      status.u32,
					      rte_memory_order_acquire,
					      rte_memory_order_relaxed);
	}

	ret_prev_status->u32 = prev_status.u32;
	return 0;
}

/*
 * if timer is pending, mark timer as running