Function rte_eth_add_rx_callback

dpdk/lib/ethdev/rte_ethdev.c:5721–5778

const struct rte_eth_rxtx_callback *
rte_eth_add_rx_callback(uint16_t port_id, uint16_t queue_id,
		rte_rx_callback_fn fn, void *user_param)
{
#ifndef RTE_ETHDEV_RXTX_CALLBACKS
	rte_errno = ENOTSUP;
	return NULL;
#endif
	struct rte_eth_dev *dev;

	/* check input parameters */
	if (!rte_eth_dev_is_valid_port(port_id) || fn == NULL ||
		    queue_id >= rte_eth_devices[port_id].data->nb_rx_queues) {
		rte_errno = EINVAL;
		return NULL;
	}
	dev = &rte_eth_devices[port_id];
	if (rte_eth_dev_is_rx_hairpin_queue(dev, queue_id)) {
		rte_errno = EINVAL;
		return NULL;
	}
	struct rte_eth_rxtx_callback *cb = rte_zmalloc(NULL, sizeof(*cb), 0);

	if (cb == NULL) {
		rte_errno = ENOMEM;
		return NULL;
	}

	cb->fn.rx = fn;
	cb->param = user_param;

	rte_spinlock_lock(&eth_dev_rx_cb_lock);
	/* Add the callbacks in fifo order. */
	struct rte_eth_rxtx_callback *tail =
		rte_eth_devices[port_id].post_rx_burst_cbs[queue_id];

	if (!tail) {
		/* Stores to cb->fn and cb->param should complete before
		 * cb is visible to data plane.
		 */
		rte_atomic_store_explicit(
			&rte_eth_devices[port_id].post_rx_burst_cbs[queue_id],
			cb, rte_memory_order_release);

	} else {
		while (tail->next)
			tail = tail->next;
		/* Stores to cb->fn and cb->param should complete before
		 * cb is visible to data plane.
		 */
		rte_atomic_store_explicit(&tail->next, cb, rte_memory_order_release);
	}
	rte_spinlock_unlock(&eth_dev_rx_cb_lock);

	rte_eth_trace_add_rx_callback(port_id, queue_id, fn, user_param, cb);

	return cb;
}