sch_netem.c

linux 内核源代码

	init_crandom(&q->dup_cor, c->dup_corr);
	return 0;
}

static int get_reorder(struct Qdisc *sch, const struct rtattr *attr)
{
	struct netem_sched_data *q = qdisc_priv(sch);
	const struct tc_netem_reorder *r = RTA_DATA(attr);

	if (RTA_PAYLOAD(attr) != sizeof(*r))
		return -EINVAL;

	q->reorder = r->probability;
	init_crandom(&q->reorder_cor, r->correlation);
	return 0;
}

static int get_corrupt(struct Qdisc *sch, const struct rtattr *attr)
{
	struct netem_sched_data *q = qdisc_priv(sch);
	const struct tc_netem_corrupt *r = RTA_DATA(attr);

	if (RTA_PAYLOAD(attr) != sizeof(*r))
		return -EINVAL;

	q->corrupt = r->probability;
	init_crandom(&q->corrupt_cor, r->correlation);
	return 0;
}

/* Parse netlink message to set options */
static int netem_change(struct Qdisc *sch, struct rtattr *opt)
{
	struct netem_sched_data *q = qdisc_priv(sch);
	struct tc_netem_qopt *qopt;
	int ret;

	if (opt == NULL || RTA_PAYLOAD(opt) < sizeof(*qopt))
		return -EINVAL;

	qopt = RTA_DATA(opt);
	ret = set_fifo_limit(q->qdisc, qopt->limit);
	if (ret) {
		pr_debug("netem: can't set fifo limit\n");
		return ret;
	}

	q->latency = qopt->latency;
	q->jitter = qopt->jitter;
	q->limit = qopt->limit;
	q->gap = qopt->gap;
	q->counter = 0;
	q->loss = qopt->loss;
	q->duplicate = qopt->duplicate;

	/* for compatibility with earlier versions.
	 * if gap is set, need to assume 100% probability
	 */
	if (q->gap)
		q->reorder = ~0;

	/* Handle nested options after initial queue options.
	 * Should have put all options in nested format but too late now.
	 */
	if (RTA_PAYLOAD(opt) > sizeof(*qopt)) {
		struct rtattr *tb[TCA_NETEM_MAX];
		if (rtattr_parse(tb, TCA_NETEM_MAX,
				 RTA_DATA(opt) + sizeof(*qopt),
				 RTA_PAYLOAD(opt) - sizeof(*qopt)))
			return -EINVAL;

		if (tb[TCA_NETEM_CORR-1]) {
			ret = get_correlation(sch, tb[TCA_NETEM_CORR-1]);
			if (ret)
				return ret;
		}

		if (tb[TCA_NETEM_DELAY_DIST-1]) {
			ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST-1]);
			if (ret)
				return ret;
		}

		if (tb[TCA_NETEM_REORDER-1]) {
			ret = get_reorder(sch, tb[TCA_NETEM_REORDER-1]);
			if (ret)
				return ret;
		}

		if (tb[TCA_NETEM_CORRUPT-1]) {
			ret = get_corrupt(sch, tb[TCA_NETEM_CORRUPT-1]);
			if (ret)
				return ret;
		}
	}

	return 0;
}

/*
 * Special case version of FIFO queue for use by netem.
 * It queues in order based on timestamps in skb's
 */
struct fifo_sched_data {
	u32 limit;
	psched_time_t oldest;
};

static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
{
	struct fifo_sched_data *q = qdisc_priv(sch);
	struct sk_buff_head *list = &sch->q;
	psched_time_t tnext = ((struct netem_skb_cb *)nskb->cb)->time_to_send;
	struct sk_buff *skb;

	if (likely(skb_queue_len(list) < q->limit)) {
		/* Optimize for add at tail */
		if (likely(skb_queue_empty(list) || tnext >= q->oldest)) {
			q->oldest = tnext;
			return qdisc_enqueue_tail(nskb, sch);
		}

		skb_queue_reverse_walk(list, skb) {
			const struct netem_skb_cb *cb
				= (const struct netem_skb_cb *)skb->cb;

			if (tnext >= cb->time_to_send)
				break;
		}

		__skb_queue_after(list, skb, nskb);

		sch->qstats.backlog += nskb->len;
		sch->bstats.bytes += nskb->len;
		sch->bstats.packets++;

		return NET_XMIT_SUCCESS;
	}

	return qdisc_reshape_fail(nskb, sch);
}

static int tfifo_init(struct Qdisc *sch, struct rtattr *opt)
{
	struct fifo_sched_data *q = qdisc_priv(sch);

	if (opt) {
		struct tc_fifo_qopt *ctl = RTA_DATA(opt);
		if (RTA_PAYLOAD(opt) < sizeof(*ctl))
			return -EINVAL;

		q->limit = ctl->limit;
	} else
		q->limit = max_t(u32, sch->dev->tx_queue_len, 1);

	q->oldest = PSCHED_PASTPERFECT;
	return 0;
}

static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb)
{
	struct fifo_sched_data *q = qdisc_priv(sch);
	struct tc_fifo_qopt opt = { .limit = q->limit };

	RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
	return skb->len;

rtattr_failure:
	return -1;
}

static struct Qdisc_ops tfifo_qdisc_ops = {
	.id		=	"tfifo",
	.priv_size	=	sizeof(struct fifo_sched_data),
	.enqueue	=	tfifo_enqueue,
	.dequeue	=	qdisc_dequeue_head,
	.requeue	=	qdisc_requeue,
	.drop		=	qdisc_queue_drop,
	.init		=	tfifo_init,
	.reset		=	qdisc_reset_queue,
	.change		=	tfifo_init,
	.dump		=	tfifo_dump,
};

static int netem_init(struct Qdisc *sch, struct rtattr *opt)
{
	struct netem_sched_data *q = qdisc_priv(sch);
	int ret;

	if (!opt)
		return -EINVAL;

	qdisc_watchdog_init(&q->watchdog, sch);

	q->qdisc = qdisc_create_dflt(sch->dev, &tfifo_qdisc_ops,
				     TC_H_MAKE(sch->handle, 1));
	if (!q->qdisc) {
		pr_debug("netem: qdisc create failed\n");
		return -ENOMEM;
	}

	ret = netem_change(sch, opt);
	if (ret) {
		pr_debug("netem: change failed\n");
		qdisc_destroy(q->qdisc);
	}
	return ret;
}

static void netem_destroy(struct Qdisc *sch)
{
	struct netem_sched_data *q = qdisc_priv(sch);

	qdisc_watchdog_cancel(&q->watchdog);
	qdisc_destroy(q->qdisc);
	kfree(q->delay_dist);
}

static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
{
	const struct netem_sched_data *q = qdisc_priv(sch);
	unsigned char *b = skb_tail_pointer(skb);
	struct rtattr *rta = (struct rtattr *) b;
	struct tc_netem_qopt qopt;
	struct tc_netem_corr cor;
	struct tc_netem_reorder reorder;
	struct tc_netem_corrupt corrupt;

	qopt.latency = q->latency;
	qopt.jitter = q->jitter;
	qopt.limit = q->limit;
	qopt.loss = q->loss;
	qopt.gap = q->gap;
	qopt.duplicate = q->duplicate;
	RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);

	cor.delay_corr = q->delay_cor.rho;
	cor.loss_corr = q->loss_cor.rho;
	cor.dup_corr = q->dup_cor.rho;
	RTA_PUT(skb, TCA_NETEM_CORR, sizeof(cor), &cor);

	reorder.probability = q->reorder;
	reorder.correlation = q->reorder_cor.rho;
	RTA_PUT(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder);

	corrupt.probability = q->corrupt;
	corrupt.correlation = q->corrupt_cor.rho;
	RTA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);

	rta->rta_len = skb_tail_pointer(skb) - b;

	return skb->len;

rtattr_failure:
	nlmsg_trim(skb, b);
	return -1;
}

static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
			  struct sk_buff *skb, struct tcmsg *tcm)
{
	struct netem_sched_data *q = qdisc_priv(sch);

	if (cl != 1) 	/* only one class */
		return -ENOENT;

	tcm->tcm_handle |= TC_H_MIN(1);
	tcm->tcm_info = q->qdisc->handle;

	return 0;
}

static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
		     struct Qdisc **old)
{
	struct netem_sched_data *q = qdisc_priv(sch);

	if (new == NULL)
		new = &noop_qdisc;

	sch_tree_lock(sch);
	*old = xchg(&q->qdisc, new);
	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
	qdisc_reset(*old);
	sch_tree_unlock(sch);

	return 0;
}

static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
{
	struct netem_sched_data *q = qdisc_priv(sch);
	return q->qdisc;
}

static unsigned long netem_get(struct Qdisc *sch, u32 classid)
{
	return 1;
}

static void netem_put(struct Qdisc *sch, unsigned long arg)
{
}

static int netem_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
			    struct rtattr **tca, unsigned long *arg)
{
	return -ENOSYS;
}

static int netem_delete(struct Qdisc *sch, unsigned long arg)
{
	return -ENOSYS;
}

static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
{
	if (!walker->stop) {
		if (walker->count >= walker->skip)
			if (walker->fn(sch, 1, walker) < 0) {
				walker->stop = 1;
				return;
			}
		walker->count++;
	}
}

static struct tcf_proto **netem_find_tcf(struct Qdisc *sch, unsigned long cl)
{
	return NULL;
}

static struct Qdisc_class_ops netem_class_ops = {
	.graft		=	netem_graft,
	.leaf		=	netem_leaf,
	.get		=	netem_get,
	.put		=	netem_put,
	.change		=	netem_change_class,
	.delete		=	netem_delete,
	.walk		=	netem_walk,
	.tcf_chain	=	netem_find_tcf,
	.dump		=	netem_dump_class,
};

static struct Qdisc_ops netem_qdisc_ops = {
	.id		=	"netem",
	.cl_ops		=	&netem_class_ops,
	.priv_size	=	sizeof(struct netem_sched_data),
	.enqueue	=	netem_enqueue,
	.dequeue	=	netem_dequeue,
	.requeue	=	netem_requeue,
	.drop		=	netem_drop,
	.init		=	netem_init,
	.reset		=	netem_reset,
	.destroy	=	netem_destroy,
	.change		=	netem_change,
	.dump		=	netem_dump,
	.owner		=	THIS_MODULE,
};


static int __init netem_module_init(void)
{
	pr_info("netem: version " VERSION "\n");
	return register_qdisc(&netem_qdisc_ops);
}
static void __exit netem_module_exit(void)
{
	unregister_qdisc(&netem_qdisc_ops);
}
module_init(netem_module_init)
module_exit(netem_module_exit)
MODULE_LICENSE("GPL");