1 files changed, 465 insertions, 0 deletions
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
new file mode 100644
index 00000000..b8e15631
--- /dev/null
+++ b/net/sched/sch_tbf.c
@@ -0,0 +1,465 @@
+/*
+ * net/sched/sch_tbf.c	Token Bucket Filter queue.
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *		Dmitry Torokhov <dtor@mail.ru> - allow attaching inner qdiscs -
+ *						 original idea by Martin Devera
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <net/netlink.h>
+#include <net/pkt_sched.h>
+
+
+/*	Simple Token Bucket Filter.
+	=======================================
+
+	SOURCE.
+	-------
+
+	None.
+
+	Description.
+	------------
+
+	A data flow obeys TBF with rate R and depth B, if for any
+	time interval t_i...t_f the number of transmitted bits
+	does not exceed B + R*(t_f-t_i).
+
+	Packetized version of this definition:
+	The sequence of packets of sizes s_i served at moments t_i
+	obeys TBF, if for any i<=k:
+
+	s_i+....+s_k <= B + R*(t_k - t_i)
+
+	Algorithm.
+	----------
+
+	Let N(t_i) be B/R initially and N(t) grow continuously with time as:
+
+	N(t+delta) = min{B/R, N(t) + delta}
+
+	If the first packet in queue has length S, it may be
+	transmitted only at the time t_* when S/R <= N(t_*),
+	and in this case N(t) jumps:
+
+	N(t_* + 0) = N(t_* - 0) - S/R.
+
+
+
+	Actually, QoS requires two TBF to be applied to a data stream.
+	One of them controls steady state burst size, another
+	one with rate P (peak rate) and depth M (equal to link MTU)
+	limits bursts at a smaller time scale.
+
+	It is easy to see that P>R, and B>M. If P is infinity, this double
+	TBF is equivalent to a single one.
+
+	When TBF works in reshaping mode, latency is estimated as:
+
+	lat = max ((L-B)/R, (L-M)/P)
+
+
+	NOTES.
+	------
+
+	If TBF throttles, it starts a watchdog timer, which will wake it up
+	when it is ready to transmit.
+	Note that the minimal timer resolution is 1/HZ.
+	If no new packets arrive during this period,
+	or if the device is not awaken by EOI for some previous packet,
+	TBF can stop its activity for 1/HZ.
+
+
+	This means, that with depth B, the maximal rate is
+
+	R_crit = B*HZ
+
+	F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes.
+
+	Note that the peak rate TBF is much more tough: with MTU 1500
+	P_crit = 150Kbytes/sec. So, if you need greater peak
+	rates, use alpha with HZ=1000 :-)
+
+	With classful TBF, limit is just kept for backwards compatibility.
+	It is passed to the default bfifo qdisc - if the inner qdisc is
+	changed the limit is not effective anymore.
+*/
+
+struct tbf_sched_data {
+/* Parameters */
+	u32		limit;		/* Maximal length of backlog: bytes */
+	u32		buffer;		/* Token bucket depth/rate: MUST BE >= MTU/B */
+	u32		mtu;
+	u32		max_size;
+	struct qdisc_rate_table	*R_tab;
+	struct qdisc_rate_table	*P_tab;
+
+/* Variables */
+	long	tokens;			/* Current number of B tokens */
+	long	ptokens;		/* Current number of P tokens */
+	psched_time_t	t_c;		/* Time check-point */
+	struct Qdisc	*qdisc;		/* Inner qdisc, default - bfifo queue */
+	struct qdisc_watchdog watchdog;	/* Watchdog timer */
+};
+
+#define L2T(q, L)   qdisc_l2t((q)->R_tab, L)
+#define L2T_P(q, L) qdisc_l2t((q)->P_tab, L)
+
+static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+	int ret;
+
+	if (qdisc_pkt_len(skb) > q->max_size)
+		return qdisc_reshape_fail(skb, sch);
+
+	ret = qdisc_enqueue(skb, q->qdisc);
+	if (ret != NET_XMIT_SUCCESS) {
+		if (net_xmit_drop_count(ret))
+			sch->qstats.drops++;
+		return ret;
+	}
+
+	sch->q.qlen++;
+	return NET_XMIT_SUCCESS;
+}
+
+static unsigned int tbf_drop(struct Qdisc *sch)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+	unsigned int len = 0;
+
+	if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
+		sch->q.qlen--;
+		sch->qstats.drops++;
+	}
+	return len;
+}
+
+static struct sk_buff *tbf_dequeue(struct Qdisc *sch)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+	struct sk_buff *skb;
+
+	skb = q->qdisc->ops->peek(q->qdisc);
+
+	if (skb) {
+		psched_time_t now;
+		long toks;
+		long ptoks = 0;
+		unsigned int len = qdisc_pkt_len(skb);
+
+		now = psched_get_time();
+		toks = psched_tdiff_bounded(now, q->t_c, q->buffer);
+
+		if (q->P_tab) {
+			ptoks = toks + q->ptokens;
+			if (ptoks > (long)q->mtu)
+				ptoks = q->mtu;
+			ptoks -= L2T_P(q, len);
+		}
+		toks += q->tokens;
+		if (toks > (long)q->buffer)
+			toks = q->buffer;
+		toks -= L2T(q, len);
+
+		if ((toks|ptoks) >= 0) {
+			skb = qdisc_dequeue_peeked(q->qdisc);
+			if (unlikely(!skb))
+				return NULL;
+
+			q->t_c = now;
+			q->tokens = toks;
+			q->ptokens = ptoks;
+			sch->q.qlen--;
+			qdisc_unthrottled(sch);
+			qdisc_bstats_update(sch, skb);
+			return skb;
+		}
+
+		qdisc_watchdog_schedule(&q->watchdog,
+					now + max_t(long, -toks, -ptoks));
+
+		/* Maybe we have a shorter packet in the queue,
+		   which can be sent now. It sounds cool,
+		   but, however, this is wrong in principle.
+		   We MUST NOT reorder packets under these circumstances.
+
+		   Really, if we split the flow into independent
+		   subflows, it would be a very good solution.
+		   This is the main idea of all FQ algorithms
+		   (cf. CSZ, HPFQ, HFSC)
+		 */
+
+		sch->qstats.overlimits++;
+	}
+	return NULL;
+}
+
+static void tbf_reset(struct Qdisc *sch)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+
+	qdisc_reset(q->qdisc);
+	sch->q.qlen = 0;
+	q->t_c = psched_get_time();
+	q->tokens = q->buffer;
+	q->ptokens = q->mtu;
+	qdisc_watchdog_cancel(&q->watchdog);
+}
+
+static const struct nla_policy tbf_policy[TCA_TBF_MAX + 1] = {
+	[TCA_TBF_PARMS]	= { .len = sizeof(struct tc_tbf_qopt) },
+	[TCA_TBF_RTAB]	= { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
+	[TCA_TBF_PTAB]	= { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
+};
+
+static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
+{
+	int err;
+	struct tbf_sched_data *q = qdisc_priv(sch);
+	struct nlattr *tb[TCA_TBF_PTAB + 1];
+	struct tc_tbf_qopt *qopt;
+	struct qdisc_rate_table *rtab = NULL;
+	struct qdisc_rate_table *ptab = NULL;
+	struct Qdisc *child = NULL;
+	int max_size, n;
+
+	err = nla_parse_nested(tb, TCA_TBF_PTAB, opt, tbf_policy);
+	if (err < 0)
+		return err;
+
+	err = -EINVAL;
+	if (tb[TCA_TBF_PARMS] == NULL)
+		goto done;
+
+	qopt = nla_data(tb[TCA_TBF_PARMS]);
+	rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB]);
+	if (rtab == NULL)
+		goto done;
+
+	if (qopt->peakrate.rate) {
+		if (qopt->peakrate.rate > qopt->rate.rate)
+			ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB]);
+		if (ptab == NULL)
+			goto done;
+	}
+
+	for (n = 0; n < 256; n++)
+		if (rtab->data[n] > qopt->buffer)
+			break;
+	max_size = (n << qopt->rate.cell_log) - 1;
+	if (ptab) {
+		int size;
+
+		for (n = 0; n < 256; n++)
+			if (ptab->data[n] > qopt->mtu)
+				break;
+		size = (n << qopt->peakrate.cell_log) - 1;
+		if (size < max_size)
+			max_size = size;
+	}
+	if (max_size < 0)
+		goto done;
+
+	if (q->qdisc != &noop_qdisc) {
+		err = fifo_set_limit(q->qdisc, qopt->limit);
+		if (err)
+			goto done;
+	} else if (qopt->limit > 0) {
+		child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit);
+		if (IS_ERR(child)) {
+			err = PTR_ERR(child);
+			goto done;
+		}
+	}
+
+	sch_tree_lock(sch);
+	if (child) {
+		qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
+		qdisc_destroy(q->qdisc);
+		q->qdisc = child;
+	}
+	q->limit = qopt->limit;
+	q->mtu = qopt->mtu;
+	q->max_size = max_size;
+	q->buffer = qopt->buffer;
+	q->tokens = q->buffer;
+	q->ptokens = q->mtu;
+
+	swap(q->R_tab, rtab);
+	swap(q->P_tab, ptab);
+
+	sch_tree_unlock(sch);
+	err = 0;
+done:
+	if (rtab)
+		qdisc_put_rtab(rtab);
+	if (ptab)
+		qdisc_put_rtab(ptab);
+	return err;
+}
+
+static int tbf_init(struct Qdisc *sch, struct nlattr *opt)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+
+	if (opt == NULL)
+		return -EINVAL;
+
+	q->t_c = psched_get_time();
+	qdisc_watchdog_init(&q->watchdog, sch);
+	q->qdisc = &noop_qdisc;
+
+	return tbf_change(sch, opt);
+}
+
+static void tbf_destroy(struct Qdisc *sch)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+
+	qdisc_watchdog_cancel(&q->watchdog);
+
+	if (q->P_tab)
+		qdisc_put_rtab(q->P_tab);
+	if (q->R_tab)
+		qdisc_put_rtab(q->R_tab);
+
+	qdisc_destroy(q->qdisc);
+}
+
+static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+	struct nlattr *nest;
+	struct tc_tbf_qopt opt;
+
+	sch->qstats.backlog = q->qdisc->qstats.backlog;
+	nest = nla_nest_start(skb, TCA_OPTIONS);
+	if (nest == NULL)
+		goto nla_put_failure;
+
+	opt.limit = q->limit;
+	opt.rate = q->R_tab->rate;
+	if (q->P_tab)
+		opt.peakrate = q->P_tab->rate;
+	else
+		memset(&opt.peakrate, 0, sizeof(opt.peakrate));
+	opt.mtu = q->mtu;
+	opt.buffer = q->buffer;
+	NLA_PUT(skb, TCA_TBF_PARMS, sizeof(opt), &opt);
+
+	nla_nest_end(skb, nest);
+	return skb->len;
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -1;
+}
+
+static int tbf_dump_class(struct Qdisc *sch, unsigned long cl,
+			  struct sk_buff *skb, struct tcmsg *tcm)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+
+	tcm->tcm_handle |= TC_H_MIN(1);
+	tcm->tcm_info = q->qdisc->handle;
+
+	return 0;
+}
+
+static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+		     struct Qdisc **old)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+
+	if (new == NULL)
+		new = &noop_qdisc;
+
+	sch_tree_lock(sch);
+	*old = q->qdisc;
+	q->qdisc = new;
+	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
+	qdisc_reset(*old);
+	sch_tree_unlock(sch);
+
+	return 0;
+}
+
+static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg)
+{
+	struct tbf_sched_data *q = qdisc_priv(sch);
+	return q->qdisc;
+}
+
+static unsigned long tbf_get(struct Qdisc *sch, u32 classid)
+{
+	return 1;
+}
+
+static void tbf_put(struct Qdisc *sch, unsigned long arg)
+{
+}
+
+static void tbf_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 const struct Qdisc_class_ops tbf_class_ops = {
+	.graft		=	tbf_graft,
+	.leaf		=	tbf_leaf,
+	.get		=	tbf_get,
+	.put		=	tbf_put,
+	.walk		=	tbf_walk,
+	.dump		=	tbf_dump_class,
+};
+
+static struct Qdisc_ops tbf_qdisc_ops __read_mostly = {
+	.next		=	NULL,
+	.cl_ops		=	&tbf_class_ops,
+	.id		=	"tbf",
+	.priv_size	=	sizeof(struct tbf_sched_data),
+	.enqueue	=	tbf_enqueue,
+	.dequeue	=	tbf_dequeue,
+	.peek		=	qdisc_peek_dequeued,
+	.drop		=	tbf_drop,
+	.init		=	tbf_init,
+	.reset		=	tbf_reset,
+	.destroy	=	tbf_destroy,
+	.change		=	tbf_change,
+	.dump		=	tbf_dump,
+	.owner		=	THIS_MODULE,
+};
+
+static int __init tbf_module_init(void)
+{
+	return register_qdisc(&tbf_qdisc_ops);
+}
+
+static void __exit tbf_module_exit(void)
+{
+	unregister_qdisc(&tbf_qdisc_ops);
+}
+module_init(tbf_module_init)
+module_exit(tbf_module_exit)
+MODULE_LICENSE("GPL");