1 files changed, 647 insertions, 0 deletions

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
new file mode 100644
index 0000000..fe1508e
--- /dev/null
+++ b/net/sched/sch_sfq.c
@@ -0,0 +1,647 @@
+/*
+ * net/sched/sch_sfq.c	Stochastic Fairness Queueing discipline.
+ *
+ *		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>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/jiffies.h>
+#include <linux/string.h>
+#include <linux/in.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/ipv6.h>
+#include <linux/skbuff.h>
+#include <linux/jhash.h>
+#include <net/ip.h>
+#include <net/netlink.h>
+#include <net/pkt_sched.h>
+
+
+/*	Stochastic Fairness Queuing algorithm.
+	=======================================
+
+	Source:
+	Paul E. McKenney "Stochastic Fairness Queuing",
+	IEEE INFOCOMM'90 Proceedings, San Francisco, 1990.
+
+	Paul E. McKenney "Stochastic Fairness Queuing",
+	"Interworking: Research and Experience", v.2, 1991, p.113-131.
+
+
+	See also:
+	M. Shreedhar and George Varghese "Efficient Fair
+	Queuing using Deficit Round Robin", Proc. SIGCOMM 95.
+
+
+	This is not the thing that is usually called (W)FQ nowadays.
+	It does not use any timestamp mechanism, but instead
+	processes queues in round-robin order.
+
+	ADVANTAGE:
+
+	- It is very cheap. Both CPU and memory requirements are minimal.
+
+	DRAWBACKS:
+
+	- "Stochastic" -> It is not 100% fair.
+	When hash collisions occur, several flows are considered as one.
+
+	- "Round-robin" -> It introduces larger delays than virtual clock
+	based schemes, and should not be used for isolating interactive
+	traffic	from non-interactive. It means, that this scheduler
+	should be used as leaf of CBQ or P3, which put interactive traffic
+	to higher priority band.
+
+	We still need true WFQ for top level CSZ, but using WFQ
+	for the best effort traffic is absolutely pointless:
+	SFQ is superior for this purpose.
+
+	IMPLEMENTATION:
+	This implementation limits maximal queue length to 128;
+	maximal mtu to 2^15-1; number of hash buckets to 1024.
+	The only goal of this restrictions was that all data
+	fit into one 4K page :-). Struct sfq_sched_data is
+	organized in anti-cache manner: all the data for a bucket
+	are scattered over different locations. This is not good,
+	but it allowed me to put it into 4K.
+
+	It is easy to increase these values, but not in flight.  */
+
+#define SFQ_DEPTH		128
+#define SFQ_HASH_DIVISOR	1024
+
+/* This type should contain at least SFQ_DEPTH*2 values */
+typedef unsigned char sfq_index;
+
+struct sfq_head
+{
+	sfq_index	next;
+	sfq_index	prev;
+};
+
+struct sfq_sched_data
+{
+/* Parameters */
+	int		perturb_period;
+	unsigned	quantum;	/* Allotment per round: MUST BE >= MTU */
+	int		limit;
+
+/* Variables */
+	struct tcf_proto *filter_list;
+	struct timer_list perturb_timer;
+	u32		perturbation;
+	sfq_index	tail;		/* Index of current slot in round */
+	sfq_index	max_depth;	/* Maximal depth */
+
+	sfq_index	ht[SFQ_HASH_DIVISOR];	/* Hash table */
+	sfq_index	next[SFQ_DEPTH];	/* Active slots link */
+	short		allot[SFQ_DEPTH];	/* Current allotment per slot */
+	unsigned short	hash[SFQ_DEPTH];	/* Hash value indexed by slots */
+	struct sk_buff_head	qs[SFQ_DEPTH];		/* Slot queue */
+	struct sfq_head	dep[SFQ_DEPTH*2];	/* Linked list of slots, indexed by depth */
+};
+
+static __inline__ unsigned sfq_fold_hash(struct sfq_sched_data *q, u32 h, u32 h1)
+{
+	return jhash_2words(h, h1, q->perturbation) & (SFQ_HASH_DIVISOR - 1);
+}
+
+static unsigned sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
+{
+	u32 h, h2;
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+	{
+		const struct iphdr *iph = ip_hdr(skb);
+		h = iph->daddr;
+		h2 = iph->saddr ^ iph->protocol;
+		if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
+		    (iph->protocol == IPPROTO_TCP ||
+		     iph->protocol == IPPROTO_UDP ||
+		     iph->protocol == IPPROTO_UDPLITE ||
+		     iph->protocol == IPPROTO_SCTP ||
+		     iph->protocol == IPPROTO_DCCP ||
+		     iph->protocol == IPPROTO_ESP))
+			h2 ^= *(((u32*)iph) + iph->ihl);
+		break;
+	}
+	case htons(ETH_P_IPV6):
+	{
+		struct ipv6hdr *iph = ipv6_hdr(skb);
+		h = iph->daddr.s6_addr32[3];
+		h2 = iph->saddr.s6_addr32[3] ^ iph->nexthdr;
+		if (iph->nexthdr == IPPROTO_TCP ||
+		    iph->nexthdr == IPPROTO_UDP ||
+		    iph->nexthdr == IPPROTO_UDPLITE ||
+		    iph->nexthdr == IPPROTO_SCTP ||
+		    iph->nexthdr == IPPROTO_DCCP ||
+		    iph->nexthdr == IPPROTO_ESP)
+			h2 ^= *(u32*)&iph[1];
+		break;
+	}
+	default:
+		h = (unsigned long)skb->dst ^ skb->protocol;
+		h2 = (unsigned long)skb->sk;
+	}
+
+	return sfq_fold_hash(q, h, h2);
+}
+
+static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch,
+				 int *qerr)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	struct tcf_result res;
+	int result;
+
+	if (TC_H_MAJ(skb->priority) == sch->handle &&
+	    TC_H_MIN(skb->priority) > 0 &&
+	    TC_H_MIN(skb->priority) <= SFQ_HASH_DIVISOR)
+		return TC_H_MIN(skb->priority);
+
+	if (!q->filter_list)
+		return sfq_hash(q, skb) + 1;
+
+	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
+	result = tc_classify(skb, q->filter_list, &res);
+	if (result >= 0) {
+#ifdef CONFIG_NET_CLS_ACT
+		switch (result) {
+		case TC_ACT_STOLEN:
+		case TC_ACT_QUEUED:
+			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
+		case TC_ACT_SHOT:
+			return 0;
+		}
+#endif
+		if (TC_H_MIN(res.classid) <= SFQ_HASH_DIVISOR)
+			return TC_H_MIN(res.classid);
+	}
+	return 0;
+}
+
+static inline void sfq_link(struct sfq_sched_data *q, sfq_index x)
+{
+	sfq_index p, n;
+	int d = q->qs[x].qlen + SFQ_DEPTH;
+
+	p = d;
+	n = q->dep[d].next;
+	q->dep[x].next = n;
+	q->dep[x].prev = p;
+	q->dep[p].next = q->dep[n].prev = x;
+}
+
+static inline void sfq_dec(struct sfq_sched_data *q, sfq_index x)
+{
+	sfq_index p, n;
+
+	n = q->dep[x].next;
+	p = q->dep[x].prev;
+	q->dep[p].next = n;
+	q->dep[n].prev = p;
+
+	if (n == p && q->max_depth == q->qs[x].qlen + 1)
+		q->max_depth--;
+
+	sfq_link(q, x);
+}
+
+static inline void sfq_inc(struct sfq_sched_data *q, sfq_index x)
+{
+	sfq_index p, n;
+	int d;
+
+	n = q->dep[x].next;
+	p = q->dep[x].prev;
+	q->dep[p].next = n;
+	q->dep[n].prev = p;
+	d = q->qs[x].qlen;
+	if (q->max_depth < d)
+		q->max_depth = d;
+
+	sfq_link(q, x);
+}
+
+static unsigned int sfq_drop(struct Qdisc *sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	sfq_index d = q->max_depth;
+	struct sk_buff *skb;
+	unsigned int len;
+
+	/* Queue is full! Find the longest slot and
+	   drop a packet from it */
+
+	if (d > 1) {
+		sfq_index x = q->dep[d + SFQ_DEPTH].next;
+		skb = q->qs[x].prev;
+		len = qdisc_pkt_len(skb);
+		__skb_unlink(skb, &q->qs[x]);
+		kfree_skb(skb);
+		sfq_dec(q, x);
+		sch->q.qlen--;
+		sch->qstats.drops++;
+		sch->qstats.backlog -= len;
+		return len;
+	}
+
+	if (d == 1) {
+		/* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */
+		d = q->next[q->tail];
+		q->next[q->tail] = q->next[d];
+		q->allot[q->next[d]] += q->quantum;
+		skb = q->qs[d].prev;
+		len = qdisc_pkt_len(skb);
+		__skb_unlink(skb, &q->qs[d]);
+		kfree_skb(skb);
+		sfq_dec(q, d);
+		sch->q.qlen--;
+		q->ht[q->hash[d]] = SFQ_DEPTH;
+		sch->qstats.drops++;
+		sch->qstats.backlog -= len;
+		return len;
+	}
+
+	return 0;
+}
+
+static int
+sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	unsigned int hash;
+	sfq_index x;
+	int ret;
+
+	hash = sfq_classify(skb, sch, &ret);
+	if (hash == 0) {
+		if (ret & __NET_XMIT_BYPASS)
+			sch->qstats.drops++;
+		kfree_skb(skb);
+		return ret;
+	}
+	hash--;
+
+	x = q->ht[hash];
+	if (x == SFQ_DEPTH) {
+		q->ht[hash] = x = q->dep[SFQ_DEPTH].next;
+		q->hash[x] = hash;
+	}
+
+	/* If selected queue has length q->limit, this means that
+	 * all another queues are empty and that we do simple tail drop,
+	 * i.e. drop _this_ packet.
+	 */
+	if (q->qs[x].qlen >= q->limit)
+		return qdisc_drop(skb, sch);
+
+	sch->qstats.backlog += qdisc_pkt_len(skb);
+	__skb_queue_tail(&q->qs[x], skb);
+	sfq_inc(q, x);
+	if (q->qs[x].qlen == 1) {		/* The flow is new */
+		if (q->tail == SFQ_DEPTH) {	/* It is the first flow */
+			q->tail = x;
+			q->next[x] = x;
+			q->allot[x] = q->quantum;
+		} else {
+			q->next[x] = q->next[q->tail];
+			q->next[q->tail] = x;
+			q->tail = x;
+		}
+	}
+	if (++sch->q.qlen <= q->limit) {
+		sch->bstats.bytes += qdisc_pkt_len(skb);
+		sch->bstats.packets++;
+		return 0;
+	}
+
+	sfq_drop(sch);
+	return NET_XMIT_CN;
+}
+
+static int
+sfq_requeue(struct sk_buff *skb, struct Qdisc *sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	unsigned int hash;
+	sfq_index x;
+	int ret;
+
+	hash = sfq_classify(skb, sch, &ret);
+	if (hash == 0) {
+		if (ret & __NET_XMIT_BYPASS)
+			sch->qstats.drops++;
+		kfree_skb(skb);
+		return ret;
+	}
+	hash--;
+
+	x = q->ht[hash];
+	if (x == SFQ_DEPTH) {
+		q->ht[hash] = x = q->dep[SFQ_DEPTH].next;
+		q->hash[x] = hash;
+	}
+
+	sch->qstats.backlog += qdisc_pkt_len(skb);
+	__skb_queue_head(&q->qs[x], skb);
+	/* If selected queue has length q->limit+1, this means that
+	 * all another queues are empty and we do simple tail drop.
+	 * This packet is still requeued at head of queue, tail packet
+	 * is dropped.
+	 */
+	if (q->qs[x].qlen > q->limit) {
+		skb = q->qs[x].prev;
+		__skb_unlink(skb, &q->qs[x]);
+		sch->qstats.drops++;
+		sch->qstats.backlog -= qdisc_pkt_len(skb);
+		kfree_skb(skb);
+		return NET_XMIT_CN;
+	}
+
+	sfq_inc(q, x);
+	if (q->qs[x].qlen == 1) {		/* The flow is new */
+		if (q->tail == SFQ_DEPTH) {	/* It is the first flow */
+			q->tail = x;
+			q->next[x] = x;
+			q->allot[x] = q->quantum;
+		} else {
+			q->next[x] = q->next[q->tail];
+			q->next[q->tail] = x;
+			q->tail = x;
+		}
+	}
+
+	if (++sch->q.qlen <= q->limit) {
+		sch->qstats.requeues++;
+		return 0;
+	}
+
+	sch->qstats.drops++;
+	sfq_drop(sch);
+	return NET_XMIT_CN;
+}
+
+
+
+
+static struct sk_buff *
+sfq_dequeue(struct Qdisc *sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	struct sk_buff *skb;
+	sfq_index a, old_a;
+
+	/* No active slots */
+	if (q->tail == SFQ_DEPTH)
+		return NULL;
+
+	a = old_a = q->next[q->tail];
+
+	/* Grab packet */
+	skb = __skb_dequeue(&q->qs[a]);
+	sfq_dec(q, a);
+	sch->q.qlen--;
+	sch->qstats.backlog -= qdisc_pkt_len(skb);
+
+	/* Is the slot empty? */
+	if (q->qs[a].qlen == 0) {
+		q->ht[q->hash[a]] = SFQ_DEPTH;
+		a = q->next[a];
+		if (a == old_a) {
+			q->tail = SFQ_DEPTH;
+			return skb;
+		}
+		q->next[q->tail] = a;
+		q->allot[a] += q->quantum;
+	} else if ((q->allot[a] -= qdisc_pkt_len(skb)) <= 0) {
+		q->tail = a;
+		a = q->next[a];
+		q->allot[a] += q->quantum;
+	}
+	return skb;
+}
+
+static void
+sfq_reset(struct Qdisc *sch)
+{
+	struct sk_buff *skb;
+
+	while ((skb = sfq_dequeue(sch)) != NULL)
+		kfree_skb(skb);
+}
+
+static void sfq_perturbation(unsigned long arg)
+{
+	struct Qdisc *sch = (struct Qdisc *)arg;
+	struct sfq_sched_data *q = qdisc_priv(sch);
+
+	q->perturbation = net_random();
+
+	if (q->perturb_period)
+		mod_timer(&q->perturb_timer, jiffies + q->perturb_period);
+}
+
+static int sfq_change(struct Qdisc *sch, struct nlattr *opt)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	struct tc_sfq_qopt *ctl = nla_data(opt);
+	unsigned int qlen;
+
+	if (opt->nla_len < nla_attr_size(sizeof(*ctl)))
+		return -EINVAL;
+
+	sch_tree_lock(sch);
+	q->quantum = ctl->quantum ? : psched_mtu(qdisc_dev(sch));
+	q->perturb_period = ctl->perturb_period * HZ;
+	if (ctl->limit)
+		q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1);
+
+	qlen = sch->q.qlen;
+	while (sch->q.qlen > q->limit)
+		sfq_drop(sch);
+	qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen);
+
+	del_timer(&q->perturb_timer);
+	if (q->perturb_period) {
+		mod_timer(&q->perturb_timer, jiffies + q->perturb_period);
+		q->perturbation = net_random();
+	}
+	sch_tree_unlock(sch);
+	return 0;
+}
+
+static int sfq_init(struct Qdisc *sch, struct nlattr *opt)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	int i;
+
+	q->perturb_timer.function = sfq_perturbation;
+	q->perturb_timer.data = (unsigned long)sch;;
+	init_timer_deferrable(&q->perturb_timer);
+
+	for (i = 0; i < SFQ_HASH_DIVISOR; i++)
+		q->ht[i] = SFQ_DEPTH;
+
+	for (i = 0; i < SFQ_DEPTH; i++) {
+		skb_queue_head_init(&q->qs[i]);
+		q->dep[i + SFQ_DEPTH].next = i + SFQ_DEPTH;
+		q->dep[i + SFQ_DEPTH].prev = i + SFQ_DEPTH;
+	}
+
+	q->limit = SFQ_DEPTH - 1;
+	q->max_depth = 0;
+	q->tail = SFQ_DEPTH;
+	if (opt == NULL) {
+		q->quantum = psched_mtu(qdisc_dev(sch));
+		q->perturb_period = 0;
+		q->perturbation = net_random();
+	} else {
+		int err = sfq_change(sch, opt);
+		if (err)
+			return err;
+	}
+
+	for (i = 0; i < SFQ_DEPTH; i++)
+		sfq_link(q, i);
+	return 0;
+}
+
+static void sfq_destroy(struct Qdisc *sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+
+	tcf_destroy_chain(&q->filter_list);
+	q->perturb_period = 0;
+	del_timer_sync(&q->perturb_timer);
+}
+
+static int sfq_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	unsigned char *b = skb_tail_pointer(skb);
+	struct tc_sfq_qopt opt;
+
+	opt.quantum = q->quantum;
+	opt.perturb_period = q->perturb_period / HZ;
+
+	opt.limit = q->limit;
+	opt.divisor = SFQ_HASH_DIVISOR;
+	opt.flows = q->limit;
+
+	NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
+
+	return skb->len;
+
+nla_put_failure:
+	nlmsg_trim(skb, b);
+	return -1;
+}
+
+static int sfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
+			    struct nlattr **tca, unsigned long *arg)
+{
+	return -EOPNOTSUPP;
+}
+
+static unsigned long sfq_get(struct Qdisc *sch, u32 classid)
+{
+	return 0;
+}
+
+static struct tcf_proto **sfq_find_tcf(struct Qdisc *sch, unsigned long cl)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+
+	if (cl)
+		return NULL;
+	return &q->filter_list;
+}
+
+static int sfq_dump_class(struct Qdisc *sch, unsigned long cl,
+			  struct sk_buff *skb, struct tcmsg *tcm)
+{
+	tcm->tcm_handle |= TC_H_MIN(cl);
+	return 0;
+}
+
+static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
+				struct gnet_dump *d)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	sfq_index idx = q->ht[cl-1];
+	struct gnet_stats_queue qs = { .qlen = q->qs[idx].qlen };
+	struct tc_sfq_xstats xstats = { .allot = q->allot[idx] };
+
+	if (gnet_stats_copy_queue(d, &qs) < 0)
+		return -1;
+	return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
+}
+
+static void sfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	unsigned int i;
+
+	if (arg->stop)
+		return;
+
+	for (i = 0; i < SFQ_HASH_DIVISOR; i++) {
+		if (q->ht[i] == SFQ_DEPTH ||
+		    arg->count < arg->skip) {
+			arg->count++;
+			continue;
+		}
+		if (arg->fn(sch, i + 1, arg) < 0) {
+			arg->stop = 1;
+			break;
+		}
+		arg->count++;
+	}
+}
+
+static const struct Qdisc_class_ops sfq_class_ops = {
+	.get		=	sfq_get,
+	.change		=	sfq_change_class,
+	.tcf_chain	=	sfq_find_tcf,
+	.dump		=	sfq_dump_class,
+	.dump_stats	=	sfq_dump_class_stats,
+	.walk		=	sfq_walk,
+};
+
+static struct Qdisc_ops sfq_qdisc_ops __read_mostly = {
+	.cl_ops		=	&sfq_class_ops,
+	.id		=	"sfq",
+	.priv_size	=	sizeof(struct sfq_sched_data),
+	.enqueue	=	sfq_enqueue,
+	.dequeue	=	sfq_dequeue,
+	.requeue	=	sfq_requeue,
+	.drop		=	sfq_drop,
+	.init		=	sfq_init,
+	.reset		=	sfq_reset,
+	.destroy	=	sfq_destroy,
+	.change		=	NULL,
+	.dump		=	sfq_dump,
+	.owner		=	THIS_MODULE,
+};
+
+static int __init sfq_module_init(void)
+{
+	return register_qdisc(&sfq_qdisc_ops);
+}
+static void __exit sfq_module_exit(void)
+{
+	unregister_qdisc(&sfq_qdisc_ops);
+}
+module_init(sfq_module_init)
+module_exit(sfq_module_exit)
+MODULE_LICENSE("GPL");