--- /dev/null
+/*
+ * Fair Queue CoDel 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.
+ *
+ * Copyright (C) 2012 Eric Dumazet <edumazet@google.com>
+ */
+
+#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/skbuff.h>
+#include <linux/jhash.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <net/netlink.h>
+#include <net/pkt_sched.h>
+#include <net/flow_keys.h>
+#include <net/codel.h>
+
+/* Fair Queue CoDel.
+ *
+ * Principles :
+ * Packets are classified (internal classifier or external) on flows.
+ * This is a Stochastic model (as we use a hash, several flows
+ * might be hashed on same slot)
+ * Each flow has a CoDel managed queue.
+ * Flows are linked onto two (Round Robin) lists,
+ * so that new flows have priority on old ones.
+ *
+ * For a given flow, packets are not reordered (CoDel uses a FIFO)
+ * head drops only.
+ * ECN capability is on by default.
+ * Low memory footprint (64 bytes per flow)
+ */
+
+struct fq_codel_flow {
+ struct sk_buff *head;
+ struct sk_buff *tail;
+ struct list_head flowchain;
+ int deficit;
+ u32 dropped; /* number of drops (or ECN marks) on this flow */
+ struct codel_vars cvars;
+}; /* please try to keep this structure <= 64 bytes */
+
+struct fq_codel_sched_data {
+ struct tcf_proto *filter_list; /* optional external classifier */
+ struct fq_codel_flow *flows; /* Flows table [flows_cnt] */
+ u32 *backlogs; /* backlog table [flows_cnt] */
+ u32 flows_cnt; /* number of flows */
+ u32 perturbation; /* hash perturbation */
+ u32 quantum; /* psched_mtu(qdisc_dev(sch)); */
+ struct codel_params cparams;
+ struct codel_stats cstats;
+ u32 drop_overlimit;
+ u32 new_flow_count;
+
+ struct list_head new_flows; /* list of new flows */
+ struct list_head old_flows; /* list of old flows */
+};
+
+static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
+ const struct sk_buff *skb)
+{
+ struct flow_keys keys;
+ unsigned int hash;
+
+ skb_flow_dissect(skb, &keys);
+ hash = jhash_3words((__force u32)keys.dst,
+ (__force u32)keys.src ^ keys.ip_proto,
+ (__force u32)keys.ports, q->perturbation);
+ return ((u64)hash * q->flows_cnt) >> 32;
+}
+
+static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,
+ int *qerr)
+{
+ struct fq_codel_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) <= q->flows_cnt)
+ return TC_H_MIN(skb->priority);
+
+ if (!q->filter_list)
+ return fq_codel_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) <= q->flows_cnt)
+ return TC_H_MIN(res.classid);
+ }
+ return 0;
+}
+
+/* helper functions : might be changed when/if skb use a standard list_head */
+
+/* remove one skb from head of slot queue */
+static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
+{
+ struct sk_buff *skb = flow->head;
+
+ flow->head = skb->next;
+ skb->next = NULL;
+ return skb;
+}
+
+/* add skb to flow queue (tail add) */
+static inline void flow_queue_add(struct fq_codel_flow *flow,
+ struct sk_buff *skb)
+{
+ if (flow->head == NULL)
+ flow->head = skb;
+ else
+ flow->tail->next = skb;
+ flow->tail = skb;
+ skb->next = NULL;
+}
+
+static unsigned int fq_codel_drop(struct Qdisc *sch)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+ struct sk_buff *skb;
+ unsigned int maxbacklog = 0, idx = 0, i, len;
+ struct fq_codel_flow *flow;
+
+ /* Queue is full! Find the fat flow and drop packet from it.
+ * This might sound expensive, but with 1024 flows, we scan
+ * 4KB of memory, and we dont need to handle a complex tree
+ * in fast path (packet queue/enqueue) with many cache misses.
+ */
+ for (i = 0; i < q->flows_cnt; i++) {
+ if (q->backlogs[i] > maxbacklog) {
+ maxbacklog = q->backlogs[i];
+ idx = i;
+ }
+ }
+ flow = &q->flows[idx];
+ skb = dequeue_head(flow);
+ len = qdisc_pkt_len(skb);
+ q->backlogs[idx] -= len;
+ kfree_skb(skb);
+ sch->q.qlen--;
+ sch->qstats.drops++;
+ sch->qstats.backlog -= len;
+ flow->dropped++;
+ return idx;
+}
+
+static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+ unsigned int idx;
+ struct fq_codel_flow *flow;
+ int uninitialized_var(ret);
+
+ idx = fq_codel_classify(skb, sch, &ret);
+ if (idx == 0) {
+ if (ret & __NET_XMIT_BYPASS)
+ sch->qstats.drops++;
+ kfree_skb(skb);
+ return ret;
+ }
+ idx--;
+
+ codel_set_enqueue_time(skb);
+ flow = &q->flows[idx];
+ flow_queue_add(flow, skb);
+ q->backlogs[idx] += qdisc_pkt_len(skb);
+ sch->qstats.backlog += qdisc_pkt_len(skb);
+
+ if (list_empty(&flow->flowchain)) {
+ list_add_tail(&flow->flowchain, &q->new_flows);
+ codel_vars_init(&flow->cvars);
+ q->new_flow_count++;
+ flow->deficit = q->quantum;
+ flow->dropped = 0;
+ }
+ if (++sch->q.qlen < sch->limit)
+ return NET_XMIT_SUCCESS;
+
+ q->drop_overlimit++;
+ /* Return Congestion Notification only if we dropped a packet
+ * from this flow.
+ */
+ if (fq_codel_drop(sch) == idx)
+ return NET_XMIT_CN;
+
+ /* As we dropped a packet, better let upper stack know this */
+ qdisc_tree_decrease_qlen(sch, 1);
+ return NET_XMIT_SUCCESS;
+}
+
+/* This is the specific function called from codel_dequeue()
+ * to dequeue a packet from queue. Note: backlog is handled in
+ * codel, we dont need to reduce it here.
+ */
+static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
+{
+ struct fq_codel_flow *flow;
+ struct sk_buff *skb = NULL;
+
+ flow = container_of(vars, struct fq_codel_flow, cvars);
+ if (flow->head) {
+ skb = dequeue_head(flow);
+ sch->qstats.backlog -= qdisc_pkt_len(skb);
+ sch->q.qlen--;
+ }
+ return skb;
+}
+
+static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+ struct sk_buff *skb;
+ struct fq_codel_flow *flow;
+ struct list_head *head;
+ u32 prev_drop_count, prev_ecn_mark;
+
+begin:
+ head = &q->new_flows;
+ if (list_empty(head)) {
+ head = &q->old_flows;
+ if (list_empty(head))
+ return NULL;
+ }
+ flow = list_first_entry(head, struct fq_codel_flow, flowchain);
+
+ if (flow->deficit <= 0) {
+ flow->deficit += q->quantum;
+ list_move_tail(&flow->flowchain, &q->old_flows);
+ goto begin;
+ }
+
+ prev_drop_count = q->cstats.drop_count;
+ prev_ecn_mark = q->cstats.ecn_mark;
+
+ skb = codel_dequeue(sch, &q->cparams, &flow->cvars, &q->cstats,
+ dequeue, &q->backlogs[flow - q->flows]);
+
+ flow->dropped += q->cstats.drop_count - prev_drop_count;
+ flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
+
+ if (!skb) {
+ /* force a pass through old_flows to prevent starvation */
+ if ((head == &q->new_flows) && !list_empty(&q->old_flows))
+ list_move_tail(&flow->flowchain, &q->old_flows);
+ else
+ list_del_init(&flow->flowchain);
+ goto begin;
+ }
+ qdisc_bstats_update(sch, skb);
+ flow->deficit -= qdisc_pkt_len(skb);
+ /* We cant call qdisc_tree_decrease_qlen() if our qlen is 0,
+ * or HTB crashes. Defer it for next round.
+ */
+ if (q->cstats.drop_count && sch->q.qlen) {
+ qdisc_tree_decrease_qlen(sch, q->cstats.drop_count);
+ q->cstats.drop_count = 0;
+ }
+ return skb;
+}
+
+static void fq_codel_reset(struct Qdisc *sch)
+{
+ struct sk_buff *skb;
+
+ while ((skb = fq_codel_dequeue(sch)) != NULL)
+ kfree_skb(skb);
+}
+
+static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
+ [TCA_FQ_CODEL_TARGET] = { .type = NLA_U32 },
+ [TCA_FQ_CODEL_LIMIT] = { .type = NLA_U32 },
+ [TCA_FQ_CODEL_INTERVAL] = { .type = NLA_U32 },
+ [TCA_FQ_CODEL_ECN] = { .type = NLA_U32 },
+ [TCA_FQ_CODEL_FLOWS] = { .type = NLA_U32 },
+ [TCA_FQ_CODEL_QUANTUM] = { .type = NLA_U32 },
+};
+
+static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+ struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
+ int err;
+
+ if (!opt)
+ return -EINVAL;
+
+ err = nla_parse_nested(tb, TCA_FQ_CODEL_MAX, opt, fq_codel_policy);
+ if (err < 0)
+ return err;
+ if (tb[TCA_FQ_CODEL_FLOWS]) {
+ if (q->flows)
+ return -EINVAL;
+ q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
+ if (!q->flows_cnt ||
+ q->flows_cnt > 65536)
+ return -EINVAL;
+ }
+ sch_tree_lock(sch);
+
+ if (tb[TCA_FQ_CODEL_TARGET]) {
+ u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
+
+ q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
+ }
+
+ if (tb[TCA_FQ_CODEL_INTERVAL]) {
+ u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
+
+ q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
+ }
+
+ if (tb[TCA_FQ_CODEL_LIMIT])
+ sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
+
+ if (tb[TCA_FQ_CODEL_ECN])
+ q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
+
+ if (tb[TCA_FQ_CODEL_QUANTUM])
+ q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
+
+ while (sch->q.qlen > sch->limit) {
+ struct sk_buff *skb = fq_codel_dequeue(sch);
+
+ kfree_skb(skb);
+ q->cstats.drop_count++;
+ }
+ qdisc_tree_decrease_qlen(sch, q->cstats.drop_count);
+ q->cstats.drop_count = 0;
+
+ sch_tree_unlock(sch);
+ return 0;
+}
+
+static void *fq_codel_zalloc(size_t sz)
+{
+ void *ptr = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN);
+
+ if (!ptr)
+ ptr = vzalloc(sz);
+ return ptr;
+}
+
+static void fq_codel_free(void *addr)
+{
+ if (addr) {
+ if (is_vmalloc_addr(addr))
+ vfree(addr);
+ else
+ kfree(addr);
+ }
+}
+
+static void fq_codel_destroy(struct Qdisc *sch)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+
+ tcf_destroy_chain(&q->filter_list);
+ fq_codel_free(q->backlogs);
+ fq_codel_free(q->flows);
+}
+
+static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+ int i;
+
+ sch->limit = 10*1024;
+ q->flows_cnt = 1024;
+ q->quantum = psched_mtu(qdisc_dev(sch));
+ q->perturbation = net_random();
+ INIT_LIST_HEAD(&q->new_flows);
+ INIT_LIST_HEAD(&q->old_flows);
+ codel_params_init(&q->cparams);
+ codel_stats_init(&q->cstats);
+ q->cparams.ecn = true;
+
+ if (opt) {
+ int err = fq_codel_change(sch, opt);
+ if (err)
+ return err;
+ }
+
+ if (!q->flows) {
+ q->flows = fq_codel_zalloc(q->flows_cnt *
+ sizeof(struct fq_codel_flow));
+ if (!q->flows)
+ return -ENOMEM;
+ q->backlogs = fq_codel_zalloc(q->flows_cnt * sizeof(u32));
+ if (!q->backlogs) {
+ fq_codel_free(q->flows);
+ return -ENOMEM;
+ }
+ for (i = 0; i < q->flows_cnt; i++) {
+ struct fq_codel_flow *flow = q->flows + i;
+
+ INIT_LIST_HEAD(&flow->flowchain);
+ }
+ }
+ if (sch->limit >= 1)
+ sch->flags |= TCQ_F_CAN_BYPASS;
+ else
+ sch->flags &= ~TCQ_F_CAN_BYPASS;
+ return 0;
+}
+
+static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+ struct nlattr *opts;
+
+ opts = nla_nest_start(skb, TCA_OPTIONS);
+ if (opts == NULL)
+ goto nla_put_failure;
+
+ if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
+ codel_time_to_us(q->cparams.target)) ||
+ nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
+ sch->limit) ||
+ nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
+ codel_time_to_us(q->cparams.interval)) ||
+ nla_put_u32(skb, TCA_FQ_CODEL_ECN,
+ q->cparams.ecn) ||
+ nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
+ q->quantum) ||
+ nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
+ q->flows_cnt))
+ goto nla_put_failure;
+
+ nla_nest_end(skb, opts);
+ return skb->len;
+
+nla_put_failure:
+ return -1;
+}
+
+static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+ struct tc_fq_codel_xstats st = {
+ .type = TCA_FQ_CODEL_XSTATS_QDISC,
+ .qdisc_stats.maxpacket = q->cstats.maxpacket,
+ .qdisc_stats.drop_overlimit = q->drop_overlimit,
+ .qdisc_stats.ecn_mark = q->cstats.ecn_mark,
+ .qdisc_stats.new_flow_count = q->new_flow_count,
+ };
+ struct list_head *pos;
+
+ list_for_each(pos, &q->new_flows)
+ st.qdisc_stats.new_flows_len++;
+
+ list_for_each(pos, &q->old_flows)
+ st.qdisc_stats.old_flows_len++;
+
+ return gnet_stats_copy_app(d, &st, sizeof(st));
+}
+
+static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
+{
+ return NULL;
+}
+
+static unsigned long fq_codel_get(struct Qdisc *sch, u32 classid)
+{
+ return 0;
+}
+
+static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
+ u32 classid)
+{
+ /* we cannot bypass queue discipline anymore */
+ sch->flags &= ~TCQ_F_CAN_BYPASS;
+ return 0;
+}
+
+static void fq_codel_put(struct Qdisc *q, unsigned long cl)
+{
+}
+
+static struct tcf_proto **fq_codel_find_tcf(struct Qdisc *sch, unsigned long cl)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+
+ if (cl)
+ return NULL;
+ return &q->filter_list;
+}
+
+static int fq_codel_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 fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
+ struct gnet_dump *d)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+ u32 idx = cl - 1;
+ struct gnet_stats_queue qs = { 0 };
+ struct tc_fq_codel_xstats xstats;
+
+ if (idx < q->flows_cnt) {
+ const struct fq_codel_flow *flow = &q->flows[idx];
+ const struct sk_buff *skb = flow->head;
+
+ memset(&xstats, 0, sizeof(xstats));
+ xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
+ xstats.class_stats.deficit = flow->deficit;
+ xstats.class_stats.ldelay =
+ codel_time_to_us(flow->cvars.ldelay);
+ xstats.class_stats.count = flow->cvars.count;
+ xstats.class_stats.lastcount = flow->cvars.lastcount;
+ xstats.class_stats.dropping = flow->cvars.dropping;
+ if (flow->cvars.dropping) {
+ codel_tdiff_t delta = flow->cvars.drop_next -
+ codel_get_time();
+
+ xstats.class_stats.drop_next = (delta >= 0) ?
+ codel_time_to_us(delta) :
+ -codel_time_to_us(-delta);
+ }
+ while (skb) {
+ qs.qlen++;
+ skb = skb->next;
+ }
+ qs.backlog = q->backlogs[idx];
+ qs.drops = flow->dropped;
+ }
+ if (gnet_stats_copy_queue(d, &qs) < 0)
+ return -1;
+ if (idx < q->flows_cnt)
+ return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
+ return 0;
+}
+
+static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
+{
+ struct fq_codel_sched_data *q = qdisc_priv(sch);
+ unsigned int i;
+
+ if (arg->stop)
+ return;
+
+ for (i = 0; i < q->flows_cnt; i++) {
+ if (list_empty(&q->flows[i].flowchain) ||
+ 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 fq_codel_class_ops = {
+ .leaf = fq_codel_leaf,
+ .get = fq_codel_get,
+ .put = fq_codel_put,
+ .tcf_chain = fq_codel_find_tcf,
+ .bind_tcf = fq_codel_bind,
+ .unbind_tcf = fq_codel_put,
+ .dump = fq_codel_dump_class,
+ .dump_stats = fq_codel_dump_class_stats,
+ .walk = fq_codel_walk,
+};
+
+static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
+ .cl_ops = &fq_codel_class_ops,
+ .id = "fq_codel",
+ .priv_size = sizeof(struct fq_codel_sched_data),
+ .enqueue = fq_codel_enqueue,
+ .dequeue = fq_codel_dequeue,
+ .peek = qdisc_peek_dequeued,
+ .drop = fq_codel_drop,
+ .init = fq_codel_init,
+ .reset = fq_codel_reset,
+ .destroy = fq_codel_destroy,
+ .change = fq_codel_change,
+ .dump = fq_codel_dump,
+ .dump_stats = fq_codel_dump_stats,
+ .owner = THIS_MODULE,
+};
+
+static int __init fq_codel_module_init(void)
+{
+ return register_qdisc(&fq_codel_qdisc_ops);
+}
+
+static void __exit fq_codel_module_exit(void)
+{
+ unregister_qdisc(&fq_codel_qdisc_ops);
+}
+
+module_init(fq_codel_module_init)
+module_exit(fq_codel_module_exit)
+MODULE_AUTHOR("Eric Dumazet");
+MODULE_LICENSE("GPL");
projects / karo-tx-linux.git / commitdiff