| /* |
| * 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 __rcu *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 reciprocal_scale(hash, q->flows_cnt); |
| } |
| |
| 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_proto *filter; |
| 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); |
| |
| filter = rcu_dereference_bh(q->filter_list); |
| if (!filter) |
| return fq_codel_hash(q, skb) + 1; |
| |
| *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; |
| result = tc_classify(skb, filter, &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; |
| sch->q.qlen--; |
| qdisc_qstats_drop(sch); |
| qdisc_qstats_backlog_dec(sch, skb); |
| kfree_skb(skb); |
| 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, prev_backlog; |
| struct fq_codel_flow *flow; |
| int uninitialized_var(ret); |
| |
| idx = fq_codel_classify(skb, sch, &ret); |
| if (idx == 0) { |
| if (ret & __NET_XMIT_BYPASS) |
| qdisc_qstats_drop(sch); |
| 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); |
| qdisc_qstats_backlog_inc(sch, skb); |
| |
| if (list_empty(&flow->flowchain)) { |
| list_add_tail(&flow->flowchain, &q->new_flows); |
| q->new_flow_count++; |
| flow->deficit = q->quantum; |
| flow->dropped = 0; |
| } |
| if (++sch->q.qlen <= sch->limit) |
| return NET_XMIT_SUCCESS; |
| |
| prev_backlog = sch->qstats.backlog; |
| 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_reduce_backlog(sch, 1, prev_backlog - sch->qstats.backlog); |
| 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_sched_data *q = qdisc_priv(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); |
| q->backlogs[flow - q->flows] -= 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; |
| unsigned int prev_backlog; |
| |
| 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; |
| prev_backlog = sch->qstats.backlog; |
| |
| skb = codel_dequeue(sch, &q->cparams, &flow->cvars, &q->cstats, |
| dequeue); |
| |
| 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_reduce_backlog() if our qlen is 0, |
| * or HTB crashes. Defer it for next round. |
| */ |
| if (q->cstats.drop_count && sch->q.qlen) { |
| qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, |
| q->cstats.drop_len); |
| q->cstats.drop_count = 0; |
| q->cstats.drop_len = 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); |
| |
| q->cstats.drop_len += qdisc_pkt_len(skb); |
| kfree_skb(skb); |
| q->cstats.drop_count++; |
| } |
| qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len); |
| q->cstats.drop_count = 0; |
| q->cstats.drop_len = 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) |
| { |
| kvfree(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 = prandom_u32(); |
| INIT_LIST_HEAD(&q->new_flows); |
| INIT_LIST_HEAD(&q->old_flows); |
| codel_params_init(&q->cparams, sch); |
| 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); |
| codel_vars_init(&flow->cvars); |
| } |
| } |
| 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; |
| |
| return nla_nest_end(skb, opts); |
| |
| 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, |
| }; |
| struct list_head *pos; |
| |
| st.qdisc_stats.maxpacket = q->cstats.maxpacket; |
| st.qdisc_stats.drop_overlimit = q->drop_overlimit; |
| st.qdisc_stats.ecn_mark = q->cstats.ecn_mark; |
| st.qdisc_stats.new_flow_count = q->new_flow_count; |
| |
| 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 __rcu **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, NULL, &qs, 0) < 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"); |