1 /* 2 * Codel - The Controlled-Delay Active Queue Management algorithm 3 * 4 * Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com> 5 * Copyright (C) 2011-2012 Van Jacobson <van@pollere.net> 6 * 7 * Implemented on linux by : 8 * Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net> 9 * Copyright (C) 2012 Eric Dumazet <edumazet@google.com> 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions, and the following disclaimer, 16 * without modification. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. The names of the authors may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * Alternatively, provided that this notice is retained in full, this 24 * software may be distributed under the terms of the GNU General 25 * Public License ("GPL") version 2, in which case the provisions of the 26 * GPL apply INSTEAD OF those given above. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 39 * DAMAGE. 40 * 41 */ 42 43 #include <linux/module.h> 44 #include <linux/slab.h> 45 #include <linux/types.h> 46 #include <linux/kernel.h> 47 #include <linux/errno.h> 48 #include <linux/skbuff.h> 49 #include <linux/prefetch.h> 50 #include <net/pkt_sched.h> 51 #include <net/codel.h> 52 53 54 #define DEFAULT_CODEL_LIMIT 1000 55 56 struct codel_sched_data { 57 struct codel_params params; 58 struct codel_vars vars; 59 struct codel_stats stats; 60 u32 drop_overlimit; 61 }; 62 63 /* This is the specific function called from codel_dequeue() 64 * to dequeue a packet from queue. Note: backlog is handled in 65 * codel, we dont need to reduce it here. 66 */ 67 static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch) 68 { 69 struct sk_buff *skb = __skb_dequeue(&sch->q); 70 71 prefetch(&skb->end); /* we'll need skb_shinfo() */ 72 return skb; 73 } 74 75 static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch) 76 { 77 struct codel_sched_data *q = qdisc_priv(sch); 78 struct sk_buff *skb; 79 80 skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue); 81 82 /* We cant call qdisc_tree_decrease_qlen() if our qlen is 0, 83 * or HTB crashes. Defer it for next round. 84 */ 85 if (q->stats.drop_count && sch->q.qlen) { 86 qdisc_tree_decrease_qlen(sch, q->stats.drop_count); 87 q->stats.drop_count = 0; 88 } 89 if (skb) 90 qdisc_bstats_update(sch, skb); 91 return skb; 92 } 93 94 static int codel_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch) 95 { 96 struct codel_sched_data *q; 97 98 if (likely(qdisc_qlen(sch) < sch->limit)) { 99 codel_set_enqueue_time(skb); 100 return qdisc_enqueue_tail(skb, sch); 101 } 102 q = qdisc_priv(sch); 103 q->drop_overlimit++; 104 return qdisc_drop(skb, sch); 105 } 106 107 static const struct nla_policy codel_policy[TCA_CODEL_MAX + 1] = { 108 [TCA_CODEL_TARGET] = { .type = NLA_U32 }, 109 [TCA_CODEL_LIMIT] = { .type = NLA_U32 }, 110 [TCA_CODEL_INTERVAL] = { .type = NLA_U32 }, 111 [TCA_CODEL_ECN] = { .type = NLA_U32 }, 112 }; 113 114 static int codel_change(struct Qdisc *sch, struct nlattr *opt) 115 { 116 struct codel_sched_data *q = qdisc_priv(sch); 117 struct nlattr *tb[TCA_CODEL_MAX + 1]; 118 unsigned int qlen; 119 int err; 120 121 if (!opt) 122 return -EINVAL; 123 124 err = nla_parse_nested(tb, TCA_CODEL_MAX, opt, codel_policy); 125 if (err < 0) 126 return err; 127 128 sch_tree_lock(sch); 129 130 if (tb[TCA_CODEL_TARGET]) { 131 u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]); 132 133 q->params.target = ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT; 134 } 135 136 if (tb[TCA_CODEL_INTERVAL]) { 137 u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]); 138 139 q->params.interval = ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT; 140 } 141 142 if (tb[TCA_CODEL_LIMIT]) 143 sch->limit = nla_get_u32(tb[TCA_CODEL_LIMIT]); 144 145 if (tb[TCA_CODEL_ECN]) 146 q->params.ecn = !!nla_get_u32(tb[TCA_CODEL_ECN]); 147 148 qlen = sch->q.qlen; 149 while (sch->q.qlen > sch->limit) { 150 struct sk_buff *skb = __skb_dequeue(&sch->q); 151 152 qdisc_qstats_backlog_dec(sch, skb); 153 qdisc_drop(skb, sch); 154 } 155 qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen); 156 157 sch_tree_unlock(sch); 158 return 0; 159 } 160 161 static int codel_init(struct Qdisc *sch, struct nlattr *opt) 162 { 163 struct codel_sched_data *q = qdisc_priv(sch); 164 165 sch->limit = DEFAULT_CODEL_LIMIT; 166 167 codel_params_init(&q->params); 168 codel_vars_init(&q->vars); 169 codel_stats_init(&q->stats); 170 171 if (opt) { 172 int err = codel_change(sch, opt); 173 174 if (err) 175 return err; 176 } 177 178 if (sch->limit >= 1) 179 sch->flags |= TCQ_F_CAN_BYPASS; 180 else 181 sch->flags &= ~TCQ_F_CAN_BYPASS; 182 183 return 0; 184 } 185 186 static int codel_dump(struct Qdisc *sch, struct sk_buff *skb) 187 { 188 struct codel_sched_data *q = qdisc_priv(sch); 189 struct nlattr *opts; 190 191 opts = nla_nest_start(skb, TCA_OPTIONS); 192 if (opts == NULL) 193 goto nla_put_failure; 194 195 if (nla_put_u32(skb, TCA_CODEL_TARGET, 196 codel_time_to_us(q->params.target)) || 197 nla_put_u32(skb, TCA_CODEL_LIMIT, 198 sch->limit) || 199 nla_put_u32(skb, TCA_CODEL_INTERVAL, 200 codel_time_to_us(q->params.interval)) || 201 nla_put_u32(skb, TCA_CODEL_ECN, 202 q->params.ecn)) 203 goto nla_put_failure; 204 205 return nla_nest_end(skb, opts); 206 207 nla_put_failure: 208 nla_nest_cancel(skb, opts); 209 return -1; 210 } 211 212 static int codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 213 { 214 const struct codel_sched_data *q = qdisc_priv(sch); 215 struct tc_codel_xstats st = { 216 .maxpacket = q->stats.maxpacket, 217 .count = q->vars.count, 218 .lastcount = q->vars.lastcount, 219 .drop_overlimit = q->drop_overlimit, 220 .ldelay = codel_time_to_us(q->vars.ldelay), 221 .dropping = q->vars.dropping, 222 .ecn_mark = q->stats.ecn_mark, 223 }; 224 225 if (q->vars.dropping) { 226 codel_tdiff_t delta = q->vars.drop_next - codel_get_time(); 227 228 if (delta >= 0) 229 st.drop_next = codel_time_to_us(delta); 230 else 231 st.drop_next = -codel_time_to_us(-delta); 232 } 233 234 return gnet_stats_copy_app(d, &st, sizeof(st)); 235 } 236 237 static void codel_reset(struct Qdisc *sch) 238 { 239 struct codel_sched_data *q = qdisc_priv(sch); 240 241 qdisc_reset_queue(sch); 242 codel_vars_init(&q->vars); 243 } 244 245 static struct Qdisc_ops codel_qdisc_ops __read_mostly = { 246 .id = "codel", 247 .priv_size = sizeof(struct codel_sched_data), 248 249 .enqueue = codel_qdisc_enqueue, 250 .dequeue = codel_qdisc_dequeue, 251 .peek = qdisc_peek_dequeued, 252 .init = codel_init, 253 .reset = codel_reset, 254 .change = codel_change, 255 .dump = codel_dump, 256 .dump_stats = codel_dump_stats, 257 .owner = THIS_MODULE, 258 }; 259 260 static int __init codel_module_init(void) 261 { 262 return register_qdisc(&codel_qdisc_ops); 263 } 264 265 static void __exit codel_module_exit(void) 266 { 267 unregister_qdisc(&codel_qdisc_ops); 268 } 269 270 module_init(codel_module_init) 271 module_exit(codel_module_exit) 272 273 MODULE_DESCRIPTION("Controlled Delay queue discipline"); 274 MODULE_AUTHOR("Dave Taht"); 275 MODULE_AUTHOR("Eric Dumazet"); 276 MODULE_LICENSE("Dual BSD/GPL"); 277