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) 2012,2015 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 #include <net/codel_impl.h> 53 #include <net/codel_qdisc.h> 54 55 56 #define DEFAULT_CODEL_LIMIT 1000 57 58 struct codel_sched_data { 59 struct codel_params params; 60 struct codel_vars vars; 61 struct codel_stats stats; 62 u32 drop_overlimit; 63 }; 64 65 /* This is the specific function called from codel_dequeue() 66 * to dequeue a packet from queue. Note: backlog is handled in 67 * codel, we dont need to reduce it here. 68 */ 69 static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx) 70 { 71 struct Qdisc *sch = ctx; 72 struct sk_buff *skb = __skb_dequeue(&sch->q); 73 74 if (skb) 75 sch->qstats.backlog -= qdisc_pkt_len(skb); 76 77 prefetch(&skb->end); /* we'll need skb_shinfo() */ 78 return skb; 79 } 80 81 static void drop_func(struct sk_buff *skb, void *ctx) 82 { 83 struct Qdisc *sch = ctx; 84 85 qdisc_drop(skb, sch); 86 } 87 88 static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch) 89 { 90 struct codel_sched_data *q = qdisc_priv(sch); 91 struct sk_buff *skb; 92 93 skb = codel_dequeue(sch, &sch->qstats.backlog, &q->params, &q->vars, 94 &q->stats, qdisc_pkt_len, codel_get_enqueue_time, 95 drop_func, dequeue_func); 96 97 /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0, 98 * or HTB crashes. Defer it for next round. 99 */ 100 if (q->stats.drop_count && sch->q.qlen) { 101 qdisc_tree_reduce_backlog(sch, q->stats.drop_count, q->stats.drop_len); 102 q->stats.drop_count = 0; 103 q->stats.drop_len = 0; 104 } 105 if (skb) 106 qdisc_bstats_update(sch, skb); 107 return skb; 108 } 109 110 static int codel_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch) 111 { 112 struct codel_sched_data *q; 113 114 if (likely(qdisc_qlen(sch) < sch->limit)) { 115 codel_set_enqueue_time(skb); 116 return qdisc_enqueue_tail(skb, sch); 117 } 118 q = qdisc_priv(sch); 119 q->drop_overlimit++; 120 return qdisc_drop(skb, sch); 121 } 122 123 static const struct nla_policy codel_policy[TCA_CODEL_MAX + 1] = { 124 [TCA_CODEL_TARGET] = { .type = NLA_U32 }, 125 [TCA_CODEL_LIMIT] = { .type = NLA_U32 }, 126 [TCA_CODEL_INTERVAL] = { .type = NLA_U32 }, 127 [TCA_CODEL_ECN] = { .type = NLA_U32 }, 128 [TCA_CODEL_CE_THRESHOLD]= { .type = NLA_U32 }, 129 }; 130 131 static int codel_change(struct Qdisc *sch, struct nlattr *opt) 132 { 133 struct codel_sched_data *q = qdisc_priv(sch); 134 struct nlattr *tb[TCA_CODEL_MAX + 1]; 135 unsigned int qlen, dropped = 0; 136 int err; 137 138 if (!opt) 139 return -EINVAL; 140 141 err = nla_parse_nested(tb, TCA_CODEL_MAX, opt, codel_policy); 142 if (err < 0) 143 return err; 144 145 sch_tree_lock(sch); 146 147 if (tb[TCA_CODEL_TARGET]) { 148 u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]); 149 150 q->params.target = ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT; 151 } 152 153 if (tb[TCA_CODEL_CE_THRESHOLD]) { 154 u64 val = nla_get_u32(tb[TCA_CODEL_CE_THRESHOLD]); 155 156 q->params.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT; 157 } 158 159 if (tb[TCA_CODEL_INTERVAL]) { 160 u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]); 161 162 q->params.interval = ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT; 163 } 164 165 if (tb[TCA_CODEL_LIMIT]) 166 sch->limit = nla_get_u32(tb[TCA_CODEL_LIMIT]); 167 168 if (tb[TCA_CODEL_ECN]) 169 q->params.ecn = !!nla_get_u32(tb[TCA_CODEL_ECN]); 170 171 qlen = sch->q.qlen; 172 while (sch->q.qlen > sch->limit) { 173 struct sk_buff *skb = __skb_dequeue(&sch->q); 174 175 dropped += qdisc_pkt_len(skb); 176 qdisc_qstats_backlog_dec(sch, skb); 177 qdisc_drop(skb, sch); 178 } 179 qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen, dropped); 180 181 sch_tree_unlock(sch); 182 return 0; 183 } 184 185 static int codel_init(struct Qdisc *sch, struct nlattr *opt) 186 { 187 struct codel_sched_data *q = qdisc_priv(sch); 188 189 sch->limit = DEFAULT_CODEL_LIMIT; 190 191 codel_params_init(&q->params); 192 codel_vars_init(&q->vars); 193 codel_stats_init(&q->stats); 194 q->params.mtu = psched_mtu(qdisc_dev(sch)); 195 196 if (opt) { 197 int err = codel_change(sch, opt); 198 199 if (err) 200 return err; 201 } 202 203 if (sch->limit >= 1) 204 sch->flags |= TCQ_F_CAN_BYPASS; 205 else 206 sch->flags &= ~TCQ_F_CAN_BYPASS; 207 208 return 0; 209 } 210 211 static int codel_dump(struct Qdisc *sch, struct sk_buff *skb) 212 { 213 struct codel_sched_data *q = qdisc_priv(sch); 214 struct nlattr *opts; 215 216 opts = nla_nest_start(skb, TCA_OPTIONS); 217 if (opts == NULL) 218 goto nla_put_failure; 219 220 if (nla_put_u32(skb, TCA_CODEL_TARGET, 221 codel_time_to_us(q->params.target)) || 222 nla_put_u32(skb, TCA_CODEL_LIMIT, 223 sch->limit) || 224 nla_put_u32(skb, TCA_CODEL_INTERVAL, 225 codel_time_to_us(q->params.interval)) || 226 nla_put_u32(skb, TCA_CODEL_ECN, 227 q->params.ecn)) 228 goto nla_put_failure; 229 if (q->params.ce_threshold != CODEL_DISABLED_THRESHOLD && 230 nla_put_u32(skb, TCA_CODEL_CE_THRESHOLD, 231 codel_time_to_us(q->params.ce_threshold))) 232 goto nla_put_failure; 233 return nla_nest_end(skb, opts); 234 235 nla_put_failure: 236 nla_nest_cancel(skb, opts); 237 return -1; 238 } 239 240 static int codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 241 { 242 const struct codel_sched_data *q = qdisc_priv(sch); 243 struct tc_codel_xstats st = { 244 .maxpacket = q->stats.maxpacket, 245 .count = q->vars.count, 246 .lastcount = q->vars.lastcount, 247 .drop_overlimit = q->drop_overlimit, 248 .ldelay = codel_time_to_us(q->vars.ldelay), 249 .dropping = q->vars.dropping, 250 .ecn_mark = q->stats.ecn_mark, 251 .ce_mark = q->stats.ce_mark, 252 }; 253 254 if (q->vars.dropping) { 255 codel_tdiff_t delta = q->vars.drop_next - codel_get_time(); 256 257 if (delta >= 0) 258 st.drop_next = codel_time_to_us(delta); 259 else 260 st.drop_next = -codel_time_to_us(-delta); 261 } 262 263 return gnet_stats_copy_app(d, &st, sizeof(st)); 264 } 265 266 static void codel_reset(struct Qdisc *sch) 267 { 268 struct codel_sched_data *q = qdisc_priv(sch); 269 270 qdisc_reset_queue(sch); 271 codel_vars_init(&q->vars); 272 } 273 274 static struct Qdisc_ops codel_qdisc_ops __read_mostly = { 275 .id = "codel", 276 .priv_size = sizeof(struct codel_sched_data), 277 278 .enqueue = codel_qdisc_enqueue, 279 .dequeue = codel_qdisc_dequeue, 280 .peek = qdisc_peek_dequeued, 281 .init = codel_init, 282 .reset = codel_reset, 283 .change = codel_change, 284 .dump = codel_dump, 285 .dump_stats = codel_dump_stats, 286 .owner = THIS_MODULE, 287 }; 288 289 static int __init codel_module_init(void) 290 { 291 return register_qdisc(&codel_qdisc_ops); 292 } 293 294 static void __exit codel_module_exit(void) 295 { 296 unregister_qdisc(&codel_qdisc_ops); 297 } 298 299 module_init(codel_module_init) 300 module_exit(codel_module_exit) 301 302 MODULE_DESCRIPTION("Controlled Delay queue discipline"); 303 MODULE_AUTHOR("Dave Taht"); 304 MODULE_AUTHOR("Eric Dumazet"); 305 MODULE_LICENSE("Dual BSD/GPL"); 306