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 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_reduce_backlog() 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_reduce_backlog(sch, q->stats.drop_count, q->stats.drop_len); 87 q->stats.drop_count = 0; 88 q->stats.drop_len = 0; 89 } 90 if (skb) 91 qdisc_bstats_update(sch, skb); 92 return skb; 93 } 94 95 static int codel_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch) 96 { 97 struct codel_sched_data *q; 98 99 if (likely(qdisc_qlen(sch) < sch->limit)) { 100 codel_set_enqueue_time(skb); 101 return qdisc_enqueue_tail(skb, sch); 102 } 103 q = qdisc_priv(sch); 104 q->drop_overlimit++; 105 return qdisc_drop(skb, sch); 106 } 107 108 static const struct nla_policy codel_policy[TCA_CODEL_MAX + 1] = { 109 [TCA_CODEL_TARGET] = { .type = NLA_U32 }, 110 [TCA_CODEL_LIMIT] = { .type = NLA_U32 }, 111 [TCA_CODEL_INTERVAL] = { .type = NLA_U32 }, 112 [TCA_CODEL_ECN] = { .type = NLA_U32 }, 113 [TCA_CODEL_CE_THRESHOLD]= { .type = NLA_U32 }, 114 }; 115 116 static int codel_change(struct Qdisc *sch, struct nlattr *opt) 117 { 118 struct codel_sched_data *q = qdisc_priv(sch); 119 struct nlattr *tb[TCA_CODEL_MAX + 1]; 120 unsigned int qlen, dropped = 0; 121 int err; 122 123 if (!opt) 124 return -EINVAL; 125 126 err = nla_parse_nested(tb, TCA_CODEL_MAX, opt, codel_policy); 127 if (err < 0) 128 return err; 129 130 sch_tree_lock(sch); 131 132 if (tb[TCA_CODEL_TARGET]) { 133 u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]); 134 135 q->params.target = ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT; 136 } 137 138 if (tb[TCA_CODEL_CE_THRESHOLD]) { 139 u64 val = nla_get_u32(tb[TCA_CODEL_CE_THRESHOLD]); 140 141 q->params.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT; 142 } 143 144 if (tb[TCA_CODEL_INTERVAL]) { 145 u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]); 146 147 q->params.interval = ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT; 148 } 149 150 if (tb[TCA_CODEL_LIMIT]) 151 sch->limit = nla_get_u32(tb[TCA_CODEL_LIMIT]); 152 153 if (tb[TCA_CODEL_ECN]) 154 q->params.ecn = !!nla_get_u32(tb[TCA_CODEL_ECN]); 155 156 qlen = sch->q.qlen; 157 while (sch->q.qlen > sch->limit) { 158 struct sk_buff *skb = __skb_dequeue(&sch->q); 159 160 dropped += qdisc_pkt_len(skb); 161 qdisc_qstats_backlog_dec(sch, skb); 162 qdisc_drop(skb, sch); 163 } 164 qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen, dropped); 165 166 sch_tree_unlock(sch); 167 return 0; 168 } 169 170 static int codel_init(struct Qdisc *sch, struct nlattr *opt) 171 { 172 struct codel_sched_data *q = qdisc_priv(sch); 173 174 sch->limit = DEFAULT_CODEL_LIMIT; 175 176 codel_params_init(&q->params, sch); 177 codel_vars_init(&q->vars); 178 codel_stats_init(&q->stats); 179 180 if (opt) { 181 int err = codel_change(sch, opt); 182 183 if (err) 184 return err; 185 } 186 187 if (sch->limit >= 1) 188 sch->flags |= TCQ_F_CAN_BYPASS; 189 else 190 sch->flags &= ~TCQ_F_CAN_BYPASS; 191 192 return 0; 193 } 194 195 static int codel_dump(struct Qdisc *sch, struct sk_buff *skb) 196 { 197 struct codel_sched_data *q = qdisc_priv(sch); 198 struct nlattr *opts; 199 200 opts = nla_nest_start(skb, TCA_OPTIONS); 201 if (opts == NULL) 202 goto nla_put_failure; 203 204 if (nla_put_u32(skb, TCA_CODEL_TARGET, 205 codel_time_to_us(q->params.target)) || 206 nla_put_u32(skb, TCA_CODEL_LIMIT, 207 sch->limit) || 208 nla_put_u32(skb, TCA_CODEL_INTERVAL, 209 codel_time_to_us(q->params.interval)) || 210 nla_put_u32(skb, TCA_CODEL_ECN, 211 q->params.ecn)) 212 goto nla_put_failure; 213 if (q->params.ce_threshold != CODEL_DISABLED_THRESHOLD && 214 nla_put_u32(skb, TCA_CODEL_CE_THRESHOLD, 215 codel_time_to_us(q->params.ce_threshold))) 216 goto nla_put_failure; 217 return nla_nest_end(skb, opts); 218 219 nla_put_failure: 220 nla_nest_cancel(skb, opts); 221 return -1; 222 } 223 224 static int codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 225 { 226 const struct codel_sched_data *q = qdisc_priv(sch); 227 struct tc_codel_xstats st = { 228 .maxpacket = q->stats.maxpacket, 229 .count = q->vars.count, 230 .lastcount = q->vars.lastcount, 231 .drop_overlimit = q->drop_overlimit, 232 .ldelay = codel_time_to_us(q->vars.ldelay), 233 .dropping = q->vars.dropping, 234 .ecn_mark = q->stats.ecn_mark, 235 .ce_mark = q->stats.ce_mark, 236 }; 237 238 if (q->vars.dropping) { 239 codel_tdiff_t delta = q->vars.drop_next - codel_get_time(); 240 241 if (delta >= 0) 242 st.drop_next = codel_time_to_us(delta); 243 else 244 st.drop_next = -codel_time_to_us(-delta); 245 } 246 247 return gnet_stats_copy_app(d, &st, sizeof(st)); 248 } 249 250 static void codel_reset(struct Qdisc *sch) 251 { 252 struct codel_sched_data *q = qdisc_priv(sch); 253 254 qdisc_reset_queue(sch); 255 codel_vars_init(&q->vars); 256 } 257 258 static struct Qdisc_ops codel_qdisc_ops __read_mostly = { 259 .id = "codel", 260 .priv_size = sizeof(struct codel_sched_data), 261 262 .enqueue = codel_qdisc_enqueue, 263 .dequeue = codel_qdisc_dequeue, 264 .peek = qdisc_peek_dequeued, 265 .init = codel_init, 266 .reset = codel_reset, 267 .change = codel_change, 268 .dump = codel_dump, 269 .dump_stats = codel_dump_stats, 270 .owner = THIS_MODULE, 271 }; 272 273 static int __init codel_module_init(void) 274 { 275 return register_qdisc(&codel_qdisc_ops); 276 } 277 278 static void __exit codel_module_exit(void) 279 { 280 unregister_qdisc(&codel_qdisc_ops); 281 } 282 283 module_init(codel_module_init) 284 module_exit(codel_module_exit) 285 286 MODULE_DESCRIPTION("Controlled Delay queue discipline"); 287 MODULE_AUTHOR("Dave Taht"); 288 MODULE_AUTHOR("Eric Dumazet"); 289 MODULE_LICENSE("Dual BSD/GPL"); 290