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