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 = __qdisc_dequeue_head(&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 kfree_skb(skb); 86 qdisc_qstats_drop(sch); 87 } 88 89 static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch) 90 { 91 struct codel_sched_data *q = qdisc_priv(sch); 92 struct sk_buff *skb; 93 94 skb = codel_dequeue(sch, &sch->qstats.backlog, &q->params, &q->vars, 95 &q->stats, qdisc_pkt_len, codel_get_enqueue_time, 96 drop_func, dequeue_func); 97 98 /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0, 99 * or HTB crashes. Defer it for next round. 100 */ 101 if (q->stats.drop_count && sch->q.qlen) { 102 qdisc_tree_reduce_backlog(sch, q->stats.drop_count, q->stats.drop_len); 103 q->stats.drop_count = 0; 104 q->stats.drop_len = 0; 105 } 106 if (skb) 107 qdisc_bstats_update(sch, skb); 108 return skb; 109 } 110 111 static int codel_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, 112 struct sk_buff **to_free) 113 { 114 struct codel_sched_data *q; 115 116 if (likely(qdisc_qlen(sch) < sch->limit)) { 117 codel_set_enqueue_time(skb); 118 return qdisc_enqueue_tail(skb, sch); 119 } 120 q = qdisc_priv(sch); 121 q->drop_overlimit++; 122 return qdisc_drop(skb, sch, to_free); 123 } 124 125 static const struct nla_policy codel_policy[TCA_CODEL_MAX + 1] = { 126 [TCA_CODEL_TARGET] = { .type = NLA_U32 }, 127 [TCA_CODEL_LIMIT] = { .type = NLA_U32 }, 128 [TCA_CODEL_INTERVAL] = { .type = NLA_U32 }, 129 [TCA_CODEL_ECN] = { .type = NLA_U32 }, 130 [TCA_CODEL_CE_THRESHOLD]= { .type = NLA_U32 }, 131 }; 132 133 static int codel_change(struct Qdisc *sch, struct nlattr *opt, 134 struct netlink_ext_ack *extack) 135 { 136 struct codel_sched_data *q = qdisc_priv(sch); 137 struct nlattr *tb[TCA_CODEL_MAX + 1]; 138 unsigned int qlen, dropped = 0; 139 int err; 140 141 if (!opt) 142 return -EINVAL; 143 144 err = nla_parse_nested(tb, TCA_CODEL_MAX, opt, codel_policy, NULL); 145 if (err < 0) 146 return err; 147 148 sch_tree_lock(sch); 149 150 if (tb[TCA_CODEL_TARGET]) { 151 u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]); 152 153 q->params.target = ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT; 154 } 155 156 if (tb[TCA_CODEL_CE_THRESHOLD]) { 157 u64 val = nla_get_u32(tb[TCA_CODEL_CE_THRESHOLD]); 158 159 q->params.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT; 160 } 161 162 if (tb[TCA_CODEL_INTERVAL]) { 163 u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]); 164 165 q->params.interval = ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT; 166 } 167 168 if (tb[TCA_CODEL_LIMIT]) 169 sch->limit = nla_get_u32(tb[TCA_CODEL_LIMIT]); 170 171 if (tb[TCA_CODEL_ECN]) 172 q->params.ecn = !!nla_get_u32(tb[TCA_CODEL_ECN]); 173 174 qlen = sch->q.qlen; 175 while (sch->q.qlen > sch->limit) { 176 struct sk_buff *skb = __qdisc_dequeue_head(&sch->q); 177 178 dropped += qdisc_pkt_len(skb); 179 qdisc_qstats_backlog_dec(sch, skb); 180 rtnl_qdisc_drop(skb, sch); 181 } 182 qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen, dropped); 183 184 sch_tree_unlock(sch); 185 return 0; 186 } 187 188 static int codel_init(struct Qdisc *sch, struct nlattr *opt, 189 struct netlink_ext_ack *extack) 190 { 191 struct codel_sched_data *q = qdisc_priv(sch); 192 193 sch->limit = DEFAULT_CODEL_LIMIT; 194 195 codel_params_init(&q->params); 196 codel_vars_init(&q->vars); 197 codel_stats_init(&q->stats); 198 q->params.mtu = psched_mtu(qdisc_dev(sch)); 199 200 if (opt) { 201 int err = codel_change(sch, opt, extack); 202 203 if (err) 204 return err; 205 } 206 207 if (sch->limit >= 1) 208 sch->flags |= TCQ_F_CAN_BYPASS; 209 else 210 sch->flags &= ~TCQ_F_CAN_BYPASS; 211 212 return 0; 213 } 214 215 static int codel_dump(struct Qdisc *sch, struct sk_buff *skb) 216 { 217 struct codel_sched_data *q = qdisc_priv(sch); 218 struct nlattr *opts; 219 220 opts = nla_nest_start(skb, TCA_OPTIONS); 221 if (opts == NULL) 222 goto nla_put_failure; 223 224 if (nla_put_u32(skb, TCA_CODEL_TARGET, 225 codel_time_to_us(q->params.target)) || 226 nla_put_u32(skb, TCA_CODEL_LIMIT, 227 sch->limit) || 228 nla_put_u32(skb, TCA_CODEL_INTERVAL, 229 codel_time_to_us(q->params.interval)) || 230 nla_put_u32(skb, TCA_CODEL_ECN, 231 q->params.ecn)) 232 goto nla_put_failure; 233 if (q->params.ce_threshold != CODEL_DISABLED_THRESHOLD && 234 nla_put_u32(skb, TCA_CODEL_CE_THRESHOLD, 235 codel_time_to_us(q->params.ce_threshold))) 236 goto nla_put_failure; 237 return nla_nest_end(skb, opts); 238 239 nla_put_failure: 240 nla_nest_cancel(skb, opts); 241 return -1; 242 } 243 244 static int codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 245 { 246 const struct codel_sched_data *q = qdisc_priv(sch); 247 struct tc_codel_xstats st = { 248 .maxpacket = q->stats.maxpacket, 249 .count = q->vars.count, 250 .lastcount = q->vars.lastcount, 251 .drop_overlimit = q->drop_overlimit, 252 .ldelay = codel_time_to_us(q->vars.ldelay), 253 .dropping = q->vars.dropping, 254 .ecn_mark = q->stats.ecn_mark, 255 .ce_mark = q->stats.ce_mark, 256 }; 257 258 if (q->vars.dropping) { 259 codel_tdiff_t delta = q->vars.drop_next - codel_get_time(); 260 261 if (delta >= 0) 262 st.drop_next = codel_time_to_us(delta); 263 else 264 st.drop_next = -codel_time_to_us(-delta); 265 } 266 267 return gnet_stats_copy_app(d, &st, sizeof(st)); 268 } 269 270 static void codel_reset(struct Qdisc *sch) 271 { 272 struct codel_sched_data *q = qdisc_priv(sch); 273 274 qdisc_reset_queue(sch); 275 codel_vars_init(&q->vars); 276 } 277 278 static struct Qdisc_ops codel_qdisc_ops __read_mostly = { 279 .id = "codel", 280 .priv_size = sizeof(struct codel_sched_data), 281 282 .enqueue = codel_qdisc_enqueue, 283 .dequeue = codel_qdisc_dequeue, 284 .peek = qdisc_peek_dequeued, 285 .init = codel_init, 286 .reset = codel_reset, 287 .change = codel_change, 288 .dump = codel_dump, 289 .dump_stats = codel_dump_stats, 290 .owner = THIS_MODULE, 291 }; 292 293 static int __init codel_module_init(void) 294 { 295 return register_qdisc(&codel_qdisc_ops); 296 } 297 298 static void __exit codel_module_exit(void) 299 { 300 unregister_qdisc(&codel_qdisc_ops); 301 } 302 303 module_init(codel_module_init) 304 module_exit(codel_module_exit) 305 306 MODULE_DESCRIPTION("Controlled Delay queue discipline"); 307 MODULE_AUTHOR("Dave Taht"); 308 MODULE_AUTHOR("Eric Dumazet"); 309 MODULE_LICENSE("Dual BSD/GPL"); 310