1 /* 2 * net/sched/sch_gred.c Generic Random Early Detection queue. 3 * 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 * 10 * Authors: J Hadi Salim (hadi@cyberus.ca) 1998-2002 11 * 12 * 991129: - Bug fix with grio mode 13 * - a better sing. AvgQ mode with Grio(WRED) 14 * - A finer grained VQ dequeue based on sugestion 15 * from Ren Liu 16 * - More error checks 17 * 18 * For all the glorious comments look at include/net/red.h 19 */ 20 21 #include <linux/slab.h> 22 #include <linux/module.h> 23 #include <linux/types.h> 24 #include <linux/kernel.h> 25 #include <linux/skbuff.h> 26 #include <net/pkt_sched.h> 27 #include <net/red.h> 28 29 #define GRED_DEF_PRIO (MAX_DPs / 2) 30 #define GRED_VQ_MASK (MAX_DPs - 1) 31 32 struct gred_sched_data; 33 struct gred_sched; 34 35 struct gred_sched_data 36 { 37 u32 limit; /* HARD maximal queue length */ 38 u32 DP; /* the drop pramaters */ 39 u32 bytesin; /* bytes seen on virtualQ so far*/ 40 u32 packetsin; /* packets seen on virtualQ so far*/ 41 u32 backlog; /* bytes on the virtualQ */ 42 u8 prio; /* the prio of this vq */ 43 44 struct red_parms parms; 45 struct red_stats stats; 46 }; 47 48 enum { 49 GRED_WRED_MODE = 1, 50 GRED_RIO_MODE, 51 }; 52 53 struct gred_sched 54 { 55 struct gred_sched_data *tab[MAX_DPs]; 56 unsigned long flags; 57 u32 red_flags; 58 u32 DPs; 59 u32 def; 60 struct red_parms wred_set; 61 }; 62 63 static inline int gred_wred_mode(struct gred_sched *table) 64 { 65 return test_bit(GRED_WRED_MODE, &table->flags); 66 } 67 68 static inline void gred_enable_wred_mode(struct gred_sched *table) 69 { 70 __set_bit(GRED_WRED_MODE, &table->flags); 71 } 72 73 static inline void gred_disable_wred_mode(struct gred_sched *table) 74 { 75 __clear_bit(GRED_WRED_MODE, &table->flags); 76 } 77 78 static inline int gred_rio_mode(struct gred_sched *table) 79 { 80 return test_bit(GRED_RIO_MODE, &table->flags); 81 } 82 83 static inline void gred_enable_rio_mode(struct gred_sched *table) 84 { 85 __set_bit(GRED_RIO_MODE, &table->flags); 86 } 87 88 static inline void gred_disable_rio_mode(struct gred_sched *table) 89 { 90 __clear_bit(GRED_RIO_MODE, &table->flags); 91 } 92 93 static inline int gred_wred_mode_check(struct Qdisc *sch) 94 { 95 struct gred_sched *table = qdisc_priv(sch); 96 int i; 97 98 /* Really ugly O(n^2) but shouldn't be necessary too frequent. */ 99 for (i = 0; i < table->DPs; i++) { 100 struct gred_sched_data *q = table->tab[i]; 101 int n; 102 103 if (q == NULL) 104 continue; 105 106 for (n = 0; n < table->DPs; n++) 107 if (table->tab[n] && table->tab[n] != q && 108 table->tab[n]->prio == q->prio) 109 return 1; 110 } 111 112 return 0; 113 } 114 115 static inline unsigned int gred_backlog(struct gred_sched *table, 116 struct gred_sched_data *q, 117 struct Qdisc *sch) 118 { 119 if (gred_wred_mode(table)) 120 return sch->qstats.backlog; 121 else 122 return q->backlog; 123 } 124 125 static inline u16 tc_index_to_dp(struct sk_buff *skb) 126 { 127 return skb->tc_index & GRED_VQ_MASK; 128 } 129 130 static inline void gred_load_wred_set(struct gred_sched *table, 131 struct gred_sched_data *q) 132 { 133 q->parms.qavg = table->wred_set.qavg; 134 q->parms.qidlestart = table->wred_set.qidlestart; 135 } 136 137 static inline void gred_store_wred_set(struct gred_sched *table, 138 struct gred_sched_data *q) 139 { 140 table->wred_set.qavg = q->parms.qavg; 141 } 142 143 static inline int gred_use_ecn(struct gred_sched *t) 144 { 145 return t->red_flags & TC_RED_ECN; 146 } 147 148 static inline int gred_use_harddrop(struct gred_sched *t) 149 { 150 return t->red_flags & TC_RED_HARDDROP; 151 } 152 153 static int gred_enqueue(struct sk_buff *skb, struct Qdisc* sch) 154 { 155 struct gred_sched_data *q=NULL; 156 struct gred_sched *t= qdisc_priv(sch); 157 unsigned long qavg = 0; 158 u16 dp = tc_index_to_dp(skb); 159 160 if (dp >= t->DPs || (q = t->tab[dp]) == NULL) { 161 dp = t->def; 162 163 if ((q = t->tab[dp]) == NULL) { 164 /* Pass through packets not assigned to a DP 165 * if no default DP has been configured. This 166 * allows for DP flows to be left untouched. 167 */ 168 if (skb_queue_len(&sch->q) < qdisc_dev(sch)->tx_queue_len) 169 return qdisc_enqueue_tail(skb, sch); 170 else 171 goto drop; 172 } 173 174 /* fix tc_index? --could be controvesial but needed for 175 requeueing */ 176 skb->tc_index = (skb->tc_index & ~GRED_VQ_MASK) | dp; 177 } 178 179 /* sum up all the qaves of prios <= to ours to get the new qave */ 180 if (!gred_wred_mode(t) && gred_rio_mode(t)) { 181 int i; 182 183 for (i = 0; i < t->DPs; i++) { 184 if (t->tab[i] && t->tab[i]->prio < q->prio && 185 !red_is_idling(&t->tab[i]->parms)) 186 qavg +=t->tab[i]->parms.qavg; 187 } 188 189 } 190 191 q->packetsin++; 192 q->bytesin += qdisc_pkt_len(skb); 193 194 if (gred_wred_mode(t)) 195 gred_load_wred_set(t, q); 196 197 q->parms.qavg = red_calc_qavg(&q->parms, gred_backlog(t, q, sch)); 198 199 if (red_is_idling(&q->parms)) 200 red_end_of_idle_period(&q->parms); 201 202 if (gred_wred_mode(t)) 203 gred_store_wred_set(t, q); 204 205 switch (red_action(&q->parms, q->parms.qavg + qavg)) { 206 case RED_DONT_MARK: 207 break; 208 209 case RED_PROB_MARK: 210 sch->qstats.overlimits++; 211 if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) { 212 q->stats.prob_drop++; 213 goto congestion_drop; 214 } 215 216 q->stats.prob_mark++; 217 break; 218 219 case RED_HARD_MARK: 220 sch->qstats.overlimits++; 221 if (gred_use_harddrop(t) || !gred_use_ecn(t) || 222 !INET_ECN_set_ce(skb)) { 223 q->stats.forced_drop++; 224 goto congestion_drop; 225 } 226 q->stats.forced_mark++; 227 break; 228 } 229 230 if (q->backlog + qdisc_pkt_len(skb) <= q->limit) { 231 q->backlog += qdisc_pkt_len(skb); 232 return qdisc_enqueue_tail(skb, sch); 233 } 234 235 q->stats.pdrop++; 236 drop: 237 return qdisc_drop(skb, sch); 238 239 congestion_drop: 240 qdisc_drop(skb, sch); 241 return NET_XMIT_CN; 242 } 243 244 static struct sk_buff *gred_dequeue(struct Qdisc* sch) 245 { 246 struct sk_buff *skb; 247 struct gred_sched *t = qdisc_priv(sch); 248 249 skb = qdisc_dequeue_head(sch); 250 251 if (skb) { 252 struct gred_sched_data *q; 253 u16 dp = tc_index_to_dp(skb); 254 255 if (dp >= t->DPs || (q = t->tab[dp]) == NULL) { 256 if (net_ratelimit()) 257 printk(KERN_WARNING "GRED: Unable to relocate " 258 "VQ 0x%x after dequeue, screwing up " 259 "backlog.\n", tc_index_to_dp(skb)); 260 } else { 261 q->backlog -= qdisc_pkt_len(skb); 262 263 if (!q->backlog && !gred_wred_mode(t)) 264 red_start_of_idle_period(&q->parms); 265 } 266 267 return skb; 268 } 269 270 if (gred_wred_mode(t) && !red_is_idling(&t->wred_set)) 271 red_start_of_idle_period(&t->wred_set); 272 273 return NULL; 274 } 275 276 static unsigned int gred_drop(struct Qdisc* sch) 277 { 278 struct sk_buff *skb; 279 struct gred_sched *t = qdisc_priv(sch); 280 281 skb = qdisc_dequeue_tail(sch); 282 if (skb) { 283 unsigned int len = qdisc_pkt_len(skb); 284 struct gred_sched_data *q; 285 u16 dp = tc_index_to_dp(skb); 286 287 if (dp >= t->DPs || (q = t->tab[dp]) == NULL) { 288 if (net_ratelimit()) 289 printk(KERN_WARNING "GRED: Unable to relocate " 290 "VQ 0x%x while dropping, screwing up " 291 "backlog.\n", tc_index_to_dp(skb)); 292 } else { 293 q->backlog -= len; 294 q->stats.other++; 295 296 if (!q->backlog && !gred_wred_mode(t)) 297 red_start_of_idle_period(&q->parms); 298 } 299 300 qdisc_drop(skb, sch); 301 return len; 302 } 303 304 if (gred_wred_mode(t) && !red_is_idling(&t->wred_set)) 305 red_start_of_idle_period(&t->wred_set); 306 307 return 0; 308 309 } 310 311 static void gred_reset(struct Qdisc* sch) 312 { 313 int i; 314 struct gred_sched *t = qdisc_priv(sch); 315 316 qdisc_reset_queue(sch); 317 318 for (i = 0; i < t->DPs; i++) { 319 struct gred_sched_data *q = t->tab[i]; 320 321 if (!q) 322 continue; 323 324 red_restart(&q->parms); 325 q->backlog = 0; 326 } 327 } 328 329 static inline void gred_destroy_vq(struct gred_sched_data *q) 330 { 331 kfree(q); 332 } 333 334 static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps) 335 { 336 struct gred_sched *table = qdisc_priv(sch); 337 struct tc_gred_sopt *sopt; 338 int i; 339 340 if (dps == NULL) 341 return -EINVAL; 342 343 sopt = nla_data(dps); 344 345 if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs) 346 return -EINVAL; 347 348 sch_tree_lock(sch); 349 table->DPs = sopt->DPs; 350 table->def = sopt->def_DP; 351 table->red_flags = sopt->flags; 352 353 /* 354 * Every entry point to GRED is synchronized with the above code 355 * and the DP is checked against DPs, i.e. shadowed VQs can no 356 * longer be found so we can unlock right here. 357 */ 358 sch_tree_unlock(sch); 359 360 if (sopt->grio) { 361 gred_enable_rio_mode(table); 362 gred_disable_wred_mode(table); 363 if (gred_wred_mode_check(sch)) 364 gred_enable_wred_mode(table); 365 } else { 366 gred_disable_rio_mode(table); 367 gred_disable_wred_mode(table); 368 } 369 370 for (i = table->DPs; i < MAX_DPs; i++) { 371 if (table->tab[i]) { 372 printk(KERN_WARNING "GRED: Warning: Destroying " 373 "shadowed VQ 0x%x\n", i); 374 gred_destroy_vq(table->tab[i]); 375 table->tab[i] = NULL; 376 } 377 } 378 379 return 0; 380 } 381 382 static inline int gred_change_vq(struct Qdisc *sch, int dp, 383 struct tc_gred_qopt *ctl, int prio, u8 *stab) 384 { 385 struct gred_sched *table = qdisc_priv(sch); 386 struct gred_sched_data *q; 387 388 if (table->tab[dp] == NULL) { 389 table->tab[dp] = kzalloc(sizeof(*q), GFP_KERNEL); 390 if (table->tab[dp] == NULL) 391 return -ENOMEM; 392 } 393 394 q = table->tab[dp]; 395 q->DP = dp; 396 q->prio = prio; 397 q->limit = ctl->limit; 398 399 if (q->backlog == 0) 400 red_end_of_idle_period(&q->parms); 401 402 red_set_parms(&q->parms, 403 ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog, 404 ctl->Scell_log, stab); 405 406 return 0; 407 } 408 409 static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = { 410 [TCA_GRED_PARMS] = { .len = sizeof(struct tc_gred_qopt) }, 411 [TCA_GRED_STAB] = { .len = 256 }, 412 [TCA_GRED_DPS] = { .len = sizeof(struct tc_gred_sopt) }, 413 }; 414 415 static int gred_change(struct Qdisc *sch, struct nlattr *opt) 416 { 417 struct gred_sched *table = qdisc_priv(sch); 418 struct tc_gred_qopt *ctl; 419 struct nlattr *tb[TCA_GRED_MAX + 1]; 420 int err, prio = GRED_DEF_PRIO; 421 u8 *stab; 422 423 if (opt == NULL) 424 return -EINVAL; 425 426 err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy); 427 if (err < 0) 428 return err; 429 430 if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL) 431 return gred_change_table_def(sch, opt); 432 433 if (tb[TCA_GRED_PARMS] == NULL || 434 tb[TCA_GRED_STAB] == NULL) 435 return -EINVAL; 436 437 err = -EINVAL; 438 ctl = nla_data(tb[TCA_GRED_PARMS]); 439 stab = nla_data(tb[TCA_GRED_STAB]); 440 441 if (ctl->DP >= table->DPs) 442 goto errout; 443 444 if (gred_rio_mode(table)) { 445 if (ctl->prio == 0) { 446 int def_prio = GRED_DEF_PRIO; 447 448 if (table->tab[table->def]) 449 def_prio = table->tab[table->def]->prio; 450 451 printk(KERN_DEBUG "GRED: DP %u does not have a prio " 452 "setting default to %d\n", ctl->DP, def_prio); 453 454 prio = def_prio; 455 } else 456 prio = ctl->prio; 457 } 458 459 sch_tree_lock(sch); 460 461 err = gred_change_vq(sch, ctl->DP, ctl, prio, stab); 462 if (err < 0) 463 goto errout_locked; 464 465 if (gred_rio_mode(table)) { 466 gred_disable_wred_mode(table); 467 if (gred_wred_mode_check(sch)) 468 gred_enable_wred_mode(table); 469 } 470 471 err = 0; 472 473 errout_locked: 474 sch_tree_unlock(sch); 475 errout: 476 return err; 477 } 478 479 static int gred_init(struct Qdisc *sch, struct nlattr *opt) 480 { 481 struct nlattr *tb[TCA_GRED_MAX + 1]; 482 int err; 483 484 if (opt == NULL) 485 return -EINVAL; 486 487 err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy); 488 if (err < 0) 489 return err; 490 491 if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB]) 492 return -EINVAL; 493 494 return gred_change_table_def(sch, tb[TCA_GRED_DPS]); 495 } 496 497 static int gred_dump(struct Qdisc *sch, struct sk_buff *skb) 498 { 499 struct gred_sched *table = qdisc_priv(sch); 500 struct nlattr *parms, *opts = NULL; 501 int i; 502 struct tc_gred_sopt sopt = { 503 .DPs = table->DPs, 504 .def_DP = table->def, 505 .grio = gred_rio_mode(table), 506 .flags = table->red_flags, 507 }; 508 509 opts = nla_nest_start(skb, TCA_OPTIONS); 510 if (opts == NULL) 511 goto nla_put_failure; 512 NLA_PUT(skb, TCA_GRED_DPS, sizeof(sopt), &sopt); 513 parms = nla_nest_start(skb, TCA_GRED_PARMS); 514 if (parms == NULL) 515 goto nla_put_failure; 516 517 for (i = 0; i < MAX_DPs; i++) { 518 struct gred_sched_data *q = table->tab[i]; 519 struct tc_gred_qopt opt; 520 521 memset(&opt, 0, sizeof(opt)); 522 523 if (!q) { 524 /* hack -- fix at some point with proper message 525 This is how we indicate to tc that there is no VQ 526 at this DP */ 527 528 opt.DP = MAX_DPs + i; 529 goto append_opt; 530 } 531 532 opt.limit = q->limit; 533 opt.DP = q->DP; 534 opt.backlog = q->backlog; 535 opt.prio = q->prio; 536 opt.qth_min = q->parms.qth_min >> q->parms.Wlog; 537 opt.qth_max = q->parms.qth_max >> q->parms.Wlog; 538 opt.Wlog = q->parms.Wlog; 539 opt.Plog = q->parms.Plog; 540 opt.Scell_log = q->parms.Scell_log; 541 opt.other = q->stats.other; 542 opt.early = q->stats.prob_drop; 543 opt.forced = q->stats.forced_drop; 544 opt.pdrop = q->stats.pdrop; 545 opt.packets = q->packetsin; 546 opt.bytesin = q->bytesin; 547 548 if (gred_wred_mode(table)) { 549 q->parms.qidlestart = 550 table->tab[table->def]->parms.qidlestart; 551 q->parms.qavg = table->tab[table->def]->parms.qavg; 552 } 553 554 opt.qave = red_calc_qavg(&q->parms, q->parms.qavg); 555 556 append_opt: 557 if (nla_append(skb, sizeof(opt), &opt) < 0) 558 goto nla_put_failure; 559 } 560 561 nla_nest_end(skb, parms); 562 563 return nla_nest_end(skb, opts); 564 565 nla_put_failure: 566 nla_nest_cancel(skb, opts); 567 return -EMSGSIZE; 568 } 569 570 static void gred_destroy(struct Qdisc *sch) 571 { 572 struct gred_sched *table = qdisc_priv(sch); 573 int i; 574 575 for (i = 0; i < table->DPs; i++) { 576 if (table->tab[i]) 577 gred_destroy_vq(table->tab[i]); 578 } 579 } 580 581 static struct Qdisc_ops gred_qdisc_ops __read_mostly = { 582 .id = "gred", 583 .priv_size = sizeof(struct gred_sched), 584 .enqueue = gred_enqueue, 585 .dequeue = gred_dequeue, 586 .peek = qdisc_peek_head, 587 .drop = gred_drop, 588 .init = gred_init, 589 .reset = gred_reset, 590 .destroy = gred_destroy, 591 .change = gred_change, 592 .dump = gred_dump, 593 .owner = THIS_MODULE, 594 }; 595 596 static int __init gred_module_init(void) 597 { 598 return register_qdisc(&gred_qdisc_ops); 599 } 600 601 static void __exit gred_module_exit(void) 602 { 603 unregister_qdisc(&gred_qdisc_ops); 604 } 605 606 module_init(gred_module_init) 607 module_exit(gred_module_exit) 608 609 MODULE_LICENSE("GPL"); 610