net/sched/sch_prio.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/sched/sch_prio.c Simple 3-band priority "scheduler".
   4  *
   5  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   6  * Fixes:       19990609: J Hadi Salim <hadi@nortelnetworks.com>:
   7  *              Init --  EINVAL when opt undefined
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/string.h>
  15 #include <linux/errno.h>
  16 #include <linux/skbuff.h>
  17 #include <net/netlink.h>
  18 #include <net/pkt_sched.h>
  19 #include <net/pkt_cls.h>
  20
  21 struct prio_sched_data {
  22         int bands;
  23         struct tcf_proto __rcu *filter_list;
  24         struct tcf_block *block;
  25         u8  prio2band[TC_PRIO_MAX+1];
  26         struct Qdisc *queues[TCQ_PRIO_BANDS];
  27 };
  28
  29
  30 static struct Qdisc *
  31 prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
  32 {
  33         struct prio_sched_data *q = qdisc_priv(sch);
  34         u32 band = skb->priority;
  35         struct tcf_result res;
  36         struct tcf_proto *fl;
  37         int err;
  38
  39         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
  40         if (TC_H_MAJ(skb->priority) != sch->handle) {
  41                 fl = rcu_dereference_bh(q->filter_list);
  42                 err = tcf_classify(skb, NULL, fl, &res, false);
  43 #ifdef CONFIG_NET_CLS_ACT
  44                 switch (err) {
  45                 case TC_ACT_STOLEN:
  46                 case TC_ACT_QUEUED:
  47                 case TC_ACT_TRAP:
  48                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
  49                         fallthrough;
  50                 case TC_ACT_SHOT:
  51                         return NULL;
  52                 }
  53 #endif
  54                 if (!fl || err < 0) {
  55                         if (TC_H_MAJ(band))
  56                                 band = 0;
  57                         return q->queues[q->prio2band[band & TC_PRIO_MAX]];
  58                 }
  59                 band = res.classid;
  60         }
  61         band = TC_H_MIN(band) - 1;
  62         if (band >= q->bands)
  63                 return q->queues[q->prio2band[0]];
  64
  65         return q->queues[band];
  66 }
  67
  68 static int
  69 prio_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
  70 {
  71         unsigned int len = qdisc_pkt_len(skb);
  72         struct Qdisc *qdisc;
  73         int ret;
  74
  75         qdisc = prio_classify(skb, sch, &ret);
  76 #ifdef CONFIG_NET_CLS_ACT
  77         if (qdisc == NULL) {
  78
  79                 if (ret & __NET_XMIT_BYPASS)
  80                         qdisc_qstats_drop(sch);
  81                 __qdisc_drop(skb, to_free);
  82                 return ret;
  83         }
  84 #endif
  85
  86         ret = qdisc_enqueue(skb, qdisc, to_free);
  87         if (ret == NET_XMIT_SUCCESS) {
  88                 sch->qstats.backlog += len;
  89                 sch->q.qlen++;
  90                 return NET_XMIT_SUCCESS;
  91         }
  92         if (net_xmit_drop_count(ret))
  93                 qdisc_qstats_drop(sch);
  94         return ret;
  95 }
  96
  97 static struct sk_buff *prio_peek(struct Qdisc *sch)
  98 {
  99         struct prio_sched_data *q = qdisc_priv(sch);
 100         int prio;
 101
 102         for (prio = 0; prio < q->bands; prio++) {
 103                 struct Qdisc *qdisc = q->queues[prio];
 104                 struct sk_buff *skb = qdisc->ops->peek(qdisc);
 105                 if (skb)
 106                         return skb;
 107         }
 108         return NULL;
 109 }
 110
 111 static struct sk_buff *prio_dequeue(struct Qdisc *sch)
 112 {
 113         struct prio_sched_data *q = qdisc_priv(sch);
 114         int prio;
 115
 116         for (prio = 0; prio < q->bands; prio++) {
 117                 struct Qdisc *qdisc = q->queues[prio];
 118                 struct sk_buff *skb = qdisc_dequeue_peeked(qdisc);
 119                 if (skb) {
 120                         qdisc_bstats_update(sch, skb);
 121                         qdisc_qstats_backlog_dec(sch, skb);
 122                         sch->q.qlen--;
 123                         return skb;
 124                 }
 125         }
 126         return NULL;
 127
 128 }
 129
 130 static void
 131 prio_reset(struct Qdisc *sch)
 132 {
 133         int prio;
 134         struct prio_sched_data *q = qdisc_priv(sch);
 135
 136         for (prio = 0; prio < q->bands; prio++)
 137                 qdisc_reset(q->queues[prio]);
 138 }
 139
 140 static int prio_offload(struct Qdisc *sch, struct tc_prio_qopt *qopt)
 141 {
 142         struct net_device *dev = qdisc_dev(sch);
 143         struct tc_prio_qopt_offload opt = {
 144                 .handle = sch->handle,
 145                 .parent = sch->parent,
 146         };
 147
 148         if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
 149                 return -EOPNOTSUPP;
 150
 151         if (qopt) {
 152                 opt.command = TC_PRIO_REPLACE;
 153                 opt.replace_params.bands = qopt->bands;
 154                 memcpy(&opt.replace_params.priomap, qopt->priomap,
 155                        TC_PRIO_MAX + 1);
 156                 opt.replace_params.qstats = &sch->qstats;
 157         } else {
 158                 opt.command = TC_PRIO_DESTROY;
 159         }
 160
 161         return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_PRIO, &opt);
 162 }
 163
 164 static void
 165 prio_destroy(struct Qdisc *sch)
 166 {
 167         int prio;
 168         struct prio_sched_data *q = qdisc_priv(sch);
 169
 170         tcf_block_put(q->block);
 171         prio_offload(sch, NULL);
 172         for (prio = 0; prio < q->bands; prio++)
 173                 qdisc_put(q->queues[prio]);
 174 }
 175
 176 static int prio_tune(struct Qdisc *sch, struct nlattr *opt,
 177                      struct netlink_ext_ack *extack)
 178 {
 179         struct prio_sched_data *q = qdisc_priv(sch);
 180         struct Qdisc *queues[TCQ_PRIO_BANDS];
 181         int oldbands = q->bands, i;
 182         struct tc_prio_qopt *qopt;
 183
 184         if (nla_len(opt) < sizeof(*qopt))
 185                 return -EINVAL;
 186         qopt = nla_data(opt);
 187
 188         if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < TCQ_MIN_PRIO_BANDS)
 189                 return -EINVAL;
 190
 191         for (i = 0; i <= TC_PRIO_MAX; i++) {
 192                 if (qopt->priomap[i] >= qopt->bands)
 193                         return -EINVAL;
 194         }
 195
 196         /* Before commit, make sure we can allocate all new qdiscs */
 197         for (i = oldbands; i < qopt->bands; i++) {
 198                 queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 199                                               TC_H_MAKE(sch->handle, i + 1),
 200                                               extack);
 201                 if (!queues[i]) {
 202                         while (i > oldbands)
 203                                 qdisc_put(queues[--i]);
 204                         return -ENOMEM;
 205                 }
 206         }
 207
 208         prio_offload(sch, qopt);
 209         sch_tree_lock(sch);
 210         q->bands = qopt->bands;
 211         memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 212
 213         for (i = q->bands; i < oldbands; i++)
 214                 qdisc_tree_flush_backlog(q->queues[i]);
 215
 216         for (i = oldbands; i < q->bands; i++) {
 217                 q->queues[i] = queues[i];
 218                 if (q->queues[i] != &noop_qdisc)
 219                         qdisc_hash_add(q->queues[i], true);
 220         }
 221
 222         sch_tree_unlock(sch);
 223
 224         for (i = q->bands; i < oldbands; i++)
 225                 qdisc_put(q->queues[i]);
 226         return 0;
 227 }
 228
 229 static int prio_init(struct Qdisc *sch, struct nlattr *opt,
 230                      struct netlink_ext_ack *extack)
 231 {
 232         struct prio_sched_data *q = qdisc_priv(sch);
 233         int err;
 234
 235         if (!opt)
 236                 return -EINVAL;
 237
 238         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
 239         if (err)
 240                 return err;
 241
 242         return prio_tune(sch, opt, extack);
 243 }
 244
 245 static int prio_dump_offload(struct Qdisc *sch)
 246 {
 247         struct tc_prio_qopt_offload hw_stats = {
 248                 .command = TC_PRIO_STATS,
 249                 .handle = sch->handle,
 250                 .parent = sch->parent,
 251                 {
 252                         .stats = {
 253                                 .bstats = &sch->bstats,
 254                                 .qstats = &sch->qstats,
 255                         },
 256                 },
 257         };
 258
 259         return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_PRIO, &hw_stats);
 260 }
 261
 262 static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
 263 {
 264         struct prio_sched_data *q = qdisc_priv(sch);
 265         unsigned char *b = skb_tail_pointer(skb);
 266         struct tc_prio_qopt opt;
 267         int err;
 268
 269         opt.bands = q->bands;
 270         memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);
 271
 272         err = prio_dump_offload(sch);
 273         if (err)
 274                 goto nla_put_failure;
 275
 276         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 277                 goto nla_put_failure;
 278
 279         return skb->len;
 280
 281 nla_put_failure:
 282         nlmsg_trim(skb, b);
 283         return -1;
 284 }
 285
 286 static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 287                       struct Qdisc **old, struct netlink_ext_ack *extack)
 288 {
 289         struct prio_sched_data *q = qdisc_priv(sch);
 290         struct tc_prio_qopt_offload graft_offload;
 291         unsigned long band = arg - 1;
 292
 293         if (!new) {
 294                 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 295                                         TC_H_MAKE(sch->handle, arg), extack);
 296                 if (!new)
 297                         new = &noop_qdisc;
 298                 else
 299                         qdisc_hash_add(new, true);
 300         }
 301
 302         *old = qdisc_replace(sch, new, &q->queues[band]);
 303
 304         graft_offload.handle = sch->handle;
 305         graft_offload.parent = sch->parent;
 306         graft_offload.graft_params.band = band;
 307         graft_offload.graft_params.child_handle = new->handle;
 308         graft_offload.command = TC_PRIO_GRAFT;
 309
 310         qdisc_offload_graft_helper(qdisc_dev(sch), sch, new, *old,
 311                                    TC_SETUP_QDISC_PRIO, &graft_offload,
 312                                    extack);
 313         return 0;
 314 }
 315
 316 static struct Qdisc *
 317 prio_leaf(struct Qdisc *sch, unsigned long arg)
 318 {
 319         struct prio_sched_data *q = qdisc_priv(sch);
 320         unsigned long band = arg - 1;
 321
 322         return q->queues[band];
 323 }
 324
 325 static unsigned long prio_find(struct Qdisc *sch, u32 classid)
 326 {
 327         struct prio_sched_data *q = qdisc_priv(sch);
 328         unsigned long band = TC_H_MIN(classid);
 329
 330         if (band - 1 >= q->bands)
 331                 return 0;
 332         return band;
 333 }
 334
 335 static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
 336 {
 337         return prio_find(sch, classid);
 338 }
 339
 340
 341 static void prio_unbind(struct Qdisc *q, unsigned long cl)
 342 {
 343 }
 344
 345 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
 346                            struct tcmsg *tcm)
 347 {
 348         struct prio_sched_data *q = qdisc_priv(sch);
 349
 350         tcm->tcm_handle |= TC_H_MIN(cl);
 351         tcm->tcm_info = q->queues[cl-1]->handle;
 352         return 0;
 353 }
 354
 355 static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 356                                  struct gnet_dump *d)
 357 {
 358         struct prio_sched_data *q = qdisc_priv(sch);
 359         struct Qdisc *cl_q;
 360
 361         cl_q = q->queues[cl - 1];
 362         if (gnet_stats_copy_basic(d, cl_q->cpu_bstats,
 363                                   &cl_q->bstats, true) < 0 ||
 364             qdisc_qstats_copy(d, cl_q) < 0)
 365                 return -1;
 366
 367         return 0;
 368 }
 369
 370 static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 371 {
 372         struct prio_sched_data *q = qdisc_priv(sch);
 373         int prio;
 374
 375         if (arg->stop)
 376                 return;
 377
 378         for (prio = 0; prio < q->bands; prio++) {
 379                 if (!tc_qdisc_stats_dump(sch, prio + 1, arg))
 380                         break;
 381         }
 382 }
 383
 384 static struct tcf_block *prio_tcf_block(struct Qdisc *sch, unsigned long cl,
 385                                         struct netlink_ext_ack *extack)
 386 {
 387         struct prio_sched_data *q = qdisc_priv(sch);
 388
 389         if (cl)
 390                 return NULL;
 391         return q->block;
 392 }
 393
 394 static const struct Qdisc_class_ops prio_class_ops = {
 395         .graft          =       prio_graft,
 396         .leaf           =       prio_leaf,
 397         .find           =       prio_find,
 398         .walk           =       prio_walk,
 399         .tcf_block      =       prio_tcf_block,
 400         .bind_tcf       =       prio_bind,
 401         .unbind_tcf     =       prio_unbind,
 402         .dump           =       prio_dump_class,
 403         .dump_stats     =       prio_dump_class_stats,
 404 };
 405
 406 static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
 407         .next           =       NULL,
 408         .cl_ops         =       &prio_class_ops,
 409         .id             =       "prio",
 410         .priv_size      =       sizeof(struct prio_sched_data),
 411         .enqueue        =       prio_enqueue,
 412         .dequeue        =       prio_dequeue,
 413         .peek           =       prio_peek,
 414         .init           =       prio_init,
 415         .reset          =       prio_reset,
 416         .destroy        =       prio_destroy,
 417         .change         =       prio_tune,
 418         .dump           =       prio_dump,
 419         .owner          =       THIS_MODULE,
 420 };
 421 MODULE_ALIAS_NET_SCH("prio");
 422
 423 static int __init prio_module_init(void)
 424 {
 425         return register_qdisc(&prio_qdisc_ops);
 426 }
 427
 428 static void __exit prio_module_exit(void)
 429 {
 430         unregister_qdisc(&prio_qdisc_ops);
 431 }
 432
 433 module_init(prio_module_init)
 434 module_exit(prio_module_exit)
 435
 436 MODULE_LICENSE("GPL");
 437 MODULE_DESCRIPTION("Simple 3-band priority qdisc");