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, 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                         /* fall through */
  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         sch->qstats.backlog = 0;
 139         sch->q.qlen = 0;
 140 }
 141
 142 static int prio_offload(struct Qdisc *sch, struct tc_prio_qopt *qopt)
 143 {
 144         struct net_device *dev = qdisc_dev(sch);
 145         struct tc_prio_qopt_offload opt = {
 146                 .handle = sch->handle,
 147                 .parent = sch->parent,
 148         };
 149
 150         if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
 151                 return -EOPNOTSUPP;
 152
 153         if (qopt) {
 154                 opt.command = TC_PRIO_REPLACE;
 155                 opt.replace_params.bands = qopt->bands;
 156                 memcpy(&opt.replace_params.priomap, qopt->priomap,
 157                        TC_PRIO_MAX + 1);
 158                 opt.replace_params.qstats = &sch->qstats;
 159         } else {
 160                 opt.command = TC_PRIO_DESTROY;
 161         }
 162
 163         return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_PRIO, &opt);
 164 }
 165
 166 static void
 167 prio_destroy(struct Qdisc *sch)
 168 {
 169         int prio;
 170         struct prio_sched_data *q = qdisc_priv(sch);
 171
 172         tcf_block_put(q->block);
 173         prio_offload(sch, NULL);
 174         for (prio = 0; prio < q->bands; prio++)
 175                 qdisc_put(q->queues[prio]);
 176 }
 177
 178 static int prio_tune(struct Qdisc *sch, struct nlattr *opt,
 179                      struct netlink_ext_ack *extack)
 180 {
 181         struct prio_sched_data *q = qdisc_priv(sch);
 182         struct Qdisc *queues[TCQ_PRIO_BANDS];
 183         int oldbands = q->bands, i;
 184         struct tc_prio_qopt *qopt;
 185
 186         if (nla_len(opt) < sizeof(*qopt))
 187                 return -EINVAL;
 188         qopt = nla_data(opt);
 189
 190         if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < 2)
 191                 return -EINVAL;
 192
 193         for (i = 0; i <= TC_PRIO_MAX; i++) {
 194                 if (qopt->priomap[i] >= qopt->bands)
 195                         return -EINVAL;
 196         }
 197
 198         /* Before commit, make sure we can allocate all new qdiscs */
 199         for (i = oldbands; i < qopt->bands; i++) {
 200                 queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 201                                               TC_H_MAKE(sch->handle, i + 1),
 202                                               extack);
 203                 if (!queues[i]) {
 204                         while (i > oldbands)
 205                                 qdisc_put(queues[--i]);
 206                         return -ENOMEM;
 207                 }
 208         }
 209
 210         prio_offload(sch, qopt);
 211         sch_tree_lock(sch);
 212         q->bands = qopt->bands;
 213         memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 214
 215         for (i = q->bands; i < oldbands; i++)
 216                 qdisc_tree_flush_backlog(q->queues[i]);
 217
 218         for (i = oldbands; i < q->bands; i++) {
 219                 q->queues[i] = queues[i];
 220                 if (q->queues[i] != &noop_qdisc)
 221                         qdisc_hash_add(q->queues[i], true);
 222         }
 223
 224         sch_tree_unlock(sch);
 225
 226         for (i = q->bands; i < oldbands; i++)
 227                 qdisc_put(q->queues[i]);
 228         return 0;
 229 }
 230
 231 static int prio_init(struct Qdisc *sch, struct nlattr *opt,
 232                      struct netlink_ext_ack *extack)
 233 {
 234         struct prio_sched_data *q = qdisc_priv(sch);
 235         int err;
 236
 237         if (!opt)
 238                 return -EINVAL;
 239
 240         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
 241         if (err)
 242                 return err;
 243
 244         return prio_tune(sch, opt, extack);
 245 }
 246
 247 static int prio_dump_offload(struct Qdisc *sch)
 248 {
 249         struct tc_prio_qopt_offload hw_stats = {
 250                 .command = TC_PRIO_STATS,
 251                 .handle = sch->handle,
 252                 .parent = sch->parent,
 253                 {
 254                         .stats = {
 255                                 .bstats = &sch->bstats,
 256                                 .qstats = &sch->qstats,
 257                         },
 258                 },
 259         };
 260
 261         return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_PRIO, &hw_stats);
 262 }
 263
 264 static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
 265 {
 266         struct prio_sched_data *q = qdisc_priv(sch);
 267         unsigned char *b = skb_tail_pointer(skb);
 268         struct tc_prio_qopt opt;
 269         int err;
 270
 271         opt.bands = q->bands;
 272         memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);
 273
 274         err = prio_dump_offload(sch);
 275         if (err)
 276                 goto nla_put_failure;
 277
 278         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 279                 goto nla_put_failure;
 280
 281         return skb->len;
 282
 283 nla_put_failure:
 284         nlmsg_trim(skb, b);
 285         return -1;
 286 }
 287
 288 static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 289                       struct Qdisc **old, struct netlink_ext_ack *extack)
 290 {
 291         struct prio_sched_data *q = qdisc_priv(sch);
 292         struct tc_prio_qopt_offload graft_offload;
 293         unsigned long band = arg - 1;
 294
 295         if (!new) {
 296                 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 297                                         TC_H_MAKE(sch->handle, arg), extack);
 298                 if (!new)
 299                         new = &noop_qdisc;
 300                 else
 301                         qdisc_hash_add(new, true);
 302         }
 303
 304         *old = qdisc_replace(sch, new, &q->queues[band]);
 305
 306         graft_offload.handle = sch->handle;
 307         graft_offload.parent = sch->parent;
 308         graft_offload.graft_params.band = band;
 309         graft_offload.graft_params.child_handle = new->handle;
 310         graft_offload.command = TC_PRIO_GRAFT;
 311
 312         qdisc_offload_graft_helper(qdisc_dev(sch), sch, new, *old,
 313                                    TC_SETUP_QDISC_PRIO, &graft_offload,
 314                                    extack);
 315         return 0;
 316 }
 317
 318 static struct Qdisc *
 319 prio_leaf(struct Qdisc *sch, unsigned long arg)
 320 {
 321         struct prio_sched_data *q = qdisc_priv(sch);
 322         unsigned long band = arg - 1;
 323
 324         return q->queues[band];
 325 }
 326
 327 static unsigned long prio_find(struct Qdisc *sch, u32 classid)
 328 {
 329         struct prio_sched_data *q = qdisc_priv(sch);
 330         unsigned long band = TC_H_MIN(classid);
 331
 332         if (band - 1 >= q->bands)
 333                 return 0;
 334         return band;
 335 }
 336
 337 static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
 338 {
 339         return prio_find(sch, classid);
 340 }
 341
 342
 343 static void prio_unbind(struct Qdisc *q, unsigned long cl)
 344 {
 345 }
 346
 347 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
 348                            struct tcmsg *tcm)
 349 {
 350         struct prio_sched_data *q = qdisc_priv(sch);
 351
 352         tcm->tcm_handle |= TC_H_MIN(cl);
 353         tcm->tcm_info = q->queues[cl-1]->handle;
 354         return 0;
 355 }
 356
 357 static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 358                                  struct gnet_dump *d)
 359 {
 360         struct prio_sched_data *q = qdisc_priv(sch);
 361         struct Qdisc *cl_q;
 362
 363         cl_q = q->queues[cl - 1];
 364         if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 365                                   d, cl_q->cpu_bstats, &cl_q->bstats) < 0 ||
 366             qdisc_qstats_copy(d, cl_q) < 0)
 367                 return -1;
 368
 369         return 0;
 370 }
 371
 372 static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 373 {
 374         struct prio_sched_data *q = qdisc_priv(sch);
 375         int prio;
 376
 377         if (arg->stop)
 378                 return;
 379
 380         for (prio = 0; prio < q->bands; prio++) {
 381                 if (arg->count < arg->skip) {
 382                         arg->count++;
 383                         continue;
 384                 }
 385                 if (arg->fn(sch, prio + 1, arg) < 0) {
 386                         arg->stop = 1;
 387                         break;
 388                 }
 389                 arg->count++;
 390         }
 391 }
 392
 393 static struct tcf_block *prio_tcf_block(struct Qdisc *sch, unsigned long cl,
 394                                         struct netlink_ext_ack *extack)
 395 {
 396         struct prio_sched_data *q = qdisc_priv(sch);
 397
 398         if (cl)
 399                 return NULL;
 400         return q->block;
 401 }
 402
 403 static const struct Qdisc_class_ops prio_class_ops = {
 404         .graft          =       prio_graft,
 405         .leaf           =       prio_leaf,
 406         .find           =       prio_find,
 407         .walk           =       prio_walk,
 408         .tcf_block      =       prio_tcf_block,
 409         .bind_tcf       =       prio_bind,
 410         .unbind_tcf     =       prio_unbind,
 411         .dump           =       prio_dump_class,
 412         .dump_stats     =       prio_dump_class_stats,
 413 };
 414
 415 static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
 416         .next           =       NULL,
 417         .cl_ops         =       &prio_class_ops,
 418         .id             =       "prio",
 419         .priv_size      =       sizeof(struct prio_sched_data),
 420         .enqueue        =       prio_enqueue,
 421         .dequeue        =       prio_dequeue,
 422         .peek           =       prio_peek,
 423         .init           =       prio_init,
 424         .reset          =       prio_reset,
 425         .destroy        =       prio_destroy,
 426         .change         =       prio_tune,
 427         .dump           =       prio_dump,
 428         .owner          =       THIS_MODULE,
 429 };
 430
 431 static int __init prio_module_init(void)
 432 {
 433         return register_qdisc(&prio_qdisc_ops);
 434 }
 435
 436 static void __exit prio_module_exit(void)
 437 {
 438         unregister_qdisc(&prio_qdisc_ops);
 439 }
 440
 441 module_init(prio_module_init)
 442 module_exit(prio_module_exit)
 443
 444 MODULE_LICENSE("GPL");