net/sched/sch_prio.c

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