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                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
  52                 case TC_ACT_SHOT:
  53                         return NULL;
  54                 }
  55 #endif
  56                 if (!fl || err < 0) {
  57                         if (TC_H_MAJ(band))
  58                                 band = 0;
  59                         return q->queues[q->prio2band[band & TC_PRIO_MAX]];
  60                 }
  61                 band = res.classid;
  62         }
  63         band = TC_H_MIN(band) - 1;
  64         if (band >= q->bands)
  65                 return q->queues[q->prio2band[0]];
  66
  67         return q->queues[band];
  68 }
  69
  70 static int
  71 prio_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
  72 {
  73         struct Qdisc *qdisc;
  74         int ret;
  75
  76         qdisc = prio_classify(skb, sch, &ret);
  77 #ifdef CONFIG_NET_CLS_ACT
  78         if (qdisc == NULL) {
  79
  80                 if (ret & __NET_XMIT_BYPASS)
  81                         qdisc_qstats_drop(sch);
  82                 kfree_skb(skb);
  83                 return ret;
  84         }
  85 #endif
  86
  87         ret = qdisc_enqueue(skb, qdisc, to_free);
  88         if (ret == NET_XMIT_SUCCESS) {
  89                 qdisc_qstats_backlog_inc(sch, skb);
  90                 sch->q.qlen++;
  91                 return NET_XMIT_SUCCESS;
  92         }
  93         if (net_xmit_drop_count(ret))
  94                 qdisc_qstats_drop(sch);
  95         return ret;
  96 }
  97
  98 static struct sk_buff *prio_peek(struct Qdisc *sch)
  99 {
 100         struct prio_sched_data *q = qdisc_priv(sch);
 101         int prio;
 102
 103         for (prio = 0; prio < q->bands; prio++) {
 104                 struct Qdisc *qdisc = q->queues[prio];
 105                 struct sk_buff *skb = qdisc->ops->peek(qdisc);
 106                 if (skb)
 107                         return skb;
 108         }
 109         return NULL;
 110 }
 111
 112 static struct sk_buff *prio_dequeue(struct Qdisc *sch)
 113 {
 114         struct prio_sched_data *q = qdisc_priv(sch);
 115         int prio;
 116
 117         for (prio = 0; prio < q->bands; prio++) {
 118                 struct Qdisc *qdisc = q->queues[prio];
 119                 struct sk_buff *skb = qdisc_dequeue_peeked(qdisc);
 120                 if (skb) {
 121                         qdisc_bstats_update(sch, skb);
 122                         qdisc_qstats_backlog_dec(sch, skb);
 123                         sch->q.qlen--;
 124                         return skb;
 125                 }
 126         }
 127         return NULL;
 128
 129 }
 130
 131 static void
 132 prio_reset(struct Qdisc *sch)
 133 {
 134         int prio;
 135         struct prio_sched_data *q = qdisc_priv(sch);
 136
 137         for (prio = 0; prio < q->bands; prio++)
 138                 qdisc_reset(q->queues[prio]);
 139         sch->qstats.backlog = 0;
 140         sch->q.qlen = 0;
 141 }
 142
 143 static void
 144 prio_destroy(struct Qdisc *sch)
 145 {
 146         int prio;
 147         struct prio_sched_data *q = qdisc_priv(sch);
 148
 149         tcf_block_put(q->block);
 150         for (prio = 0; prio < q->bands; prio++)
 151                 qdisc_destroy(q->queues[prio]);
 152 }
 153
 154 static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
 155 {
 156         struct prio_sched_data *q = qdisc_priv(sch);
 157         struct Qdisc *queues[TCQ_PRIO_BANDS];
 158         int oldbands = q->bands, i;
 159         struct tc_prio_qopt *qopt;
 160
 161         if (nla_len(opt) < sizeof(*qopt))
 162                 return -EINVAL;
 163         qopt = nla_data(opt);
 164
 165         if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < 2)
 166                 return -EINVAL;
 167
 168         for (i = 0; i <= TC_PRIO_MAX; i++) {
 169                 if (qopt->priomap[i] >= qopt->bands)
 170                         return -EINVAL;
 171         }
 172
 173         /* Before commit, make sure we can allocate all new qdiscs */
 174         for (i = oldbands; i < qopt->bands; i++) {
 175                 queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 176                                               TC_H_MAKE(sch->handle, i + 1));
 177                 if (!queues[i]) {
 178                         while (i > oldbands)
 179                                 qdisc_destroy(queues[--i]);
 180                         return -ENOMEM;
 181                 }
 182         }
 183
 184         sch_tree_lock(sch);
 185         q->bands = qopt->bands;
 186         memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 187
 188         for (i = q->bands; i < oldbands; i++) {
 189                 struct Qdisc *child = q->queues[i];
 190
 191                 qdisc_tree_reduce_backlog(child, child->q.qlen,
 192                                           child->qstats.backlog);
 193                 qdisc_destroy(child);
 194         }
 195
 196         for (i = oldbands; i < q->bands; i++) {
 197                 q->queues[i] = queues[i];
 198                 if (q->queues[i] != &noop_qdisc)
 199                         qdisc_hash_add(q->queues[i], true);
 200         }
 201
 202         sch_tree_unlock(sch);
 203         return 0;
 204 }
 205
 206 static int prio_init(struct Qdisc *sch, struct nlattr *opt)
 207 {
 208         struct prio_sched_data *q = qdisc_priv(sch);
 209         int err;
 210
 211         if (!opt)
 212                 return -EINVAL;
 213
 214         err = tcf_block_get(&q->block, &q->filter_list);
 215         if (err)
 216                 return err;
 217
 218         return prio_tune(sch, opt);
 219 }
 220
 221 static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
 222 {
 223         struct prio_sched_data *q = qdisc_priv(sch);
 224         unsigned char *b = skb_tail_pointer(skb);
 225         struct tc_prio_qopt opt;
 226
 227         opt.bands = q->bands;
 228         memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);
 229
 230         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 231                 goto nla_put_failure;
 232
 233         return skb->len;
 234
 235 nla_put_failure:
 236         nlmsg_trim(skb, b);
 237         return -1;
 238 }
 239
 240 static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 241                       struct Qdisc **old)
 242 {
 243         struct prio_sched_data *q = qdisc_priv(sch);
 244         unsigned long band = arg - 1;
 245
 246         if (new == NULL)
 247                 new = &noop_qdisc;
 248
 249         *old = qdisc_replace(sch, new, &q->queues[band]);
 250         return 0;
 251 }
 252
 253 static struct Qdisc *
 254 prio_leaf(struct Qdisc *sch, unsigned long arg)
 255 {
 256         struct prio_sched_data *q = qdisc_priv(sch);
 257         unsigned long band = arg - 1;
 258
 259         return q->queues[band];
 260 }
 261
 262 static unsigned long prio_get(struct Qdisc *sch, u32 classid)
 263 {
 264         struct prio_sched_data *q = qdisc_priv(sch);
 265         unsigned long band = TC_H_MIN(classid);
 266
 267         if (band - 1 >= q->bands)
 268                 return 0;
 269         return band;
 270 }
 271
 272 static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
 273 {
 274         return prio_get(sch, classid);
 275 }
 276
 277
 278 static void prio_put(struct Qdisc *q, unsigned long cl)
 279 {
 280 }
 281
 282 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
 283                            struct tcmsg *tcm)
 284 {
 285         struct prio_sched_data *q = qdisc_priv(sch);
 286
 287         tcm->tcm_handle |= TC_H_MIN(cl);
 288         tcm->tcm_info = q->queues[cl-1]->handle;
 289         return 0;
 290 }
 291
 292 static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 293                                  struct gnet_dump *d)
 294 {
 295         struct prio_sched_data *q = qdisc_priv(sch);
 296         struct Qdisc *cl_q;
 297
 298         cl_q = q->queues[cl - 1];
 299         if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 300                                   d, NULL, &cl_q->bstats) < 0 ||
 301             gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0)
 302                 return -1;
 303
 304         return 0;
 305 }
 306
 307 static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 308 {
 309         struct prio_sched_data *q = qdisc_priv(sch);
 310         int prio;
 311
 312         if (arg->stop)
 313                 return;
 314
 315         for (prio = 0; prio < q->bands; prio++) {
 316                 if (arg->count < arg->skip) {
 317                         arg->count++;
 318                         continue;
 319                 }
 320                 if (arg->fn(sch, prio + 1, arg) < 0) {
 321                         arg->stop = 1;
 322                         break;
 323                 }
 324                 arg->count++;
 325         }
 326 }
 327
 328 static struct tcf_block *prio_tcf_block(struct Qdisc *sch, unsigned long cl)
 329 {
 330         struct prio_sched_data *q = qdisc_priv(sch);
 331
 332         if (cl)
 333                 return NULL;
 334         return q->block;
 335 }
 336
 337 static const struct Qdisc_class_ops prio_class_ops = {
 338         .graft          =       prio_graft,
 339         .leaf           =       prio_leaf,
 340         .get            =       prio_get,
 341         .put            =       prio_put,
 342         .walk           =       prio_walk,
 343         .tcf_block      =       prio_tcf_block,
 344         .bind_tcf       =       prio_bind,
 345         .unbind_tcf     =       prio_put,
 346         .dump           =       prio_dump_class,
 347         .dump_stats     =       prio_dump_class_stats,
 348 };
 349
 350 static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
 351         .next           =       NULL,
 352         .cl_ops         =       &prio_class_ops,
 353         .id             =       "prio",
 354         .priv_size      =       sizeof(struct prio_sched_data),
 355         .enqueue        =       prio_enqueue,
 356         .dequeue        =       prio_dequeue,
 357         .peek           =       prio_peek,
 358         .init           =       prio_init,
 359         .reset          =       prio_reset,
 360         .destroy        =       prio_destroy,
 361         .change         =       prio_tune,
 362         .dump           =       prio_dump,
 363         .owner          =       THIS_MODULE,
 364 };
 365
 366 static int __init prio_module_init(void)
 367 {
 368         return register_qdisc(&prio_qdisc_ops);
 369 }
 370
 371 static void __exit prio_module_exit(void)
 372 {
 373         unregister_qdisc(&prio_qdisc_ops);
 374 }
 375
 376 module_init(prio_module_init)
 377 module_exit(prio_module_exit)
 378
 379 MODULE_LICENSE("GPL");