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         u8  prio2band[TC_PRIO_MAX+1];
  29         struct Qdisc *queues[TCQ_PRIO_BANDS];
  30 };
  31
  32
  33 static struct Qdisc *
  34 prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
  35 {
  36         struct prio_sched_data *q = qdisc_priv(sch);
  37         u32 band = skb->priority;
  38         struct tcf_result res;
  39         struct tcf_proto *fl;
  40         int err;
  41
  42         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
  43         if (TC_H_MAJ(skb->priority) != sch->handle) {
  44                 fl = rcu_dereference_bh(q->filter_list);
  45                 err = tc_classify(skb, fl, &res, false);
  46 #ifdef CONFIG_NET_CLS_ACT
  47                 switch (err) {
  48                 case TC_ACT_STOLEN:
  49                 case TC_ACT_QUEUED:
  50                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
  51                 case TC_ACT_SHOT:
  52                         return NULL;
  53                 }
  54 #endif
  55                 if (!fl || err < 0) {
  56                         if (TC_H_MAJ(band))
  57                                 band = 0;
  58                         return q->queues[q->prio2band[band & TC_PRIO_MAX]];
  59                 }
  60                 band = res.classid;
  61         }
  62         band = TC_H_MIN(band) - 1;
  63         if (band >= q->bands)
  64                 return q->queues[q->prio2band[0]];
  65
  66         return q->queues[band];
  67 }
  68
  69 static int
  70 prio_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
  71 {
  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                 kfree_skb(skb);
  82                 return ret;
  83         }
  84 #endif
  85
  86         ret = qdisc_enqueue(skb, qdisc, to_free);
  87         if (ret == NET_XMIT_SUCCESS) {
  88                 qdisc_qstats_backlog_inc(sch, skb);
  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 void
 143 prio_destroy(struct Qdisc *sch)
 144 {
 145         int prio;
 146         struct prio_sched_data *q = qdisc_priv(sch);
 147
 148         tcf_destroy_chain(&q->filter_list);
 149         for (prio = 0; prio < q->bands; prio++)
 150                 qdisc_destroy(q->queues[prio]);
 151 }
 152
 153 static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
 154 {
 155         struct prio_sched_data *q = qdisc_priv(sch);
 156         struct Qdisc *queues[TCQ_PRIO_BANDS];
 157         int oldbands = q->bands, i;
 158         struct tc_prio_qopt *qopt;
 159
 160         if (nla_len(opt) < sizeof(*qopt))
 161                 return -EINVAL;
 162         qopt = nla_data(opt);
 163
 164         if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < 2)
 165                 return -EINVAL;
 166
 167         for (i = 0; i <= TC_PRIO_MAX; i++) {
 168                 if (qopt->priomap[i] >= qopt->bands)
 169                         return -EINVAL;
 170         }
 171
 172         /* Before commit, make sure we can allocate all new qdiscs */
 173         for (i = oldbands; i < qopt->bands; i++) {
 174                 queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 175                                               TC_H_MAKE(sch->handle, i + 1));
 176                 if (!queues[i]) {
 177                         while (i > oldbands)
 178                                 qdisc_destroy(queues[--i]);
 179                         return -ENOMEM;
 180                 }
 181         }
 182
 183         sch_tree_lock(sch);
 184         q->bands = qopt->bands;
 185         memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 186
 187         for (i = q->bands; i < oldbands; i++) {
 188                 struct Qdisc *child = q->queues[i];
 189
 190                 qdisc_tree_reduce_backlog(child, child->q.qlen,
 191                                           child->qstats.backlog);
 192                 qdisc_destroy(child);
 193         }
 194
 195         for (i = oldbands; i < q->bands; i++) {
 196                 q->queues[i] = queues[i];
 197                 if (q->queues[i] != &noop_qdisc)
 198                         qdisc_hash_add(q->queues[i], true);
 199         }
 200
 201         sch_tree_unlock(sch);
 202         return 0;
 203 }
 204
 205 static int prio_init(struct Qdisc *sch, struct nlattr *opt)
 206 {
 207         if (!opt)
 208                 return -EINVAL;
 209
 210         return prio_tune(sch, opt);
 211 }
 212
 213 static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
 214 {
 215         struct prio_sched_data *q = qdisc_priv(sch);
 216         unsigned char *b = skb_tail_pointer(skb);
 217         struct tc_prio_qopt opt;
 218
 219         opt.bands = q->bands;
 220         memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);
 221
 222         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 223                 goto nla_put_failure;
 224
 225         return skb->len;
 226
 227 nla_put_failure:
 228         nlmsg_trim(skb, b);
 229         return -1;
 230 }
 231
 232 static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 233                       struct Qdisc **old)
 234 {
 235         struct prio_sched_data *q = qdisc_priv(sch);
 236         unsigned long band = arg - 1;
 237
 238         if (new == NULL)
 239                 new = &noop_qdisc;
 240
 241         *old = qdisc_replace(sch, new, &q->queues[band]);
 242         return 0;
 243 }
 244
 245 static struct Qdisc *
 246 prio_leaf(struct Qdisc *sch, unsigned long arg)
 247 {
 248         struct prio_sched_data *q = qdisc_priv(sch);
 249         unsigned long band = arg - 1;
 250
 251         return q->queues[band];
 252 }
 253
 254 static unsigned long prio_get(struct Qdisc *sch, u32 classid)
 255 {
 256         struct prio_sched_data *q = qdisc_priv(sch);
 257         unsigned long band = TC_H_MIN(classid);
 258
 259         if (band - 1 >= q->bands)
 260                 return 0;
 261         return band;
 262 }
 263
 264 static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
 265 {
 266         return prio_get(sch, classid);
 267 }
 268
 269
 270 static void prio_put(struct Qdisc *q, unsigned long cl)
 271 {
 272 }
 273
 274 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
 275                            struct tcmsg *tcm)
 276 {
 277         struct prio_sched_data *q = qdisc_priv(sch);
 278
 279         tcm->tcm_handle |= TC_H_MIN(cl);
 280         tcm->tcm_info = q->queues[cl-1]->handle;
 281         return 0;
 282 }
 283
 284 static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 285                                  struct gnet_dump *d)
 286 {
 287         struct prio_sched_data *q = qdisc_priv(sch);
 288         struct Qdisc *cl_q;
 289
 290         cl_q = q->queues[cl - 1];
 291         if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 292                                   d, NULL, &cl_q->bstats) < 0 ||
 293             gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0)
 294                 return -1;
 295
 296         return 0;
 297 }
 298
 299 static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 300 {
 301         struct prio_sched_data *q = qdisc_priv(sch);
 302         int prio;
 303
 304         if (arg->stop)
 305                 return;
 306
 307         for (prio = 0; prio < q->bands; prio++) {
 308                 if (arg->count < arg->skip) {
 309                         arg->count++;
 310                         continue;
 311                 }
 312                 if (arg->fn(sch, prio + 1, arg) < 0) {
 313                         arg->stop = 1;
 314                         break;
 315                 }
 316                 arg->count++;
 317         }
 318 }
 319
 320 static struct tcf_proto __rcu **prio_find_tcf(struct Qdisc *sch,
 321                                               unsigned long cl)
 322 {
 323         struct prio_sched_data *q = qdisc_priv(sch);
 324
 325         if (cl)
 326                 return NULL;
 327         return &q->filter_list;
 328 }
 329
 330 static const struct Qdisc_class_ops prio_class_ops = {
 331         .graft          =       prio_graft,
 332         .leaf           =       prio_leaf,
 333         .get            =       prio_get,
 334         .put            =       prio_put,
 335         .walk           =       prio_walk,
 336         .tcf_chain      =       prio_find_tcf,
 337         .bind_tcf       =       prio_bind,
 338         .unbind_tcf     =       prio_put,
 339         .dump           =       prio_dump_class,
 340         .dump_stats     =       prio_dump_class_stats,
 341 };
 342
 343 static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
 344         .next           =       NULL,
 345         .cl_ops         =       &prio_class_ops,
 346         .id             =       "prio",
 347         .priv_size      =       sizeof(struct prio_sched_data),
 348         .enqueue        =       prio_enqueue,
 349         .dequeue        =       prio_dequeue,
 350         .peek           =       prio_peek,
 351         .init           =       prio_init,
 352         .reset          =       prio_reset,
 353         .destroy        =       prio_destroy,
 354         .change         =       prio_tune,
 355         .dump           =       prio_dump,
 356         .owner          =       THIS_MODULE,
 357 };
 358
 359 static int __init prio_module_init(void)
 360 {
 361         return register_qdisc(&prio_qdisc_ops);
 362 }
 363
 364 static void __exit prio_module_exit(void)
 365 {
 366         unregister_qdisc(&prio_qdisc_ops);
 367 }
 368
 369 module_init(prio_module_init)
 370 module_exit(prio_module_exit)
 371
 372 MODULE_LICENSE("GPL");