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