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
  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)
  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);
  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 unsigned int prio_drop(struct Qdisc *sch)
 131 {
 132         struct prio_sched_data *q = qdisc_priv(sch);
 133         int prio;
 134         unsigned int len;
 135         struct Qdisc *qdisc;
 136
 137         for (prio = q->bands-1; prio >= 0; prio--) {
 138                 qdisc = q->queues[prio];
 139                 if (qdisc->ops->drop && (len = qdisc->ops->drop(qdisc)) != 0) {
 140                         sch->qstats.backlog -= len;
 141                         sch->q.qlen--;
 142                         return len;
 143                 }
 144         }
 145         return 0;
 146 }
 147
 148
 149 static void
 150 prio_reset(struct Qdisc *sch)
 151 {
 152         int prio;
 153         struct prio_sched_data *q = qdisc_priv(sch);
 154
 155         for (prio = 0; prio < q->bands; prio++)
 156                 qdisc_reset(q->queues[prio]);
 157         sch->qstats.backlog = 0;
 158         sch->q.qlen = 0;
 159 }
 160
 161 static void
 162 prio_destroy(struct Qdisc *sch)
 163 {
 164         int prio;
 165         struct prio_sched_data *q = qdisc_priv(sch);
 166
 167         tcf_destroy_chain(&q->filter_list);
 168         for (prio = 0; prio < q->bands; prio++)
 169                 qdisc_destroy(q->queues[prio]);
 170 }
 171
 172 static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
 173 {
 174         struct prio_sched_data *q = qdisc_priv(sch);
 175         struct Qdisc *queues[TCQ_PRIO_BANDS];
 176         int oldbands = q->bands, i;
 177         struct tc_prio_qopt *qopt;
 178
 179         if (nla_len(opt) < sizeof(*qopt))
 180                 return -EINVAL;
 181         qopt = nla_data(opt);
 182
 183         if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < 2)
 184                 return -EINVAL;
 185
 186         for (i = 0; i <= TC_PRIO_MAX; i++) {
 187                 if (qopt->priomap[i] >= qopt->bands)
 188                         return -EINVAL;
 189         }
 190
 191         /* Before commit, make sure we can allocate all new qdiscs */
 192         for (i = oldbands; i < qopt->bands; i++) {
 193                 queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 194                                               TC_H_MAKE(sch->handle, i + 1));
 195                 if (!queues[i]) {
 196                         while (i > oldbands)
 197                                 qdisc_destroy(queues[--i]);
 198                         return -ENOMEM;
 199                 }
 200         }
 201
 202         sch_tree_lock(sch);
 203         q->bands = qopt->bands;
 204         memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 205
 206         for (i = q->bands; i < oldbands; i++) {
 207                 struct Qdisc *child = q->queues[i];
 208
 209                 qdisc_tree_reduce_backlog(child, child->q.qlen,
 210                                           child->qstats.backlog);
 211                 qdisc_destroy(child);
 212         }
 213
 214         for (i = oldbands; i < q->bands; i++)
 215                 q->queues[i] = queues[i];
 216
 217         sch_tree_unlock(sch);
 218         return 0;
 219 }
 220
 221 static int prio_init(struct Qdisc *sch, struct nlattr *opt)
 222 {
 223         if (!opt)
 224                 return -EINVAL;
 225
 226         return prio_tune(sch, opt);
 227 }
 228
 229 static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
 230 {
 231         struct prio_sched_data *q = qdisc_priv(sch);
 232         unsigned char *b = skb_tail_pointer(skb);
 233         struct tc_prio_qopt opt;
 234
 235         opt.bands = q->bands;
 236         memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);
 237
 238         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 239                 goto nla_put_failure;
 240
 241         return skb->len;
 242
 243 nla_put_failure:
 244         nlmsg_trim(skb, b);
 245         return -1;
 246 }
 247
 248 static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 249                       struct Qdisc **old)
 250 {
 251         struct prio_sched_data *q = qdisc_priv(sch);
 252         unsigned long band = arg - 1;
 253
 254         if (new == NULL)
 255                 new = &noop_qdisc;
 256
 257         *old = qdisc_replace(sch, new, &q->queues[band]);
 258         return 0;
 259 }
 260
 261 static struct Qdisc *
 262 prio_leaf(struct Qdisc *sch, unsigned long arg)
 263 {
 264         struct prio_sched_data *q = qdisc_priv(sch);
 265         unsigned long band = arg - 1;
 266
 267         return q->queues[band];
 268 }
 269
 270 static unsigned long prio_get(struct Qdisc *sch, u32 classid)
 271 {
 272         struct prio_sched_data *q = qdisc_priv(sch);
 273         unsigned long band = TC_H_MIN(classid);
 274
 275         if (band - 1 >= q->bands)
 276                 return 0;
 277         return band;
 278 }
 279
 280 static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
 281 {
 282         return prio_get(sch, classid);
 283 }
 284
 285
 286 static void prio_put(struct Qdisc *q, unsigned long cl)
 287 {
 288 }
 289
 290 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
 291                            struct tcmsg *tcm)
 292 {
 293         struct prio_sched_data *q = qdisc_priv(sch);
 294
 295         tcm->tcm_handle |= TC_H_MIN(cl);
 296         tcm->tcm_info = q->queues[cl-1]->handle;
 297         return 0;
 298 }
 299
 300 static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 301                                  struct gnet_dump *d)
 302 {
 303         struct prio_sched_data *q = qdisc_priv(sch);
 304         struct Qdisc *cl_q;
 305
 306         cl_q = q->queues[cl - 1];
 307         if (gnet_stats_copy_basic(d, NULL, &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_proto __rcu **prio_find_tcf(struct Qdisc *sch,
 336                                               unsigned long cl)
 337 {
 338         struct prio_sched_data *q = qdisc_priv(sch);
 339
 340         if (cl)
 341                 return NULL;
 342         return &q->filter_list;
 343 }
 344
 345 static const struct Qdisc_class_ops prio_class_ops = {
 346         .graft          =       prio_graft,
 347         .leaf           =       prio_leaf,
 348         .get            =       prio_get,
 349         .put            =       prio_put,
 350         .walk           =       prio_walk,
 351         .tcf_chain      =       prio_find_tcf,
 352         .bind_tcf       =       prio_bind,
 353         .unbind_tcf     =       prio_put,
 354         .dump           =       prio_dump_class,
 355         .dump_stats     =       prio_dump_class_stats,
 356 };
 357
 358 static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
 359         .next           =       NULL,
 360         .cl_ops         =       &prio_class_ops,
 361         .id             =       "prio",
 362         .priv_size      =       sizeof(struct prio_sched_data),
 363         .enqueue        =       prio_enqueue,
 364         .dequeue        =       prio_dequeue,
 365         .peek           =       prio_peek,
 366         .drop           =       prio_drop,
 367         .init           =       prio_init,
 368         .reset          =       prio_reset,
 369         .destroy        =       prio_destroy,
 370         .change         =       prio_tune,
 371         .dump           =       prio_dump,
 372         .owner          =       THIS_MODULE,
 373 };
 374
 375 static int __init prio_module_init(void)
 376 {
 377         return register_qdisc(&prio_qdisc_ops);
 378 }
 379
 380 static void __exit prio_module_exit(void)
 381 {
 382         unregister_qdisc(&prio_qdisc_ops);
 383 }
 384
 385 module_init(prio_module_init)
 386 module_exit(prio_module_exit)
 387
 388 MODULE_LICENSE("GPL");