net/sched/sch_mq.c

   1 /*
   2  * net/sched/sch_mq.c           Classful multiqueue dummy scheduler
   3  *
   4  * Copyright (c) 2009 Patrick McHardy <kaber@trash.net>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * version 2 as published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/types.h>
  12 #include <linux/slab.h>
  13 #include <linux/kernel.h>
  14 #include <linux/export.h>
  15 #include <linux/string.h>
  16 #include <linux/errno.h>
  17 #include <linux/skbuff.h>
  18 #include <net/netlink.h>
  19 #include <net/pkt_sched.h>
  20 #include <net/sch_generic.h>
  21
  22 struct mq_sched {
  23         struct Qdisc            **qdiscs;
  24 };
  25
  26 static void mq_destroy(struct Qdisc *sch)
  27 {
  28         struct net_device *dev = qdisc_dev(sch);
  29         struct mq_sched *priv = qdisc_priv(sch);
  30         unsigned int ntx;
  31
  32         if (!priv->qdiscs)
  33                 return;
  34         for (ntx = 0; ntx < dev->num_tx_queues && priv->qdiscs[ntx]; ntx++)
  35                 qdisc_destroy(priv->qdiscs[ntx]);
  36         kfree(priv->qdiscs);
  37 }
  38
  39 static int mq_init(struct Qdisc *sch, struct nlattr *opt,
  40                    struct netlink_ext_ack *extack)
  41 {
  42         struct net_device *dev = qdisc_dev(sch);
  43         struct mq_sched *priv = qdisc_priv(sch);
  44         struct netdev_queue *dev_queue;
  45         struct Qdisc *qdisc;
  46         unsigned int ntx;
  47
  48         if (sch->parent != TC_H_ROOT)
  49                 return -EOPNOTSUPP;
  50
  51         if (!netif_is_multiqueue(dev))
  52                 return -EOPNOTSUPP;
  53
  54         /* pre-allocate qdiscs, attachment can't fail */
  55         priv->qdiscs = kcalloc(dev->num_tx_queues, sizeof(priv->qdiscs[0]),
  56                                GFP_KERNEL);
  57         if (!priv->qdiscs)
  58                 return -ENOMEM;
  59
  60         for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
  61                 dev_queue = netdev_get_tx_queue(dev, ntx);
  62                 qdisc = qdisc_create_dflt(dev_queue, get_default_qdisc_ops(dev, ntx),
  63                                           TC_H_MAKE(TC_H_MAJ(sch->handle),
  64                                                     TC_H_MIN(ntx + 1)),
  65                                           extack);
  66                 if (!qdisc)
  67                         return -ENOMEM;
  68                 priv->qdiscs[ntx] = qdisc;
  69                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
  70         }
  71
  72         sch->flags |= TCQ_F_MQROOT;
  73         return 0;
  74 }
  75
  76 static void mq_attach(struct Qdisc *sch)
  77 {
  78         struct net_device *dev = qdisc_dev(sch);
  79         struct mq_sched *priv = qdisc_priv(sch);
  80         struct Qdisc *qdisc, *old;
  81         unsigned int ntx;
  82
  83         for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
  84                 qdisc = priv->qdiscs[ntx];
  85                 old = dev_graft_qdisc(qdisc->dev_queue, qdisc);
  86                 if (old)
  87                         qdisc_destroy(old);
  88 #ifdef CONFIG_NET_SCHED
  89                 if (ntx < dev->real_num_tx_queues)
  90                         qdisc_hash_add(qdisc, false);
  91 #endif
  92
  93         }
  94         kfree(priv->qdiscs);
  95         priv->qdiscs = NULL;
  96 }
  97
  98 static int mq_dump(struct Qdisc *sch, struct sk_buff *skb)
  99 {
 100         struct net_device *dev = qdisc_dev(sch);
 101         struct Qdisc *qdisc;
 102         unsigned int ntx;
 103         __u32 qlen = 0;
 104
 105         sch->q.qlen = 0;
 106         memset(&sch->bstats, 0, sizeof(sch->bstats));
 107         memset(&sch->qstats, 0, sizeof(sch->qstats));
 108
 109         /* MQ supports lockless qdiscs. However, statistics accounting needs
 110          * to account for all, none, or a mix of locked and unlocked child
 111          * qdiscs. Percpu stats are added to counters in-band and locking
 112          * qdisc totals are added at end.
 113          */
 114         for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
 115                 qdisc = netdev_get_tx_queue(dev, ntx)->qdisc_sleeping;
 116                 spin_lock_bh(qdisc_lock(qdisc));
 117
 118                 if (qdisc_is_percpu_stats(qdisc)) {
 119                         qlen = qdisc_qlen_sum(qdisc);
 120                         __gnet_stats_copy_basic(NULL, &sch->bstats,
 121                                                 qdisc->cpu_bstats,
 122                                                 &qdisc->bstats);
 123                         __gnet_stats_copy_queue(&sch->qstats,
 124                                                 qdisc->cpu_qstats,
 125                                                 &qdisc->qstats, qlen);
 126                 } else {
 127                         sch->q.qlen             += qdisc->q.qlen;
 128                         sch->bstats.bytes       += qdisc->bstats.bytes;
 129                         sch->bstats.packets     += qdisc->bstats.packets;
 130                         sch->qstats.backlog     += qdisc->qstats.backlog;
 131                         sch->qstats.drops       += qdisc->qstats.drops;
 132                         sch->qstats.requeues    += qdisc->qstats.requeues;
 133                         sch->qstats.overlimits  += qdisc->qstats.overlimits;
 134                 }
 135
 136                 spin_unlock_bh(qdisc_lock(qdisc));
 137         }
 138
 139         return 0;
 140 }
 141
 142 static struct netdev_queue *mq_queue_get(struct Qdisc *sch, unsigned long cl)
 143 {
 144         struct net_device *dev = qdisc_dev(sch);
 145         unsigned long ntx = cl - 1;
 146
 147         if (ntx >= dev->num_tx_queues)
 148                 return NULL;
 149         return netdev_get_tx_queue(dev, ntx);
 150 }
 151
 152 static struct netdev_queue *mq_select_queue(struct Qdisc *sch,
 153                                             struct tcmsg *tcm)
 154 {
 155         return mq_queue_get(sch, TC_H_MIN(tcm->tcm_parent));
 156 }
 157
 158 static int mq_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
 159                     struct Qdisc **old, struct netlink_ext_ack *extack)
 160 {
 161         struct netdev_queue *dev_queue = mq_queue_get(sch, cl);
 162         struct net_device *dev = qdisc_dev(sch);
 163
 164         if (dev->flags & IFF_UP)
 165                 dev_deactivate(dev);
 166
 167         *old = dev_graft_qdisc(dev_queue, new);
 168         if (new)
 169                 new->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
 170         if (dev->flags & IFF_UP)
 171                 dev_activate(dev);
 172         return 0;
 173 }
 174
 175 static struct Qdisc *mq_leaf(struct Qdisc *sch, unsigned long cl)
 176 {
 177         struct netdev_queue *dev_queue = mq_queue_get(sch, cl);
 178
 179         return dev_queue->qdisc_sleeping;
 180 }
 181
 182 static unsigned long mq_find(struct Qdisc *sch, u32 classid)
 183 {
 184         unsigned int ntx = TC_H_MIN(classid);
 185
 186         if (!mq_queue_get(sch, ntx))
 187                 return 0;
 188         return ntx;
 189 }
 190
 191 static int mq_dump_class(struct Qdisc *sch, unsigned long cl,
 192                          struct sk_buff *skb, struct tcmsg *tcm)
 193 {
 194         struct netdev_queue *dev_queue = mq_queue_get(sch, cl);
 195
 196         tcm->tcm_parent = TC_H_ROOT;
 197         tcm->tcm_handle |= TC_H_MIN(cl);
 198         tcm->tcm_info = dev_queue->qdisc_sleeping->handle;
 199         return 0;
 200 }
 201
 202 static int mq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 203                                struct gnet_dump *d)
 204 {
 205         struct netdev_queue *dev_queue = mq_queue_get(sch, cl);
 206
 207         sch = dev_queue->qdisc_sleeping;
 208         if (gnet_stats_copy_basic(&sch->running, d, NULL, &sch->bstats) < 0 ||
 209             gnet_stats_copy_queue(d, NULL, &sch->qstats, sch->q.qlen) < 0)
 210                 return -1;
 211         return 0;
 212 }
 213
 214 static void mq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 215 {
 216         struct net_device *dev = qdisc_dev(sch);
 217         unsigned int ntx;
 218
 219         if (arg->stop)
 220                 return;
 221
 222         arg->count = arg->skip;
 223         for (ntx = arg->skip; ntx < dev->num_tx_queues; ntx++) {
 224                 if (arg->fn(sch, ntx + 1, arg) < 0) {
 225                         arg->stop = 1;
 226                         break;
 227                 }
 228                 arg->count++;
 229         }
 230 }
 231
 232 static const struct Qdisc_class_ops mq_class_ops = {
 233         .select_queue   = mq_select_queue,
 234         .graft          = mq_graft,
 235         .leaf           = mq_leaf,
 236         .find           = mq_find,
 237         .walk           = mq_walk,
 238         .dump           = mq_dump_class,
 239         .dump_stats     = mq_dump_class_stats,
 240 };
 241
 242 struct Qdisc_ops mq_qdisc_ops __read_mostly = {
 243         .cl_ops         = &mq_class_ops,
 244         .id             = "mq",
 245         .priv_size      = sizeof(struct mq_sched),
 246         .init           = mq_init,
 247         .destroy        = mq_destroy,
 248         .attach         = mq_attach,
 249         .dump           = mq_dump,
 250         .owner          = THIS_MODULE,
 251 };