linux/net/core/netprio_cgroup.c
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   1/*
   2 * net/core/netprio_cgroup.c    Priority Control Group
   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:     Neil Horman <nhorman@tuxdriver.com>
  10 */
  11
  12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14#include <linux/module.h>
  15#include <linux/slab.h>
  16#include <linux/types.h>
  17#include <linux/string.h>
  18#include <linux/errno.h>
  19#include <linux/skbuff.h>
  20#include <linux/cgroup.h>
  21#include <linux/rcupdate.h>
  22#include <linux/atomic.h>
  23#include <net/rtnetlink.h>
  24#include <net/pkt_cls.h>
  25#include <net/sock.h>
  26#include <net/netprio_cgroup.h>
  27
  28#include <linux/fdtable.h>
  29
  30#define PRIOIDX_SZ 128
  31
  32static unsigned long prioidx_map[PRIOIDX_SZ];
  33static DEFINE_SPINLOCK(prioidx_map_lock);
  34static atomic_t max_prioidx = ATOMIC_INIT(0);
  35
  36static inline struct cgroup_netprio_state *cgrp_netprio_state(struct cgroup *cgrp)
  37{
  38        return container_of(cgroup_subsys_state(cgrp, net_prio_subsys_id),
  39                            struct cgroup_netprio_state, css);
  40}
  41
  42static int get_prioidx(u32 *prio)
  43{
  44        unsigned long flags;
  45        u32 prioidx;
  46
  47        spin_lock_irqsave(&prioidx_map_lock, flags);
  48        prioidx = find_first_zero_bit(prioidx_map, sizeof(unsigned long) * PRIOIDX_SZ);
  49        if (prioidx == sizeof(unsigned long) * PRIOIDX_SZ) {
  50                spin_unlock_irqrestore(&prioidx_map_lock, flags);
  51                return -ENOSPC;
  52        }
  53        set_bit(prioidx, prioidx_map);
  54        if (atomic_read(&max_prioidx) < prioidx)
  55                atomic_set(&max_prioidx, prioidx);
  56        spin_unlock_irqrestore(&prioidx_map_lock, flags);
  57        *prio = prioidx;
  58        return 0;
  59}
  60
  61static void put_prioidx(u32 idx)
  62{
  63        unsigned long flags;
  64
  65        spin_lock_irqsave(&prioidx_map_lock, flags);
  66        clear_bit(idx, prioidx_map);
  67        spin_unlock_irqrestore(&prioidx_map_lock, flags);
  68}
  69
  70static int extend_netdev_table(struct net_device *dev, u32 new_len)
  71{
  72        size_t new_size = sizeof(struct netprio_map) +
  73                           ((sizeof(u32) * new_len));
  74        struct netprio_map *new_priomap = kzalloc(new_size, GFP_KERNEL);
  75        struct netprio_map *old_priomap;
  76
  77        old_priomap  = rtnl_dereference(dev->priomap);
  78
  79        if (!new_priomap) {
  80                pr_warn("Unable to alloc new priomap!\n");
  81                return -ENOMEM;
  82        }
  83
  84        if (old_priomap)
  85                memcpy(new_priomap->priomap, old_priomap->priomap,
  86                       old_priomap->priomap_len *
  87                       sizeof(old_priomap->priomap[0]));
  88
  89        new_priomap->priomap_len = new_len;
  90
  91        rcu_assign_pointer(dev->priomap, new_priomap);
  92        if (old_priomap)
  93                kfree_rcu(old_priomap, rcu);
  94        return 0;
  95}
  96
  97static int write_update_netdev_table(struct net_device *dev)
  98{
  99        int ret = 0;
 100        u32 max_len;
 101        struct netprio_map *map;
 102
 103        max_len = atomic_read(&max_prioidx) + 1;
 104        map = rtnl_dereference(dev->priomap);
 105        if (!map || map->priomap_len < max_len)
 106                ret = extend_netdev_table(dev, max_len);
 107
 108        return ret;
 109}
 110
 111static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp)
 112{
 113        struct cgroup_netprio_state *cs;
 114        int ret = -EINVAL;
 115
 116        cs = kzalloc(sizeof(*cs), GFP_KERNEL);
 117        if (!cs)
 118                return ERR_PTR(-ENOMEM);
 119
 120        if (cgrp->parent && cgrp_netprio_state(cgrp->parent)->prioidx)
 121                goto out;
 122
 123        ret = get_prioidx(&cs->prioidx);
 124        if (ret < 0) {
 125                pr_warn("No space in priority index array\n");
 126                goto out;
 127        }
 128
 129        return &cs->css;
 130out:
 131        kfree(cs);
 132        return ERR_PTR(ret);
 133}
 134
 135static void cgrp_destroy(struct cgroup *cgrp)
 136{
 137        struct cgroup_netprio_state *cs;
 138        struct net_device *dev;
 139        struct netprio_map *map;
 140
 141        cs = cgrp_netprio_state(cgrp);
 142        rtnl_lock();
 143        for_each_netdev(&init_net, dev) {
 144                map = rtnl_dereference(dev->priomap);
 145                if (map && cs->prioidx < map->priomap_len)
 146                        map->priomap[cs->prioidx] = 0;
 147        }
 148        rtnl_unlock();
 149        put_prioidx(cs->prioidx);
 150        kfree(cs);
 151}
 152
 153static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
 154{
 155        return (u64)cgrp_netprio_state(cgrp)->prioidx;
 156}
 157
 158static int read_priomap(struct cgroup *cont, struct cftype *cft,
 159                        struct cgroup_map_cb *cb)
 160{
 161        struct net_device *dev;
 162        u32 prioidx = cgrp_netprio_state(cont)->prioidx;
 163        u32 priority;
 164        struct netprio_map *map;
 165
 166        rcu_read_lock();
 167        for_each_netdev_rcu(&init_net, dev) {
 168                map = rcu_dereference(dev->priomap);
 169                priority = (map && prioidx < map->priomap_len) ? map->priomap[prioidx] : 0;
 170                cb->fill(cb, dev->name, priority);
 171        }
 172        rcu_read_unlock();
 173        return 0;
 174}
 175
 176static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
 177                         const char *buffer)
 178{
 179        char *devname = kstrdup(buffer, GFP_KERNEL);
 180        int ret = -EINVAL;
 181        u32 prioidx = cgrp_netprio_state(cgrp)->prioidx;
 182        unsigned long priority;
 183        char *priostr;
 184        struct net_device *dev;
 185        struct netprio_map *map;
 186
 187        if (!devname)
 188                return -ENOMEM;
 189
 190        /*
 191         * Minimally sized valid priomap string
 192         */
 193        if (strlen(devname) < 3)
 194                goto out_free_devname;
 195
 196        priostr = strstr(devname, " ");
 197        if (!priostr)
 198                goto out_free_devname;
 199
 200        /*
 201         *Separate the devname from the associated priority
 202         *and advance the priostr pointer to the priority value
 203         */
 204        *priostr = '\0';
 205        priostr++;
 206
 207        /*
 208         * If the priostr points to NULL, we're at the end of the passed
 209         * in string, and its not a valid write
 210         */
 211        if (*priostr == '\0')
 212                goto out_free_devname;
 213
 214        ret = kstrtoul(priostr, 10, &priority);
 215        if (ret < 0)
 216                goto out_free_devname;
 217
 218        ret = -ENODEV;
 219
 220        dev = dev_get_by_name(&init_net, devname);
 221        if (!dev)
 222                goto out_free_devname;
 223
 224        rtnl_lock();
 225        ret = write_update_netdev_table(dev);
 226        if (ret < 0)
 227                goto out_put_dev;
 228
 229        map = rtnl_dereference(dev->priomap);
 230        if (map)
 231                map->priomap[prioidx] = priority;
 232
 233out_put_dev:
 234        rtnl_unlock();
 235        dev_put(dev);
 236
 237out_free_devname:
 238        kfree(devname);
 239        return ret;
 240}
 241
 242static int update_netprio(const void *v, struct file *file, unsigned n)
 243{
 244        int err;
 245        struct socket *sock = sock_from_file(file, &err);
 246        if (sock)
 247                sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v;
 248        return 0;
 249}
 250
 251void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 252{
 253        struct task_struct *p;
 254        void *v;
 255
 256        cgroup_taskset_for_each(p, cgrp, tset) {
 257                task_lock(p);
 258                v = (void *)(unsigned long)task_netprioidx(p);
 259                iterate_fd(p->files, 0, update_netprio, v);
 260                task_unlock(p);
 261        }
 262}
 263
 264static struct cftype ss_files[] = {
 265        {
 266                .name = "prioidx",
 267                .read_u64 = read_prioidx,
 268        },
 269        {
 270                .name = "ifpriomap",
 271                .read_map = read_priomap,
 272                .write_string = write_priomap,
 273        },
 274        { }     /* terminate */
 275};
 276
 277struct cgroup_subsys net_prio_subsys = {
 278        .name           = "net_prio",
 279        .create         = cgrp_create,
 280        .destroy        = cgrp_destroy,
 281        .attach         = net_prio_attach,
 282        .subsys_id      = net_prio_subsys_id,
 283        .base_cftypes   = ss_files,
 284        .module         = THIS_MODULE,
 285
 286        /*
 287         * net_prio has artificial limit on the number of cgroups and
 288         * disallows nesting making it impossible to co-mount it with other
 289         * hierarchical subsystems.  Remove the artificially low PRIOIDX_SZ
 290         * limit and properly nest configuration such that children follow
 291         * their parents' configurations by default and are allowed to
 292         * override and remove the following.
 293         */
 294        .broken_hierarchy = true,
 295};
 296
 297static int netprio_device_event(struct notifier_block *unused,
 298                                unsigned long event, void *ptr)
 299{
 300        struct net_device *dev = ptr;
 301        struct netprio_map *old;
 302
 303        /*
 304         * Note this is called with rtnl_lock held so we have update side
 305         * protection on our rcu assignments
 306         */
 307
 308        switch (event) {
 309        case NETDEV_UNREGISTER:
 310                old = rtnl_dereference(dev->priomap);
 311                RCU_INIT_POINTER(dev->priomap, NULL);
 312                if (old)
 313                        kfree_rcu(old, rcu);
 314                break;
 315        }
 316        return NOTIFY_DONE;
 317}
 318
 319static struct notifier_block netprio_device_notifier = {
 320        .notifier_call = netprio_device_event
 321};
 322
 323static int __init init_cgroup_netprio(void)
 324{
 325        int ret;
 326
 327        ret = cgroup_load_subsys(&net_prio_subsys);
 328        if (ret)
 329                goto out;
 330
 331        register_netdevice_notifier(&netprio_device_notifier);
 332
 333out:
 334        return ret;
 335}
 336
 337static void __exit exit_cgroup_netprio(void)
 338{
 339        struct netprio_map *old;
 340        struct net_device *dev;
 341
 342        unregister_netdevice_notifier(&netprio_device_notifier);
 343
 344        cgroup_unload_subsys(&net_prio_subsys);
 345
 346        rtnl_lock();
 347        for_each_netdev(&init_net, dev) {
 348                old = rtnl_dereference(dev->priomap);
 349                RCU_INIT_POINTER(dev->priomap, NULL);
 350                if (old)
 351                        kfree_rcu(old, rcu);
 352        }
 353        rtnl_unlock();
 354}
 355
 356module_init(init_cgroup_netprio);
 357module_exit(exit_cgroup_netprio);
 358MODULE_LICENSE("GPL v2");
 359
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