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        int i;
  77
  78        old_priomap  = rtnl_dereference(dev->priomap);
  79
  80        if (!new_priomap) {
  81                pr_warn("Unable to alloc new priomap!\n");
  82                return -ENOMEM;
  83        }
  84
  85        for (i = 0;
  86             old_priomap && (i < old_priomap->priomap_len);
  87             i++)
  88                new_priomap->priomap[i] = old_priomap->priomap[i];
  89
  90        new_priomap->priomap_len = new_len;
  91
  92        rcu_assign_pointer(dev->priomap, new_priomap);
  93        if (old_priomap)
  94                kfree_rcu(old_priomap, rcu);
  95        return 0;
  96}
  97
  98static int write_update_netdev_table(struct net_device *dev)
  99{
 100        int ret = 0;
 101        u32 max_len;
 102        struct netprio_map *map;
 103
 104        max_len = atomic_read(&max_prioidx) + 1;
 105        map = rtnl_dereference(dev->priomap);
 106        if (!map || map->priomap_len < max_len)
 107                ret = extend_netdev_table(dev, max_len);
 108
 109        return ret;
 110}
 111
 112static int update_netdev_tables(void)
 113{
 114        int ret = 0;
 115        struct net_device *dev;
 116        u32 max_len;
 117        struct netprio_map *map;
 118
 119        rtnl_lock();
 120        max_len = atomic_read(&max_prioidx) + 1;
 121        for_each_netdev(&init_net, dev) {
 122                map = rtnl_dereference(dev->priomap);
 123                /*
 124                 * don't allocate priomap if we didn't
 125                 * change net_prio.ifpriomap (map == NULL),
 126                 * this will speed up skb_update_prio.
 127                 */
 128                if (map && map->priomap_len < max_len) {
 129                        ret = extend_netdev_table(dev, max_len);
 130                        if (ret < 0)
 131                                break;
 132                }
 133        }
 134        rtnl_unlock();
 135        return ret;
 136}
 137
 138static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp)
 139{
 140        struct cgroup_netprio_state *cs;
 141        int ret = -EINVAL;
 142
 143        cs = kzalloc(sizeof(*cs), GFP_KERNEL);
 144        if (!cs)
 145                return ERR_PTR(-ENOMEM);
 146
 147        if (cgrp->parent && cgrp_netprio_state(cgrp->parent)->prioidx)
 148                goto out;
 149
 150        ret = get_prioidx(&cs->prioidx);
 151        if (ret < 0) {
 152                pr_warn("No space in priority index array\n");
 153                goto out;
 154        }
 155
 156        ret = update_netdev_tables();
 157        if (ret < 0) {
 158                put_prioidx(cs->prioidx);
 159                goto out;
 160        }
 161
 162        return &cs->css;
 163out:
 164        kfree(cs);
 165        return ERR_PTR(ret);
 166}
 167
 168static void cgrp_destroy(struct cgroup *cgrp)
 169{
 170        struct cgroup_netprio_state *cs;
 171        struct net_device *dev;
 172        struct netprio_map *map;
 173
 174        cs = cgrp_netprio_state(cgrp);
 175        rtnl_lock();
 176        for_each_netdev(&init_net, dev) {
 177                map = rtnl_dereference(dev->priomap);
 178                if (map && cs->prioidx < map->priomap_len)
 179                        map->priomap[cs->prioidx] = 0;
 180        }
 181        rtnl_unlock();
 182        put_prioidx(cs->prioidx);
 183        kfree(cs);
 184}
 185
 186static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
 187{
 188        return (u64)cgrp_netprio_state(cgrp)->prioidx;
 189}
 190
 191static int read_priomap(struct cgroup *cont, struct cftype *cft,
 192                        struct cgroup_map_cb *cb)
 193{
 194        struct net_device *dev;
 195        u32 prioidx = cgrp_netprio_state(cont)->prioidx;
 196        u32 priority;
 197        struct netprio_map *map;
 198
 199        rcu_read_lock();
 200        for_each_netdev_rcu(&init_net, dev) {
 201                map = rcu_dereference(dev->priomap);
 202                priority = (map && prioidx < map->priomap_len) ? map->priomap[prioidx] : 0;
 203                cb->fill(cb, dev->name, priority);
 204        }
 205        rcu_read_unlock();
 206        return 0;
 207}
 208
 209static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
 210                         const char *buffer)
 211{
 212        char *devname = kstrdup(buffer, GFP_KERNEL);
 213        int ret = -EINVAL;
 214        u32 prioidx = cgrp_netprio_state(cgrp)->prioidx;
 215        unsigned long priority;
 216        char *priostr;
 217        struct net_device *dev;
 218        struct netprio_map *map;
 219
 220        if (!devname)
 221                return -ENOMEM;
 222
 223        /*
 224         * Minimally sized valid priomap string
 225         */
 226        if (strlen(devname) < 3)
 227                goto out_free_devname;
 228
 229        priostr = strstr(devname, " ");
 230        if (!priostr)
 231                goto out_free_devname;
 232
 233        /*
 234         *Separate the devname from the associated priority
 235         *and advance the priostr pointer to the priority value
 236         */
 237        *priostr = '\0';
 238        priostr++;
 239
 240        /*
 241         * If the priostr points to NULL, we're at the end of the passed
 242         * in string, and its not a valid write
 243         */
 244        if (*priostr == '\0')
 245                goto out_free_devname;
 246
 247        ret = kstrtoul(priostr, 10, &priority);
 248        if (ret < 0)
 249                goto out_free_devname;
 250
 251        ret = -ENODEV;
 252
 253        dev = dev_get_by_name(&init_net, devname);
 254        if (!dev)
 255                goto out_free_devname;
 256
 257        rtnl_lock();
 258        ret = write_update_netdev_table(dev);
 259        if (ret < 0)
 260                goto out_put_dev;
 261
 262        map = rtnl_dereference(dev->priomap);
 263        if (map)
 264                map->priomap[prioidx] = priority;
 265
 266out_put_dev:
 267        rtnl_unlock();
 268        dev_put(dev);
 269
 270out_free_devname:
 271        kfree(devname);
 272        return ret;
 273}
 274
 275void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 276{
 277        struct task_struct *p;
 278
 279        cgroup_taskset_for_each(p, cgrp, tset) {
 280                unsigned int fd;
 281                struct fdtable *fdt;
 282                struct files_struct *files;
 283
 284                task_lock(p);
 285                files = p->files;
 286                if (!files) {
 287                        task_unlock(p);
 288                        continue;
 289                }
 290
 291                spin_lock(&files->file_lock);
 292                fdt = files_fdtable(files);
 293                for (fd = 0; fd < fdt->max_fds; fd++) {
 294                        struct file *file;
 295                        struct socket *sock;
 296                        int err;
 297
 298                        file = fcheck_files(files, fd);
 299                        if (!file)
 300                                continue;
 301
 302                        sock = sock_from_file(file, &err);
 303                        if (sock)
 304                                sock_update_netprioidx(sock->sk, p);
 305                }
 306                spin_unlock(&files->file_lock);
 307                task_unlock(p);
 308        }
 309}
 310
 311static struct cftype ss_files[] = {
 312        {
 313                .name = "prioidx",
 314                .read_u64 = read_prioidx,
 315        },
 316        {
 317                .name = "ifpriomap",
 318                .read_map = read_priomap,
 319                .write_string = write_priomap,
 320        },
 321        { }     /* terminate */
 322};
 323
 324struct cgroup_subsys net_prio_subsys = {
 325        .name           = "net_prio",
 326        .create         = cgrp_create,
 327        .destroy        = cgrp_destroy,
 328        .attach         = net_prio_attach,
 329#ifdef CONFIG_NETPRIO_CGROUP
 330        .subsys_id      = net_prio_subsys_id,
 331#endif
 332        .base_cftypes   = ss_files,
 333        .module         = THIS_MODULE
 334};
 335
 336static int netprio_device_event(struct notifier_block *unused,
 337                                unsigned long event, void *ptr)
 338{
 339        struct net_device *dev = ptr;
 340        struct netprio_map *old;
 341
 342        /*
 343         * Note this is called with rtnl_lock held so we have update side
 344         * protection on our rcu assignments
 345         */
 346
 347        switch (event) {
 348        case NETDEV_UNREGISTER:
 349                old = rtnl_dereference(dev->priomap);
 350                RCU_INIT_POINTER(dev->priomap, NULL);
 351                if (old)
 352                        kfree_rcu(old, rcu);
 353                break;
 354        }
 355        return NOTIFY_DONE;
 356}
 357
 358static struct notifier_block netprio_device_notifier = {
 359        .notifier_call = netprio_device_event
 360};
 361
 362static int __init init_cgroup_netprio(void)
 363{
 364        int ret;
 365
 366        ret = cgroup_load_subsys(&net_prio_subsys);
 367        if (ret)
 368                goto out;
 369#ifndef CONFIG_NETPRIO_CGROUP
 370        smp_wmb();
 371        net_prio_subsys_id = net_prio_subsys.subsys_id;
 372#endif
 373
 374        register_netdevice_notifier(&netprio_device_notifier);
 375
 376out:
 377        return ret;
 378}
 379
 380static void __exit exit_cgroup_netprio(void)
 381{
 382        struct netprio_map *old;
 383        struct net_device *dev;
 384
 385        unregister_netdevice_notifier(&netprio_device_notifier);
 386
 387        cgroup_unload_subsys(&net_prio_subsys);
 388
 389#ifndef CONFIG_NETPRIO_CGROUP
 390        net_prio_subsys_id = -1;
 391        synchronize_rcu();
 392#endif
 393
 394        rtnl_lock();
 395        for_each_netdev(&init_net, dev) {
 396                old = rtnl_dereference(dev->priomap);
 397                RCU_INIT_POINTER(dev->priomap, NULL);
 398                if (old)
 399                        kfree_rcu(old, rcu);
 400        }
 401        rtnl_unlock();
 402}
 403
 404module_init(init_cgroup_netprio);
 405module_exit(exit_cgroup_netprio);
 406MODULE_LICENSE("GPL v2");
 407
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