net/core/netprio_cgroup.c

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