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_subsys *ss,
  27                                                struct cgroup *cgrp);
  28 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp);
  29 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp);
  30
  31 struct cgroup_subsys net_prio_subsys = {
  32         .name           = "net_prio",
  33         .create         = cgrp_create,
  34         .destroy        = cgrp_destroy,
  35         .populate       = cgrp_populate,
  36 #ifdef CONFIG_NETPRIO_CGROUP
  37         .subsys_id      = net_prio_subsys_id,
  38 #endif
  39         .module         = THIS_MODULE
  40 };
  41
  42 #define PRIOIDX_SZ 128
  43
  44 static unsigned long prioidx_map[PRIOIDX_SZ];
  45 static DEFINE_SPINLOCK(prioidx_map_lock);
  46 static atomic_t max_prioidx = ATOMIC_INIT(0);
  47
  48 static inline struct cgroup_netprio_state *cgrp_netprio_state(struct cgroup *cgrp)
  49 {
  50         return container_of(cgroup_subsys_state(cgrp, net_prio_subsys_id),
  51                             struct cgroup_netprio_state, css);
  52 }
  53
  54 static int get_prioidx(u32 *prio)
  55 {
  56         unsigned long flags;
  57         u32 prioidx;
  58
  59         spin_lock_irqsave(&prioidx_map_lock, flags);
  60         prioidx = find_first_zero_bit(prioidx_map, sizeof(unsigned long) * PRIOIDX_SZ);
  61         set_bit(prioidx, prioidx_map);
  62         spin_unlock_irqrestore(&prioidx_map_lock, flags);
  63         if (prioidx == sizeof(unsigned long) * PRIOIDX_SZ)
  64                 return -ENOSPC;
  65
  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);
 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_subsys *ss,
 124                                                  struct cgroup *cgrp)
 125 {
 126         struct cgroup_netprio_state *cs;
 127         int ret;
 128
 129         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
 130         if (!cs)
 131                 return ERR_PTR(-ENOMEM);
 132
 133         if (cgrp->parent && cgrp_netprio_state(cgrp->parent)->prioidx) {
 134                 kfree(cs);
 135                 return ERR_PTR(-EINVAL);
 136         }
 137
 138         ret = get_prioidx(&cs->prioidx);
 139         if (ret != 0) {
 140                 printk(KERN_WARNING "No space in priority index array\n");
 141                 kfree(cs);
 142                 return ERR_PTR(ret);
 143         }
 144
 145         return &cs->css;
 146 }
 147
 148 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
 149 {
 150         struct cgroup_netprio_state *cs;
 151         struct net_device *dev;
 152         struct netprio_map *map;
 153
 154         cs = cgrp_netprio_state(cgrp);
 155         rtnl_lock();
 156         for_each_netdev(&init_net, dev) {
 157                 map = rtnl_dereference(dev->priomap);
 158                 if (map)
 159                         map->priomap[cs->prioidx] = 0;
 160         }
 161         rtnl_unlock();
 162         put_prioidx(cs->prioidx);
 163         kfree(cs);
 164 }
 165
 166 static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
 167 {
 168         return (u64)cgrp_netprio_state(cgrp)->prioidx;
 169 }
 170
 171 static int read_priomap(struct cgroup *cont, struct cftype *cft,
 172                         struct cgroup_map_cb *cb)
 173 {
 174         struct net_device *dev;
 175         u32 prioidx = cgrp_netprio_state(cont)->prioidx;
 176         u32 priority;
 177         struct netprio_map *map;
 178
 179         rcu_read_lock();
 180         for_each_netdev_rcu(&init_net, dev) {
 181                 map = rcu_dereference(dev->priomap);
 182                 priority = map ? map->priomap[prioidx] : 0;
 183                 cb->fill(cb, dev->name, priority);
 184         }
 185         rcu_read_unlock();
 186         return 0;
 187 }
 188
 189 static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
 190                          const char *buffer)
 191 {
 192         char *devname = kstrdup(buffer, GFP_KERNEL);
 193         int ret = -EINVAL;
 194         u32 prioidx = cgrp_netprio_state(cgrp)->prioidx;
 195         unsigned long priority;
 196         char *priostr;
 197         struct net_device *dev;
 198         struct netprio_map *map;
 199
 200         if (!devname)
 201                 return -ENOMEM;
 202
 203         /*
 204          * Minimally sized valid priomap string
 205          */
 206         if (strlen(devname) < 3)
 207                 goto out_free_devname;
 208
 209         priostr = strstr(devname, " ");
 210         if (!priostr)
 211                 goto out_free_devname;
 212
 213         /*
 214          *Separate the devname from the associated priority
 215          *and advance the priostr poitner to the priority value
 216          */
 217         *priostr = '\0';
 218         priostr++;
 219
 220         /*
 221          * If the priostr points to NULL, we're at the end of the passed
 222          * in string, and its not a valid write
 223          */
 224         if (*priostr == '\0')
 225                 goto out_free_devname;
 226
 227         ret = kstrtoul(priostr, 10, &priority);
 228         if (ret < 0)
 229                 goto out_free_devname;
 230
 231         ret = -ENODEV;
 232
 233         dev = dev_get_by_name(&init_net, devname);
 234         if (!dev)
 235                 goto out_free_devname;
 236
 237         update_netdev_tables();
 238         ret = 0;
 239         rcu_read_lock();
 240         map = rcu_dereference(dev->priomap);
 241         if (map)
 242                 map->priomap[prioidx] = priority;
 243         rcu_read_unlock();
 244         dev_put(dev);
 245
 246 out_free_devname:
 247         kfree(devname);
 248         return ret;
 249 }
 250
 251 static struct cftype ss_files[] = {
 252         {
 253                 .name = "prioidx",
 254                 .read_u64 = read_prioidx,
 255         },
 256         {
 257                 .name = "ifpriomap",
 258                 .read_map = read_priomap,
 259                 .write_string = write_priomap,
 260         },
 261 };
 262
 263 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
 264 {
 265         return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
 266 }
 267
 268 static int netprio_device_event(struct notifier_block *unused,
 269                                 unsigned long event, void *ptr)
 270 {
 271         struct net_device *dev = ptr;
 272         struct netprio_map *old;
 273         u32 max_len = atomic_read(&max_prioidx);
 274
 275         /*
 276          * Note this is called with rtnl_lock held so we have update side
 277          * protection on our rcu assignments
 278          */
 279
 280         switch (event) {
 281
 282         case NETDEV_REGISTER:
 283                 if (max_len)
 284                         extend_netdev_table(dev, max_len);
 285                 break;
 286         case NETDEV_UNREGISTER:
 287                 old = rtnl_dereference(dev->priomap);
 288                 RCU_INIT_POINTER(dev->priomap, NULL);
 289                 if (old)
 290                         kfree_rcu(old, rcu);
 291                 break;
 292         }
 293         return NOTIFY_DONE;
 294 }
 295
 296 static struct notifier_block netprio_device_notifier = {
 297         .notifier_call = netprio_device_event
 298 };
 299
 300 static int __init init_cgroup_netprio(void)
 301 {
 302         int ret;
 303
 304         ret = cgroup_load_subsys(&net_prio_subsys);
 305         if (ret)
 306                 goto out;
 307 #ifndef CONFIG_NETPRIO_CGROUP
 308         smp_wmb();
 309         net_prio_subsys_id = net_prio_subsys.subsys_id;
 310 #endif
 311
 312         register_netdevice_notifier(&netprio_device_notifier);
 313
 314 out:
 315         return ret;
 316 }
 317
 318 static void __exit exit_cgroup_netprio(void)
 319 {
 320         struct netprio_map *old;
 321         struct net_device *dev;
 322
 323         unregister_netdevice_notifier(&netprio_device_notifier);
 324
 325         cgroup_unload_subsys(&net_prio_subsys);
 326
 327 #ifndef CONFIG_NETPRIO_CGROUP
 328         net_prio_subsys_id = -1;
 329         synchronize_rcu();
 330 #endif
 331
 332         rtnl_lock();
 333         for_each_netdev(&init_net, dev) {
 334                 old = rtnl_dereference(dev->priomap);
 335                 RCU_INIT_POINTER(dev->priomap, NULL);
 336                 if (old)
 337                         kfree_rcu(old, rcu);
 338         }
 339         rtnl_unlock();
 340 }
 341
 342 module_init(init_cgroup_netprio);
 343 module_exit(exit_cgroup_netprio);
 344 MODULE_LICENSE("GPL v2");