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