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 #include <linux/fdtable.h>
  29
  30 #define PRIOMAP_MIN_SZ          128
  31 #define PRIOIDX_SZ 128
  32
  33 static unsigned long prioidx_map[PRIOIDX_SZ];
  34 static DEFINE_SPINLOCK(prioidx_map_lock);
  35
  36 static 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
  42 static 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         spin_unlock_irqrestore(&prioidx_map_lock, flags);
  55         *prio = prioidx;
  56         return 0;
  57 }
  58
  59 static void put_prioidx(u32 idx)
  60 {
  61         unsigned long flags;
  62
  63         spin_lock_irqsave(&prioidx_map_lock, flags);
  64         clear_bit(idx, prioidx_map);
  65         spin_unlock_irqrestore(&prioidx_map_lock, flags);
  66 }
  67
  68 /*
  69  * Extend @dev->priomap so that it's large enough to accomodate
  70  * @target_idx.  @dev->priomap.priomap_len > @target_idx after successful
  71  * return.  Must be called under rtnl lock.
  72  */
  73 static int extend_netdev_table(struct net_device *dev, u32 target_idx)
  74 {
  75         struct netprio_map *old, *new;
  76         size_t new_sz, new_len;
  77
  78         /* is the existing priomap large enough? */
  79         old = rtnl_dereference(dev->priomap);
  80         if (old && old->priomap_len > target_idx)
  81                 return 0;
  82
  83         /*
  84          * Determine the new size.  Let's keep it power-of-two.  We start
  85          * from PRIOMAP_MIN_SZ and double it until it's large enough to
  86          * accommodate @target_idx.
  87          */
  88         new_sz = PRIOMAP_MIN_SZ;
  89         while (true) {
  90                 new_len = (new_sz - offsetof(struct netprio_map, priomap)) /
  91                         sizeof(new->priomap[0]);
  92                 if (new_len > target_idx)
  93                         break;
  94                 new_sz *= 2;
  95                 /* overflowed? */
  96                 if (WARN_ON(new_sz < PRIOMAP_MIN_SZ))
  97                         return -ENOSPC;
  98         }
  99
 100         /* allocate & copy */
 101         new = kzalloc(new_sz, GFP_KERNEL);
 102         if (!new) {
 103                 pr_warn("Unable to alloc new priomap!\n");
 104                 return -ENOMEM;
 105         }
 106
 107         if (old)
 108                 memcpy(new->priomap, old->priomap,
 109                        old->priomap_len * sizeof(old->priomap[0]));
 110
 111         new->priomap_len = new_len;
 112
 113         /* install the new priomap */
 114         rcu_assign_pointer(dev->priomap, new);
 115         if (old)
 116                 kfree_rcu(old, rcu);
 117         return 0;
 118 }
 119
 120 static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
 121 {
 122         struct cgroup_netprio_state *cs;
 123         int ret = -EINVAL;
 124
 125         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
 126         if (!cs)
 127                 return ERR_PTR(-ENOMEM);
 128
 129         if (cgrp->parent && cgrp_netprio_state(cgrp->parent)->prioidx)
 130                 goto out;
 131
 132         ret = get_prioidx(&cs->prioidx);
 133         if (ret < 0) {
 134                 pr_warn("No space in priority index array\n");
 135                 goto out;
 136         }
 137
 138         return &cs->css;
 139 out:
 140         kfree(cs);
 141         return ERR_PTR(ret);
 142 }
 143
 144 static void cgrp_css_free(struct cgroup *cgrp)
 145 {
 146         struct cgroup_netprio_state *cs;
 147         struct net_device *dev;
 148         struct netprio_map *map;
 149
 150         cs = cgrp_netprio_state(cgrp);
 151         rtnl_lock();
 152         for_each_netdev(&init_net, dev) {
 153                 map = rtnl_dereference(dev->priomap);
 154                 if (map && cs->prioidx < map->priomap_len)
 155                         map->priomap[cs->prioidx] = 0;
 156         }
 157         rtnl_unlock();
 158         put_prioidx(cs->prioidx);
 159         kfree(cs);
 160 }
 161
 162 static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
 163 {
 164         return (u64)cgrp_netprio_state(cgrp)->prioidx;
 165 }
 166
 167 static int read_priomap(struct cgroup *cont, struct cftype *cft,
 168                         struct cgroup_map_cb *cb)
 169 {
 170         struct net_device *dev;
 171         u32 prioidx = cgrp_netprio_state(cont)->prioidx;
 172         u32 priority;
 173         struct netprio_map *map;
 174
 175         rcu_read_lock();
 176         for_each_netdev_rcu(&init_net, dev) {
 177                 map = rcu_dereference(dev->priomap);
 178                 priority = (map && prioidx < map->priomap_len) ? map->priomap[prioidx] : 0;
 179                 cb->fill(cb, dev->name, priority);
 180         }
 181         rcu_read_unlock();
 182         return 0;
 183 }
 184
 185 static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
 186                          const char *buffer)
 187 {
 188         u32 prioidx = cgrp_netprio_state(cgrp)->prioidx;
 189         char devname[IFNAMSIZ + 1];
 190         struct net_device *dev;
 191         struct netprio_map *map;
 192         u32 prio;
 193         int ret;
 194
 195         if (sscanf(buffer, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2)
 196                 return -EINVAL;
 197
 198         dev = dev_get_by_name(&init_net, devname);
 199         if (!dev)
 200                 return -ENODEV;
 201
 202         rtnl_lock();
 203
 204         ret = extend_netdev_table(dev, prioidx);
 205         if (ret)
 206                 goto out_unlock;
 207
 208         map = rtnl_dereference(dev->priomap);
 209         if (map)
 210                 map->priomap[prioidx] = prio;
 211 out_unlock:
 212         rtnl_unlock();
 213         dev_put(dev);
 214         return ret;
 215 }
 216
 217 static int update_netprio(const void *v, struct file *file, unsigned n)
 218 {
 219         int err;
 220         struct socket *sock = sock_from_file(file, &err);
 221         if (sock)
 222                 sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v;
 223         return 0;
 224 }
 225
 226 void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 227 {
 228         struct task_struct *p;
 229         void *v;
 230
 231         cgroup_taskset_for_each(p, cgrp, tset) {
 232                 task_lock(p);
 233                 v = (void *)(unsigned long)task_netprioidx(p);
 234                 iterate_fd(p->files, 0, update_netprio, v);
 235                 task_unlock(p);
 236         }
 237 }
 238
 239 static struct cftype ss_files[] = {
 240         {
 241                 .name = "prioidx",
 242                 .read_u64 = read_prioidx,
 243         },
 244         {
 245                 .name = "ifpriomap",
 246                 .read_map = read_priomap,
 247                 .write_string = write_priomap,
 248         },
 249         { }     /* terminate */
 250 };
 251
 252 struct cgroup_subsys net_prio_subsys = {
 253         .name           = "net_prio",
 254         .css_alloc      = cgrp_css_alloc,
 255         .css_free       = cgrp_css_free,
 256         .attach         = net_prio_attach,
 257         .subsys_id      = net_prio_subsys_id,
 258         .base_cftypes   = ss_files,
 259         .module         = THIS_MODULE,
 260
 261         /*
 262          * net_prio has artificial limit on the number of cgroups and
 263          * disallows nesting making it impossible to co-mount it with other
 264          * hierarchical subsystems.  Remove the artificially low PRIOIDX_SZ
 265          * limit and properly nest configuration such that children follow
 266          * their parents' configurations by default and are allowed to
 267          * override and remove the following.
 268          */
 269         .broken_hierarchy = true,
 270 };
 271
 272 static int netprio_device_event(struct notifier_block *unused,
 273                                 unsigned long event, void *ptr)
 274 {
 275         struct net_device *dev = ptr;
 276         struct netprio_map *old;
 277
 278         /*
 279          * Note this is called with rtnl_lock held so we have update side
 280          * protection on our rcu assignments
 281          */
 282
 283         switch (event) {
 284         case NETDEV_UNREGISTER:
 285                 old = rtnl_dereference(dev->priomap);
 286                 RCU_INIT_POINTER(dev->priomap, NULL);
 287                 if (old)
 288                         kfree_rcu(old, rcu);
 289                 break;
 290         }
 291         return NOTIFY_DONE;
 292 }
 293
 294 static struct notifier_block netprio_device_notifier = {
 295         .notifier_call = netprio_device_event
 296 };
 297
 298 static int __init init_cgroup_netprio(void)
 299 {
 300         int ret;
 301
 302         ret = cgroup_load_subsys(&net_prio_subsys);
 303         if (ret)
 304                 goto out;
 305
 306         register_netdevice_notifier(&netprio_device_notifier);
 307
 308 out:
 309         return ret;
 310 }
 311
 312 static void __exit exit_cgroup_netprio(void)
 313 {
 314         struct netprio_map *old;
 315         struct net_device *dev;
 316
 317         unregister_netdevice_notifier(&netprio_device_notifier);
 318
 319         cgroup_unload_subsys(&net_prio_subsys);
 320
 321         rtnl_lock();
 322         for_each_netdev(&init_net, dev) {
 323                 old = rtnl_dereference(dev->priomap);
 324                 RCU_INIT_POINTER(dev->priomap, NULL);
 325                 if (old)
 326                         kfree_rcu(old, rcu);
 327         }
 328         rtnl_unlock();
 329 }
 330
 331 module_init(init_cgroup_netprio);
 332 module_exit(exit_cgroup_netprio);
 333 MODULE_LICENSE("GPL v2");