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
  32 static inline struct cgroup_netprio_state *cgrp_netprio_state(struct cgroup *cgrp)
  33 {
  34         return container_of(cgroup_subsys_state(cgrp, net_prio_subsys_id),
  35                             struct cgroup_netprio_state, css);
  36 }
  37
  38 /*
  39  * Extend @dev->priomap so that it's large enough to accomodate
  40  * @target_idx.  @dev->priomap.priomap_len > @target_idx after successful
  41  * return.  Must be called under rtnl lock.
  42  */
  43 static int extend_netdev_table(struct net_device *dev, u32 target_idx)
  44 {
  45         struct netprio_map *old, *new;
  46         size_t new_sz, new_len;
  47
  48         /* is the existing priomap large enough? */
  49         old = rtnl_dereference(dev->priomap);
  50         if (old && old->priomap_len > target_idx)
  51                 return 0;
  52
  53         /*
  54          * Determine the new size.  Let's keep it power-of-two.  We start
  55          * from PRIOMAP_MIN_SZ and double it until it's large enough to
  56          * accommodate @target_idx.
  57          */
  58         new_sz = PRIOMAP_MIN_SZ;
  59         while (true) {
  60                 new_len = (new_sz - offsetof(struct netprio_map, priomap)) /
  61                         sizeof(new->priomap[0]);
  62                 if (new_len > target_idx)
  63                         break;
  64                 new_sz *= 2;
  65                 /* overflowed? */
  66                 if (WARN_ON(new_sz < PRIOMAP_MIN_SZ))
  67                         return -ENOSPC;
  68         }
  69
  70         /* allocate & copy */
  71         new = kzalloc(new_sz, GFP_KERNEL);
  72         if (!new)
  73                 return -ENOMEM;
  74
  75         if (old)
  76                 memcpy(new->priomap, old->priomap,
  77                        old->priomap_len * sizeof(old->priomap[0]));
  78
  79         new->priomap_len = new_len;
  80
  81         /* install the new priomap */
  82         rcu_assign_pointer(dev->priomap, new);
  83         if (old)
  84                 kfree_rcu(old, rcu);
  85         return 0;
  86 }
  87
  88 /**
  89  * netprio_prio - return the effective netprio of a cgroup-net_device pair
  90  * @cgrp: cgroup part of the target pair
  91  * @dev: net_device part of the target pair
  92  *
  93  * Should be called under RCU read or rtnl lock.
  94  */
  95 static u32 netprio_prio(struct cgroup *cgrp, struct net_device *dev)
  96 {
  97         struct netprio_map *map = rcu_dereference_rtnl(dev->priomap);
  98
  99         if (map && cgrp->id < map->priomap_len)
 100                 return map->priomap[cgrp->id];
 101         return 0;
 102 }
 103
 104 /**
 105  * netprio_set_prio - set netprio on a cgroup-net_device pair
 106  * @cgrp: cgroup part of the target pair
 107  * @dev: net_device part of the target pair
 108  * @prio: prio to set
 109  *
 110  * Set netprio to @prio on @cgrp-@dev pair.  Should be called under rtnl
 111  * lock and may fail under memory pressure for non-zero @prio.
 112  */
 113 static int netprio_set_prio(struct cgroup *cgrp, struct net_device *dev,
 114                             u32 prio)
 115 {
 116         struct netprio_map *map;
 117         int ret;
 118
 119         /* avoid extending priomap for zero writes */
 120         map = rtnl_dereference(dev->priomap);
 121         if (!prio && (!map || map->priomap_len <= cgrp->id))
 122                 return 0;
 123
 124         ret = extend_netdev_table(dev, cgrp->id);
 125         if (ret)
 126                 return ret;
 127
 128         map = rtnl_dereference(dev->priomap);
 129         map->priomap[cgrp->id] = prio;
 130         return 0;
 131 }
 132
 133 static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
 134 {
 135         struct cgroup_netprio_state *cs;
 136
 137         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
 138         if (!cs)
 139                 return ERR_PTR(-ENOMEM);
 140
 141         return &cs->css;
 142 }
 143
 144 static int cgrp_css_online(struct cgroup *cgrp)
 145 {
 146         struct cgroup *parent = cgrp->parent;
 147         struct net_device *dev;
 148         int ret = 0;
 149
 150         if (!parent)
 151                 return 0;
 152
 153         rtnl_lock();
 154         /*
 155          * Inherit prios from the parent.  As all prios are set during
 156          * onlining, there is no need to clear them on offline.
 157          */
 158         for_each_netdev(&init_net, dev) {
 159                 u32 prio = netprio_prio(parent, dev);
 160
 161                 ret = netprio_set_prio(cgrp, dev, prio);
 162                 if (ret)
 163                         break;
 164         }
 165         rtnl_unlock();
 166         return ret;
 167 }
 168
 169 static void cgrp_css_free(struct cgroup *cgrp)
 170 {
 171         kfree(cgrp_netprio_state(cgrp));
 172 }
 173
 174 static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
 175 {
 176         return cgrp->id;
 177 }
 178
 179 static int read_priomap(struct cgroup *cont, struct cftype *cft,
 180                         struct cgroup_map_cb *cb)
 181 {
 182         struct net_device *dev;
 183
 184         rcu_read_lock();
 185         for_each_netdev_rcu(&init_net, dev)
 186                 cb->fill(cb, dev->name, netprio_prio(cont, dev));
 187         rcu_read_unlock();
 188         return 0;
 189 }
 190
 191 static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
 192                          const char *buffer)
 193 {
 194         char devname[IFNAMSIZ + 1];
 195         struct net_device *dev;
 196         u32 prio;
 197         int ret;
 198
 199         if (sscanf(buffer, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2)
 200                 return -EINVAL;
 201
 202         dev = dev_get_by_name(&init_net, devname);
 203         if (!dev)
 204                 return -ENODEV;
 205
 206         rtnl_lock();
 207
 208         ret = netprio_set_prio(cgrp, dev, prio);
 209
 210         rtnl_unlock();
 211         dev_put(dev);
 212         return ret;
 213 }
 214
 215 static int update_netprio(const void *v, struct file *file, unsigned n)
 216 {
 217         int err;
 218         struct socket *sock = sock_from_file(file, &err);
 219         if (sock)
 220                 sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v;
 221         return 0;
 222 }
 223
 224 static void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 225 {
 226         struct task_struct *p;
 227         void *v;
 228
 229         cgroup_taskset_for_each(p, cgrp, tset) {
 230                 task_lock(p);
 231                 v = (void *)(unsigned long)task_netprioidx(p);
 232                 iterate_fd(p->files, 0, update_netprio, v);
 233                 task_unlock(p);
 234         }
 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         .css_alloc      = cgrp_css_alloc,
 253         .css_online     = cgrp_css_online,
 254         .css_free       = cgrp_css_free,
 255         .attach         = net_prio_attach,
 256         .subsys_id      = net_prio_subsys_id,
 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
 295         register_netdevice_notifier(&netprio_device_notifier);
 296
 297 out:
 298         return ret;
 299 }
 300
 301 static void __exit exit_cgroup_netprio(void)
 302 {
 303         struct netprio_map *old;
 304         struct net_device *dev;
 305
 306         unregister_netdevice_notifier(&netprio_device_notifier);
 307
 308         cgroup_unload_subsys(&net_prio_subsys);
 309
 310         rtnl_lock();
 311         for_each_netdev(&init_net, dev) {
 312                 old = rtnl_dereference(dev->priomap);
 313                 RCU_INIT_POINTER(dev->priomap, NULL);
 314                 if (old)
 315                         kfree_rcu(old, rcu);
 316         }
 317         rtnl_unlock();
 318 }
 319
 320 module_init(init_cgroup_netprio);
 321 module_exit(exit_cgroup_netprio);
 322 MODULE_LICENSE("GPL v2");