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 pr_warn("Unable to alloc new priomap!\n"); 74 return -ENOMEM; 75 } 76 77 if (old) 78 memcpy(new->priomap, old->priomap, 79 old->priomap_len * sizeof(old->priomap[0])); 80 81 new->priomap_len = new_len; 82 83 /* install the new priomap */ 84 rcu_assign_pointer(dev->priomap, new); 85 if (old) 86 kfree_rcu(old, rcu); 87 return 0; 88 } 89 90 /** 91 * netprio_prio - return the effective netprio of a cgroup-net_device pair 92 * @cgrp: cgroup part of the target pair 93 * @dev: net_device part of the target pair 94 * 95 * Should be called under RCU read or rtnl lock. 96 */ 97 static u32 netprio_prio(struct cgroup *cgrp, struct net_device *dev) 98 { 99 struct netprio_map *map = rcu_dereference_rtnl(dev->priomap); 100 101 if (map && cgrp->id < map->priomap_len) 102 return map->priomap[cgrp->id]; 103 return 0; 104 } 105 106 /** 107 * netprio_set_prio - set netprio on a cgroup-net_device pair 108 * @cgrp: cgroup part of the target pair 109 * @dev: net_device part of the target pair 110 * @prio: prio to set 111 * 112 * Set netprio to @prio on @cgrp-@dev pair. Should be called under rtnl 113 * lock and may fail under memory pressure for non-zero @prio. 114 */ 115 static int netprio_set_prio(struct cgroup *cgrp, struct net_device *dev, 116 u32 prio) 117 { 118 struct netprio_map *map; 119 int ret; 120 121 /* avoid extending priomap for zero writes */ 122 map = rtnl_dereference(dev->priomap); 123 if (!prio && (!map || map->priomap_len <= cgrp->id)) 124 return 0; 125 126 ret = extend_netdev_table(dev, cgrp->id); 127 if (ret) 128 return ret; 129 130 map = rtnl_dereference(dev->priomap); 131 map->priomap[cgrp->id] = prio; 132 return 0; 133 } 134 135 static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp) 136 { 137 struct cgroup_netprio_state *cs; 138 139 cs = kzalloc(sizeof(*cs), GFP_KERNEL); 140 if (!cs) 141 return ERR_PTR(-ENOMEM); 142 143 return &cs->css; 144 } 145 146 static int cgrp_css_online(struct cgroup *cgrp) 147 { 148 struct cgroup *parent = cgrp->parent; 149 struct net_device *dev; 150 int ret = 0; 151 152 if (!parent) 153 return 0; 154 155 rtnl_lock(); 156 /* 157 * Inherit prios from the parent. As all prios are set during 158 * onlining, there is no need to clear them on offline. 159 */ 160 for_each_netdev(&init_net, dev) { 161 u32 prio = netprio_prio(parent, dev); 162 163 ret = netprio_set_prio(cgrp, dev, prio); 164 if (ret) 165 break; 166 } 167 rtnl_unlock(); 168 return ret; 169 } 170 171 static void cgrp_css_free(struct cgroup *cgrp) 172 { 173 kfree(cgrp_netprio_state(cgrp)); 174 } 175 176 static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft) 177 { 178 return cgrp->id; 179 } 180 181 static int read_priomap(struct cgroup *cont, struct cftype *cft, 182 struct cgroup_map_cb *cb) 183 { 184 struct net_device *dev; 185 186 rcu_read_lock(); 187 for_each_netdev_rcu(&init_net, dev) 188 cb->fill(cb, dev->name, netprio_prio(cont, dev)); 189 rcu_read_unlock(); 190 return 0; 191 } 192 193 static int write_priomap(struct cgroup *cgrp, struct cftype *cft, 194 const char *buffer) 195 { 196 char devname[IFNAMSIZ + 1]; 197 struct net_device *dev; 198 u32 prio; 199 int ret; 200 201 if (sscanf(buffer, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2) 202 return -EINVAL; 203 204 dev = dev_get_by_name(&init_net, devname); 205 if (!dev) 206 return -ENODEV; 207 208 rtnl_lock(); 209 210 ret = netprio_set_prio(cgrp, dev, prio); 211 212 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 static 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_online = cgrp_css_online, 256 .css_free = cgrp_css_free, 257 .attach = net_prio_attach, 258 .subsys_id = net_prio_subsys_id, 259 .base_cftypes = ss_files, 260 .module = THIS_MODULE, 261 }; 262 263 static int netprio_device_event(struct notifier_block *unused, 264 unsigned long event, void *ptr) 265 { 266 struct net_device *dev = ptr; 267 struct netprio_map *old; 268 269 /* 270 * Note this is called with rtnl_lock held so we have update side 271 * protection on our rcu assignments 272 */ 273 274 switch (event) { 275 case NETDEV_UNREGISTER: 276 old = rtnl_dereference(dev->priomap); 277 RCU_INIT_POINTER(dev->priomap, NULL); 278 if (old) 279 kfree_rcu(old, rcu); 280 break; 281 } 282 return NOTIFY_DONE; 283 } 284 285 static struct notifier_block netprio_device_notifier = { 286 .notifier_call = netprio_device_event 287 }; 288 289 static int __init init_cgroup_netprio(void) 290 { 291 int ret; 292 293 ret = cgroup_load_subsys(&net_prio_subsys); 294 if (ret) 295 goto out; 296 297 register_netdevice_notifier(&netprio_device_notifier); 298 299 out: 300 return ret; 301 } 302 303 static void __exit exit_cgroup_netprio(void) 304 { 305 struct netprio_map *old; 306 struct net_device *dev; 307 308 unregister_netdevice_notifier(&netprio_device_notifier); 309 310 cgroup_unload_subsys(&net_prio_subsys); 311 312 rtnl_lock(); 313 for_each_netdev(&init_net, dev) { 314 old = rtnl_dereference(dev->priomap); 315 RCU_INIT_POINTER(dev->priomap, NULL); 316 if (old) 317 kfree_rcu(old, rcu); 318 } 319 rtnl_unlock(); 320 } 321 322 module_init(init_cgroup_netprio); 323 module_exit(exit_cgroup_netprio); 324 MODULE_LICENSE("GPL v2"); 325