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 /* 33 * Extend @dev->priomap so that it's large enough to accomodate 34 * @target_idx. @dev->priomap.priomap_len > @target_idx after successful 35 * return. Must be called under rtnl lock. 36 */ 37 static int extend_netdev_table(struct net_device *dev, u32 target_idx) 38 { 39 struct netprio_map *old, *new; 40 size_t new_sz, new_len; 41 42 /* is the existing priomap large enough? */ 43 old = rtnl_dereference(dev->priomap); 44 if (old && old->priomap_len > target_idx) 45 return 0; 46 47 /* 48 * Determine the new size. Let's keep it power-of-two. We start 49 * from PRIOMAP_MIN_SZ and double it until it's large enough to 50 * accommodate @target_idx. 51 */ 52 new_sz = PRIOMAP_MIN_SZ; 53 while (true) { 54 new_len = (new_sz - offsetof(struct netprio_map, priomap)) / 55 sizeof(new->priomap[0]); 56 if (new_len > target_idx) 57 break; 58 new_sz *= 2; 59 /* overflowed? */ 60 if (WARN_ON(new_sz < PRIOMAP_MIN_SZ)) 61 return -ENOSPC; 62 } 63 64 /* allocate & copy */ 65 new = kzalloc(new_sz, GFP_KERNEL); 66 if (!new) 67 return -ENOMEM; 68 69 if (old) 70 memcpy(new->priomap, old->priomap, 71 old->priomap_len * sizeof(old->priomap[0])); 72 73 new->priomap_len = new_len; 74 75 /* install the new priomap */ 76 rcu_assign_pointer(dev->priomap, new); 77 if (old) 78 kfree_rcu(old, rcu); 79 return 0; 80 } 81 82 /** 83 * netprio_prio - return the effective netprio of a cgroup-net_device pair 84 * @css: css part of the target pair 85 * @dev: net_device part of the target pair 86 * 87 * Should be called under RCU read or rtnl lock. 88 */ 89 static u32 netprio_prio(struct cgroup_subsys_state *css, struct net_device *dev) 90 { 91 struct netprio_map *map = rcu_dereference_rtnl(dev->priomap); 92 int id = css->cgroup->id; 93 94 if (map && id < map->priomap_len) 95 return map->priomap[id]; 96 return 0; 97 } 98 99 /** 100 * netprio_set_prio - set netprio on a cgroup-net_device pair 101 * @css: css part of the target pair 102 * @dev: net_device part of the target pair 103 * @prio: prio to set 104 * 105 * Set netprio to @prio on @css-@dev pair. Should be called under rtnl 106 * lock and may fail under memory pressure for non-zero @prio. 107 */ 108 static int netprio_set_prio(struct cgroup_subsys_state *css, 109 struct net_device *dev, u32 prio) 110 { 111 struct netprio_map *map; 112 int id = css->cgroup->id; 113 int ret; 114 115 /* avoid extending priomap for zero writes */ 116 map = rtnl_dereference(dev->priomap); 117 if (!prio && (!map || map->priomap_len <= id)) 118 return 0; 119 120 ret = extend_netdev_table(dev, id); 121 if (ret) 122 return ret; 123 124 map = rtnl_dereference(dev->priomap); 125 map->priomap[id] = prio; 126 return 0; 127 } 128 129 static struct cgroup_subsys_state * 130 cgrp_css_alloc(struct cgroup_subsys_state *parent_css) 131 { 132 struct cgroup_subsys_state *css; 133 134 css = kzalloc(sizeof(*css), GFP_KERNEL); 135 if (!css) 136 return ERR_PTR(-ENOMEM); 137 138 return css; 139 } 140 141 static int cgrp_css_online(struct cgroup_subsys_state *css) 142 { 143 struct cgroup_subsys_state *parent_css = css_parent(css); 144 struct net_device *dev; 145 int ret = 0; 146 147 if (!parent_css) 148 return 0; 149 150 rtnl_lock(); 151 /* 152 * Inherit prios from the parent. As all prios are set during 153 * onlining, there is no need to clear them on offline. 154 */ 155 for_each_netdev(&init_net, dev) { 156 u32 prio = netprio_prio(parent_css, dev); 157 158 ret = netprio_set_prio(css, dev, prio); 159 if (ret) 160 break; 161 } 162 rtnl_unlock(); 163 return ret; 164 } 165 166 static void cgrp_css_free(struct cgroup_subsys_state *css) 167 { 168 kfree(css); 169 } 170 171 static u64 read_prioidx(struct cgroup_subsys_state *css, struct cftype *cft) 172 { 173 return css->cgroup->id; 174 } 175 176 static int read_priomap(struct cgroup_subsys_state *css, struct cftype *cft, 177 struct cgroup_map_cb *cb) 178 { 179 struct net_device *dev; 180 181 rcu_read_lock(); 182 for_each_netdev_rcu(&init_net, dev) 183 cb->fill(cb, dev->name, netprio_prio(css, dev)); 184 rcu_read_unlock(); 185 return 0; 186 } 187 188 static int write_priomap(struct cgroup_subsys_state *css, struct cftype *cft, 189 const char *buffer) 190 { 191 char devname[IFNAMSIZ + 1]; 192 struct net_device *dev; 193 u32 prio; 194 int ret; 195 196 if (sscanf(buffer, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2) 197 return -EINVAL; 198 199 dev = dev_get_by_name(&init_net, devname); 200 if (!dev) 201 return -ENODEV; 202 203 rtnl_lock(); 204 205 ret = netprio_set_prio(css, dev, prio); 206 207 rtnl_unlock(); 208 dev_put(dev); 209 return ret; 210 } 211 212 static int update_netprio(const void *v, struct file *file, unsigned n) 213 { 214 int err; 215 struct socket *sock = sock_from_file(file, &err); 216 if (sock) 217 sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v; 218 return 0; 219 } 220 221 static void net_prio_attach(struct cgroup_subsys_state *css, 222 struct cgroup_taskset *tset) 223 { 224 struct task_struct *p; 225 void *v = (void *)(unsigned long)css->cgroup->id; 226 227 cgroup_taskset_for_each(p, css, tset) { 228 task_lock(p); 229 iterate_fd(p->files, 0, update_netprio, v); 230 task_unlock(p); 231 } 232 } 233 234 static struct cftype ss_files[] = { 235 { 236 .name = "prioidx", 237 .read_u64 = read_prioidx, 238 }, 239 { 240 .name = "ifpriomap", 241 .read_map = read_priomap, 242 .write_string = write_priomap, 243 }, 244 { } /* terminate */ 245 }; 246 247 struct cgroup_subsys net_prio_subsys = { 248 .name = "net_prio", 249 .css_alloc = cgrp_css_alloc, 250 .css_online = cgrp_css_online, 251 .css_free = cgrp_css_free, 252 .attach = net_prio_attach, 253 .subsys_id = net_prio_subsys_id, 254 .base_cftypes = ss_files, 255 .module = THIS_MODULE, 256 }; 257 258 static int netprio_device_event(struct notifier_block *unused, 259 unsigned long event, void *ptr) 260 { 261 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 262 struct netprio_map *old; 263 264 /* 265 * Note this is called with rtnl_lock held so we have update side 266 * protection on our rcu assignments 267 */ 268 269 switch (event) { 270 case NETDEV_UNREGISTER: 271 old = rtnl_dereference(dev->priomap); 272 RCU_INIT_POINTER(dev->priomap, NULL); 273 if (old) 274 kfree_rcu(old, rcu); 275 break; 276 } 277 return NOTIFY_DONE; 278 } 279 280 static struct notifier_block netprio_device_notifier = { 281 .notifier_call = netprio_device_event 282 }; 283 284 static int __init init_cgroup_netprio(void) 285 { 286 int ret; 287 288 ret = cgroup_load_subsys(&net_prio_subsys); 289 if (ret) 290 goto out; 291 292 register_netdevice_notifier(&netprio_device_notifier); 293 294 out: 295 return ret; 296 } 297 298 static void __exit exit_cgroup_netprio(void) 299 { 300 struct netprio_map *old; 301 struct net_device *dev; 302 303 unregister_netdevice_notifier(&netprio_device_notifier); 304 305 cgroup_unload_subsys(&net_prio_subsys); 306 307 rtnl_lock(); 308 for_each_netdev(&init_net, dev) { 309 old = rtnl_dereference(dev->priomap); 310 RCU_INIT_POINTER(dev->priomap, NULL); 311 if (old) 312 kfree_rcu(old, rcu); 313 } 314 rtnl_unlock(); 315 } 316 317 module_init(init_cgroup_netprio); 318 module_exit(exit_cgroup_netprio); 319 MODULE_LICENSE("GPL v2"); 320