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 /* 31 * netprio allocates per-net_device priomap array which is indexed by 32 * css->id. Limiting css ID to 16bits doesn't lose anything. 33 */ 34 #define NETPRIO_ID_MAX USHRT_MAX 35 36 #define PRIOMAP_MIN_SZ 128 37 38 /* 39 * Extend @dev->priomap so that it's large enough to accommodate 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 * @css: css 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_subsys_state *css, struct net_device *dev) 96 { 97 struct netprio_map *map = rcu_dereference_rtnl(dev->priomap); 98 int id = css->cgroup->id; 99 100 if (map && id < map->priomap_len) 101 return map->priomap[id]; 102 return 0; 103 } 104 105 /** 106 * netprio_set_prio - set netprio on a cgroup-net_device pair 107 * @css: css part of the target pair 108 * @dev: net_device part of the target pair 109 * @prio: prio to set 110 * 111 * Set netprio to @prio on @css-@dev pair. Should be called under rtnl 112 * lock and may fail under memory pressure for non-zero @prio. 113 */ 114 static int netprio_set_prio(struct cgroup_subsys_state *css, 115 struct net_device *dev, u32 prio) 116 { 117 struct netprio_map *map; 118 int id = css->cgroup->id; 119 int ret; 120 121 /* avoid extending priomap for zero writes */ 122 map = rtnl_dereference(dev->priomap); 123 if (!prio && (!map || map->priomap_len <= id)) 124 return 0; 125 126 ret = extend_netdev_table(dev, id); 127 if (ret) 128 return ret; 129 130 map = rtnl_dereference(dev->priomap); 131 map->priomap[id] = prio; 132 return 0; 133 } 134 135 static struct cgroup_subsys_state * 136 cgrp_css_alloc(struct cgroup_subsys_state *parent_css) 137 { 138 struct cgroup_subsys_state *css; 139 140 css = kzalloc(sizeof(*css), GFP_KERNEL); 141 if (!css) 142 return ERR_PTR(-ENOMEM); 143 144 return css; 145 } 146 147 static int cgrp_css_online(struct cgroup_subsys_state *css) 148 { 149 struct cgroup_subsys_state *parent_css = css->parent; 150 struct net_device *dev; 151 int ret = 0; 152 153 if (css->id > NETPRIO_ID_MAX) 154 return -ENOSPC; 155 156 if (!parent_css) 157 return 0; 158 159 rtnl_lock(); 160 /* 161 * Inherit prios from the parent. As all prios are set during 162 * onlining, there is no need to clear them on offline. 163 */ 164 for_each_netdev(&init_net, dev) { 165 u32 prio = netprio_prio(parent_css, dev); 166 167 ret = netprio_set_prio(css, dev, prio); 168 if (ret) 169 break; 170 } 171 rtnl_unlock(); 172 return ret; 173 } 174 175 static void cgrp_css_free(struct cgroup_subsys_state *css) 176 { 177 kfree(css); 178 } 179 180 static u64 read_prioidx(struct cgroup_subsys_state *css, struct cftype *cft) 181 { 182 return css->cgroup->id; 183 } 184 185 static int read_priomap(struct seq_file *sf, void *v) 186 { 187 struct net_device *dev; 188 189 rcu_read_lock(); 190 for_each_netdev_rcu(&init_net, dev) 191 seq_printf(sf, "%s %u\n", dev->name, 192 netprio_prio(seq_css(sf), dev)); 193 rcu_read_unlock(); 194 return 0; 195 } 196 197 static ssize_t write_priomap(struct kernfs_open_file *of, 198 char *buf, size_t nbytes, loff_t off) 199 { 200 char devname[IFNAMSIZ + 1]; 201 struct net_device *dev; 202 u32 prio; 203 int ret; 204 205 if (sscanf(buf, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2) 206 return -EINVAL; 207 208 dev = dev_get_by_name(&init_net, devname); 209 if (!dev) 210 return -ENODEV; 211 212 cgroup_sk_alloc_disable(); 213 214 rtnl_lock(); 215 216 ret = netprio_set_prio(of_css(of), dev, prio); 217 218 rtnl_unlock(); 219 dev_put(dev); 220 return ret ?: nbytes; 221 } 222 223 static int update_netprio(const void *v, struct file *file, unsigned n) 224 { 225 int err; 226 struct socket *sock = sock_from_file(file, &err); 227 if (sock) { 228 spin_lock(&cgroup_sk_update_lock); 229 sock_cgroup_set_prioidx(&sock->sk->sk_cgrp_data, 230 (unsigned long)v); 231 spin_unlock(&cgroup_sk_update_lock); 232 } 233 return 0; 234 } 235 236 static void net_prio_attach(struct cgroup_taskset *tset) 237 { 238 struct task_struct *p; 239 struct cgroup_subsys_state *css; 240 241 cgroup_taskset_for_each(p, css, tset) { 242 void *v = (void *)(unsigned long)css->cgroup->id; 243 244 task_lock(p); 245 iterate_fd(p->files, 0, update_netprio, v); 246 task_unlock(p); 247 } 248 } 249 250 static struct cftype ss_files[] = { 251 { 252 .name = "prioidx", 253 .read_u64 = read_prioidx, 254 }, 255 { 256 .name = "ifpriomap", 257 .seq_show = read_priomap, 258 .write = write_priomap, 259 }, 260 { } /* terminate */ 261 }; 262 263 struct cgroup_subsys net_prio_cgrp_subsys = { 264 .css_alloc = cgrp_css_alloc, 265 .css_online = cgrp_css_online, 266 .css_free = cgrp_css_free, 267 .attach = net_prio_attach, 268 .legacy_cftypes = ss_files, 269 }; 270 271 static int netprio_device_event(struct notifier_block *unused, 272 unsigned long event, void *ptr) 273 { 274 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 275 struct netprio_map *old; 276 277 /* 278 * Note this is called with rtnl_lock held so we have update side 279 * protection on our rcu assignments 280 */ 281 282 switch (event) { 283 case NETDEV_UNREGISTER: 284 old = rtnl_dereference(dev->priomap); 285 RCU_INIT_POINTER(dev->priomap, NULL); 286 if (old) 287 kfree_rcu(old, rcu); 288 break; 289 } 290 return NOTIFY_DONE; 291 } 292 293 static struct notifier_block netprio_device_notifier = { 294 .notifier_call = netprio_device_event 295 }; 296 297 static int __init init_cgroup_netprio(void) 298 { 299 register_netdevice_notifier(&netprio_device_notifier); 300 return 0; 301 } 302 303 subsys_initcall(init_cgroup_netprio); 304 MODULE_LICENSE("GPL v2"); 305