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Linux/net/core/netprio_cgroup.c

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  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 accommodate
 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;
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 seq_file *sf, void *v)
177 {
178         struct net_device *dev;
179 
180         rcu_read_lock();
181         for_each_netdev_rcu(&init_net, dev)
182                 seq_printf(sf, "%s %u\n", dev->name,
183                            netprio_prio(seq_css(sf), dev));
184         rcu_read_unlock();
185         return 0;
186 }
187 
188 static ssize_t write_priomap(struct kernfs_open_file *of,
189                              char *buf, size_t nbytes, loff_t off)
190 {
191         char devname[IFNAMSIZ + 1];
192         struct net_device *dev;
193         u32 prio;
194         int ret;
195 
196         if (sscanf(buf, "%"__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(of_css(of), dev, prio);
206 
207         rtnl_unlock();
208         dev_put(dev);
209         return ret ?: nbytes;
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, 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                 .seq_show = read_priomap,
242                 .write = write_priomap,
243         },
244         { }     /* terminate */
245 };
246 
247 struct cgroup_subsys net_prio_cgrp_subsys = {
248         .css_alloc      = cgrp_css_alloc,
249         .css_online     = cgrp_css_online,
250         .css_free       = cgrp_css_free,
251         .attach         = net_prio_attach,
252         .legacy_cftypes = ss_files,
253 };
254 
255 static int netprio_device_event(struct notifier_block *unused,
256                                 unsigned long event, void *ptr)
257 {
258         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
259         struct netprio_map *old;
260 
261         /*
262          * Note this is called with rtnl_lock held so we have update side
263          * protection on our rcu assignments
264          */
265 
266         switch (event) {
267         case NETDEV_UNREGISTER:
268                 old = rtnl_dereference(dev->priomap);
269                 RCU_INIT_POINTER(dev->priomap, NULL);
270                 if (old)
271                         kfree_rcu(old, rcu);
272                 break;
273         }
274         return NOTIFY_DONE;
275 }
276 
277 static struct notifier_block netprio_device_notifier = {
278         .notifier_call = netprio_device_event
279 };
280 
281 static int __init init_cgroup_netprio(void)
282 {
283         register_netdevice_notifier(&netprio_device_notifier);
284         return 0;
285 }
286 
287 subsys_initcall(init_cgroup_netprio);
288 MODULE_LICENSE("GPL v2");
289 

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