Phonet: convert devices list to RCU
[linux-3.10.git] / net / phonet / pn_dev.c
1 /*
2  * File: pn_dev.c
3  *
4  * Phonet network device
5  *
6  * Copyright (C) 2008 Nokia Corporation.
7  *
8  * Contact: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
9  * Original author: Sakari Ailus <sakari.ailus@nokia.com>
10  *
11  * This program is free software; you can redistribute it and/or
12  * modify it under the terms of the GNU General Public License
13  * version 2 as published by the Free Software Foundation.
14  *
15  * This program is distributed in the hope that it will be useful, but
16  * WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
23  * 02110-1301 USA
24  */
25
26 #include <linux/kernel.h>
27 #include <linux/net.h>
28 #include <linux/netdevice.h>
29 #include <linux/phonet.h>
30 #include <linux/proc_fs.h>
31 #include <linux/if_arp.h>
32 #include <net/sock.h>
33 #include <net/netns/generic.h>
34 #include <net/phonet/pn_dev.h>
35
36 struct phonet_routes {
37         struct mutex            lock;
38         struct net_device       *table[64];
39 };
40
41 struct phonet_net {
42         struct phonet_device_list pndevs;
43         struct phonet_routes routes;
44 };
45
46 int phonet_net_id __read_mostly;
47
48 struct phonet_device_list *phonet_device_list(struct net *net)
49 {
50         struct phonet_net *pnn = net_generic(net, phonet_net_id);
51         return &pnn->pndevs;
52 }
53
54 /* Allocate new Phonet device. */
55 static struct phonet_device *__phonet_device_alloc(struct net_device *dev)
56 {
57         struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
58         struct phonet_device *pnd = kmalloc(sizeof(*pnd), GFP_ATOMIC);
59         if (pnd == NULL)
60                 return NULL;
61         pnd->netdev = dev;
62         bitmap_zero(pnd->addrs, 64);
63
64         BUG_ON(!mutex_is_locked(&pndevs->lock));
65         list_add_rcu(&pnd->list, &pndevs->list);
66         return pnd;
67 }
68
69 static struct phonet_device *__phonet_get(struct net_device *dev)
70 {
71         struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
72         struct phonet_device *pnd;
73
74         BUG_ON(!mutex_is_locked(&pndevs->lock));
75         list_for_each_entry(pnd, &pndevs->list, list) {
76                 if (pnd->netdev == dev)
77                         return pnd;
78         }
79         return NULL;
80 }
81
82 static struct phonet_device *__phonet_get_rcu(struct net_device *dev)
83 {
84         struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
85         struct phonet_device *pnd;
86
87         list_for_each_entry_rcu(pnd, &pndevs->list, list) {
88                 if (pnd->netdev == dev)
89                         return pnd;
90         }
91         return NULL;
92 }
93
94 static void phonet_device_destroy(struct net_device *dev)
95 {
96         struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
97         struct phonet_device *pnd;
98
99         ASSERT_RTNL();
100
101         mutex_lock(&pndevs->lock);
102         pnd = __phonet_get(dev);
103         if (pnd)
104                 list_del_rcu(&pnd->list);
105         mutex_unlock(&pndevs->lock);
106
107         if (pnd) {
108                 u8 addr;
109
110                 for (addr = find_first_bit(pnd->addrs, 64); addr < 64;
111                         addr = find_next_bit(pnd->addrs, 64, 1+addr))
112                         phonet_address_notify(RTM_DELADDR, dev, addr);
113                 kfree(pnd);
114         }
115 }
116
117 struct net_device *phonet_device_get(struct net *net)
118 {
119         struct phonet_device_list *pndevs = phonet_device_list(net);
120         struct phonet_device *pnd;
121         struct net_device *dev = NULL;
122
123         rcu_read_lock();
124         list_for_each_entry_rcu(pnd, &pndevs->list, list) {
125                 dev = pnd->netdev;
126                 BUG_ON(!dev);
127
128                 if ((dev->reg_state == NETREG_REGISTERED) &&
129                         ((pnd->netdev->flags & IFF_UP)) == IFF_UP)
130                         break;
131                 dev = NULL;
132         }
133         if (dev)
134                 dev_hold(dev);
135         rcu_read_unlock();
136         return dev;
137 }
138
139 int phonet_address_add(struct net_device *dev, u8 addr)
140 {
141         struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
142         struct phonet_device *pnd;
143         int err = 0;
144
145         mutex_lock(&pndevs->lock);
146         /* Find or create Phonet-specific device data */
147         pnd = __phonet_get(dev);
148         if (pnd == NULL)
149                 pnd = __phonet_device_alloc(dev);
150         if (unlikely(pnd == NULL))
151                 err = -ENOMEM;
152         else if (test_and_set_bit(addr >> 2, pnd->addrs))
153                 err = -EEXIST;
154         mutex_unlock(&pndevs->lock);
155         return err;
156 }
157
158 int phonet_address_del(struct net_device *dev, u8 addr)
159 {
160         struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
161         struct phonet_device *pnd;
162         int err = 0;
163
164         mutex_lock(&pndevs->lock);
165         pnd = __phonet_get(dev);
166         if (!pnd || !test_and_clear_bit(addr >> 2, pnd->addrs)) {
167                 err = -EADDRNOTAVAIL;
168                 pnd = NULL;
169         } else if (bitmap_empty(pnd->addrs, 64))
170                 list_del_rcu(&pnd->list);
171         else
172                 pnd = NULL;
173         mutex_unlock(&pndevs->lock);
174
175         if (pnd) {
176                 synchronize_rcu();
177                 kfree(pnd);
178         }
179         return err;
180 }
181
182 /* Gets a source address toward a destination, through a interface. */
183 u8 phonet_address_get(struct net_device *dev, u8 daddr)
184 {
185         struct phonet_device *pnd;
186         u8 saddr;
187
188         rcu_read_lock();
189         pnd = __phonet_get_rcu(dev);
190         if (pnd) {
191                 BUG_ON(bitmap_empty(pnd->addrs, 64));
192
193                 /* Use same source address as destination, if possible */
194                 if (test_bit(daddr >> 2, pnd->addrs))
195                         saddr = daddr;
196                 else
197                         saddr = find_first_bit(pnd->addrs, 64) << 2;
198         } else
199                 saddr = PN_NO_ADDR;
200         rcu_read_unlock();
201
202         if (saddr == PN_NO_ADDR) {
203                 /* Fallback to another device */
204                 struct net_device *def_dev;
205
206                 def_dev = phonet_device_get(dev_net(dev));
207                 if (def_dev) {
208                         if (def_dev != dev)
209                                 saddr = phonet_address_get(def_dev, daddr);
210                         dev_put(def_dev);
211                 }
212         }
213         return saddr;
214 }
215
216 int phonet_address_lookup(struct net *net, u8 addr)
217 {
218         struct phonet_device_list *pndevs = phonet_device_list(net);
219         struct phonet_device *pnd;
220         int err = -EADDRNOTAVAIL;
221
222         rcu_read_lock();
223         list_for_each_entry_rcu(pnd, &pndevs->list, list) {
224                 /* Don't allow unregistering devices! */
225                 if ((pnd->netdev->reg_state != NETREG_REGISTERED) ||
226                                 ((pnd->netdev->flags & IFF_UP)) != IFF_UP)
227                         continue;
228
229                 if (test_bit(addr >> 2, pnd->addrs)) {
230                         err = 0;
231                         goto found;
232                 }
233         }
234 found:
235         rcu_read_unlock();
236         return err;
237 }
238
239 /* automatically configure a Phonet device, if supported */
240 static int phonet_device_autoconf(struct net_device *dev)
241 {
242         struct if_phonet_req req;
243         int ret;
244
245         if (!dev->netdev_ops->ndo_do_ioctl)
246                 return -EOPNOTSUPP;
247
248         ret = dev->netdev_ops->ndo_do_ioctl(dev, (struct ifreq *)&req,
249                                                 SIOCPNGAUTOCONF);
250         if (ret < 0)
251                 return ret;
252
253         ASSERT_RTNL();
254         ret = phonet_address_add(dev, req.ifr_phonet_autoconf.device);
255         if (ret)
256                 return ret;
257         phonet_address_notify(RTM_NEWADDR, dev,
258                                 req.ifr_phonet_autoconf.device);
259         return 0;
260 }
261
262 static void phonet_route_autodel(struct net_device *dev)
263 {
264         struct phonet_net *pnn = net_generic(dev_net(dev), phonet_net_id);
265         unsigned i;
266         DECLARE_BITMAP(deleted, 64);
267
268         /* Remove left-over Phonet routes */
269         bitmap_zero(deleted, 64);
270         mutex_lock(&pnn->routes.lock);
271         for (i = 0; i < 64; i++)
272                 if (dev == pnn->routes.table[i]) {
273                         rcu_assign_pointer(pnn->routes.table[i], NULL);
274                         set_bit(i, deleted);
275                 }
276         mutex_unlock(&pnn->routes.lock);
277
278         if (bitmap_empty(deleted, 64))
279                 return; /* short-circuit RCU */
280         synchronize_rcu();
281         for (i = find_first_bit(deleted, 64); i < 64;
282                         i = find_next_bit(deleted, 64, i + 1)) {
283                 rtm_phonet_notify(RTM_DELROUTE, dev, i);
284                 dev_put(dev);
285         }
286 }
287
288 /* notify Phonet of device events */
289 static int phonet_device_notify(struct notifier_block *me, unsigned long what,
290                                 void *arg)
291 {
292         struct net_device *dev = arg;
293
294         switch (what) {
295         case NETDEV_REGISTER:
296                 if (dev->type == ARPHRD_PHONET)
297                         phonet_device_autoconf(dev);
298                 break;
299         case NETDEV_UNREGISTER:
300                 phonet_device_destroy(dev);
301                 phonet_route_autodel(dev);
302                 break;
303         }
304         return 0;
305
306 }
307
308 static struct notifier_block phonet_device_notifier = {
309         .notifier_call = phonet_device_notify,
310         .priority = 0,
311 };
312
313 /* Per-namespace Phonet devices handling */
314 static int phonet_init_net(struct net *net)
315 {
316         struct phonet_net *pnn = kzalloc(sizeof(*pnn), GFP_KERNEL);
317         if (!pnn)
318                 return -ENOMEM;
319
320         if (!proc_net_fops_create(net, "phonet", 0, &pn_sock_seq_fops)) {
321                 kfree(pnn);
322                 return -ENOMEM;
323         }
324
325         INIT_LIST_HEAD(&pnn->pndevs.list);
326         mutex_init(&pnn->pndevs.lock);
327         mutex_init(&pnn->routes.lock);
328         net_assign_generic(net, phonet_net_id, pnn);
329         return 0;
330 }
331
332 static void phonet_exit_net(struct net *net)
333 {
334         struct phonet_net *pnn = net_generic(net, phonet_net_id);
335         struct net_device *dev;
336         unsigned i;
337
338         rtnl_lock();
339         for_each_netdev(net, dev)
340                 phonet_device_destroy(dev);
341
342         for (i = 0; i < 64; i++) {
343                 dev = pnn->routes.table[i];
344                 if (dev) {
345                         rtm_phonet_notify(RTM_DELROUTE, dev, i);
346                         dev_put(dev);
347                 }
348         }
349         rtnl_unlock();
350
351         proc_net_remove(net, "phonet");
352         kfree(pnn);
353 }
354
355 static struct pernet_operations phonet_net_ops = {
356         .init = phonet_init_net,
357         .exit = phonet_exit_net,
358 };
359
360 /* Initialize Phonet devices list */
361 int __init phonet_device_init(void)
362 {
363         int err = register_pernet_gen_device(&phonet_net_id, &phonet_net_ops);
364         if (err)
365                 return err;
366
367         register_netdevice_notifier(&phonet_device_notifier);
368         err = phonet_netlink_register();
369         if (err)
370                 phonet_device_exit();
371         return err;
372 }
373
374 void phonet_device_exit(void)
375 {
376         rtnl_unregister_all(PF_PHONET);
377         unregister_netdevice_notifier(&phonet_device_notifier);
378         unregister_pernet_gen_device(phonet_net_id, &phonet_net_ops);
379 }
380
381 int phonet_route_add(struct net_device *dev, u8 daddr)
382 {
383         struct phonet_net *pnn = net_generic(dev_net(dev), phonet_net_id);
384         struct phonet_routes *routes = &pnn->routes;
385         int err = -EEXIST;
386
387         daddr = daddr >> 2;
388         mutex_lock(&routes->lock);
389         if (routes->table[daddr] == NULL) {
390                 rcu_assign_pointer(routes->table[daddr], dev);
391                 dev_hold(dev);
392                 err = 0;
393         }
394         mutex_unlock(&routes->lock);
395         return err;
396 }
397
398 int phonet_route_del(struct net_device *dev, u8 daddr)
399 {
400         struct phonet_net *pnn = net_generic(dev_net(dev), phonet_net_id);
401         struct phonet_routes *routes = &pnn->routes;
402
403         daddr = daddr >> 2;
404         mutex_lock(&routes->lock);
405         if (dev == routes->table[daddr])
406                 rcu_assign_pointer(routes->table[daddr], NULL);
407         else
408                 dev = NULL;
409         mutex_unlock(&routes->lock);
410
411         if (!dev)
412                 return -ENOENT;
413         synchronize_rcu();
414         dev_put(dev);
415         return 0;
416 }
417
418 struct net_device *phonet_route_get(struct net *net, u8 daddr)
419 {
420         struct phonet_net *pnn = net_generic(net, phonet_net_id);
421         struct phonet_routes *routes = &pnn->routes;
422         struct net_device *dev;
423
424         ASSERT_RTNL(); /* no need to hold the device */
425
426         daddr >>= 2;
427         rcu_read_lock();
428         dev = rcu_dereference(routes->table[daddr]);
429         rcu_read_unlock();
430         return dev;
431 }
432
433 struct net_device *phonet_route_output(struct net *net, u8 daddr)
434 {
435         struct phonet_net *pnn = net_generic(net, phonet_net_id);
436         struct phonet_routes *routes = &pnn->routes;
437         struct net_device *dev;
438
439         daddr >>= 2;
440         rcu_read_lock();
441         dev = rcu_dereference(routes->table[daddr]);
442         if (dev)
443                 dev_hold(dev);
444         rcu_read_unlock();
445
446         if (!dev)
447                 dev = phonet_device_get(net); /* Default route */
448         return dev;
449 }