connector: add module alias
[linux-2.6.git] / drivers / connector / connector.c
1 /*
2  *      connector.c
3  *
4  * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
5  * All rights reserved.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20  */
21
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/list.h>
25 #include <linux/skbuff.h>
26 #include <linux/netlink.h>
27 #include <linux/moduleparam.h>
28 #include <linux/connector.h>
29 #include <linux/slab.h>
30 #include <linux/mutex.h>
31 #include <linux/proc_fs.h>
32 #include <linux/spinlock.h>
33
34 #include <net/sock.h>
35
36 MODULE_LICENSE("GPL");
37 MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
38 MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
39 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);
40
41 static struct cn_dev cdev;
42
43 static int cn_already_initialized;
44
45 /*
46  * msg->seq and msg->ack are used to determine message genealogy.
47  * When someone sends message it puts there locally unique sequence
48  * and random acknowledge numbers.  Sequence number may be copied into
49  * nlmsghdr->nlmsg_seq too.
50  *
51  * Sequence number is incremented with each message to be sent.
52  *
53  * If we expect reply to our message then the sequence number in
54  * received message MUST be the same as in original message, and
55  * acknowledge number MUST be the same + 1.
56  *
57  * If we receive a message and its sequence number is not equal to the
58  * one we are expecting then it is a new message.
59  *
60  * If we receive a message and its sequence number is the same as one
61  * we are expecting but it's acknowledgement number is not equal to
62  * the acknowledgement number in the original message + 1, then it is
63  * a new message.
64  *
65  */
66 int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
67 {
68         struct cn_callback_entry *__cbq;
69         unsigned int size;
70         struct sk_buff *skb;
71         struct nlmsghdr *nlh;
72         struct cn_msg *data;
73         struct cn_dev *dev = &cdev;
74         u32 group = 0;
75         int found = 0;
76
77         if (!__group) {
78                 spin_lock_bh(&dev->cbdev->queue_lock);
79                 list_for_each_entry(__cbq, &dev->cbdev->queue_list,
80                                     callback_entry) {
81                         if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
82                                 found = 1;
83                                 group = __cbq->group;
84                                 break;
85                         }
86                 }
87                 spin_unlock_bh(&dev->cbdev->queue_lock);
88
89                 if (!found)
90                         return -ENODEV;
91         } else {
92                 group = __group;
93         }
94
95         if (!netlink_has_listeners(dev->nls, group))
96                 return -ESRCH;
97
98         size = NLMSG_SPACE(sizeof(*msg) + msg->len);
99
100         skb = alloc_skb(size, gfp_mask);
101         if (!skb)
102                 return -ENOMEM;
103
104         nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh));
105
106         data = NLMSG_DATA(nlh);
107
108         memcpy(data, msg, sizeof(*data) + msg->len);
109
110         NETLINK_CB(skb).dst_group = group;
111
112         return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
113
114 nlmsg_failure:
115         kfree_skb(skb);
116         return -EINVAL;
117 }
118 EXPORT_SYMBOL_GPL(cn_netlink_send);
119
120 /*
121  * Callback helper - queues work and setup destructor for given data.
122  */
123 static int cn_call_callback(struct sk_buff *skb)
124 {
125         struct cn_callback_entry *__cbq, *__new_cbq;
126         struct cn_dev *dev = &cdev;
127         struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(skb));
128         int err = -ENODEV;
129
130         spin_lock_bh(&dev->cbdev->queue_lock);
131         list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
132                 if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
133                         if (likely(!work_pending(&__cbq->work) &&
134                                         __cbq->data.skb == NULL)) {
135                                 __cbq->data.skb = skb;
136
137                                 if (queue_work(dev->cbdev->cn_queue,
138                                                &__cbq->work))
139                                         err = 0;
140                                 else
141                                         err = -EINVAL;
142                         } else {
143                                 struct cn_callback_data *d;
144
145                                 err = -ENOMEM;
146                                 __new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
147                                 if (__new_cbq) {
148                                         d = &__new_cbq->data;
149                                         d->skb = skb;
150                                         d->callback = __cbq->data.callback;
151                                         d->free = __new_cbq;
152
153                                         INIT_WORK(&__new_cbq->work,
154                                                         &cn_queue_wrapper);
155
156                                         if (queue_work(dev->cbdev->cn_queue,
157                                                        &__new_cbq->work))
158                                                 err = 0;
159                                         else {
160                                                 kfree(__new_cbq);
161                                                 err = -EINVAL;
162                                         }
163                                 }
164                         }
165                         break;
166                 }
167         }
168         spin_unlock_bh(&dev->cbdev->queue_lock);
169
170         return err;
171 }
172
173 /*
174  * Main netlink receiving function.
175  *
176  * It checks skb, netlink header and msg sizes, and calls callback helper.
177  */
178 static void cn_rx_skb(struct sk_buff *__skb)
179 {
180         struct nlmsghdr *nlh;
181         int err;
182         struct sk_buff *skb;
183
184         skb = skb_get(__skb);
185
186         if (skb->len >= NLMSG_SPACE(0)) {
187                 nlh = nlmsg_hdr(skb);
188
189                 if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
190                     skb->len < nlh->nlmsg_len ||
191                     nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
192                         kfree_skb(skb);
193                         return;
194                 }
195
196                 err = cn_call_callback(skb);
197                 if (err < 0)
198                         kfree_skb(skb);
199         }
200 }
201
202 /*
203  * Callback add routing - adds callback with given ID and name.
204  * If there is registered callback with the same ID it will not be added.
205  *
206  * May sleep.
207  */
208 int cn_add_callback(struct cb_id *id, char *name,
209                     void (*callback)(struct cn_msg *, struct netlink_skb_parms *))
210 {
211         int err;
212         struct cn_dev *dev = &cdev;
213
214         if (!cn_already_initialized)
215                 return -EAGAIN;
216
217         err = cn_queue_add_callback(dev->cbdev, name, id, callback);
218         if (err)
219                 return err;
220
221         return 0;
222 }
223 EXPORT_SYMBOL_GPL(cn_add_callback);
224
225 /*
226  * Callback remove routing - removes callback
227  * with given ID.
228  * If there is no registered callback with given
229  * ID nothing happens.
230  *
231  * May sleep while waiting for reference counter to become zero.
232  */
233 void cn_del_callback(struct cb_id *id)
234 {
235         struct cn_dev *dev = &cdev;
236
237         cn_queue_del_callback(dev->cbdev, id);
238 }
239 EXPORT_SYMBOL_GPL(cn_del_callback);
240
241 static int cn_proc_show(struct seq_file *m, void *v)
242 {
243         struct cn_queue_dev *dev = cdev.cbdev;
244         struct cn_callback_entry *cbq;
245
246         seq_printf(m, "Name            ID\n");
247
248         spin_lock_bh(&dev->queue_lock);
249
250         list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
251                 seq_printf(m, "%-15s %u:%u\n",
252                            cbq->id.name,
253                            cbq->id.id.idx,
254                            cbq->id.id.val);
255         }
256
257         spin_unlock_bh(&dev->queue_lock);
258
259         return 0;
260 }
261
262 static int cn_proc_open(struct inode *inode, struct file *file)
263 {
264         return single_open(file, cn_proc_show, NULL);
265 }
266
267 static const struct file_operations cn_file_ops = {
268         .owner   = THIS_MODULE,
269         .open    = cn_proc_open,
270         .read    = seq_read,
271         .llseek  = seq_lseek,
272         .release = single_release
273 };
274
275 static int __devinit cn_init(void)
276 {
277         struct cn_dev *dev = &cdev;
278
279         dev->input = cn_rx_skb;
280
281         dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
282                                          CN_NETLINK_USERS + 0xf,
283                                          dev->input, NULL, THIS_MODULE);
284         if (!dev->nls)
285                 return -EIO;
286
287         dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
288         if (!dev->cbdev) {
289                 netlink_kernel_release(dev->nls);
290                 return -EINVAL;
291         }
292
293         cn_already_initialized = 1;
294
295         proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);
296
297         return 0;
298 }
299
300 static void __devexit cn_fini(void)
301 {
302         struct cn_dev *dev = &cdev;
303
304         cn_already_initialized = 0;
305
306         proc_net_remove(&init_net, "connector");
307
308         cn_queue_free_dev(dev->cbdev);
309         netlink_kernel_release(dev->nls);
310 }
311
312 subsys_initcall(cn_init);
313 module_exit(cn_fini);