linux/drivers/connector/connector.c
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   1/*
   2 *      connector.c
   3 * 
   4 * 2004-2005 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru>
   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/mutex.h>
  30#include <linux/proc_fs.h>
  31#include <linux/spinlock.h>
  32
  33#include <net/sock.h>
  34
  35MODULE_LICENSE("GPL");
  36MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
  37MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
  38
  39static u32 cn_idx = CN_IDX_CONNECTOR;
  40static u32 cn_val = CN_VAL_CONNECTOR;
  41
  42module_param(cn_idx, uint, 0);
  43module_param(cn_val, uint, 0);
  44MODULE_PARM_DESC(cn_idx, "Connector's main device idx.");
  45MODULE_PARM_DESC(cn_val, "Connector's main device val.");
  46
  47static DEFINE_MUTEX(notify_lock);
  48static LIST_HEAD(notify_list);
  49
  50static struct cn_dev cdev;
  51
  52static int cn_already_initialized;
  53
  54/*
  55 * msg->seq and msg->ack are used to determine message genealogy.
  56 * When someone sends message it puts there locally unique sequence
  57 * and random acknowledge numbers.  Sequence number may be copied into
  58 * nlmsghdr->nlmsg_seq too.
  59 *
  60 * Sequence number is incremented with each message to be sent.
  61 *
  62 * If we expect reply to our message then the sequence number in
  63 * received message MUST be the same as in original message, and
  64 * acknowledge number MUST be the same + 1.
  65 *
  66 * If we receive a message and its sequence number is not equal to the
  67 * one we are expecting then it is a new message.
  68 *
  69 * If we receive a message and its sequence number is the same as one
  70 * we are expecting but it's acknowledgement number is not equal to
  71 * the acknowledgement number in the original message + 1, then it is
  72 * a new message.
  73 *
  74 */
  75int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
  76{
  77        struct cn_callback_entry *__cbq;
  78        unsigned int size;
  79        struct sk_buff *skb;
  80        struct nlmsghdr *nlh;
  81        struct cn_msg *data;
  82        struct cn_dev *dev = &cdev;
  83        u32 group = 0;
  84        int found = 0;
  85
  86        if (!__group) {
  87                spin_lock_bh(&dev->cbdev->queue_lock);
  88                list_for_each_entry(__cbq, &dev->cbdev->queue_list,
  89                                    callback_entry) {
  90                        if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
  91                                found = 1;
  92                                group = __cbq->group;
  93                                break;
  94                        }
  95                }
  96                spin_unlock_bh(&dev->cbdev->queue_lock);
  97
  98                if (!found)
  99                        return -ENODEV;
 100        } else {
 101                group = __group;
 102        }
 103
 104        if (!netlink_has_listeners(dev->nls, group))
 105                return -ESRCH;
 106
 107        size = NLMSG_SPACE(sizeof(*msg) + msg->len);
 108
 109        skb = alloc_skb(size, gfp_mask);
 110        if (!skb)
 111                return -ENOMEM;
 112
 113        nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh));
 114
 115        data = NLMSG_DATA(nlh);
 116
 117        memcpy(data, msg, sizeof(*data) + msg->len);
 118
 119        NETLINK_CB(skb).dst_group = group;
 120
 121        return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
 122
 123nlmsg_failure:
 124        kfree_skb(skb);
 125        return -EINVAL;
 126}
 127EXPORT_SYMBOL_GPL(cn_netlink_send);
 128
 129/*
 130 * Callback helper - queues work and setup destructor for given data.
 131 */
 132static int cn_call_callback(struct cn_msg *msg, void (*destruct_data)(void *), void *data)
 133{
 134        struct cn_callback_entry *__cbq, *__new_cbq;
 135        struct cn_dev *dev = &cdev;
 136        int err = -ENODEV;
 137
 138        spin_lock_bh(&dev->cbdev->queue_lock);
 139        list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
 140                if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
 141                        if (likely(!work_pending(&__cbq->work) &&
 142                                        __cbq->data.ddata == NULL)) {
 143                                __cbq->data.callback_priv = msg;
 144
 145                                __cbq->data.ddata = data;
 146                                __cbq->data.destruct_data = destruct_data;
 147
 148                                if (queue_work(dev->cbdev->cn_queue,
 149                                                        &__cbq->work))
 150                                        err = 0;
 151                                else
 152                                        err = -EINVAL;
 153                        } else {
 154                                struct cn_callback_data *d;
 155                                
 156                                err = -ENOMEM;
 157                                __new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
 158                                if (__new_cbq) {
 159                                        d = &__new_cbq->data;
 160                                        d->callback_priv = msg;
 161                                        d->callback = __cbq->data.callback;
 162                                        d->ddata = data;
 163                                        d->destruct_data = destruct_data;
 164                                        d->free = __new_cbq;
 165
 166                                        INIT_WORK(&__new_cbq->work,
 167                                                        &cn_queue_wrapper);
 168
 169                                        if (queue_work(dev->cbdev->cn_queue,
 170                                                    &__new_cbq->work))
 171                                                err = 0;
 172                                        else {
 173                                                kfree(__new_cbq);
 174                                                err = -EINVAL;
 175                                        }
 176                                }
 177                        }
 178                        break;
 179                }
 180        }
 181        spin_unlock_bh(&dev->cbdev->queue_lock);
 182
 183        return err;
 184}
 185
 186/*
 187 * Main netlink receiving function.
 188 *
 189 * It checks skb, netlink header and msg sizes, and calls callback helper.
 190 */
 191static void cn_rx_skb(struct sk_buff *__skb)
 192{
 193        struct cn_msg *msg;
 194        struct nlmsghdr *nlh;
 195        int err;
 196        struct sk_buff *skb;
 197
 198        skb = skb_get(__skb);
 199
 200        if (skb->len >= NLMSG_SPACE(0)) {
 201                nlh = nlmsg_hdr(skb);
 202
 203                if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
 204                    skb->len < nlh->nlmsg_len ||
 205                    nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
 206                        kfree_skb(skb);
 207                        return;
 208                }
 209
 210                msg = NLMSG_DATA(nlh);
 211                err = cn_call_callback(msg, (void (*)(void *))kfree_skb, skb);
 212                if (err < 0)
 213                        kfree_skb(skb);
 214        }
 215}
 216
 217/*
 218 * Notification routing.
 219 *
 220 * Gets id and checks if there are notification request for it's idx
 221 * and val.  If there are such requests notify the listeners with the
 222 * given notify event.
 223 *
 224 */
 225static void cn_notify(struct cb_id *id, u32 notify_event)
 226{
 227        struct cn_ctl_entry *ent;
 228
 229        mutex_lock(&notify_lock);
 230        list_for_each_entry(ent, &notify_list, notify_entry) {
 231                int i;
 232                struct cn_notify_req *req;
 233                struct cn_ctl_msg *ctl = ent->msg;
 234                int idx_found, val_found;
 235
 236                idx_found = val_found = 0;
 237
 238                req = (struct cn_notify_req *)ctl->data;
 239                for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
 240                        if (id->idx >= req->first && 
 241                                        id->idx < req->first + req->range) {
 242                                idx_found = 1;
 243                                break;
 244                        }
 245                }
 246
 247                for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
 248                        if (id->val >= req->first && 
 249                                        id->val < req->first + req->range) {
 250                                val_found = 1;
 251                                break;
 252                        }
 253                }
 254
 255                if (idx_found && val_found) {
 256                        struct cn_msg m = { .ack = notify_event, };
 257
 258                        memcpy(&m.id, id, sizeof(m.id));
 259                        cn_netlink_send(&m, ctl->group, GFP_KERNEL);
 260                }
 261        }
 262        mutex_unlock(&notify_lock);
 263}
 264
 265/*
 266 * Callback add routing - adds callback with given ID and name.
 267 * If there is registered callback with the same ID it will not be added.
 268 *
 269 * May sleep.
 270 */
 271int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *))
 272{
 273        int err;
 274        struct cn_dev *dev = &cdev;
 275
 276        if (!cn_already_initialized)
 277                return -EAGAIN;
 278
 279        err = cn_queue_add_callback(dev->cbdev, name, id, callback);
 280        if (err)
 281                return err;
 282
 283        cn_notify(id, 0);
 284
 285        return 0;
 286}
 287EXPORT_SYMBOL_GPL(cn_add_callback);
 288
 289/*
 290 * Callback remove routing - removes callback
 291 * with given ID.
 292 * If there is no registered callback with given
 293 * ID nothing happens.
 294 *
 295 * May sleep while waiting for reference counter to become zero.
 296 */
 297void cn_del_callback(struct cb_id *id)
 298{
 299        struct cn_dev *dev = &cdev;
 300
 301        cn_queue_del_callback(dev->cbdev, id);
 302        cn_notify(id, 1);
 303}
 304EXPORT_SYMBOL_GPL(cn_del_callback);
 305
 306/*
 307 * Checks two connector's control messages to be the same.
 308 * Returns 1 if they are the same or if the first one is corrupted.
 309 */
 310static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
 311{
 312        int i;
 313        struct cn_notify_req *req1, *req2;
 314
 315        if (m1->idx_notify_num != m2->idx_notify_num)
 316                return 0;
 317
 318        if (m1->val_notify_num != m2->val_notify_num)
 319                return 0;
 320
 321        if (m1->len != m2->len)
 322                return 0;
 323
 324        if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
 325            m1->len)
 326                return 1;
 327
 328        req1 = (struct cn_notify_req *)m1->data;
 329        req2 = (struct cn_notify_req *)m2->data;
 330
 331        for (i = 0; i < m1->idx_notify_num; ++i) {
 332                if (req1->first != req2->first || req1->range != req2->range)
 333                        return 0;
 334                req1++;
 335                req2++;
 336        }
 337
 338        for (i = 0; i < m1->val_notify_num; ++i) {
 339                if (req1->first != req2->first || req1->range != req2->range)
 340                        return 0;
 341                req1++;
 342                req2++;
 343        }
 344
 345        return 1;
 346}
 347
 348/*
 349 * Main connector device's callback.
 350 *
 351 * Used for notification of a request's processing.
 352 */
 353static void cn_callback(void *data)
 354{
 355        struct cn_msg *msg = data;
 356        struct cn_ctl_msg *ctl;
 357        struct cn_ctl_entry *ent;
 358        u32 size;
 359
 360        if (msg->len < sizeof(*ctl))
 361                return;
 362
 363        ctl = (struct cn_ctl_msg *)msg->data;
 364
 365        size = (sizeof(*ctl) + ((ctl->idx_notify_num +
 366                                 ctl->val_notify_num) *
 367                                sizeof(struct cn_notify_req)));
 368
 369        if (msg->len != size)
 370                return;
 371
 372        if (ctl->len + sizeof(*ctl) != msg->len)
 373                return;
 374
 375        /*
 376         * Remove notification.
 377         */
 378        if (ctl->group == 0) {
 379                struct cn_ctl_entry *n;
 380
 381                mutex_lock(&notify_lock);
 382                list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
 383                        if (cn_ctl_msg_equals(ent->msg, ctl)) {
 384                                list_del(&ent->notify_entry);
 385                                kfree(ent);
 386                        }
 387                }
 388                mutex_unlock(&notify_lock);
 389
 390                return;
 391        }
 392
 393        size += sizeof(*ent);
 394
 395        ent = kzalloc(size, GFP_KERNEL);
 396        if (!ent)
 397                return;
 398
 399        ent->msg = (struct cn_ctl_msg *)(ent + 1);
 400
 401        memcpy(ent->msg, ctl, size - sizeof(*ent));
 402
 403        mutex_lock(&notify_lock);
 404        list_add(&ent->notify_entry, &notify_list);
 405        mutex_unlock(&notify_lock);
 406}
 407
 408static int cn_proc_show(struct seq_file *m, void *v)
 409{
 410        struct cn_queue_dev *dev = cdev.cbdev;
 411        struct cn_callback_entry *cbq;
 412
 413        seq_printf(m, "Name            ID\n");
 414
 415        spin_lock_bh(&dev->queue_lock);
 416
 417        list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
 418                seq_printf(m, "%-15s %u:%u\n",
 419                           cbq->id.name,
 420                           cbq->id.id.idx,
 421                           cbq->id.id.val);
 422        }
 423
 424        spin_unlock_bh(&dev->queue_lock);
 425
 426        return 0;
 427}
 428
 429static int cn_proc_open(struct inode *inode, struct file *file)
 430{
 431        return single_open(file, cn_proc_show, NULL);
 432}
 433
 434static const struct file_operations cn_file_ops = {
 435        .owner   = THIS_MODULE,
 436        .open    = cn_proc_open,
 437        .read    = seq_read,
 438        .llseek  = seq_lseek,
 439        .release = single_release
 440};
 441
 442static int __devinit cn_init(void)
 443{
 444        struct cn_dev *dev = &cdev;
 445        int err;
 446
 447        dev->input = cn_rx_skb;
 448        dev->id.idx = cn_idx;
 449        dev->id.val = cn_val;
 450
 451        dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
 452                                         CN_NETLINK_USERS + 0xf,
 453                                         dev->input, NULL, THIS_MODULE);
 454        if (!dev->nls)
 455                return -EIO;
 456
 457        dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
 458        if (!dev->cbdev) {
 459                netlink_kernel_release(dev->nls);
 460                return -EINVAL;
 461        }
 462        
 463        cn_already_initialized = 1;
 464
 465        err = cn_add_callback(&dev->id, "connector", &cn_callback);
 466        if (err) {
 467                cn_already_initialized = 0;
 468                cn_queue_free_dev(dev->cbdev);
 469                netlink_kernel_release(dev->nls);
 470                return -EINVAL;
 471        }
 472
 473        proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);
 474
 475        return 0;
 476}
 477
 478static void __devexit cn_fini(void)
 479{
 480        struct cn_dev *dev = &cdev;
 481
 482        cn_already_initialized = 0;
 483
 484        proc_net_remove(&init_net, "connector");
 485
 486        cn_del_callback(&dev->id);
 487        cn_queue_free_dev(dev->cbdev);
 488        netlink_kernel_release(dev->nls);
 489}
 490
 491subsys_initcall(cn_init);
 492module_exit(cn_fini);
 493
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