drivers/w1/w1_netlink.c

   1 /*
   2  * Copyright (c) 2003 Evgeniy Polyakov <zbr@ioremap.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <linux/slab.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/netlink.h>
  18 #include <linux/connector.h>
  19
  20 #include "w1.h"
  21 #include "w1_netlink.h"
  22
  23 #if defined(CONFIG_W1_CON) && (defined(CONFIG_CONNECTOR) || (defined(CONFIG_CONNECTOR_MODULE) && defined(CONFIG_W1_MODULE)))
  24
  25 /* Bundle together everything required to process a request in one memory
  26  * allocation.
  27  */
  28 struct w1_cb_block {
  29         atomic_t refcnt;
  30         u32 portid; /* Sending process port ID */
  31         /* maximum value for first_cn->len */
  32         u16 maxlen;
  33         /* pointers to building up the reply message */
  34         struct cn_msg *first_cn; /* fixed once the structure is populated */
  35         struct cn_msg *cn; /* advances as cn_msg is appeneded */
  36         struct w1_netlink_msg *msg; /* advances as w1_netlink_msg is appened */
  37         struct w1_netlink_cmd *cmd; /* advances as cmds are appened */
  38         struct w1_netlink_msg *cur_msg; /* currently message being processed */
  39         /* copy of the original request follows */
  40         struct cn_msg request_cn;
  41         /* followed by variable length:
  42          * cn_msg, data (w1_netlink_msg and w1_netlink_cmd)
  43          * one or more struct w1_cb_node
  44          * reply first_cn, data (w1_netlink_msg and w1_netlink_cmd)
  45          */
  46 };
  47 struct w1_cb_node {
  48         struct w1_async_cmd async;
  49         /* pointers within w1_cb_block and cn data */
  50         struct w1_cb_block *block;
  51         struct w1_netlink_msg *msg;
  52         struct w1_slave *sl;
  53         struct w1_master *dev;
  54 };
  55
  56 /**
  57  * w1_reply_len() - calculate current reply length, compare to maxlen
  58  * @block: block to calculate
  59  *
  60  * Calculates the current message length including possible multiple
  61  * cn_msg and data, excludes the first sizeof(struct cn_msg).  Direclty
  62  * compariable to maxlen and usable to send the message.
  63  */
  64 static u16 w1_reply_len(struct w1_cb_block *block)
  65 {
  66         if (!block->cn)
  67                 return 0;
  68         return (u8 *)block->cn - (u8 *)block->first_cn + block->cn->len;
  69 }
  70
  71 static void w1_unref_block(struct w1_cb_block *block)
  72 {
  73         if (atomic_sub_return(1, &block->refcnt) == 0) {
  74                 u16 len = w1_reply_len(block);
  75                 if (len) {
  76                         cn_netlink_send_mult(block->first_cn, len,
  77                                 block->portid, 0, GFP_KERNEL);
  78                 }
  79                 kfree(block);
  80         }
  81 }
  82
  83 /**
  84  * w1_reply_make_space() - send message if needed to make space
  85  * @block: block to make space on
  86  * @space: how many bytes requested
  87  *
  88  * Verify there is enough room left for the caller to add "space" bytes to the
  89  * message, if there isn't send the message and reset.
  90  */
  91 static void w1_reply_make_space(struct w1_cb_block *block, u16 space)
  92 {
  93         u16 len = w1_reply_len(block);
  94         if (len + space >= block->maxlen) {
  95                 cn_netlink_send_mult(block->first_cn, len, block->portid, 0, GFP_KERNEL);
  96                 block->first_cn->len = 0;
  97                 block->cn = NULL;
  98                 block->msg = NULL;
  99                 block->cmd = NULL;
 100         }
 101 }
 102
 103 /* Early send when replies aren't bundled. */
 104 static void w1_netlink_check_send(struct w1_cb_block *block)
 105 {
 106         if (!(block->request_cn.flags & W1_CN_BUNDLE) && block->cn)
 107                 w1_reply_make_space(block, block->maxlen);
 108 }
 109
 110 /**
 111  * w1_netlink_setup_msg() - prepare to write block->msg
 112  * @block: block to operate on
 113  * @ack: determines if cn can be reused
 114  *
 115  * block->cn will be setup with the correct ack, advancing if needed
 116  * block->cn->len does not include space for block->msg
 117  * block->msg advances but remains uninitialized
 118  */
 119 static void w1_netlink_setup_msg(struct w1_cb_block *block, u32 ack)
 120 {
 121         if (block->cn && block->cn->ack == ack) {
 122                 block->msg = (struct w1_netlink_msg *)(block->cn->data + block->cn->len);
 123         } else {
 124                 /* advance or set to data */
 125                 if (block->cn)
 126                         block->cn = (struct cn_msg *)(block->cn->data +
 127                                 block->cn->len);
 128                 else
 129                         block->cn = block->first_cn;
 130
 131                 memcpy(block->cn, &block->request_cn, sizeof(*block->cn));
 132                 block->cn->len = 0;
 133                 block->cn->ack = ack;
 134                 block->msg = (struct w1_netlink_msg *)block->cn->data;
 135         }
 136 }
 137
 138 /* Append cmd to msg, include cmd->data as well.  This is because
 139  * any following data goes with the command and in the case of a read is
 140  * the results.
 141  */
 142 static void w1_netlink_queue_cmd(struct w1_cb_block *block,
 143         struct w1_netlink_cmd *cmd)
 144 {
 145         u32 space;
 146         w1_reply_make_space(block, sizeof(struct cn_msg) +
 147                 sizeof(struct w1_netlink_msg) + sizeof(*cmd) + cmd->len);
 148
 149         /* There's a status message sent after each command, so no point
 150          * in trying to bundle this cmd after an existing one, because
 151          * there won't be one.  Allocate and copy over a new cn_msg.
 152          */
 153         w1_netlink_setup_msg(block, block->request_cn.seq + 1);
 154         memcpy(block->msg, block->cur_msg, sizeof(*block->msg));
 155         block->cn->len += sizeof(*block->msg);
 156         block->msg->len = 0;
 157         block->cmd = (struct w1_netlink_cmd *)(block->msg->data);
 158
 159         space = sizeof(*cmd) + cmd->len;
 160         if (block->cmd != cmd)
 161                 memcpy(block->cmd, cmd, space);
 162         block->cn->len += space;
 163         block->msg->len += space;
 164 }
 165
 166 /* Append req_msg and req_cmd, no other commands and no data from req_cmd are
 167  * copied.
 168  */
 169 static void w1_netlink_queue_status(struct w1_cb_block *block,
 170         struct w1_netlink_msg *req_msg, struct w1_netlink_cmd *req_cmd,
 171         int error)
 172 {
 173         u16 space = sizeof(struct cn_msg) + sizeof(*req_msg) + sizeof(*req_cmd);
 174         w1_reply_make_space(block, space);
 175         w1_netlink_setup_msg(block, block->request_cn.ack);
 176
 177         memcpy(block->msg, req_msg, sizeof(*req_msg));
 178         block->cn->len += sizeof(*req_msg);
 179         block->msg->len = 0;
 180         block->msg->status = (u8)-error;
 181         if (req_cmd) {
 182                 struct w1_netlink_cmd *cmd = (struct w1_netlink_cmd *)block->msg->data;
 183                 memcpy(cmd, req_cmd, sizeof(*cmd));
 184                 block->cn->len += sizeof(*cmd);
 185                 block->msg->len += sizeof(*cmd);
 186                 cmd->len = 0;
 187         }
 188         w1_netlink_check_send(block);
 189 }
 190
 191 /**
 192  * w1_netlink_send_error() - sends the error message now
 193  * @cn: original cn_msg
 194  * @msg: original w1_netlink_msg
 195  * @portid: where to send it
 196  * @error: error status
 197  *
 198  * Use when a block isn't available to queue the message to and cn, msg
 199  * might not be contiguous.
 200  */
 201 static void w1_netlink_send_error(struct cn_msg *cn, struct w1_netlink_msg *msg,
 202         int portid, int error)
 203 {
 204         struct {
 205                 struct cn_msg cn;
 206                 struct w1_netlink_msg msg;
 207         } packet;
 208         memcpy(&packet.cn, cn, sizeof(packet.cn));
 209         memcpy(&packet.msg, msg, sizeof(packet.msg));
 210         packet.cn.len = sizeof(packet.msg);
 211         packet.msg.len = 0;
 212         packet.msg.status = (u8)-error;
 213         cn_netlink_send(&packet.cn, portid, 0, GFP_KERNEL);
 214 }
 215
 216 /**
 217  * w1_netlink_send() - sends w1 netlink notifications
 218  * @dev: w1_master the even is associated with or for
 219  * @msg: w1_netlink_msg message to be sent
 220  *
 221  * This are notifications generated from the kernel.
 222  */
 223 void w1_netlink_send(struct w1_master *dev, struct w1_netlink_msg *msg)
 224 {
 225         struct {
 226                 struct cn_msg cn;
 227                 struct w1_netlink_msg msg;
 228         } packet;
 229         memset(&packet, 0, sizeof(packet));
 230
 231         packet.cn.id.idx = CN_W1_IDX;
 232         packet.cn.id.val = CN_W1_VAL;
 233
 234         packet.cn.seq = dev->seq++;
 235         packet.cn.len = sizeof(*msg);
 236
 237         memcpy(&packet.msg, msg, sizeof(*msg));
 238         packet.msg.len = 0;
 239
 240         cn_netlink_send(&packet.cn, 0, 0, GFP_KERNEL);
 241 }
 242
 243 static void w1_send_slave(struct w1_master *dev, u64 rn)
 244 {
 245         struct w1_cb_block *block = dev->priv;
 246         struct w1_netlink_cmd *cache_cmd = block->cmd;
 247         u64 *data;
 248
 249         w1_reply_make_space(block, sizeof(*data));
 250
 251         /* Add cmd back if the packet was sent */
 252         if (!block->cmd) {
 253                 cache_cmd->len = 0;
 254                 w1_netlink_queue_cmd(block, cache_cmd);
 255         }
 256
 257         data = (u64 *)(block->cmd->data + block->cmd->len);
 258
 259         *data = rn;
 260         block->cn->len += sizeof(*data);
 261         block->msg->len += sizeof(*data);
 262         block->cmd->len += sizeof(*data);
 263 }
 264
 265 static void w1_found_send_slave(struct w1_master *dev, u64 rn)
 266 {
 267         /* update kernel slave list */
 268         w1_slave_found(dev, rn);
 269
 270         w1_send_slave(dev, rn);
 271 }
 272
 273 /* Get the current slave list, or search (with or without alarm) */
 274 static int w1_get_slaves(struct w1_master *dev, struct w1_netlink_cmd *req_cmd)
 275 {
 276         struct w1_slave *sl;
 277
 278         req_cmd->len = 0;
 279         w1_netlink_queue_cmd(dev->priv, req_cmd);
 280
 281         if (req_cmd->cmd == W1_CMD_LIST_SLAVES) {
 282                 u64 rn;
 283                 mutex_lock(&dev->list_mutex);
 284                 list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
 285                         memcpy(&rn, &sl->reg_num, sizeof(rn));
 286                         w1_send_slave(dev, rn);
 287                 }
 288                 mutex_unlock(&dev->list_mutex);
 289         } else {
 290                 w1_search_process_cb(dev, req_cmd->cmd == W1_CMD_ALARM_SEARCH ?
 291                         W1_ALARM_SEARCH : W1_SEARCH, w1_found_send_slave);
 292         }
 293
 294         return 0;
 295 }
 296
 297 static int w1_process_command_io(struct w1_master *dev,
 298         struct w1_netlink_cmd *cmd)
 299 {
 300         int err = 0;
 301
 302         switch (cmd->cmd) {
 303         case W1_CMD_TOUCH:
 304                 w1_touch_block(dev, cmd->data, cmd->len);
 305                 w1_netlink_queue_cmd(dev->priv, cmd);
 306                 break;
 307         case W1_CMD_READ:
 308                 w1_read_block(dev, cmd->data, cmd->len);
 309                 w1_netlink_queue_cmd(dev->priv, cmd);
 310                 break;
 311         case W1_CMD_WRITE:
 312                 w1_write_block(dev, cmd->data, cmd->len);
 313                 break;
 314         default:
 315                 err = -EINVAL;
 316                 break;
 317         }
 318
 319         return err;
 320 }
 321
 322 static int w1_process_command_addremove(struct w1_master *dev,
 323         struct w1_netlink_cmd *cmd)
 324 {
 325         struct w1_slave *sl;
 326         int err = 0;
 327         struct w1_reg_num *id;
 328
 329         if (cmd->len != sizeof(*id))
 330                 return -EINVAL;
 331
 332         id = (struct w1_reg_num *)cmd->data;
 333
 334         sl = w1_slave_search_device(dev, id);
 335         switch (cmd->cmd) {
 336         case W1_CMD_SLAVE_ADD:
 337                 if (sl)
 338                         err = -EINVAL;
 339                 else
 340                         err = w1_attach_slave_device(dev, id);
 341                 break;
 342         case W1_CMD_SLAVE_REMOVE:
 343                 if (sl)
 344                         w1_slave_detach(sl);
 345                 else
 346                         err = -EINVAL;
 347                 break;
 348         default:
 349                 err = -EINVAL;
 350                 break;
 351         }
 352
 353         return err;
 354 }
 355
 356 static int w1_process_command_master(struct w1_master *dev,
 357         struct w1_netlink_cmd *req_cmd)
 358 {
 359         int err = -EINVAL;
 360
 361         /* drop bus_mutex for search (does it's own locking), and add/remove
 362          * which doesn't use the bus
 363          */
 364         switch (req_cmd->cmd) {
 365         case W1_CMD_SEARCH:
 366         case W1_CMD_ALARM_SEARCH:
 367         case W1_CMD_LIST_SLAVES:
 368                 mutex_unlock(&dev->bus_mutex);
 369                 err = w1_get_slaves(dev, req_cmd);
 370                 mutex_lock(&dev->bus_mutex);
 371                 break;
 372         case W1_CMD_READ:
 373         case W1_CMD_WRITE:
 374         case W1_CMD_TOUCH:
 375                 err = w1_process_command_io(dev, req_cmd);
 376                 break;
 377         case W1_CMD_RESET:
 378                 err = w1_reset_bus(dev);
 379                 break;
 380         case W1_CMD_SLAVE_ADD:
 381         case W1_CMD_SLAVE_REMOVE:
 382                 mutex_unlock(&dev->bus_mutex);
 383                 mutex_lock(&dev->mutex);
 384                 err = w1_process_command_addremove(dev, req_cmd);
 385                 mutex_unlock(&dev->mutex);
 386                 mutex_lock(&dev->bus_mutex);
 387                 break;
 388         default:
 389                 err = -EINVAL;
 390                 break;
 391         }
 392
 393         return err;
 394 }
 395
 396 static int w1_process_command_slave(struct w1_slave *sl,
 397                 struct w1_netlink_cmd *cmd)
 398 {
 399         dev_dbg(&sl->master->dev, "%s: %02x.%012llx.%02x: cmd=%02x, len=%u.\n",
 400                 __func__, sl->reg_num.family, (unsigned long long)sl->reg_num.id,
 401                 sl->reg_num.crc, cmd->cmd, cmd->len);
 402
 403         return w1_process_command_io(sl->master, cmd);
 404 }
 405
 406 static int w1_process_command_root(struct cn_msg *req_cn, u32 portid)
 407 {
 408         struct w1_master *dev;
 409         struct cn_msg *cn;
 410         struct w1_netlink_msg *msg;
 411         u32 *id;
 412
 413         cn = kmalloc(PAGE_SIZE, GFP_KERNEL);
 414         if (!cn)
 415                 return -ENOMEM;
 416
 417         cn->id.idx = CN_W1_IDX;
 418         cn->id.val = CN_W1_VAL;
 419
 420         cn->seq = req_cn->seq;
 421         cn->ack = req_cn->seq + 1;
 422         cn->len = sizeof(struct w1_netlink_msg);
 423         msg = (struct w1_netlink_msg *)cn->data;
 424
 425         msg->type = W1_LIST_MASTERS;
 426         msg->status = 0;
 427         msg->len = 0;
 428         id = (u32 *)msg->data;
 429
 430         mutex_lock(&w1_mlock);
 431         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 432                 if (cn->len + sizeof(*id) > PAGE_SIZE - sizeof(struct cn_msg)) {
 433                         cn_netlink_send(cn, portid, 0, GFP_KERNEL);
 434                         cn->len = sizeof(struct w1_netlink_msg);
 435                         msg->len = 0;
 436                         id = (u32 *)msg->data;
 437                 }
 438
 439                 *id = dev->id;
 440                 msg->len += sizeof(*id);
 441                 cn->len += sizeof(*id);
 442                 id++;
 443         }
 444         cn_netlink_send(cn, portid, 0, GFP_KERNEL);
 445         mutex_unlock(&w1_mlock);
 446
 447         kfree(cn);
 448         return 0;
 449 }
 450
 451 static void w1_process_cb(struct w1_master *dev, struct w1_async_cmd *async_cmd)
 452 {
 453         struct w1_cb_node *node = container_of(async_cmd, struct w1_cb_node,
 454                 async);
 455         u16 mlen = node->msg->len;
 456         u16 len;
 457         int err = 0;
 458         struct w1_slave *sl = node->sl;
 459         struct w1_netlink_cmd *cmd = (struct w1_netlink_cmd *)node->msg->data;
 460
 461         mutex_lock(&dev->bus_mutex);
 462         dev->priv = node->block;
 463         if (sl && w1_reset_select_slave(sl))
 464                 err = -ENODEV;
 465         node->block->cur_msg = node->msg;
 466
 467         while (mlen && !err) {
 468                 if (cmd->len + sizeof(struct w1_netlink_cmd) > mlen) {
 469                         err = -E2BIG;
 470                         break;
 471                 }
 472
 473                 if (sl)
 474                         err = w1_process_command_slave(sl, cmd);
 475                 else
 476                         err = w1_process_command_master(dev, cmd);
 477                 w1_netlink_check_send(node->block);
 478
 479                 w1_netlink_queue_status(node->block, node->msg, cmd, err);
 480                 err = 0;
 481
 482                 len = sizeof(*cmd) + cmd->len;
 483                 cmd = (struct w1_netlink_cmd *)((u8 *)cmd + len);
 484                 mlen -= len;
 485         }
 486
 487         if (!cmd || err)
 488                 w1_netlink_queue_status(node->block, node->msg, cmd, err);
 489
 490         /* ref taken in w1_search_slave or w1_search_master_id when building
 491          * the block
 492          */
 493         if (sl)
 494                 w1_unref_slave(sl);
 495         else
 496                 atomic_dec(&dev->refcnt);
 497         dev->priv = NULL;
 498         mutex_unlock(&dev->bus_mutex);
 499
 500         mutex_lock(&dev->list_mutex);
 501         list_del(&async_cmd->async_entry);
 502         mutex_unlock(&dev->list_mutex);
 503
 504         w1_unref_block(node->block);
 505 }
 506
 507 static void w1_list_count_cmds(struct w1_netlink_msg *msg, int *cmd_count,
 508         u16 *slave_len)
 509 {
 510         struct w1_netlink_cmd *cmd = (struct w1_netlink_cmd *)msg->data;
 511         u16 mlen = msg->len;
 512         u16 len;
 513         int slave_list = 0;
 514         while (mlen) {
 515                 if (cmd->len + sizeof(struct w1_netlink_cmd) > mlen)
 516                         break;
 517
 518                 switch (cmd->cmd) {
 519                 case W1_CMD_SEARCH:
 520                 case W1_CMD_ALARM_SEARCH:
 521                 case W1_CMD_LIST_SLAVES:
 522                         ++slave_list;
 523                 }
 524                 ++*cmd_count;
 525                 len = sizeof(*cmd) + cmd->len;
 526                 cmd = (struct w1_netlink_cmd *)((u8 *)cmd + len);
 527                 mlen -= len;
 528         }
 529
 530         if (slave_list) {
 531                 struct w1_master *dev = w1_search_master_id(msg->id.mst.id);
 532                 if (dev) {
 533                         /* Bytes, and likely an overstimate, and if it isn't
 534                          * the results can still be split between packets.
 535                          */
 536                         *slave_len += sizeof(struct w1_reg_num) * slave_list *
 537                                 (dev->slave_count + dev->max_slave_count);
 538                         /* search incremented it */
 539                         atomic_dec(&dev->refcnt);
 540                 }
 541         }
 542 }
 543
 544 static void w1_cn_callback(struct cn_msg *cn, struct netlink_skb_parms *nsp)
 545 {
 546         struct w1_netlink_msg *msg = (struct w1_netlink_msg *)(cn + 1);
 547         struct w1_slave *sl;
 548         struct w1_master *dev;
 549         u16 msg_len;
 550         u16 slave_len = 0;
 551         int err = 0;
 552         struct w1_cb_block *block = NULL;
 553         struct w1_cb_node *node = NULL;
 554         int node_count = 0;
 555         int cmd_count = 0;
 556
 557         /* If any unknown flag is set let the application know, that way
 558          * applications can detect the absence of features in kernels that
 559          * don't know about them.  http://lwn.net/Articles/587527/
 560          */
 561         if (cn->flags & ~(W1_CN_BUNDLE)) {
 562                 w1_netlink_send_error(cn, msg, nsp->portid, -EINVAL);
 563                 return;
 564         }
 565
 566         /* Count the number of master or slave commands there are to allocate
 567          * space for one cb_node each.
 568          */
 569         msg_len = cn->len;
 570         while (msg_len && !err) {
 571                 if (msg->len + sizeof(struct w1_netlink_msg) > msg_len) {
 572                         err = -E2BIG;
 573                         break;
 574                 }
 575
 576                 /* count messages for nodes and allocate any additional space
 577                  * required for slave lists
 578                  */
 579                 if (msg->type == W1_MASTER_CMD || msg->type == W1_SLAVE_CMD) {
 580                         ++node_count;
 581                         w1_list_count_cmds(msg, &cmd_count, &slave_len);
 582                 }
 583
 584                 msg_len -= sizeof(struct w1_netlink_msg) + msg->len;
 585                 msg = (struct w1_netlink_msg *)(((u8 *)msg) +
 586                         sizeof(struct w1_netlink_msg) + msg->len);
 587         }
 588         msg = (struct w1_netlink_msg *)(cn + 1);
 589         if (node_count) {
 590                 int size;
 591                 int reply_size = sizeof(*cn) + cn->len + slave_len;
 592                 if (cn->flags & W1_CN_BUNDLE) {
 593                         /* bundling duplicats some of the messages */
 594                         reply_size += 2 * cmd_count * (sizeof(struct cn_msg) +
 595                                 sizeof(struct w1_netlink_msg) +
 596                                 sizeof(struct w1_netlink_cmd));
 597                 }
 598                 reply_size = min(CONNECTOR_MAX_MSG_SIZE, reply_size);
 599
 600                 /* allocate space for the block, a copy of the original message,
 601                  * one node per cmd to point into the original message,
 602                  * space for replies which is the original message size plus
 603                  * space for any list slave data and status messages
 604                  * cn->len doesn't include itself which is part of the block
 605                  * */
 606                 size =  /* block + original message */
 607                         sizeof(struct w1_cb_block) + sizeof(*cn) + cn->len +
 608                         /* space for nodes */
 609                         node_count * sizeof(struct w1_cb_node) +
 610                         /* replies */
 611                         sizeof(struct cn_msg) + reply_size;
 612                 block = kzalloc(size, GFP_KERNEL);
 613                 if (!block) {
 614                         /* if the system is already out of memory,
 615                          * (A) will this work, and (B) would it be better
 616                          * to not try?
 617                          */
 618                         w1_netlink_send_error(cn, msg, nsp->portid, -ENOMEM);
 619                         return;
 620                 }
 621                 atomic_set(&block->refcnt, 1);
 622                 block->portid = nsp->portid;
 623                 memcpy(&block->request_cn, cn, sizeof(*cn) + cn->len);
 624                 node = (struct w1_cb_node *)(block->request_cn.data + cn->len);
 625
 626                 /* Sneeky, when not bundling, reply_size is the allocated space
 627                  * required for the reply, cn_msg isn't part of maxlen so
 628                  * it should be reply_size - sizeof(struct cn_msg), however
 629                  * when checking if there is enough space, w1_reply_make_space
 630                  * is called with the full message size including cn_msg,
 631                  * because it isn't known at that time if an additional cn_msg
 632                  * will need to be allocated.  So an extra cn_msg is added
 633                  * above in "size".
 634                  */
 635                 block->maxlen = reply_size;
 636                 block->first_cn = (struct cn_msg *)(node + node_count);
 637                 memset(block->first_cn, 0, sizeof(*block->first_cn));
 638         }
 639
 640         msg_len = cn->len;
 641         while (msg_len && !err) {
 642
 643                 dev = NULL;
 644                 sl = NULL;
 645
 646                 if (msg->len + sizeof(struct w1_netlink_msg) > msg_len) {
 647                         err = -E2BIG;
 648                         break;
 649                 }
 650
 651                 /* execute on this thread, no need to process later */
 652                 if (msg->type == W1_LIST_MASTERS) {
 653                         err = w1_process_command_root(cn, nsp->portid);
 654                         goto out_cont;
 655                 }
 656
 657                 /* All following message types require additional data,
 658                  * check here before references are taken.
 659                  */
 660                 if (!msg->len) {
 661                         err = -EPROTO;
 662                         goto out_cont;
 663                 }
 664
 665                 /* both search calls take references */
 666                 if (msg->type == W1_MASTER_CMD) {
 667                         dev = w1_search_master_id(msg->id.mst.id);
 668                 } else if (msg->type == W1_SLAVE_CMD) {
 669                         sl = w1_search_slave((struct w1_reg_num *)msg->id.id);
 670                         if (sl)
 671                                 dev = sl->master;
 672                 } else {
 673                         pr_notice("%s: cn: %x.%x, wrong type: %u, len: %u.\n",
 674                                 __func__, cn->id.idx, cn->id.val,
 675                                 msg->type, msg->len);
 676                         err = -EPROTO;
 677                         goto out_cont;
 678                 }
 679
 680                 if (!dev) {
 681                         err = -ENODEV;
 682                         goto out_cont;
 683                 }
 684
 685                 err = 0;
 686
 687                 atomic_inc(&block->refcnt);
 688                 node->async.cb = w1_process_cb;
 689                 node->block = block;
 690                 node->msg = (struct w1_netlink_msg *)((u8 *)&block->request_cn +
 691                         (size_t)((u8 *)msg - (u8 *)cn));
 692                 node->sl = sl;
 693                 node->dev = dev;
 694
 695                 mutex_lock(&dev->list_mutex);
 696                 list_add_tail(&node->async.async_entry, &dev->async_list);
 697                 wake_up_process(dev->thread);
 698                 mutex_unlock(&dev->list_mutex);
 699                 ++node;
 700
 701 out_cont:
 702                 /* Can't queue because that modifies block and another
 703                  * thread could be processing the messages by now and
 704                  * there isn't a lock, send directly.
 705                  */
 706                 if (err)
 707                         w1_netlink_send_error(cn, msg, nsp->portid, err);
 708                 msg_len -= sizeof(struct w1_netlink_msg) + msg->len;
 709                 msg = (struct w1_netlink_msg *)(((u8 *)msg) +
 710                         sizeof(struct w1_netlink_msg) + msg->len);
 711
 712                 /*
 713                  * Let's allow requests for nonexisting devices.
 714                  */
 715                 if (err == -ENODEV)
 716                         err = 0;
 717         }
 718         if (block)
 719                 w1_unref_block(block);
 720 }
 721
 722 int w1_init_netlink(void)
 723 {
 724         struct cb_id w1_id = {.idx = CN_W1_IDX, .val = CN_W1_VAL};
 725
 726         return cn_add_callback(&w1_id, "w1", &w1_cn_callback);
 727 }
 728
 729 void w1_fini_netlink(void)
 730 {
 731         struct cb_id w1_id = {.idx = CN_W1_IDX, .val = CN_W1_VAL};
 732
 733         cn_del_callback(&w1_id);
 734 }
 735 #else
 736 void w1_netlink_send(struct w1_master *dev, struct w1_netlink_msg *cn)
 737 {
 738 }
 739
 740 int w1_init_netlink(void)
 741 {
 742         return 0;
 743 }
 744
 745 void w1_fini_netlink(void)
 746 {
 747 }
 748 #endif