linux/drivers/w1/w1_netlink.c
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   1/*
   2 * w1_netlink.c
   3 *
   4 * Copyright (c) 2003 Evgeniy Polyakov <zbr@ioremap.net>
   5 *
   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/slab.h>
  23#include <linux/skbuff.h>
  24#include <linux/netlink.h>
  25#include <linux/connector.h>
  26
  27#include "w1.h"
  28#include "w1_log.h"
  29#include "w1_netlink.h"
  30
  31#if defined(CONFIG_W1_CON) && (defined(CONFIG_CONNECTOR) || (defined(CONFIG_CONNECTOR_MODULE) && defined(CONFIG_W1_MODULE)))
  32
  33#define MIN(a, b)                   (((a) < (b)) ? (a) : (b))
  34
  35/* Bundle together everything required to process a request in one memory
  36 * allocation.
  37 */
  38struct w1_cb_block {
  39        atomic_t refcnt;
  40        u32 portid; /* Sending process port ID */
  41        /* maximum value for first_cn->len */
  42        u16 maxlen;
  43        /* pointers to building up the reply message */
  44        struct cn_msg *first_cn; /* fixed once the structure is populated */
  45        struct cn_msg *cn; /* advances as cn_msg is appeneded */
  46        struct w1_netlink_msg *msg; /* advances as w1_netlink_msg is appened */
  47        struct w1_netlink_cmd *cmd; /* advances as cmds are appened */
  48        struct w1_netlink_msg *cur_msg; /* currently message being processed */
  49        /* copy of the original request follows */
  50        struct cn_msg request_cn;
  51        /* followed by variable length:
  52         * cn_msg, data (w1_netlink_msg and w1_netlink_cmd)
  53         * one or more struct w1_cb_node
  54         * reply first_cn, data (w1_netlink_msg and w1_netlink_cmd)
  55         */
  56};
  57struct w1_cb_node {
  58        struct w1_async_cmd async;
  59        /* pointers within w1_cb_block and cn data */
  60        struct w1_cb_block *block;
  61        struct w1_netlink_msg *msg;
  62        struct w1_slave *sl;
  63        struct w1_master *dev;
  64};
  65
  66/**
  67 * w1_reply_len() - calculate current reply length, compare to maxlen
  68 * @block: block to calculate
  69 *
  70 * Calculates the current message length including possible multiple
  71 * cn_msg and data, excludes the first sizeof(struct cn_msg).  Direclty
  72 * compariable to maxlen and usable to send the message.
  73 */
  74static u16 w1_reply_len(struct w1_cb_block *block)
  75{
  76        if (!block->cn)
  77                return 0;
  78        return (u8 *)block->cn - (u8 *)block->first_cn + block->cn->len;
  79}
  80
  81static void w1_unref_block(struct w1_cb_block *block)
  82{
  83        if (atomic_sub_return(1, &block->refcnt) == 0) {
  84                u16 len = w1_reply_len(block);
  85                if (len) {
  86                        cn_netlink_send_mult(block->first_cn, len,
  87                                block->portid, 0, GFP_KERNEL);
  88                }
  89                kfree(block);
  90        }
  91}
  92
  93/**
  94 * w1_reply_make_space() - send message if needed to make space
  95 * @block: block to make space on
  96 * @space: how many bytes requested
  97 *
  98 * Verify there is enough room left for the caller to add "space" bytes to the
  99 * message, if there isn't send the message and reset.
 100 */
 101static void w1_reply_make_space(struct w1_cb_block *block, u16 space)
 102{
 103        u16 len = w1_reply_len(block);
 104        if (len + space >= block->maxlen) {
 105                cn_netlink_send_mult(block->first_cn, len, block->portid, 0, GFP_KERNEL);
 106                block->first_cn->len = 0;
 107                block->cn = NULL;
 108                block->msg = NULL;
 109                block->cmd = NULL;
 110        }
 111}
 112
 113/* Early send when replies aren't bundled. */
 114static void w1_netlink_check_send(struct w1_cb_block *block)
 115{
 116        if (!(block->request_cn.flags & W1_CN_BUNDLE) && block->cn)
 117                w1_reply_make_space(block, block->maxlen);
 118}
 119
 120/**
 121 * w1_netlink_setup_msg() - prepare to write block->msg
 122 * @block: block to operate on
 123 * @ack: determines if cn can be reused
 124 *
 125 * block->cn will be setup with the correct ack, advancing if needed
 126 * block->cn->len does not include space for block->msg
 127 * block->msg advances but remains uninitialized
 128 */
 129static void w1_netlink_setup_msg(struct w1_cb_block *block, u32 ack)
 130{
 131        if (block->cn && block->cn->ack == ack) {
 132                block->msg = (struct w1_netlink_msg *)(block->cn->data + block->cn->len);
 133        } else {
 134                /* advance or set to data */
 135                if (block->cn)
 136                        block->cn = (struct cn_msg *)(block->cn->data +
 137                                block->cn->len);
 138                else
 139                        block->cn = block->first_cn;
 140
 141                memcpy(block->cn, &block->request_cn, sizeof(*block->cn));
 142                block->cn->len = 0;
 143                block->cn->ack = ack;
 144                block->msg = (struct w1_netlink_msg *)block->cn->data;
 145        }
 146}
 147
 148/* Append cmd to msg, include cmd->data as well.  This is because
 149 * any following data goes with the command and in the case of a read is
 150 * the results.
 151 */
 152static void w1_netlink_queue_cmd(struct w1_cb_block *block,
 153        struct w1_netlink_cmd *cmd)
 154{
 155        u32 space;
 156        w1_reply_make_space(block, sizeof(struct cn_msg) +
 157                sizeof(struct w1_netlink_msg) + sizeof(*cmd) + cmd->len);
 158
 159        /* There's a status message sent after each command, so no point
 160         * in trying to bundle this cmd after an existing one, because
 161         * there won't be one.  Allocate and copy over a new cn_msg.
 162         */
 163        w1_netlink_setup_msg(block, block->request_cn.seq + 1);
 164        memcpy(block->msg, block->cur_msg, sizeof(*block->msg));
 165        block->cn->len += sizeof(*block->msg);
 166        block->msg->len = 0;
 167        block->cmd = (struct w1_netlink_cmd *)(block->msg->data);
 168
 169        space = sizeof(*cmd) + cmd->len;
 170        if (block->cmd != cmd)
 171                memcpy(block->cmd, cmd, space);
 172        block->cn->len += space;
 173        block->msg->len += space;
 174}
 175
 176/* Append req_msg and req_cmd, no other commands and no data from req_cmd are
 177 * copied.
 178 */
 179static void w1_netlink_queue_status(struct w1_cb_block *block,
 180        struct w1_netlink_msg *req_msg, struct w1_netlink_cmd *req_cmd,
 181        int error)
 182{
 183        u16 space = sizeof(struct cn_msg) + sizeof(*req_msg) + sizeof(*req_cmd);
 184        w1_reply_make_space(block, space);
 185        w1_netlink_setup_msg(block, block->request_cn.ack);
 186
 187        memcpy(block->msg, req_msg, sizeof(*req_msg));
 188        block->cn->len += sizeof(*req_msg);
 189        block->msg->len = 0;
 190        block->msg->status = (u8)-error;
 191        if (req_cmd) {
 192                struct w1_netlink_cmd *cmd = (struct w1_netlink_cmd *)block->msg->data;
 193                memcpy(cmd, req_cmd, sizeof(*cmd));
 194                block->cn->len += sizeof(*cmd);
 195                block->msg->len += sizeof(*cmd);
 196                cmd->len = 0;
 197        }
 198        w1_netlink_check_send(block);
 199}
 200
 201/**
 202 * w1_netlink_send_error() - sends the error message now
 203 * @cn: original cn_msg
 204 * @msg: original w1_netlink_msg
 205 * @portid: where to send it
 206 * @error: error status
 207 *
 208 * Use when a block isn't available to queue the message to and cn, msg
 209 * might not be contiguous.
 210 */
 211static void w1_netlink_send_error(struct cn_msg *cn, struct w1_netlink_msg *msg,
 212        int portid, int error)
 213{
 214        struct {
 215                struct cn_msg cn;
 216                struct w1_netlink_msg msg;
 217        } packet;
 218        memcpy(&packet.cn, cn, sizeof(packet.cn));
 219        memcpy(&packet.msg, msg, sizeof(packet.msg));
 220        packet.cn.len = sizeof(packet.msg);
 221        packet.msg.len = 0;
 222        packet.msg.status = (u8)-error;
 223        cn_netlink_send(&packet.cn, portid, 0, GFP_KERNEL);
 224}
 225
 226/**
 227 * w1_netlink_send() - sends w1 netlink notifications
 228 * @dev: w1_master the even is associated with or for
 229 * @msg: w1_netlink_msg message to be sent
 230 *
 231 * This are notifications generated from the kernel.
 232 */
 233void w1_netlink_send(struct w1_master *dev, struct w1_netlink_msg *msg)
 234{
 235        struct {
 236                struct cn_msg cn;
 237                struct w1_netlink_msg msg;
 238        } packet;
 239        memset(&packet, 0, sizeof(packet));
 240
 241        packet.cn.id.idx = CN_W1_IDX;
 242        packet.cn.id.val = CN_W1_VAL;
 243
 244        packet.cn.seq = dev->seq++;
 245        packet.cn.len = sizeof(*msg);
 246
 247        memcpy(&packet.msg, msg, sizeof(*msg));
 248        packet.msg.len = 0;
 249
 250        cn_netlink_send(&packet.cn, 0, 0, GFP_KERNEL);
 251}
 252
 253static void w1_send_slave(struct w1_master *dev, u64 rn)
 254{
 255        struct w1_cb_block *block = dev->priv;
 256        struct w1_netlink_cmd *cache_cmd = block->cmd;
 257        u64 *data;
 258
 259        w1_reply_make_space(block, sizeof(*data));
 260
 261        /* Add cmd back if the packet was sent */
 262        if (!block->cmd) {
 263                cache_cmd->len = 0;
 264                w1_netlink_queue_cmd(block, cache_cmd);
 265        }
 266
 267        data = (u64 *)(block->cmd->data + block->cmd->len);
 268
 269        *data = rn;
 270        block->cn->len += sizeof(*data);
 271        block->msg->len += sizeof(*data);
 272        block->cmd->len += sizeof(*data);
 273}
 274
 275static void w1_found_send_slave(struct w1_master *dev, u64 rn)
 276{
 277        /* update kernel slave list */
 278        w1_slave_found(dev, rn);
 279
 280        w1_send_slave(dev, rn);
 281}
 282
 283/* Get the current slave list, or search (with or without alarm) */
 284static int w1_get_slaves(struct w1_master *dev, struct w1_netlink_cmd *req_cmd)
 285{
 286        struct w1_slave *sl;
 287
 288        req_cmd->len = 0;
 289        w1_netlink_queue_cmd(dev->priv, req_cmd);
 290
 291        if (req_cmd->cmd == W1_CMD_LIST_SLAVES) {
 292                u64 rn;
 293                mutex_lock(&dev->list_mutex);
 294                list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
 295                        memcpy(&rn, &sl->reg_num, sizeof(rn));
 296                        w1_send_slave(dev, rn);
 297                }
 298                mutex_unlock(&dev->list_mutex);
 299        } else {
 300                w1_search_process_cb(dev, req_cmd->cmd == W1_CMD_ALARM_SEARCH ?
 301                        W1_ALARM_SEARCH : W1_SEARCH, w1_found_send_slave);
 302        }
 303
 304        return 0;
 305}
 306
 307static int w1_process_command_io(struct w1_master *dev,
 308        struct w1_netlink_cmd *cmd)
 309{
 310        int err = 0;
 311
 312        switch (cmd->cmd) {
 313        case W1_CMD_TOUCH:
 314                w1_touch_block(dev, cmd->data, cmd->len);
 315                w1_netlink_queue_cmd(dev->priv, cmd);
 316                break;
 317        case W1_CMD_READ:
 318                w1_read_block(dev, cmd->data, cmd->len);
 319                w1_netlink_queue_cmd(dev->priv, cmd);
 320                break;
 321        case W1_CMD_WRITE:
 322                w1_write_block(dev, cmd->data, cmd->len);
 323                break;
 324        default:
 325                err = -EINVAL;
 326                break;
 327        }
 328
 329        return err;
 330}
 331
 332static int w1_process_command_addremove(struct w1_master *dev,
 333        struct w1_netlink_cmd *cmd)
 334{
 335        struct w1_slave *sl;
 336        int err = 0;
 337        struct w1_reg_num *id;
 338
 339        if (cmd->len != sizeof(*id))
 340                return -EINVAL;
 341
 342        id = (struct w1_reg_num *)cmd->data;
 343
 344        sl = w1_slave_search_device(dev, id);
 345        switch (cmd->cmd) {
 346        case W1_CMD_SLAVE_ADD:
 347                if (sl)
 348                        err = -EINVAL;
 349                else
 350                        err = w1_attach_slave_device(dev, id);
 351                break;
 352        case W1_CMD_SLAVE_REMOVE:
 353                if (sl)
 354                        w1_slave_detach(sl);
 355                else
 356                        err = -EINVAL;
 357                break;
 358        default:
 359                err = -EINVAL;
 360                break;
 361        }
 362
 363        return err;
 364}
 365
 366static int w1_process_command_master(struct w1_master *dev,
 367        struct w1_netlink_cmd *req_cmd)
 368{
 369        int err = -EINVAL;
 370
 371        /* drop bus_mutex for search (does it's own locking), and add/remove
 372         * which doesn't use the bus
 373         */
 374        switch (req_cmd->cmd) {
 375        case W1_CMD_SEARCH:
 376        case W1_CMD_ALARM_SEARCH:
 377        case W1_CMD_LIST_SLAVES:
 378                mutex_unlock(&dev->bus_mutex);
 379                err = w1_get_slaves(dev, req_cmd);
 380                mutex_lock(&dev->bus_mutex);
 381                break;
 382        case W1_CMD_READ:
 383        case W1_CMD_WRITE:
 384        case W1_CMD_TOUCH:
 385                err = w1_process_command_io(dev, req_cmd);
 386                break;
 387        case W1_CMD_RESET:
 388                err = w1_reset_bus(dev);
 389                break;
 390        case W1_CMD_SLAVE_ADD:
 391        case W1_CMD_SLAVE_REMOVE:
 392                mutex_unlock(&dev->bus_mutex);
 393                mutex_lock(&dev->mutex);
 394                err = w1_process_command_addremove(dev, req_cmd);
 395                mutex_unlock(&dev->mutex);
 396                mutex_lock(&dev->bus_mutex);
 397                break;
 398        default:
 399                err = -EINVAL;
 400                break;
 401        }
 402
 403        return err;
 404}
 405
 406static int w1_process_command_slave(struct w1_slave *sl,
 407                struct w1_netlink_cmd *cmd)
 408{
 409        dev_dbg(&sl->master->dev, "%s: %02x.%012llx.%02x: cmd=%02x, len=%u.\n",
 410                __func__, sl->reg_num.family, (unsigned long long)sl->reg_num.id,
 411                sl->reg_num.crc, cmd->cmd, cmd->len);
 412
 413        return w1_process_command_io(sl->master, cmd);
 414}
 415
 416static int w1_process_command_root(struct cn_msg *req_cn, u32 portid)
 417{
 418        struct w1_master *dev;
 419        struct cn_msg *cn;
 420        struct w1_netlink_msg *msg;
 421        u32 *id;
 422
 423        cn = kmalloc(PAGE_SIZE, GFP_KERNEL);
 424        if (!cn)
 425                return -ENOMEM;
 426
 427        cn->id.idx = CN_W1_IDX;
 428        cn->id.val = CN_W1_VAL;
 429
 430        cn->seq = req_cn->seq;
 431        cn->ack = req_cn->seq + 1;
 432        cn->len = sizeof(struct w1_netlink_msg);
 433        msg = (struct w1_netlink_msg *)cn->data;
 434
 435        msg->type = W1_LIST_MASTERS;
 436        msg->status = 0;
 437        msg->len = 0;
 438        id = (u32 *)msg->data;
 439
 440        mutex_lock(&w1_mlock);
 441        list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 442                if (cn->len + sizeof(*id) > PAGE_SIZE - sizeof(struct cn_msg)) {
 443                        cn_netlink_send(cn, portid, 0, GFP_KERNEL);
 444                        cn->len = sizeof(struct w1_netlink_msg);
 445                        msg->len = 0;
 446                        id = (u32 *)msg->data;
 447                }
 448
 449                *id = dev->id;
 450                msg->len += sizeof(*id);
 451                cn->len += sizeof(*id);
 452                id++;
 453        }
 454        cn_netlink_send(cn, portid, 0, GFP_KERNEL);
 455        mutex_unlock(&w1_mlock);
 456
 457        kfree(cn);
 458        return 0;
 459}
 460
 461static void w1_process_cb(struct w1_master *dev, struct w1_async_cmd *async_cmd)
 462{
 463        struct w1_cb_node *node = container_of(async_cmd, struct w1_cb_node,
 464                async);
 465        u16 mlen = node->msg->len;
 466        u16 len;
 467        int err = 0;
 468        struct w1_slave *sl = node->sl;
 469        struct w1_netlink_cmd *cmd = (struct w1_netlink_cmd *)node->msg->data;
 470
 471        mutex_lock(&dev->bus_mutex);
 472        dev->priv = node->block;
 473        if (sl && w1_reset_select_slave(sl))
 474                err = -ENODEV;
 475        node->block->cur_msg = node->msg;
 476
 477        while (mlen && !err) {
 478                if (cmd->len + sizeof(struct w1_netlink_cmd) > mlen) {
 479                        err = -E2BIG;
 480                        break;
 481                }
 482
 483                if (sl)
 484                        err = w1_process_command_slave(sl, cmd);
 485                else
 486                        err = w1_process_command_master(dev, cmd);
 487                w1_netlink_check_send(node->block);
 488
 489                w1_netlink_queue_status(node->block, node->msg, cmd, err);
 490                err = 0;
 491
 492                len = sizeof(*cmd) + cmd->len;
 493                cmd = (struct w1_netlink_cmd *)((u8 *)cmd + len);
 494                mlen -= len;
 495        }
 496
 497        if (!cmd || err)
 498                w1_netlink_queue_status(node->block, node->msg, cmd, err);
 499
 500        /* ref taken in w1_search_slave or w1_search_master_id when building
 501         * the block
 502         */
 503        if (sl)
 504                w1_unref_slave(sl);
 505        else
 506                atomic_dec(&dev->refcnt);
 507        dev->priv = NULL;
 508        mutex_unlock(&dev->bus_mutex);
 509
 510        mutex_lock(&dev->list_mutex);
 511        list_del(&async_cmd->async_entry);
 512        mutex_unlock(&dev->list_mutex);
 513
 514        w1_unref_block(node->block);
 515}
 516
 517static void w1_list_count_cmds(struct w1_netlink_msg *msg, int *cmd_count,
 518        u16 *slave_len)
 519{
 520        struct w1_netlink_cmd *cmd = (struct w1_netlink_cmd *)msg->data;
 521        u16 mlen = msg->len;
 522        u16 len;
 523        int slave_list = 0;
 524        while (mlen) {
 525                if (cmd->len + sizeof(struct w1_netlink_cmd) > mlen)
 526                        break;
 527
 528                switch (cmd->cmd) {
 529                case W1_CMD_SEARCH:
 530                case W1_CMD_ALARM_SEARCH:
 531                case W1_CMD_LIST_SLAVES:
 532                        ++slave_list;
 533                }
 534                ++*cmd_count;
 535                len = sizeof(*cmd) + cmd->len;
 536                cmd = (struct w1_netlink_cmd *)((u8 *)cmd + len);
 537                mlen -= len;
 538        }
 539
 540        if (slave_list) {
 541                struct w1_master *dev = w1_search_master_id(msg->id.mst.id);
 542                if (dev) {
 543                        /* Bytes, and likely an overstimate, and if it isn't
 544                         * the results can still be split between packets.
 545                         */
 546                        *slave_len += sizeof(struct w1_reg_num) * slave_list *
 547                                (dev->slave_count + dev->max_slave_count);
 548                        /* search incremented it */
 549                        atomic_dec(&dev->refcnt);
 550                }
 551        }
 552}
 553
 554static void w1_cn_callback(struct cn_msg *cn, struct netlink_skb_parms *nsp)
 555{
 556        struct w1_netlink_msg *msg = (struct w1_netlink_msg *)(cn + 1);
 557        struct w1_slave *sl;
 558        struct w1_master *dev;
 559        u16 msg_len;
 560        u16 slave_len = 0;
 561        int err = 0;
 562        struct w1_cb_block *block = NULL;
 563        struct w1_cb_node *node = NULL;
 564        int node_count = 0;
 565        int cmd_count = 0;
 566
 567        /* If any unknown flag is set let the application know, that way
 568         * applications can detect the absence of features in kernels that
 569         * don't know about them.  http://lwn.net/Articles/587527/
 570         */
 571        if (cn->flags & ~(W1_CN_BUNDLE)) {
 572                w1_netlink_send_error(cn, msg, nsp->portid, -EINVAL);
 573                return;
 574        }
 575
 576        /* Count the number of master or slave commands there are to allocate
 577         * space for one cb_node each.
 578         */
 579        msg_len = cn->len;
 580        while (msg_len && !err) {
 581                if (msg->len + sizeof(struct w1_netlink_msg) > msg_len) {
 582                        err = -E2BIG;
 583                        break;
 584                }
 585
 586                /* count messages for nodes and allocate any additional space
 587                 * required for slave lists
 588                 */
 589                if (msg->type == W1_MASTER_CMD || msg->type == W1_SLAVE_CMD) {
 590                        ++node_count;
 591                        w1_list_count_cmds(msg, &cmd_count, &slave_len);
 592                }
 593
 594                msg_len -= sizeof(struct w1_netlink_msg) + msg->len;
 595                msg = (struct w1_netlink_msg *)(((u8 *)msg) +
 596                        sizeof(struct w1_netlink_msg) + msg->len);
 597        }
 598        msg = (struct w1_netlink_msg *)(cn + 1);
 599        if (node_count) {
 600                int size;
 601                int reply_size = sizeof(*cn) + cn->len + slave_len;
 602                if (cn->flags & W1_CN_BUNDLE) {
 603                        /* bundling duplicats some of the messages */
 604                        reply_size += 2 * cmd_count * (sizeof(struct cn_msg) +
 605                                sizeof(struct w1_netlink_msg) +
 606                                sizeof(struct w1_netlink_cmd));
 607                }
 608                reply_size = MIN(CONNECTOR_MAX_MSG_SIZE, reply_size);
 609
 610                /* allocate space for the block, a copy of the original message,
 611                 * one node per cmd to point into the original message,
 612                 * space for replies which is the original message size plus
 613                 * space for any list slave data and status messages
 614                 * cn->len doesn't include itself which is part of the block
 615                 * */
 616                size =  /* block + original message */
 617                        sizeof(struct w1_cb_block) + sizeof(*cn) + cn->len +
 618                        /* space for nodes */
 619                        node_count * sizeof(struct w1_cb_node) +
 620                        /* replies */
 621                        sizeof(struct cn_msg) + reply_size;
 622                block = kzalloc(size, GFP_KERNEL);
 623                if (!block) {
 624                        /* if the system is already out of memory,
 625                         * (A) will this work, and (B) would it be better
 626                         * to not try?
 627                         */
 628                        w1_netlink_send_error(cn, msg, nsp->portid, -ENOMEM);
 629                        return;
 630                }
 631                atomic_set(&block->refcnt, 1);
 632                block->portid = nsp->portid;
 633                memcpy(&block->request_cn, cn, sizeof(*cn) + cn->len);
 634                node = (struct w1_cb_node *)(block->request_cn.data + cn->len);
 635
 636                /* Sneeky, when not bundling, reply_size is the allocated space
 637                 * required for the reply, cn_msg isn't part of maxlen so
 638                 * it should be reply_size - sizeof(struct cn_msg), however
 639                 * when checking if there is enough space, w1_reply_make_space
 640                 * is called with the full message size including cn_msg,
 641                 * because it isn't known at that time if an additional cn_msg
 642                 * will need to be allocated.  So an extra cn_msg is added
 643                 * above in "size".
 644                 */
 645                block->maxlen = reply_size;
 646                block->first_cn = (struct cn_msg *)(node + node_count);
 647                memset(block->first_cn, 0, sizeof(*block->first_cn));
 648        }
 649
 650        msg_len = cn->len;
 651        while (msg_len && !err) {
 652
 653                dev = NULL;
 654                sl = NULL;
 655
 656                if (msg->len + sizeof(struct w1_netlink_msg) > msg_len) {
 657                        err = -E2BIG;
 658                        break;
 659                }
 660
 661                /* execute on this thread, no need to process later */
 662                if (msg->type == W1_LIST_MASTERS) {
 663                        err = w1_process_command_root(cn, nsp->portid);
 664                        goto out_cont;
 665                }
 666
 667                /* All following message types require additional data,
 668                 * check here before references are taken.
 669                 */
 670                if (!msg->len) {
 671                        err = -EPROTO;
 672                        goto out_cont;
 673                }
 674
 675                /* both search calls take references */
 676                if (msg->type == W1_MASTER_CMD) {
 677                        dev = w1_search_master_id(msg->id.mst.id);
 678                } else if (msg->type == W1_SLAVE_CMD) {
 679                        sl = w1_search_slave((struct w1_reg_num *)msg->id.id);
 680                        if (sl)
 681                                dev = sl->master;
 682                } else {
 683                        pr_notice("%s: cn: %x.%x, wrong type: %u, len: %u.\n",
 684                                __func__, cn->id.idx, cn->id.val,
 685                                msg->type, msg->len);
 686                        err = -EPROTO;
 687                        goto out_cont;
 688                }
 689
 690                if (!dev) {
 691                        err = -ENODEV;
 692                        goto out_cont;
 693                }
 694
 695                err = 0;
 696
 697                atomic_inc(&block->refcnt);
 698                node->async.cb = w1_process_cb;
 699                node->block = block;
 700                node->msg = (struct w1_netlink_msg *)((u8 *)&block->request_cn +
 701                        (size_t)((u8 *)msg - (u8 *)cn));
 702                node->sl = sl;
 703                node->dev = dev;
 704
 705                mutex_lock(&dev->list_mutex);
 706                list_add_tail(&node->async.async_entry, &dev->async_list);
 707                wake_up_process(dev->thread);
 708                mutex_unlock(&dev->list_mutex);
 709                ++node;
 710
 711out_cont:
 712                /* Can't queue because that modifies block and another
 713                 * thread could be processing the messages by now and
 714                 * there isn't a lock, send directly.
 715                 */
 716                if (err)
 717                        w1_netlink_send_error(cn, msg, nsp->portid, err);
 718                msg_len -= sizeof(struct w1_netlink_msg) + msg->len;
 719                msg = (struct w1_netlink_msg *)(((u8 *)msg) +
 720                        sizeof(struct w1_netlink_msg) + msg->len);
 721
 722                /*
 723                 * Let's allow requests for nonexisting devices.
 724                 */
 725                if (err == -ENODEV)
 726                        err = 0;
 727        }
 728        if (block)
 729                w1_unref_block(block);
 730}
 731
 732int w1_init_netlink(void)
 733{
 734        struct cb_id w1_id = {.idx = CN_W1_IDX, .val = CN_W1_VAL};
 735
 736        return cn_add_callback(&w1_id, "w1", &w1_cn_callback);
 737}
 738
 739void w1_fini_netlink(void)
 740{
 741        struct cb_id w1_id = {.idx = CN_W1_IDX, .val = CN_W1_VAL};
 742
 743        cn_del_callback(&w1_id);
 744}
 745#else
 746void w1_netlink_send(struct w1_master *dev, struct w1_netlink_msg *cn)
 747{
 748}
 749
 750int w1_init_netlink(void)
 751{
 752        return 0;
 753}
 754
 755void w1_fini_netlink(void)
 756{
 757}
 758#endif
 759