drivers/hv/channel_mgmt.c

   1 /*
   2  * Copyright (c) 2009, Microsoft Corporation.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  15  * Place - Suite 330, Boston, MA 02111-1307 USA.
  16  *
  17  * Authors:
  18  *   Haiyang Zhang <haiyangz@microsoft.com>
  19  *   Hank Janssen  <hjanssen@microsoft.com>
  20  */
  21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23 #include <linux/kernel.h>
  24 #include <linux/sched.h>
  25 #include <linux/wait.h>
  26 #include <linux/mm.h>
  27 #include <linux/slab.h>
  28 #include <linux/list.h>
  29 #include <linux/module.h>
  30 #include <linux/completion.h>
  31 #include <linux/hyperv.h>
  32
  33 #include "hyperv_vmbus.h"
  34
  35 struct vmbus_channel_message_table_entry {
  36         enum vmbus_channel_message_type message_type;
  37         void (*message_handler)(struct vmbus_channel_message_header *msg);
  38 };
  39
  40 #define MAX_MSG_TYPES                    4
  41 #define MAX_NUM_DEVICE_CLASSES_SUPPORTED 8
  42
  43 static const uuid_le
  44         supported_device_classes[MAX_NUM_DEVICE_CLASSES_SUPPORTED] = {
  45         /* {ba6163d9-04a1-4d29-b605-72e2ffb1dc7f} */
  46         /* Storage - SCSI */
  47         {
  48                 .b  = {
  49                         0xd9, 0x63, 0x61, 0xba, 0xa1, 0x04, 0x29, 0x4d,
  50                         0xb6, 0x05, 0x72, 0xe2, 0xff, 0xb1, 0xdc, 0x7f
  51                 }
  52         },
  53
  54         /* {F8615163-DF3E-46c5-913F-F2D2F965ED0E} */
  55         /* Network */
  56         {
  57                 .b = {
  58                         0x63, 0x51, 0x61, 0xF8, 0x3E, 0xDF, 0xc5, 0x46,
  59                         0x91, 0x3F, 0xF2, 0xD2, 0xF9, 0x65, 0xED, 0x0E
  60                 }
  61         },
  62
  63         /* {CFA8B69E-5B4A-4cc0-B98B-8BA1A1F3F95A} */
  64         /* Input */
  65         {
  66                 .b = {
  67                         0x9E, 0xB6, 0xA8, 0xCF, 0x4A, 0x5B, 0xc0, 0x4c,
  68                         0xB9, 0x8B, 0x8B, 0xA1, 0xA1, 0xF3, 0xF9, 0x5A
  69                 }
  70         },
  71
  72         /* {32412632-86cb-44a2-9b5c-50d1417354f5} */
  73         /* IDE */
  74         {
  75                 .b = {
  76                         0x32, 0x26, 0x41, 0x32, 0xcb, 0x86, 0xa2, 0x44,
  77                         0x9b, 0x5c, 0x50, 0xd1, 0x41, 0x73, 0x54, 0xf5
  78                 }
  79         },
  80         /* 0E0B6031-5213-4934-818B-38D90CED39DB */
  81         /* Shutdown */
  82         {
  83                 .b = {
  84                         0x31, 0x60, 0x0B, 0X0E, 0x13, 0x52, 0x34, 0x49,
  85                         0x81, 0x8B, 0x38, 0XD9, 0x0C, 0xED, 0x39, 0xDB
  86                 }
  87         },
  88         /* {9527E630-D0AE-497b-ADCE-E80AB0175CAF} */
  89         /* TimeSync */
  90         {
  91                 .b = {
  92                         0x30, 0xe6, 0x27, 0x95, 0xae, 0xd0, 0x7b, 0x49,
  93                         0xad, 0xce, 0xe8, 0x0a, 0xb0, 0x17, 0x5c, 0xaf
  94                 }
  95         },
  96         /* {57164f39-9115-4e78-ab55-382f3bd5422d} */
  97         /* Heartbeat */
  98         {
  99                 .b = {
 100                         0x39, 0x4f, 0x16, 0x57, 0x15, 0x91, 0x78, 0x4e,
 101                         0xab, 0x55, 0x38, 0x2f, 0x3b, 0xd5, 0x42, 0x2d
 102                 }
 103         },
 104         /* {A9A0F4E7-5A45-4d96-B827-8A841E8C03E6} */
 105         /* KVP */
 106         {
 107                 .b = {
 108                         0xe7, 0xf4, 0xa0, 0xa9, 0x45, 0x5a, 0x96, 0x4d,
 109                         0xb8, 0x27, 0x8a, 0x84, 0x1e, 0x8c, 0x3,  0xe6
 110         }
 111         },
 112
 113 };
 114
 115
 116 /**
 117  * prep_negotiate_resp() - Create default response for Hyper-V Negotiate message
 118  * @icmsghdrp: Pointer to msg header structure
 119  * @icmsg_negotiate: Pointer to negotiate message structure
 120  * @buf: Raw buffer channel data
 121  *
 122  * @icmsghdrp is of type &struct icmsg_hdr.
 123  * @negop is of type &struct icmsg_negotiate.
 124  * Set up and fill in default negotiate response message. This response can
 125  * come from both the vmbus driver and the hv_utils driver. The current api
 126  * will respond properly to both Windows 2008 and Windows 2008-R2 operating
 127  * systems.
 128  *
 129  * Mainly used by Hyper-V drivers.
 130  */
 131 void prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
 132                              struct icmsg_negotiate *negop,
 133                              u8 *buf)
 134 {
 135         if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 136                 icmsghdrp->icmsgsize = 0x10;
 137
 138                 negop = (struct icmsg_negotiate *)&buf[
 139                         sizeof(struct vmbuspipe_hdr) +
 140                         sizeof(struct icmsg_hdr)];
 141
 142                 if (negop->icframe_vercnt == 2 &&
 143                    negop->icversion_data[1].major == 3) {
 144                         negop->icversion_data[0].major = 3;
 145                         negop->icversion_data[0].minor = 0;
 146                         negop->icversion_data[1].major = 3;
 147                         negop->icversion_data[1].minor = 0;
 148                 } else {
 149                         negop->icversion_data[0].major = 1;
 150                         negop->icversion_data[0].minor = 0;
 151                         negop->icversion_data[1].major = 1;
 152                         negop->icversion_data[1].minor = 0;
 153                 }
 154
 155                 negop->icframe_vercnt = 1;
 156                 negop->icmsg_vercnt = 1;
 157         }
 158 }
 159 EXPORT_SYMBOL(prep_negotiate_resp);
 160
 161 /*
 162  * alloc_channel - Allocate and initialize a vmbus channel object
 163  */
 164 static struct vmbus_channel *alloc_channel(void)
 165 {
 166         struct vmbus_channel *channel;
 167
 168         channel = kzalloc(sizeof(*channel), GFP_ATOMIC);
 169         if (!channel)
 170                 return NULL;
 171
 172         spin_lock_init(&channel->inbound_lock);
 173
 174         channel->controlwq = create_workqueue("hv_vmbus_ctl");
 175         if (!channel->controlwq) {
 176                 kfree(channel);
 177                 return NULL;
 178         }
 179
 180         return channel;
 181 }
 182
 183 /*
 184  * release_hannel - Release the vmbus channel object itself
 185  */
 186 static void release_channel(struct work_struct *work)
 187 {
 188         struct vmbus_channel *channel = container_of(work,
 189                                                      struct vmbus_channel,
 190                                                      work);
 191
 192         destroy_workqueue(channel->controlwq);
 193
 194         kfree(channel);
 195 }
 196
 197 /*
 198  * free_channel - Release the resources used by the vmbus channel object
 199  */
 200 void free_channel(struct vmbus_channel *channel)
 201 {
 202
 203         /*
 204          * We have to release the channel's workqueue/thread in the vmbus's
 205          * workqueue/thread context
 206          * ie we can't destroy ourselves.
 207          */
 208         INIT_WORK(&channel->work, release_channel);
 209         queue_work(vmbus_connection.work_queue, &channel->work);
 210 }
 211
 212
 213
 214 /*
 215  * vmbus_process_rescind_offer -
 216  * Rescind the offer by initiating a device removal
 217  */
 218 static void vmbus_process_rescind_offer(struct work_struct *work)
 219 {
 220         struct vmbus_channel *channel = container_of(work,
 221                                                      struct vmbus_channel,
 222                                                      work);
 223
 224         vmbus_device_unregister(channel->device_obj);
 225 }
 226
 227 /*
 228  * vmbus_process_offer - Process the offer by creating a channel/device
 229  * associated with this offer
 230  */
 231 static void vmbus_process_offer(struct work_struct *work)
 232 {
 233         struct vmbus_channel *newchannel = container_of(work,
 234                                                         struct vmbus_channel,
 235                                                         work);
 236         struct vmbus_channel *channel;
 237         bool fnew = true;
 238         int ret;
 239         unsigned long flags;
 240
 241         /* The next possible work is rescind handling */
 242         INIT_WORK(&newchannel->work, vmbus_process_rescind_offer);
 243
 244         /* Make sure this is a new offer */
 245         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 246
 247         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 248                 if (!uuid_le_cmp(channel->offermsg.offer.if_type,
 249                         newchannel->offermsg.offer.if_type) &&
 250                         !uuid_le_cmp(channel->offermsg.offer.if_instance,
 251                                 newchannel->offermsg.offer.if_instance)) {
 252                         fnew = false;
 253                         break;
 254                 }
 255         }
 256
 257         if (fnew)
 258                 list_add_tail(&newchannel->listentry,
 259                               &vmbus_connection.chn_list);
 260
 261         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 262
 263         if (!fnew) {
 264                 free_channel(newchannel);
 265                 return;
 266         }
 267
 268         /*
 269          * Start the process of binding this offer to the driver
 270          * We need to set the DeviceObject field before calling
 271          * vmbus_child_dev_add()
 272          */
 273         newchannel->device_obj = vmbus_device_create(
 274                 &newchannel->offermsg.offer.if_type,
 275                 &newchannel->offermsg.offer.if_instance,
 276                 newchannel);
 277
 278         /*
 279          * Add the new device to the bus. This will kick off device-driver
 280          * binding which eventually invokes the device driver's AddDevice()
 281          * method.
 282          */
 283         ret = vmbus_device_register(newchannel->device_obj);
 284         if (ret != 0) {
 285                 pr_err("unable to add child device object (relid %d)\n",
 286                            newchannel->offermsg.child_relid);
 287
 288                 spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 289                 list_del(&newchannel->listentry);
 290                 spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 291
 292                 free_channel(newchannel);
 293         } else {
 294                 /*
 295                  * This state is used to indicate a successful open
 296                  * so that when we do close the channel normally, we
 297                  * can cleanup properly
 298                  */
 299                 newchannel->state = CHANNEL_OPEN_STATE;
 300         }
 301 }
 302
 303 /*
 304  * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
 305  *
 306  */
 307 static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
 308 {
 309         struct vmbus_channel_offer_channel *offer;
 310         struct vmbus_channel *newchannel;
 311         uuid_le *guidtype;
 312         uuid_le *guidinstance;
 313         int i;
 314         int fsupported = 0;
 315
 316         offer = (struct vmbus_channel_offer_channel *)hdr;
 317         for (i = 0; i < MAX_NUM_DEVICE_CLASSES_SUPPORTED; i++) {
 318                 if (!uuid_le_cmp(offer->offer.if_type,
 319                                 supported_device_classes[i])) {
 320                         fsupported = 1;
 321                         break;
 322                 }
 323         }
 324
 325         if (!fsupported)
 326                 return;
 327
 328         guidtype = &offer->offer.if_type;
 329         guidinstance = &offer->offer.if_instance;
 330
 331         /* Allocate the channel object and save this offer. */
 332         newchannel = alloc_channel();
 333         if (!newchannel) {
 334                 pr_err("Unable to allocate channel object\n");
 335                 return;
 336         }
 337
 338         memcpy(&newchannel->offermsg, offer,
 339                sizeof(struct vmbus_channel_offer_channel));
 340         newchannel->monitor_grp = (u8)offer->monitorid / 32;
 341         newchannel->monitor_bit = (u8)offer->monitorid % 32;
 342
 343         INIT_WORK(&newchannel->work, vmbus_process_offer);
 344         queue_work(newchannel->controlwq, &newchannel->work);
 345 }
 346
 347 /*
 348  * vmbus_onoffer_rescind - Rescind offer handler.
 349  *
 350  * We queue a work item to process this offer synchronously
 351  */
 352 static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 353 {
 354         struct vmbus_channel_rescind_offer *rescind;
 355         struct vmbus_channel *channel;
 356
 357         rescind = (struct vmbus_channel_rescind_offer *)hdr;
 358         channel = relid2channel(rescind->child_relid);
 359
 360         if (channel == NULL)
 361                 /* Just return here, no channel found */
 362                 return;
 363
 364         /* work is initialized for vmbus_process_rescind_offer() from
 365          * vmbus_process_offer() where the channel got created */
 366         queue_work(channel->controlwq, &channel->work);
 367 }
 368
 369 /*
 370  * vmbus_onoffers_delivered -
 371  * This is invoked when all offers have been delivered.
 372  *
 373  * Nothing to do here.
 374  */
 375 static void vmbus_onoffers_delivered(
 376                         struct vmbus_channel_message_header *hdr)
 377 {
 378 }
 379
 380 /*
 381  * vmbus_onopen_result - Open result handler.
 382  *
 383  * This is invoked when we received a response to our channel open request.
 384  * Find the matching request, copy the response and signal the requesting
 385  * thread.
 386  */
 387 static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
 388 {
 389         struct vmbus_channel_open_result *result;
 390         struct vmbus_channel_msginfo *msginfo;
 391         struct vmbus_channel_message_header *requestheader;
 392         struct vmbus_channel_open_channel *openmsg;
 393         unsigned long flags;
 394
 395         result = (struct vmbus_channel_open_result *)hdr;
 396
 397         /*
 398          * Find the open msg, copy the result and signal/unblock the wait event
 399          */
 400         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 401
 402         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 403                                 msglistentry) {
 404                 requestheader =
 405                         (struct vmbus_channel_message_header *)msginfo->msg;
 406
 407                 if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
 408                         openmsg =
 409                         (struct vmbus_channel_open_channel *)msginfo->msg;
 410                         if (openmsg->child_relid == result->child_relid &&
 411                             openmsg->openid == result->openid) {
 412                                 memcpy(&msginfo->response.open_result,
 413                                        result,
 414                                        sizeof(
 415                                         struct vmbus_channel_open_result));
 416                                 complete(&msginfo->waitevent);
 417                                 break;
 418                         }
 419                 }
 420         }
 421         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 422 }
 423
 424 /*
 425  * vmbus_ongpadl_created - GPADL created handler.
 426  *
 427  * This is invoked when we received a response to our gpadl create request.
 428  * Find the matching request, copy the response and signal the requesting
 429  * thread.
 430  */
 431 static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
 432 {
 433         struct vmbus_channel_gpadl_created *gpadlcreated;
 434         struct vmbus_channel_msginfo *msginfo;
 435         struct vmbus_channel_message_header *requestheader;
 436         struct vmbus_channel_gpadl_header *gpadlheader;
 437         unsigned long flags;
 438
 439         gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;
 440
 441         /*
 442          * Find the establish msg, copy the result and signal/unblock the wait
 443          * event
 444          */
 445         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 446
 447         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 448                                 msglistentry) {
 449                 requestheader =
 450                         (struct vmbus_channel_message_header *)msginfo->msg;
 451
 452                 if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
 453                         gpadlheader =
 454                         (struct vmbus_channel_gpadl_header *)requestheader;
 455
 456                         if ((gpadlcreated->child_relid ==
 457                              gpadlheader->child_relid) &&
 458                             (gpadlcreated->gpadl == gpadlheader->gpadl)) {
 459                                 memcpy(&msginfo->response.gpadl_created,
 460                                        gpadlcreated,
 461                                        sizeof(
 462                                         struct vmbus_channel_gpadl_created));
 463                                 complete(&msginfo->waitevent);
 464                                 break;
 465                         }
 466                 }
 467         }
 468         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 469 }
 470
 471 /*
 472  * vmbus_ongpadl_torndown - GPADL torndown handler.
 473  *
 474  * This is invoked when we received a response to our gpadl teardown request.
 475  * Find the matching request, copy the response and signal the requesting
 476  * thread.
 477  */
 478 static void vmbus_ongpadl_torndown(
 479                         struct vmbus_channel_message_header *hdr)
 480 {
 481         struct vmbus_channel_gpadl_torndown *gpadl_torndown;
 482         struct vmbus_channel_msginfo *msginfo;
 483         struct vmbus_channel_message_header *requestheader;
 484         struct vmbus_channel_gpadl_teardown *gpadl_teardown;
 485         unsigned long flags;
 486
 487         gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;
 488
 489         /*
 490          * Find the open msg, copy the result and signal/unblock the wait event
 491          */
 492         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 493
 494         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 495                                 msglistentry) {
 496                 requestheader =
 497                         (struct vmbus_channel_message_header *)msginfo->msg;
 498
 499                 if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
 500                         gpadl_teardown =
 501                         (struct vmbus_channel_gpadl_teardown *)requestheader;
 502
 503                         if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
 504                                 memcpy(&msginfo->response.gpadl_torndown,
 505                                        gpadl_torndown,
 506                                        sizeof(
 507                                         struct vmbus_channel_gpadl_torndown));
 508                                 complete(&msginfo->waitevent);
 509                                 break;
 510                         }
 511                 }
 512         }
 513         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 514 }
 515
 516 /*
 517  * vmbus_onversion_response - Version response handler
 518  *
 519  * This is invoked when we received a response to our initiate contact request.
 520  * Find the matching request, copy the response and signal the requesting
 521  * thread.
 522  */
 523 static void vmbus_onversion_response(
 524                 struct vmbus_channel_message_header *hdr)
 525 {
 526         struct vmbus_channel_msginfo *msginfo;
 527         struct vmbus_channel_message_header *requestheader;
 528         struct vmbus_channel_initiate_contact *initiate;
 529         struct vmbus_channel_version_response *version_response;
 530         unsigned long flags;
 531
 532         version_response = (struct vmbus_channel_version_response *)hdr;
 533         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 534
 535         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 536                                 msglistentry) {
 537                 requestheader =
 538                         (struct vmbus_channel_message_header *)msginfo->msg;
 539
 540                 if (requestheader->msgtype ==
 541                     CHANNELMSG_INITIATE_CONTACT) {
 542                         initiate =
 543                         (struct vmbus_channel_initiate_contact *)requestheader;
 544                         memcpy(&msginfo->response.version_response,
 545                               version_response,
 546                               sizeof(struct vmbus_channel_version_response));
 547                         complete(&msginfo->waitevent);
 548                 }
 549         }
 550         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 551 }
 552
 553 /* Channel message dispatch table */
 554 static struct vmbus_channel_message_table_entry
 555         channel_message_table[CHANNELMSG_COUNT] = {
 556         {CHANNELMSG_INVALID,                    NULL},
 557         {CHANNELMSG_OFFERCHANNEL,               vmbus_onoffer},
 558         {CHANNELMSG_RESCIND_CHANNELOFFER,       vmbus_onoffer_rescind},
 559         {CHANNELMSG_REQUESTOFFERS,              NULL},
 560         {CHANNELMSG_ALLOFFERS_DELIVERED,        vmbus_onoffers_delivered},
 561         {CHANNELMSG_OPENCHANNEL,                NULL},
 562         {CHANNELMSG_OPENCHANNEL_RESULT, vmbus_onopen_result},
 563         {CHANNELMSG_CLOSECHANNEL,               NULL},
 564         {CHANNELMSG_GPADL_HEADER,               NULL},
 565         {CHANNELMSG_GPADL_BODY,         NULL},
 566         {CHANNELMSG_GPADL_CREATED,              vmbus_ongpadl_created},
 567         {CHANNELMSG_GPADL_TEARDOWN,             NULL},
 568         {CHANNELMSG_GPADL_TORNDOWN,             vmbus_ongpadl_torndown},
 569         {CHANNELMSG_RELID_RELEASED,             NULL},
 570         {CHANNELMSG_INITIATE_CONTACT,           NULL},
 571         {CHANNELMSG_VERSION_RESPONSE,           vmbus_onversion_response},
 572         {CHANNELMSG_UNLOAD,                     NULL},
 573 };
 574
 575 /*
 576  * vmbus_onmessage - Handler for channel protocol messages.
 577  *
 578  * This is invoked in the vmbus worker thread context.
 579  */
 580 void vmbus_onmessage(void *context)
 581 {
 582         struct hv_message *msg = context;
 583         struct vmbus_channel_message_header *hdr;
 584         int size;
 585
 586         hdr = (struct vmbus_channel_message_header *)msg->u.payload;
 587         size = msg->header.payload_size;
 588
 589         if (hdr->msgtype >= CHANNELMSG_COUNT) {
 590                 pr_err("Received invalid channel message type %d size %d\n",
 591                            hdr->msgtype, size);
 592                 print_hex_dump_bytes("", DUMP_PREFIX_NONE,
 593                                      (unsigned char *)msg->u.payload, size);
 594                 return;
 595         }
 596
 597         if (channel_message_table[hdr->msgtype].message_handler)
 598                 channel_message_table[hdr->msgtype].message_handler(hdr);
 599         else
 600                 pr_err("Unhandled channel message type %d\n", hdr->msgtype);
 601 }
 602
 603 /*
 604  * vmbus_request_offers - Send a request to get all our pending offers.
 605  */
 606 int vmbus_request_offers(void)
 607 {
 608         struct vmbus_channel_message_header *msg;
 609         struct vmbus_channel_msginfo *msginfo;
 610         int ret, t;
 611
 612         msginfo = kmalloc(sizeof(*msginfo) +
 613                           sizeof(struct vmbus_channel_message_header),
 614                           GFP_KERNEL);
 615         if (!msginfo)
 616                 return -ENOMEM;
 617
 618         init_completion(&msginfo->waitevent);
 619
 620         msg = (struct vmbus_channel_message_header *)msginfo->msg;
 621
 622         msg->msgtype = CHANNELMSG_REQUESTOFFERS;
 623
 624
 625         ret = vmbus_post_msg(msg,
 626                                sizeof(struct vmbus_channel_message_header));
 627         if (ret != 0) {
 628                 pr_err("Unable to request offers - %d\n", ret);
 629
 630                 goto cleanup;
 631         }
 632
 633         t = wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
 634         if (t == 0) {
 635                 ret = -ETIMEDOUT;
 636                 goto cleanup;
 637         }
 638
 639
 640
 641 cleanup:
 642         kfree(msginfo);
 643
 644         return ret;
 645 }
 646
 647 /* eof */