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  * vmbus_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 vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
 132                                struct icmsg_negotiate *negop, u8 *buf)
 133 {
 134         if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 135                 icmsghdrp->icmsgsize = 0x10;
 136
 137                 negop = (struct icmsg_negotiate *)&buf[
 138                         sizeof(struct vmbuspipe_hdr) +
 139                         sizeof(struct icmsg_hdr)];
 140
 141                 if (negop->icframe_vercnt == 2 &&
 142                    negop->icversion_data[1].major == 3) {
 143                         negop->icversion_data[0].major = 3;
 144                         negop->icversion_data[0].minor = 0;
 145                         negop->icversion_data[1].major = 3;
 146                         negop->icversion_data[1].minor = 0;
 147                 } else {
 148                         negop->icversion_data[0].major = 1;
 149                         negop->icversion_data[0].minor = 0;
 150                         negop->icversion_data[1].major = 1;
 151                         negop->icversion_data[1].minor = 0;
 152                 }
 153
 154                 negop->icframe_vercnt = 1;
 155                 negop->icmsg_vercnt = 1;
 156         }
 157 }
 158 EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);
 159
 160 /*
 161  * alloc_channel - Allocate and initialize a vmbus channel object
 162  */
 163 static struct vmbus_channel *alloc_channel(void)
 164 {
 165         struct vmbus_channel *channel;
 166
 167         channel = kzalloc(sizeof(*channel), GFP_ATOMIC);
 168         if (!channel)
 169                 return NULL;
 170
 171         spin_lock_init(&channel->inbound_lock);
 172
 173         channel->controlwq = create_workqueue("hv_vmbus_ctl");
 174         if (!channel->controlwq) {
 175                 kfree(channel);
 176                 return NULL;
 177         }
 178
 179         return channel;
 180 }
 181
 182 /*
 183  * release_hannel - Release the vmbus channel object itself
 184  */
 185 static void release_channel(struct work_struct *work)
 186 {
 187         struct vmbus_channel *channel = container_of(work,
 188                                                      struct vmbus_channel,
 189                                                      work);
 190
 191         destroy_workqueue(channel->controlwq);
 192
 193         kfree(channel);
 194 }
 195
 196 /*
 197  * free_channel - Release the resources used by the vmbus channel object
 198  */
 199 static void free_channel(struct vmbus_channel *channel)
 200 {
 201
 202         /*
 203          * We have to release the channel's workqueue/thread in the vmbus's
 204          * workqueue/thread context
 205          * ie we can't destroy ourselves.
 206          */
 207         INIT_WORK(&channel->work, release_channel);
 208         queue_work(vmbus_connection.work_queue, &channel->work);
 209 }
 210
 211
 212
 213 /*
 214  * vmbus_process_rescind_offer -
 215  * Rescind the offer by initiating a device removal
 216  */
 217 static void vmbus_process_rescind_offer(struct work_struct *work)
 218 {
 219         struct vmbus_channel *channel = container_of(work,
 220                                                      struct vmbus_channel,
 221                                                      work);
 222
 223         vmbus_device_unregister(channel->device_obj);
 224 }
 225
 226 void vmbus_free_channels(void)
 227 {
 228         struct vmbus_channel *channel;
 229
 230         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 231                 vmbus_device_unregister(channel->device_obj);
 232                 kfree(channel->device_obj);
 233                 free_channel(channel);
 234         }
 235 }
 236
 237 /*
 238  * vmbus_process_offer - Process the offer by creating a channel/device
 239  * associated with this offer
 240  */
 241 static void vmbus_process_offer(struct work_struct *work)
 242 {
 243         struct vmbus_channel *newchannel = container_of(work,
 244                                                         struct vmbus_channel,
 245                                                         work);
 246         struct vmbus_channel *channel;
 247         bool fnew = true;
 248         int ret;
 249         unsigned long flags;
 250
 251         /* The next possible work is rescind handling */
 252         INIT_WORK(&newchannel->work, vmbus_process_rescind_offer);
 253
 254         /* Make sure this is a new offer */
 255         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 256
 257         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 258                 if (!uuid_le_cmp(channel->offermsg.offer.if_type,
 259                         newchannel->offermsg.offer.if_type) &&
 260                         !uuid_le_cmp(channel->offermsg.offer.if_instance,
 261                                 newchannel->offermsg.offer.if_instance)) {
 262                         fnew = false;
 263                         break;
 264                 }
 265         }
 266
 267         if (fnew)
 268                 list_add_tail(&newchannel->listentry,
 269                               &vmbus_connection.chn_list);
 270
 271         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 272
 273         if (!fnew) {
 274                 free_channel(newchannel);
 275                 return;
 276         }
 277
 278         /*
 279          * Start the process of binding this offer to the driver
 280          * We need to set the DeviceObject field before calling
 281          * vmbus_child_dev_add()
 282          */
 283         newchannel->device_obj = vmbus_device_create(
 284                 &newchannel->offermsg.offer.if_type,
 285                 &newchannel->offermsg.offer.if_instance,
 286                 newchannel);
 287
 288         /*
 289          * Add the new device to the bus. This will kick off device-driver
 290          * binding which eventually invokes the device driver's AddDevice()
 291          * method.
 292          */
 293         ret = vmbus_device_register(newchannel->device_obj);
 294         if (ret != 0) {
 295                 pr_err("unable to add child device object (relid %d)\n",
 296                            newchannel->offermsg.child_relid);
 297
 298                 spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 299                 list_del(&newchannel->listentry);
 300                 spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 301                 kfree(newchannel->device_obj);
 302
 303                 free_channel(newchannel);
 304         } else {
 305                 /*
 306                  * This state is used to indicate a successful open
 307                  * so that when we do close the channel normally, we
 308                  * can cleanup properly
 309                  */
 310                 newchannel->state = CHANNEL_OPEN_STATE;
 311         }
 312 }
 313
 314 /*
 315  * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
 316  *
 317  */
 318 static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
 319 {
 320         struct vmbus_channel_offer_channel *offer;
 321         struct vmbus_channel *newchannel;
 322         uuid_le *guidtype;
 323         uuid_le *guidinstance;
 324         int i;
 325         int fsupported = 0;
 326
 327         offer = (struct vmbus_channel_offer_channel *)hdr;
 328         for (i = 0; i < MAX_NUM_DEVICE_CLASSES_SUPPORTED; i++) {
 329                 if (!uuid_le_cmp(offer->offer.if_type,
 330                                 supported_device_classes[i])) {
 331                         fsupported = 1;
 332                         break;
 333                 }
 334         }
 335
 336         if (!fsupported)
 337                 return;
 338
 339         guidtype = &offer->offer.if_type;
 340         guidinstance = &offer->offer.if_instance;
 341
 342         /* Allocate the channel object and save this offer. */
 343         newchannel = alloc_channel();
 344         if (!newchannel) {
 345                 pr_err("Unable to allocate channel object\n");
 346                 return;
 347         }
 348
 349         memcpy(&newchannel->offermsg, offer,
 350                sizeof(struct vmbus_channel_offer_channel));
 351         newchannel->monitor_grp = (u8)offer->monitorid / 32;
 352         newchannel->monitor_bit = (u8)offer->monitorid % 32;
 353
 354         INIT_WORK(&newchannel->work, vmbus_process_offer);
 355         queue_work(newchannel->controlwq, &newchannel->work);
 356 }
 357
 358 /*
 359  * vmbus_onoffer_rescind - Rescind offer handler.
 360  *
 361  * We queue a work item to process this offer synchronously
 362  */
 363 static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 364 {
 365         struct vmbus_channel_rescind_offer *rescind;
 366         struct vmbus_channel *channel;
 367
 368         rescind = (struct vmbus_channel_rescind_offer *)hdr;
 369         channel = relid2channel(rescind->child_relid);
 370
 371         if (channel == NULL)
 372                 /* Just return here, no channel found */
 373                 return;
 374
 375         /* work is initialized for vmbus_process_rescind_offer() from
 376          * vmbus_process_offer() where the channel got created */
 377         queue_work(channel->controlwq, &channel->work);
 378 }
 379
 380 /*
 381  * vmbus_onoffers_delivered -
 382  * This is invoked when all offers have been delivered.
 383  *
 384  * Nothing to do here.
 385  */
 386 static void vmbus_onoffers_delivered(
 387                         struct vmbus_channel_message_header *hdr)
 388 {
 389 }
 390
 391 /*
 392  * vmbus_onopen_result - Open result handler.
 393  *
 394  * This is invoked when we received a response to our channel open request.
 395  * Find the matching request, copy the response and signal the requesting
 396  * thread.
 397  */
 398 static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
 399 {
 400         struct vmbus_channel_open_result *result;
 401         struct vmbus_channel_msginfo *msginfo;
 402         struct vmbus_channel_message_header *requestheader;
 403         struct vmbus_channel_open_channel *openmsg;
 404         unsigned long flags;
 405
 406         result = (struct vmbus_channel_open_result *)hdr;
 407
 408         /*
 409          * Find the open msg, copy the result and signal/unblock the wait event
 410          */
 411         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 412
 413         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 414                                 msglistentry) {
 415                 requestheader =
 416                         (struct vmbus_channel_message_header *)msginfo->msg;
 417
 418                 if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
 419                         openmsg =
 420                         (struct vmbus_channel_open_channel *)msginfo->msg;
 421                         if (openmsg->child_relid == result->child_relid &&
 422                             openmsg->openid == result->openid) {
 423                                 memcpy(&msginfo->response.open_result,
 424                                        result,
 425                                        sizeof(
 426                                         struct vmbus_channel_open_result));
 427                                 complete(&msginfo->waitevent);
 428                                 break;
 429                         }
 430                 }
 431         }
 432         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 433 }
 434
 435 /*
 436  * vmbus_ongpadl_created - GPADL created handler.
 437  *
 438  * This is invoked when we received a response to our gpadl create request.
 439  * Find the matching request, copy the response and signal the requesting
 440  * thread.
 441  */
 442 static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
 443 {
 444         struct vmbus_channel_gpadl_created *gpadlcreated;
 445         struct vmbus_channel_msginfo *msginfo;
 446         struct vmbus_channel_message_header *requestheader;
 447         struct vmbus_channel_gpadl_header *gpadlheader;
 448         unsigned long flags;
 449
 450         gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;
 451
 452         /*
 453          * Find the establish msg, copy the result and signal/unblock the wait
 454          * event
 455          */
 456         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 457
 458         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 459                                 msglistentry) {
 460                 requestheader =
 461                         (struct vmbus_channel_message_header *)msginfo->msg;
 462
 463                 if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
 464                         gpadlheader =
 465                         (struct vmbus_channel_gpadl_header *)requestheader;
 466
 467                         if ((gpadlcreated->child_relid ==
 468                              gpadlheader->child_relid) &&
 469                             (gpadlcreated->gpadl == gpadlheader->gpadl)) {
 470                                 memcpy(&msginfo->response.gpadl_created,
 471                                        gpadlcreated,
 472                                        sizeof(
 473                                         struct vmbus_channel_gpadl_created));
 474                                 complete(&msginfo->waitevent);
 475                                 break;
 476                         }
 477                 }
 478         }
 479         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 480 }
 481
 482 /*
 483  * vmbus_ongpadl_torndown - GPADL torndown handler.
 484  *
 485  * This is invoked when we received a response to our gpadl teardown request.
 486  * Find the matching request, copy the response and signal the requesting
 487  * thread.
 488  */
 489 static void vmbus_ongpadl_torndown(
 490                         struct vmbus_channel_message_header *hdr)
 491 {
 492         struct vmbus_channel_gpadl_torndown *gpadl_torndown;
 493         struct vmbus_channel_msginfo *msginfo;
 494         struct vmbus_channel_message_header *requestheader;
 495         struct vmbus_channel_gpadl_teardown *gpadl_teardown;
 496         unsigned long flags;
 497
 498         gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;
 499
 500         /*
 501          * Find the open msg, copy the result and signal/unblock the wait event
 502          */
 503         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 504
 505         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 506                                 msglistentry) {
 507                 requestheader =
 508                         (struct vmbus_channel_message_header *)msginfo->msg;
 509
 510                 if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
 511                         gpadl_teardown =
 512                         (struct vmbus_channel_gpadl_teardown *)requestheader;
 513
 514                         if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
 515                                 memcpy(&msginfo->response.gpadl_torndown,
 516                                        gpadl_torndown,
 517                                        sizeof(
 518                                         struct vmbus_channel_gpadl_torndown));
 519                                 complete(&msginfo->waitevent);
 520                                 break;
 521                         }
 522                 }
 523         }
 524         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 525 }
 526
 527 /*
 528  * vmbus_onversion_response - Version response handler
 529  *
 530  * This is invoked when we received a response to our initiate contact request.
 531  * Find the matching request, copy the response and signal the requesting
 532  * thread.
 533  */
 534 static void vmbus_onversion_response(
 535                 struct vmbus_channel_message_header *hdr)
 536 {
 537         struct vmbus_channel_msginfo *msginfo;
 538         struct vmbus_channel_message_header *requestheader;
 539         struct vmbus_channel_initiate_contact *initiate;
 540         struct vmbus_channel_version_response *version_response;
 541         unsigned long flags;
 542
 543         version_response = (struct vmbus_channel_version_response *)hdr;
 544         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 545
 546         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 547                                 msglistentry) {
 548                 requestheader =
 549                         (struct vmbus_channel_message_header *)msginfo->msg;
 550
 551                 if (requestheader->msgtype ==
 552                     CHANNELMSG_INITIATE_CONTACT) {
 553                         initiate =
 554                         (struct vmbus_channel_initiate_contact *)requestheader;
 555                         memcpy(&msginfo->response.version_response,
 556                               version_response,
 557                               sizeof(struct vmbus_channel_version_response));
 558                         complete(&msginfo->waitevent);
 559                 }
 560         }
 561         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 562 }
 563
 564 /* Channel message dispatch table */
 565 static struct vmbus_channel_message_table_entry
 566         channel_message_table[CHANNELMSG_COUNT] = {
 567         {CHANNELMSG_INVALID,                    NULL},
 568         {CHANNELMSG_OFFERCHANNEL,               vmbus_onoffer},
 569         {CHANNELMSG_RESCIND_CHANNELOFFER,       vmbus_onoffer_rescind},
 570         {CHANNELMSG_REQUESTOFFERS,              NULL},
 571         {CHANNELMSG_ALLOFFERS_DELIVERED,        vmbus_onoffers_delivered},
 572         {CHANNELMSG_OPENCHANNEL,                NULL},
 573         {CHANNELMSG_OPENCHANNEL_RESULT, vmbus_onopen_result},
 574         {CHANNELMSG_CLOSECHANNEL,               NULL},
 575         {CHANNELMSG_GPADL_HEADER,               NULL},
 576         {CHANNELMSG_GPADL_BODY,         NULL},
 577         {CHANNELMSG_GPADL_CREATED,              vmbus_ongpadl_created},
 578         {CHANNELMSG_GPADL_TEARDOWN,             NULL},
 579         {CHANNELMSG_GPADL_TORNDOWN,             vmbus_ongpadl_torndown},
 580         {CHANNELMSG_RELID_RELEASED,             NULL},
 581         {CHANNELMSG_INITIATE_CONTACT,           NULL},
 582         {CHANNELMSG_VERSION_RESPONSE,           vmbus_onversion_response},
 583         {CHANNELMSG_UNLOAD,                     NULL},
 584 };
 585
 586 /*
 587  * vmbus_onmessage - Handler for channel protocol messages.
 588  *
 589  * This is invoked in the vmbus worker thread context.
 590  */
 591 void vmbus_onmessage(void *context)
 592 {
 593         struct hv_message *msg = context;
 594         struct vmbus_channel_message_header *hdr;
 595         int size;
 596
 597         hdr = (struct vmbus_channel_message_header *)msg->u.payload;
 598         size = msg->header.payload_size;
 599
 600         if (hdr->msgtype >= CHANNELMSG_COUNT) {
 601                 pr_err("Received invalid channel message type %d size %d\n",
 602                            hdr->msgtype, size);
 603                 print_hex_dump_bytes("", DUMP_PREFIX_NONE,
 604                                      (unsigned char *)msg->u.payload, size);
 605                 return;
 606         }
 607
 608         if (channel_message_table[hdr->msgtype].message_handler)
 609                 channel_message_table[hdr->msgtype].message_handler(hdr);
 610         else
 611                 pr_err("Unhandled channel message type %d\n", hdr->msgtype);
 612 }
 613
 614 /*
 615  * vmbus_request_offers - Send a request to get all our pending offers.
 616  */
 617 int vmbus_request_offers(void)
 618 {
 619         struct vmbus_channel_message_header *msg;
 620         struct vmbus_channel_msginfo *msginfo;
 621         int ret, t;
 622
 623         msginfo = kmalloc(sizeof(*msginfo) +
 624                           sizeof(struct vmbus_channel_message_header),
 625                           GFP_KERNEL);
 626         if (!msginfo)
 627                 return -ENOMEM;
 628
 629         init_completion(&msginfo->waitevent);
 630
 631         msg = (struct vmbus_channel_message_header *)msginfo->msg;
 632
 633         msg->msgtype = CHANNELMSG_REQUESTOFFERS;
 634
 635
 636         ret = vmbus_post_msg(msg,
 637                                sizeof(struct vmbus_channel_message_header));
 638         if (ret != 0) {
 639                 pr_err("Unable to request offers - %d\n", ret);
 640
 641                 goto cleanup;
 642         }
 643
 644         t = wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
 645         if (t == 0) {
 646                 ret = -ETIMEDOUT;
 647                 goto cleanup;
 648         }
 649
 650
 651
 652 cleanup:
 653         kfree(msginfo);
 654
 655         return ret;
 656 }
 657
 658 /* eof */