root/drivers/misc/sgi-xp/xpc_channel.c

DEFINITIONS

1. xpc_process_connect
2. xpc_process_disconnect
3. xpc_process_openclose_chctl_flags
4. xpc_connect_channel
5. xpc_process_sent_chctl_flags
6. xpc_partition_going_down
7. xpc_initiate_connect
8. xpc_connected_callout
9. xpc_initiate_disconnect
10. xpc_disconnect_channel
11. xpc_disconnect_callout
12. xpc_allocate_msg_wait
13. xpc_initiate_send
14. xpc_initiate_send_notify
15. xpc_deliver_payload
16. xpc_initiate_received

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (c) 2004-2009 Silicon Graphics, Inc.  All Rights Reserved.
   7  */
   8 
   9 /*
  10  * Cross Partition Communication (XPC) channel support.
  11  *
  12  *      This is the part of XPC that manages the channels and
  13  *      sends/receives messages across them to/from other partitions.
  14  *
  15  */
  16 
  17 #include <linux/device.h>
  18 #include "xpc.h"
  19 
  20 /*
  21  * Process a connect message from a remote partition.
  22  *
  23  * Note: xpc_process_connect() is expecting to be called with the
  24  * spin_lock_irqsave held and will leave it locked upon return.
  25  */
  26 static void
  27 xpc_process_connect(struct xpc_channel *ch, unsigned long *irq_flags)
  28 {
  29         enum xp_retval ret;
  30 
  31         lockdep_assert_held(&ch->lock);
  32 
  33         if (!(ch->flags & XPC_C_OPENREQUEST) ||
  34             !(ch->flags & XPC_C_ROPENREQUEST)) {
  35                 /* nothing more to do for now */
  36                 return;
  37         }
  38         DBUG_ON(!(ch->flags & XPC_C_CONNECTING));
  39 
  40         if (!(ch->flags & XPC_C_SETUP)) {
  41                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
  42                 ret = xpc_arch_ops.setup_msg_structures(ch);
  43                 spin_lock_irqsave(&ch->lock, *irq_flags);
  44 
  45                 if (ret != xpSuccess)
  46                         XPC_DISCONNECT_CHANNEL(ch, ret, irq_flags);
  47                 else
  48                         ch->flags |= XPC_C_SETUP;
  49 
  50                 if (ch->flags & XPC_C_DISCONNECTING)
  51                         return;
  52         }
  53 
  54         if (!(ch->flags & XPC_C_OPENREPLY)) {
  55                 ch->flags |= XPC_C_OPENREPLY;
  56                 xpc_arch_ops.send_chctl_openreply(ch, irq_flags);
  57         }
  58 
  59         if (!(ch->flags & XPC_C_ROPENREPLY))
  60                 return;
  61 
  62         if (!(ch->flags & XPC_C_OPENCOMPLETE)) {
  63                 ch->flags |= (XPC_C_OPENCOMPLETE | XPC_C_CONNECTED);
  64                 xpc_arch_ops.send_chctl_opencomplete(ch, irq_flags);
  65         }
  66 
  67         if (!(ch->flags & XPC_C_ROPENCOMPLETE))
  68                 return;
  69 
  70         dev_info(xpc_chan, "channel %d to partition %d connected\n",
  71                  ch->number, ch->partid);
  72 
  73         ch->flags = (XPC_C_CONNECTED | XPC_C_SETUP);    /* clear all else */
  74 }
  75 
  76 /*
  77  * spin_lock_irqsave() is expected to be held on entry.
  78  */
  79 static void
  80 xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
  81 {
  82         struct xpc_partition *part = &xpc_partitions[ch->partid];
  83         u32 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);
  84 
  85         lockdep_assert_held(&ch->lock);
  86 
  87         if (!(ch->flags & XPC_C_DISCONNECTING))
  88                 return;
  89 
  90         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
  91 
  92         /* make sure all activity has settled down first */
  93 
  94         if (atomic_read(&ch->kthreads_assigned) > 0 ||
  95             atomic_read(&ch->references) > 0) {
  96                 return;
  97         }
  98         DBUG_ON((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
  99                 !(ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE));
 100 
 101         if (part->act_state == XPC_P_AS_DEACTIVATING) {
 102                 /* can't proceed until the other side disengages from us */
 103                 if (xpc_arch_ops.partition_engaged(ch->partid))
 104                         return;
 105 
 106         } else {
 107 
 108                 /* as long as the other side is up do the full protocol */
 109 
 110                 if (!(ch->flags & XPC_C_RCLOSEREQUEST))
 111                         return;
 112 
 113                 if (!(ch->flags & XPC_C_CLOSEREPLY)) {
 114                         ch->flags |= XPC_C_CLOSEREPLY;
 115                         xpc_arch_ops.send_chctl_closereply(ch, irq_flags);
 116                 }
 117 
 118                 if (!(ch->flags & XPC_C_RCLOSEREPLY))
 119                         return;
 120         }
 121 
 122         /* wake those waiting for notify completion */
 123         if (atomic_read(&ch->n_to_notify) > 0) {
 124                 /* we do callout while holding ch->lock, callout can't block */
 125                 xpc_arch_ops.notify_senders_of_disconnect(ch);
 126         }
 127 
 128         /* both sides are disconnected now */
 129 
 130         if (ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE) {
 131                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
 132                 xpc_disconnect_callout(ch, xpDisconnected);
 133                 spin_lock_irqsave(&ch->lock, *irq_flags);
 134         }
 135 
 136         DBUG_ON(atomic_read(&ch->n_to_notify) != 0);
 137 
 138         /* it's now safe to free the channel's message queues */
 139         xpc_arch_ops.teardown_msg_structures(ch);
 140 
 141         ch->func = NULL;
 142         ch->key = NULL;
 143         ch->entry_size = 0;
 144         ch->local_nentries = 0;
 145         ch->remote_nentries = 0;
 146         ch->kthreads_assigned_limit = 0;
 147         ch->kthreads_idle_limit = 0;
 148 
 149         /*
 150          * Mark the channel disconnected and clear all other flags, including
 151          * XPC_C_SETUP (because of call to
 152          * xpc_arch_ops.teardown_msg_structures()) but not including
 153          * XPC_C_WDISCONNECT (if it was set).
 154          */
 155         ch->flags = (XPC_C_DISCONNECTED | (ch->flags & XPC_C_WDISCONNECT));
 156 
 157         atomic_dec(&part->nchannels_active);
 158 
 159         if (channel_was_connected) {
 160                 dev_info(xpc_chan, "channel %d to partition %d disconnected, "
 161                          "reason=%d\n", ch->number, ch->partid, ch->reason);
 162         }
 163 
 164         if (ch->flags & XPC_C_WDISCONNECT) {
 165                 /* we won't lose the CPU since we're holding ch->lock */
 166                 complete(&ch->wdisconnect_wait);
 167         } else if (ch->delayed_chctl_flags) {
 168                 if (part->act_state != XPC_P_AS_DEACTIVATING) {
 169                         /* time to take action on any delayed chctl flags */
 170                         spin_lock(&part->chctl_lock);
 171                         part->chctl.flags[ch->number] |=
 172                             ch->delayed_chctl_flags;
 173                         spin_unlock(&part->chctl_lock);
 174                 }
 175                 ch->delayed_chctl_flags = 0;
 176         }
 177 }
 178 
 179 /*
 180  * Process a change in the channel's remote connection state.
 181  */
 182 static void
 183 xpc_process_openclose_chctl_flags(struct xpc_partition *part, int ch_number,
 184                                   u8 chctl_flags)
 185 {
 186         unsigned long irq_flags;
 187         struct xpc_openclose_args *args =
 188             &part->remote_openclose_args[ch_number];
 189         struct xpc_channel *ch = &part->channels[ch_number];
 190         enum xp_retval reason;
 191         enum xp_retval ret;
 192         int create_kthread = 0;
 193 
 194         spin_lock_irqsave(&ch->lock, irq_flags);
 195 
 196 again:
 197 
 198         if ((ch->flags & XPC_C_DISCONNECTED) &&
 199             (ch->flags & XPC_C_WDISCONNECT)) {
 200                 /*
 201                  * Delay processing chctl flags until thread waiting disconnect
 202                  * has had a chance to see that the channel is disconnected.
 203                  */
 204                 ch->delayed_chctl_flags |= chctl_flags;
 205                 goto out;
 206         }
 207 
 208         if (chctl_flags & XPC_CHCTL_CLOSEREQUEST) {
 209 
 210                 dev_dbg(xpc_chan, "XPC_CHCTL_CLOSEREQUEST (reason=%d) received "
 211                         "from partid=%d, channel=%d\n", args->reason,
 212                         ch->partid, ch->number);
 213 
 214                 /*
 215                  * If RCLOSEREQUEST is set, we're probably waiting for
 216                  * RCLOSEREPLY. We should find it and a ROPENREQUEST packed
 217                  * with this RCLOSEREQUEST in the chctl_flags.
 218                  */
 219 
 220                 if (ch->flags & XPC_C_RCLOSEREQUEST) {
 221                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTING));
 222                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 223                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREPLY));
 224                         DBUG_ON(ch->flags & XPC_C_RCLOSEREPLY);
 225 
 226                         DBUG_ON(!(chctl_flags & XPC_CHCTL_CLOSEREPLY));
 227                         chctl_flags &= ~XPC_CHCTL_CLOSEREPLY;
 228                         ch->flags |= XPC_C_RCLOSEREPLY;
 229 
 230                         /* both sides have finished disconnecting */
 231                         xpc_process_disconnect(ch, &irq_flags);
 232                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 233                         goto again;
 234                 }
 235 
 236                 if (ch->flags & XPC_C_DISCONNECTED) {
 237                         if (!(chctl_flags & XPC_CHCTL_OPENREQUEST)) {
 238                                 if (part->chctl.flags[ch_number] &
 239                                     XPC_CHCTL_OPENREQUEST) {
 240 
 241                                         DBUG_ON(ch->delayed_chctl_flags != 0);
 242                                         spin_lock(&part->chctl_lock);
 243                                         part->chctl.flags[ch_number] |=
 244                                             XPC_CHCTL_CLOSEREQUEST;
 245                                         spin_unlock(&part->chctl_lock);
 246                                 }
 247                                 goto out;
 248                         }
 249 
 250                         XPC_SET_REASON(ch, 0, 0);
 251                         ch->flags &= ~XPC_C_DISCONNECTED;
 252 
 253                         atomic_inc(&part->nchannels_active);
 254                         ch->flags |= (XPC_C_CONNECTING | XPC_C_ROPENREQUEST);
 255                 }
 256 
 257                 chctl_flags &= ~(XPC_CHCTL_OPENREQUEST | XPC_CHCTL_OPENREPLY |
 258                     XPC_CHCTL_OPENCOMPLETE);
 259 
 260                 /*
 261                  * The meaningful CLOSEREQUEST connection state fields are:
 262                  *      reason = reason connection is to be closed
 263                  */
 264 
 265                 ch->flags |= XPC_C_RCLOSEREQUEST;
 266 
 267                 if (!(ch->flags & XPC_C_DISCONNECTING)) {
 268                         reason = args->reason;
 269                         if (reason <= xpSuccess || reason > xpUnknownReason)
 270                                 reason = xpUnknownReason;
 271                         else if (reason == xpUnregistering)
 272                                 reason = xpOtherUnregistering;
 273 
 274                         XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
 275 
 276                         DBUG_ON(chctl_flags & XPC_CHCTL_CLOSEREPLY);
 277                         goto out;
 278                 }
 279 
 280                 xpc_process_disconnect(ch, &irq_flags);
 281         }
 282 
 283         if (chctl_flags & XPC_CHCTL_CLOSEREPLY) {
 284 
 285                 dev_dbg(xpc_chan, "XPC_CHCTL_CLOSEREPLY received from partid="
 286                         "%d, channel=%d\n", ch->partid, ch->number);
 287 
 288                 if (ch->flags & XPC_C_DISCONNECTED) {
 289                         DBUG_ON(part->act_state != XPC_P_AS_DEACTIVATING);
 290                         goto out;
 291                 }
 292 
 293                 DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 294 
 295                 if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
 296                         if (part->chctl.flags[ch_number] &
 297                             XPC_CHCTL_CLOSEREQUEST) {
 298 
 299                                 DBUG_ON(ch->delayed_chctl_flags != 0);
 300                                 spin_lock(&part->chctl_lock);
 301                                 part->chctl.flags[ch_number] |=
 302                                     XPC_CHCTL_CLOSEREPLY;
 303                                 spin_unlock(&part->chctl_lock);
 304                         }
 305                         goto out;
 306                 }
 307 
 308                 ch->flags |= XPC_C_RCLOSEREPLY;
 309 
 310                 if (ch->flags & XPC_C_CLOSEREPLY) {
 311                         /* both sides have finished disconnecting */
 312                         xpc_process_disconnect(ch, &irq_flags);
 313                 }
 314         }
 315 
 316         if (chctl_flags & XPC_CHCTL_OPENREQUEST) {
 317 
 318                 dev_dbg(xpc_chan, "XPC_CHCTL_OPENREQUEST (entry_size=%d, "
 319                         "local_nentries=%d) received from partid=%d, "
 320                         "channel=%d\n", args->entry_size, args->local_nentries,
 321                         ch->partid, ch->number);
 322 
 323                 if (part->act_state == XPC_P_AS_DEACTIVATING ||
 324                     (ch->flags & XPC_C_ROPENREQUEST)) {
 325                         goto out;
 326                 }
 327 
 328                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_WDISCONNECT)) {
 329                         ch->delayed_chctl_flags |= XPC_CHCTL_OPENREQUEST;
 330                         goto out;
 331                 }
 332                 DBUG_ON(!(ch->flags & (XPC_C_DISCONNECTED |
 333                                        XPC_C_OPENREQUEST)));
 334                 DBUG_ON(ch->flags & (XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
 335                                      XPC_C_OPENREPLY | XPC_C_CONNECTED));
 336 
 337                 /*
 338                  * The meaningful OPENREQUEST connection state fields are:
 339                  *      entry_size = size of channel's messages in bytes
 340                  *      local_nentries = remote partition's local_nentries
 341                  */
 342                 if (args->entry_size == 0 || args->local_nentries == 0) {
 343                         /* assume OPENREQUEST was delayed by mistake */
 344                         goto out;
 345                 }
 346 
 347                 ch->flags |= (XPC_C_ROPENREQUEST | XPC_C_CONNECTING);
 348                 ch->remote_nentries = args->local_nentries;
 349 
 350                 if (ch->flags & XPC_C_OPENREQUEST) {
 351                         if (args->entry_size != ch->entry_size) {
 352                                 XPC_DISCONNECT_CHANNEL(ch, xpUnequalMsgSizes,
 353                                                        &irq_flags);
 354                                 goto out;
 355                         }
 356                 } else {
 357                         ch->entry_size = args->entry_size;
 358 
 359                         XPC_SET_REASON(ch, 0, 0);
 360                         ch->flags &= ~XPC_C_DISCONNECTED;
 361 
 362                         atomic_inc(&part->nchannels_active);
 363                 }
 364 
 365                 xpc_process_connect(ch, &irq_flags);
 366         }
 367 
 368         if (chctl_flags & XPC_CHCTL_OPENREPLY) {
 369 
 370                 dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY (local_msgqueue_pa="
 371                         "0x%lx, local_nentries=%d, remote_nentries=%d) "
 372                         "received from partid=%d, channel=%d\n",
 373                         args->local_msgqueue_pa, args->local_nentries,
 374                         args->remote_nentries, ch->partid, ch->number);
 375 
 376                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED))
 377                         goto out;
 378 
 379                 if (!(ch->flags & XPC_C_OPENREQUEST)) {
 380                         XPC_DISCONNECT_CHANNEL(ch, xpOpenCloseError,
 381                                                &irq_flags);
 382                         goto out;
 383                 }
 384 
 385                 DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
 386                 DBUG_ON(ch->flags & XPC_C_CONNECTED);
 387 
 388                 /*
 389                  * The meaningful OPENREPLY connection state fields are:
 390                  *      local_msgqueue_pa = physical address of remote
 391                  *                          partition's local_msgqueue
 392                  *      local_nentries = remote partition's local_nentries
 393                  *      remote_nentries = remote partition's remote_nentries
 394                  */
 395                 DBUG_ON(args->local_msgqueue_pa == 0);
 396                 DBUG_ON(args->local_nentries == 0);
 397                 DBUG_ON(args->remote_nentries == 0);
 398 
 399                 ret = xpc_arch_ops.save_remote_msgqueue_pa(ch,
 400                                                       args->local_msgqueue_pa);
 401                 if (ret != xpSuccess) {
 402                         XPC_DISCONNECT_CHANNEL(ch, ret, &irq_flags);
 403                         goto out;
 404                 }
 405                 ch->flags |= XPC_C_ROPENREPLY;
 406 
 407                 if (args->local_nentries < ch->remote_nentries) {
 408                         dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY: new "
 409                                 "remote_nentries=%d, old remote_nentries=%d, "
 410                                 "partid=%d, channel=%d\n",
 411                                 args->local_nentries, ch->remote_nentries,
 412                                 ch->partid, ch->number);
 413 
 414                         ch->remote_nentries = args->local_nentries;
 415                 }
 416                 if (args->remote_nentries < ch->local_nentries) {
 417                         dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY: new "
 418                                 "local_nentries=%d, old local_nentries=%d, "
 419                                 "partid=%d, channel=%d\n",
 420                                 args->remote_nentries, ch->local_nentries,
 421                                 ch->partid, ch->number);
 422 
 423                         ch->local_nentries = args->remote_nentries;
 424                 }
 425 
 426                 xpc_process_connect(ch, &irq_flags);
 427         }
 428 
 429         if (chctl_flags & XPC_CHCTL_OPENCOMPLETE) {
 430 
 431                 dev_dbg(xpc_chan, "XPC_CHCTL_OPENCOMPLETE received from "
 432                         "partid=%d, channel=%d\n", ch->partid, ch->number);
 433 
 434                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED))
 435                         goto out;
 436 
 437                 if (!(ch->flags & XPC_C_OPENREQUEST) ||
 438                     !(ch->flags & XPC_C_OPENREPLY)) {
 439                         XPC_DISCONNECT_CHANNEL(ch, xpOpenCloseError,
 440                                                &irq_flags);
 441                         goto out;
 442                 }
 443 
 444                 DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
 445                 DBUG_ON(!(ch->flags & XPC_C_ROPENREPLY));
 446                 DBUG_ON(!(ch->flags & XPC_C_CONNECTED));
 447 
 448                 ch->flags |= XPC_C_ROPENCOMPLETE;
 449 
 450                 xpc_process_connect(ch, &irq_flags);
 451                 create_kthread = 1;
 452         }
 453 
 454 out:
 455         spin_unlock_irqrestore(&ch->lock, irq_flags);
 456 
 457         if (create_kthread)
 458                 xpc_create_kthreads(ch, 1, 0);
 459 }
 460 
 461 /*
 462  * Attempt to establish a channel connection to a remote partition.
 463  */
 464 static enum xp_retval
 465 xpc_connect_channel(struct xpc_channel *ch)
 466 {
 467         unsigned long irq_flags;
 468         struct xpc_registration *registration = &xpc_registrations[ch->number];
 469 
 470         if (mutex_trylock(&registration->mutex) == 0)
 471                 return xpRetry;
 472 
 473         if (!XPC_CHANNEL_REGISTERED(ch->number)) {
 474                 mutex_unlock(&registration->mutex);
 475                 return xpUnregistered;
 476         }
 477 
 478         spin_lock_irqsave(&ch->lock, irq_flags);
 479 
 480         DBUG_ON(ch->flags & XPC_C_CONNECTED);
 481         DBUG_ON(ch->flags & XPC_C_OPENREQUEST);
 482 
 483         if (ch->flags & XPC_C_DISCONNECTING) {
 484                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 485                 mutex_unlock(&registration->mutex);
 486                 return ch->reason;
 487         }
 488 
 489         /* add info from the channel connect registration to the channel */
 490 
 491         ch->kthreads_assigned_limit = registration->assigned_limit;
 492         ch->kthreads_idle_limit = registration->idle_limit;
 493         DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
 494         DBUG_ON(atomic_read(&ch->kthreads_idle) != 0);
 495         DBUG_ON(atomic_read(&ch->kthreads_active) != 0);
 496 
 497         ch->func = registration->func;
 498         DBUG_ON(registration->func == NULL);
 499         ch->key = registration->key;
 500 
 501         ch->local_nentries = registration->nentries;
 502 
 503         if (ch->flags & XPC_C_ROPENREQUEST) {
 504                 if (registration->entry_size != ch->entry_size) {
 505                         /* the local and remote sides aren't the same */
 506 
 507                         /*
 508                          * Because XPC_DISCONNECT_CHANNEL() can block we're
 509                          * forced to up the registration sema before we unlock
 510                          * the channel lock. But that's okay here because we're
 511                          * done with the part that required the registration
 512                          * sema. XPC_DISCONNECT_CHANNEL() requires that the
 513                          * channel lock be locked and will unlock and relock
 514                          * the channel lock as needed.
 515                          */
 516                         mutex_unlock(&registration->mutex);
 517                         XPC_DISCONNECT_CHANNEL(ch, xpUnequalMsgSizes,
 518                                                &irq_flags);
 519                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 520                         return xpUnequalMsgSizes;
 521                 }
 522         } else {
 523                 ch->entry_size = registration->entry_size;
 524 
 525                 XPC_SET_REASON(ch, 0, 0);
 526                 ch->flags &= ~XPC_C_DISCONNECTED;
 527 
 528                 atomic_inc(&xpc_partitions[ch->partid].nchannels_active);
 529         }
 530 
 531         mutex_unlock(&registration->mutex);
 532 
 533         /* initiate the connection */
 534 
 535         ch->flags |= (XPC_C_OPENREQUEST | XPC_C_CONNECTING);
 536         xpc_arch_ops.send_chctl_openrequest(ch, &irq_flags);
 537 
 538         xpc_process_connect(ch, &irq_flags);
 539 
 540         spin_unlock_irqrestore(&ch->lock, irq_flags);
 541 
 542         return xpSuccess;
 543 }
 544 
 545 void
 546 xpc_process_sent_chctl_flags(struct xpc_partition *part)
 547 {
 548         unsigned long irq_flags;
 549         union xpc_channel_ctl_flags chctl;
 550         struct xpc_channel *ch;
 551         int ch_number;
 552         u32 ch_flags;
 553 
 554         chctl.all_flags = xpc_arch_ops.get_chctl_all_flags(part);
 555 
 556         /*
 557          * Initiate channel connections for registered channels.
 558          *
 559          * For each connected channel that has pending messages activate idle
 560          * kthreads and/or create new kthreads as needed.
 561          */
 562 
 563         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
 564                 ch = &part->channels[ch_number];
 565 
 566                 /*
 567                  * Process any open or close related chctl flags, and then deal
 568                  * with connecting or disconnecting the channel as required.
 569                  */
 570 
 571                 if (chctl.flags[ch_number] & XPC_OPENCLOSE_CHCTL_FLAGS) {
 572                         xpc_process_openclose_chctl_flags(part, ch_number,
 573                                                         chctl.flags[ch_number]);
 574                 }
 575 
 576                 ch_flags = ch->flags;   /* need an atomic snapshot of flags */
 577 
 578                 if (ch_flags & XPC_C_DISCONNECTING) {
 579                         spin_lock_irqsave(&ch->lock, irq_flags);
 580                         xpc_process_disconnect(ch, &irq_flags);
 581                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 582                         continue;
 583                 }
 584 
 585                 if (part->act_state == XPC_P_AS_DEACTIVATING)
 586                         continue;
 587 
 588                 if (!(ch_flags & XPC_C_CONNECTED)) {
 589                         if (!(ch_flags & XPC_C_OPENREQUEST)) {
 590                                 DBUG_ON(ch_flags & XPC_C_SETUP);
 591                                 (void)xpc_connect_channel(ch);
 592                         }
 593                         continue;
 594                 }
 595 
 596                 /*
 597                  * Process any message related chctl flags, this may involve
 598                  * the activation of kthreads to deliver any pending messages
 599                  * sent from the other partition.
 600                  */
 601 
 602                 if (chctl.flags[ch_number] & XPC_MSG_CHCTL_FLAGS)
 603                         xpc_arch_ops.process_msg_chctl_flags(part, ch_number);
 604         }
 605 }
 606 
 607 /*
 608  * XPC's heartbeat code calls this function to inform XPC that a partition is
 609  * going down.  XPC responds by tearing down the XPartition Communication
 610  * infrastructure used for the just downed partition.
 611  *
 612  * XPC's heartbeat code will never call this function and xpc_partition_up()
 613  * at the same time. Nor will it ever make multiple calls to either function
 614  * at the same time.
 615  */
 616 void
 617 xpc_partition_going_down(struct xpc_partition *part, enum xp_retval reason)
 618 {
 619         unsigned long irq_flags;
 620         int ch_number;
 621         struct xpc_channel *ch;
 622 
 623         dev_dbg(xpc_chan, "deactivating partition %d, reason=%d\n",
 624                 XPC_PARTID(part), reason);
 625 
 626         if (!xpc_part_ref(part)) {
 627                 /* infrastructure for this partition isn't currently set up */
 628                 return;
 629         }
 630 
 631         /* disconnect channels associated with the partition going down */
 632 
 633         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
 634                 ch = &part->channels[ch_number];
 635 
 636                 xpc_msgqueue_ref(ch);
 637                 spin_lock_irqsave(&ch->lock, irq_flags);
 638 
 639                 XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
 640 
 641                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 642                 xpc_msgqueue_deref(ch);
 643         }
 644 
 645         xpc_wakeup_channel_mgr(part);
 646 
 647         xpc_part_deref(part);
 648 }
 649 
 650 /*
 651  * Called by XP at the time of channel connection registration to cause
 652  * XPC to establish connections to all currently active partitions.
 653  */
 654 void
 655 xpc_initiate_connect(int ch_number)
 656 {
 657         short partid;
 658         struct xpc_partition *part;
 659 
 660         DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);
 661 
 662         for (partid = 0; partid < xp_max_npartitions; partid++) {
 663                 part = &xpc_partitions[partid];
 664 
 665                 if (xpc_part_ref(part)) {
 666                         /*
 667                          * Initiate the establishment of a connection on the
 668                          * newly registered channel to the remote partition.
 669                          */
 670                         xpc_wakeup_channel_mgr(part);
 671                         xpc_part_deref(part);
 672                 }
 673         }
 674 }
 675 
 676 void
 677 xpc_connected_callout(struct xpc_channel *ch)
 678 {
 679         /* let the registerer know that a connection has been established */
 680 
 681         if (ch->func != NULL) {
 682                 dev_dbg(xpc_chan, "ch->func() called, reason=xpConnected, "
 683                         "partid=%d, channel=%d\n", ch->partid, ch->number);
 684 
 685                 ch->func(xpConnected, ch->partid, ch->number,
 686                          (void *)(u64)ch->local_nentries, ch->key);
 687 
 688                 dev_dbg(xpc_chan, "ch->func() returned, reason=xpConnected, "
 689                         "partid=%d, channel=%d\n", ch->partid, ch->number);
 690         }
 691 }
 692 
 693 /*
 694  * Called by XP at the time of channel connection unregistration to cause
 695  * XPC to teardown all current connections for the specified channel.
 696  *
 697  * Before returning xpc_initiate_disconnect() will wait until all connections
 698  * on the specified channel have been closed/torndown. So the caller can be
 699  * assured that they will not be receiving any more callouts from XPC to the
 700  * function they registered via xpc_connect().
 701  *
 702  * Arguments:
 703  *
 704  *      ch_number - channel # to unregister.
 705  */
 706 void
 707 xpc_initiate_disconnect(int ch_number)
 708 {
 709         unsigned long irq_flags;
 710         short partid;
 711         struct xpc_partition *part;
 712         struct xpc_channel *ch;
 713 
 714         DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);
 715 
 716         /* initiate the channel disconnect for every active partition */
 717         for (partid = 0; partid < xp_max_npartitions; partid++) {
 718                 part = &xpc_partitions[partid];
 719 
 720                 if (xpc_part_ref(part)) {
 721                         ch = &part->channels[ch_number];
 722                         xpc_msgqueue_ref(ch);
 723 
 724                         spin_lock_irqsave(&ch->lock, irq_flags);
 725 
 726                         if (!(ch->flags & XPC_C_DISCONNECTED)) {
 727                                 ch->flags |= XPC_C_WDISCONNECT;
 728 
 729                                 XPC_DISCONNECT_CHANNEL(ch, xpUnregistering,
 730                                                        &irq_flags);
 731                         }
 732 
 733                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 734 
 735                         xpc_msgqueue_deref(ch);
 736                         xpc_part_deref(part);
 737                 }
 738         }
 739 
 740         xpc_disconnect_wait(ch_number);
 741 }
 742 
 743 /*
 744  * To disconnect a channel, and reflect it back to all who may be waiting.
 745  *
 746  * An OPEN is not allowed until XPC_C_DISCONNECTING is cleared by
 747  * xpc_process_disconnect(), and if set, XPC_C_WDISCONNECT is cleared by
 748  * xpc_disconnect_wait().
 749  *
 750  * THE CHANNEL IS TO BE LOCKED BY THE CALLER AND WILL REMAIN LOCKED UPON RETURN.
 751  */
 752 void
 753 xpc_disconnect_channel(const int line, struct xpc_channel *ch,
 754                        enum xp_retval reason, unsigned long *irq_flags)
 755 {
 756         u32 channel_was_connected = (ch->flags & XPC_C_CONNECTED);
 757 
 758         lockdep_assert_held(&ch->lock);
 759 
 760         if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED))
 761                 return;
 762 
 763         DBUG_ON(!(ch->flags & (XPC_C_CONNECTING | XPC_C_CONNECTED)));
 764 
 765         dev_dbg(xpc_chan, "reason=%d, line=%d, partid=%d, channel=%d\n",
 766                 reason, line, ch->partid, ch->number);
 767 
 768         XPC_SET_REASON(ch, reason, line);
 769 
 770         ch->flags |= (XPC_C_CLOSEREQUEST | XPC_C_DISCONNECTING);
 771         /* some of these may not have been set */
 772         ch->flags &= ~(XPC_C_OPENREQUEST | XPC_C_OPENREPLY |
 773                        XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
 774                        XPC_C_CONNECTING | XPC_C_CONNECTED);
 775 
 776         xpc_arch_ops.send_chctl_closerequest(ch, irq_flags);
 777 
 778         if (channel_was_connected)
 779                 ch->flags |= XPC_C_WASCONNECTED;
 780 
 781         spin_unlock_irqrestore(&ch->lock, *irq_flags);
 782 
 783         /* wake all idle kthreads so they can exit */
 784         if (atomic_read(&ch->kthreads_idle) > 0) {
 785                 wake_up_all(&ch->idle_wq);
 786 
 787         } else if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 788                    !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
 789                 /* start a kthread that will do the xpDisconnecting callout */
 790                 xpc_create_kthreads(ch, 1, 1);
 791         }
 792 
 793         /* wake those waiting to allocate an entry from the local msg queue */
 794         if (atomic_read(&ch->n_on_msg_allocate_wq) > 0)
 795                 wake_up(&ch->msg_allocate_wq);
 796 
 797         spin_lock_irqsave(&ch->lock, *irq_flags);
 798 }
 799 
 800 void
 801 xpc_disconnect_callout(struct xpc_channel *ch, enum xp_retval reason)
 802 {
 803         /*
 804          * Let the channel's registerer know that the channel is being
 805          * disconnected. We don't want to do this if the registerer was never
 806          * informed of a connection being made.
 807          */
 808 
 809         if (ch->func != NULL) {
 810                 dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
 811                         "channel=%d\n", reason, ch->partid, ch->number);
 812 
 813                 ch->func(reason, ch->partid, ch->number, NULL, ch->key);
 814 
 815                 dev_dbg(xpc_chan, "ch->func() returned, reason=%d, partid=%d, "
 816                         "channel=%d\n", reason, ch->partid, ch->number);
 817         }
 818 }
 819 
 820 /*
 821  * Wait for a message entry to become available for the specified channel,
 822  * but don't wait any longer than 1 jiffy.
 823  */
 824 enum xp_retval
 825 xpc_allocate_msg_wait(struct xpc_channel *ch)
 826 {
 827         enum xp_retval ret;
 828         DEFINE_WAIT(wait);
 829 
 830         if (ch->flags & XPC_C_DISCONNECTING) {
 831                 DBUG_ON(ch->reason == xpInterrupted);
 832                 return ch->reason;
 833         }
 834 
 835         atomic_inc(&ch->n_on_msg_allocate_wq);
 836         prepare_to_wait(&ch->msg_allocate_wq, &wait, TASK_INTERRUPTIBLE);
 837         ret = schedule_timeout(1);
 838         finish_wait(&ch->msg_allocate_wq, &wait);
 839         atomic_dec(&ch->n_on_msg_allocate_wq);
 840 
 841         if (ch->flags & XPC_C_DISCONNECTING) {
 842                 ret = ch->reason;
 843                 DBUG_ON(ch->reason == xpInterrupted);
 844         } else if (ret == 0) {
 845                 ret = xpTimeout;
 846         } else {
 847                 ret = xpInterrupted;
 848         }
 849 
 850         return ret;
 851 }
 852 
 853 /*
 854  * Send a message that contains the user's payload on the specified channel
 855  * connected to the specified partition.
 856  *
 857  * NOTE that this routine can sleep waiting for a message entry to become
 858  * available. To not sleep, pass in the XPC_NOWAIT flag.
 859  *
 860  * Once sent, this routine will not wait for the message to be received, nor
 861  * will notification be given when it does happen.
 862  *
 863  * Arguments:
 864  *
 865  *      partid - ID of partition to which the channel is connected.
 866  *      ch_number - channel # to send message on.
 867  *      flags - see xp.h for valid flags.
 868  *      payload - pointer to the payload which is to be sent.
 869  *      payload_size - size of the payload in bytes.
 870  */
 871 enum xp_retval
 872 xpc_initiate_send(short partid, int ch_number, u32 flags, void *payload,
 873                   u16 payload_size)
 874 {
 875         struct xpc_partition *part = &xpc_partitions[partid];
 876         enum xp_retval ret = xpUnknownReason;
 877 
 878         dev_dbg(xpc_chan, "payload=0x%p, partid=%d, channel=%d\n", payload,
 879                 partid, ch_number);
 880 
 881         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
 882         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
 883         DBUG_ON(payload == NULL);
 884 
 885         if (xpc_part_ref(part)) {
 886                 ret = xpc_arch_ops.send_payload(&part->channels[ch_number],
 887                                   flags, payload, payload_size, 0, NULL, NULL);
 888                 xpc_part_deref(part);
 889         }
 890 
 891         return ret;
 892 }
 893 
 894 /*
 895  * Send a message that contains the user's payload on the specified channel
 896  * connected to the specified partition.
 897  *
 898  * NOTE that this routine can sleep waiting for a message entry to become
 899  * available. To not sleep, pass in the XPC_NOWAIT flag.
 900  *
 901  * This routine will not wait for the message to be sent or received.
 902  *
 903  * Once the remote end of the channel has received the message, the function
 904  * passed as an argument to xpc_initiate_send_notify() will be called. This
 905  * allows the sender to free up or re-use any buffers referenced by the
 906  * message, but does NOT mean the message has been processed at the remote
 907  * end by a receiver.
 908  *
 909  * If this routine returns an error, the caller's function will NOT be called.
 910  *
 911  * Arguments:
 912  *
 913  *      partid - ID of partition to which the channel is connected.
 914  *      ch_number - channel # to send message on.
 915  *      flags - see xp.h for valid flags.
 916  *      payload - pointer to the payload which is to be sent.
 917  *      payload_size - size of the payload in bytes.
 918  *      func - function to call with asynchronous notification of message
 919  *                receipt. THIS FUNCTION MUST BE NON-BLOCKING.
 920  *      key - user-defined key to be passed to the function when it's called.
 921  */
 922 enum xp_retval
 923 xpc_initiate_send_notify(short partid, int ch_number, u32 flags, void *payload,
 924                          u16 payload_size, xpc_notify_func func, void *key)
 925 {
 926         struct xpc_partition *part = &xpc_partitions[partid];
 927         enum xp_retval ret = xpUnknownReason;
 928 
 929         dev_dbg(xpc_chan, "payload=0x%p, partid=%d, channel=%d\n", payload,
 930                 partid, ch_number);
 931 
 932         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
 933         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
 934         DBUG_ON(payload == NULL);
 935         DBUG_ON(func == NULL);
 936 
 937         if (xpc_part_ref(part)) {
 938                 ret = xpc_arch_ops.send_payload(&part->channels[ch_number],
 939                           flags, payload, payload_size, XPC_N_CALL, func, key);
 940                 xpc_part_deref(part);
 941         }
 942         return ret;
 943 }
 944 
 945 /*
 946  * Deliver a message's payload to its intended recipient.
 947  */
 948 void
 949 xpc_deliver_payload(struct xpc_channel *ch)
 950 {
 951         void *payload;
 952 
 953         payload = xpc_arch_ops.get_deliverable_payload(ch);
 954         if (payload != NULL) {
 955 
 956                 /*
 957                  * This ref is taken to protect the payload itself from being
 958                  * freed before the user is finished with it, which the user
 959                  * indicates by calling xpc_initiate_received().
 960                  */
 961                 xpc_msgqueue_ref(ch);
 962 
 963                 atomic_inc(&ch->kthreads_active);
 964 
 965                 if (ch->func != NULL) {
 966                         dev_dbg(xpc_chan, "ch->func() called, payload=0x%p "
 967                                 "partid=%d channel=%d\n", payload, ch->partid,
 968                                 ch->number);
 969 
 970                         /* deliver the message to its intended recipient */
 971                         ch->func(xpMsgReceived, ch->partid, ch->number, payload,
 972                                  ch->key);
 973 
 974                         dev_dbg(xpc_chan, "ch->func() returned, payload=0x%p "
 975                                 "partid=%d channel=%d\n", payload, ch->partid,
 976                                 ch->number);
 977                 }
 978 
 979                 atomic_dec(&ch->kthreads_active);
 980         }
 981 }
 982 
 983 /*
 984  * Acknowledge receipt of a delivered message's payload.
 985  *
 986  * This function, although called by users, does not call xpc_part_ref() to
 987  * ensure that the partition infrastructure is in place. It relies on the
 988  * fact that we called xpc_msgqueue_ref() in xpc_deliver_payload().
 989  *
 990  * Arguments:
 991  *
 992  *      partid - ID of partition to which the channel is connected.
 993  *      ch_number - channel # message received on.
 994  *      payload - pointer to the payload area allocated via
 995  *                      xpc_initiate_send() or xpc_initiate_send_notify().
 996  */
 997 void
 998 xpc_initiate_received(short partid, int ch_number, void *payload)
 999 {
1000         struct xpc_partition *part = &xpc_partitions[partid];
1001         struct xpc_channel *ch;
1002 
1003         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
1004         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
1005 
1006         ch = &part->channels[ch_number];
1007         xpc_arch_ops.received_payload(ch, payload);
1008 
1009         /* the call to xpc_msgqueue_ref() was done by xpc_deliver_payload()  */
1010         xpc_msgqueue_deref(ch);
1011 }