drivers/misc/sgi-xp/xpc_channel.c

   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) 2004-2008 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         DBUG_ON(!spin_is_locked(&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_allocate_msgqueues(ch);
  43                 spin_lock_irqsave(&ch->lock, *irq_flags);
  44
  45                 if (ret != xpSuccess)
  46                         XPC_DISCONNECT_CHANNEL(ch, ret, irq_flags);
  47
  48                 ch->flags |= XPC_C_SETUP;
  49
  50                 if (ch->flags & (XPC_C_CONNECTED | XPC_C_DISCONNECTING))
  51                         return;
  52
  53                 DBUG_ON(ch->local_msgqueue == NULL);
  54                 DBUG_ON(ch->remote_msgqueue == NULL);
  55         }
  56
  57         if (!(ch->flags & XPC_C_OPENREPLY)) {
  58                 ch->flags |= XPC_C_OPENREPLY;
  59                 xpc_send_chctl_openreply(ch, irq_flags);
  60         }
  61
  62         if (!(ch->flags & XPC_C_ROPENREPLY))
  63                 return;
  64
  65         DBUG_ON(ch->remote_msgqueue_pa == 0);
  66
  67         ch->flags = (XPC_C_CONNECTED | XPC_C_SETUP);    /* clear all else */
  68
  69         dev_info(xpc_chan, "channel %d to partition %d connected\n",
  70                  ch->number, ch->partid);
  71
  72         spin_unlock_irqrestore(&ch->lock, *irq_flags);
  73         xpc_create_kthreads(ch, 1, 0);
  74         spin_lock_irqsave(&ch->lock, *irq_flags);
  75 }
  76
  77 /*
  78  * spin_lock_irqsave() is expected to be held on entry.
  79  */
  80 static void
  81 xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
  82 {
  83         struct xpc_partition *part = &xpc_partitions[ch->partid];
  84         u32 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);
  85
  86         DBUG_ON(!spin_is_locked(&ch->lock));
  87
  88         if (!(ch->flags & XPC_C_DISCONNECTING))
  89                 return;
  90
  91         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
  92
  93         /* make sure all activity has settled down first */
  94
  95         if (atomic_read(&ch->kthreads_assigned) > 0 ||
  96             atomic_read(&ch->references) > 0) {
  97                 return;
  98         }
  99         DBUG_ON((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 100                 !(ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE));
 101
 102         if (part->act_state == XPC_P_DEACTIVATING) {
 103                 /* can't proceed until the other side disengages from us */
 104                 if (xpc_partition_engaged(ch->partid))
 105                         return;
 106
 107         } else {
 108
 109                 /* as long as the other side is up do the full protocol */
 110
 111                 if (!(ch->flags & XPC_C_RCLOSEREQUEST))
 112                         return;
 113
 114                 if (!(ch->flags & XPC_C_CLOSEREPLY)) {
 115                         ch->flags |= XPC_C_CLOSEREPLY;
 116                         xpc_send_chctl_closereply(ch, irq_flags);
 117                 }
 118
 119                 if (!(ch->flags & XPC_C_RCLOSEREPLY))
 120                         return;
 121         }
 122
 123         /* wake those waiting for notify completion */
 124         if (atomic_read(&ch->n_to_notify) > 0) {
 125                 /* we do callout while holding ch->lock, callout can't block */
 126                 xpc_notify_senders_of_disconnect(ch);
 127         }
 128
 129         /* both sides are disconnected now */
 130
 131         if (ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE) {
 132                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
 133                 xpc_disconnect_callout(ch, xpDisconnected);
 134                 spin_lock_irqsave(&ch->lock, *irq_flags);
 135         }
 136
 137         /* it's now safe to free the channel's message queues */
 138         xpc_free_msgqueues(ch);
 139
 140         /*
 141          * Mark the channel disconnected and clear all other flags, including
 142          * XPC_C_SETUP (because of call to xpc_free_msgqueues()) but not
 143          * including XPC_C_WDISCONNECT (if it was set).
 144          */
 145         ch->flags = (XPC_C_DISCONNECTED | (ch->flags & XPC_C_WDISCONNECT));
 146
 147         atomic_dec(&part->nchannels_active);
 148
 149         if (channel_was_connected) {
 150                 dev_info(xpc_chan, "channel %d to partition %d disconnected, "
 151                          "reason=%d\n", ch->number, ch->partid, ch->reason);
 152         }
 153
 154         if (ch->flags & XPC_C_WDISCONNECT) {
 155                 /* we won't lose the CPU since we're holding ch->lock */
 156                 complete(&ch->wdisconnect_wait);
 157         } else if (ch->delayed_chctl_flags) {
 158                 if (part->act_state != XPC_P_DEACTIVATING) {
 159                         /* time to take action on any delayed chctl flags */
 160                         spin_lock(&part->chctl_lock);
 161                         part->chctl.flags[ch->number] |=
 162                             ch->delayed_chctl_flags;
 163                         spin_unlock(&part->chctl_lock);
 164                 }
 165                 ch->delayed_chctl_flags = 0;
 166         }
 167 }
 168
 169 /*
 170  * Process a change in the channel's remote connection state.
 171  */
 172 static void
 173 xpc_process_openclose_chctl_flags(struct xpc_partition *part, int ch_number,
 174                                   u8 chctl_flags)
 175 {
 176         unsigned long irq_flags;
 177         struct xpc_openclose_args *args =
 178             &part->remote_openclose_args[ch_number];
 179         struct xpc_channel *ch = &part->channels[ch_number];
 180         enum xp_retval reason;
 181
 182         spin_lock_irqsave(&ch->lock, irq_flags);
 183
 184 again:
 185
 186         if ((ch->flags & XPC_C_DISCONNECTED) &&
 187             (ch->flags & XPC_C_WDISCONNECT)) {
 188                 /*
 189                  * Delay processing chctl flags until thread waiting disconnect
 190                  * has had a chance to see that the channel is disconnected.
 191                  */
 192                 ch->delayed_chctl_flags |= chctl_flags;
 193                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 194                 return;
 195         }
 196
 197         if (chctl_flags & XPC_CHCTL_CLOSEREQUEST) {
 198
 199                 dev_dbg(xpc_chan, "XPC_CHCTL_CLOSEREQUEST (reason=%d) received "
 200                         "from partid=%d, channel=%d\n", args->reason,
 201                         ch->partid, ch->number);
 202
 203                 /*
 204                  * If RCLOSEREQUEST is set, we're probably waiting for
 205                  * RCLOSEREPLY. We should find it and a ROPENREQUEST packed
 206                  * with this RCLOSEREQUEST in the chctl_flags.
 207                  */
 208
 209                 if (ch->flags & XPC_C_RCLOSEREQUEST) {
 210                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTING));
 211                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 212                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREPLY));
 213                         DBUG_ON(ch->flags & XPC_C_RCLOSEREPLY);
 214
 215                         DBUG_ON(!(chctl_flags & XPC_CHCTL_CLOSEREPLY));
 216                         chctl_flags &= ~XPC_CHCTL_CLOSEREPLY;
 217                         ch->flags |= XPC_C_RCLOSEREPLY;
 218
 219                         /* both sides have finished disconnecting */
 220                         xpc_process_disconnect(ch, &irq_flags);
 221                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 222                         goto again;
 223                 }
 224
 225                 if (ch->flags & XPC_C_DISCONNECTED) {
 226                         if (!(chctl_flags & XPC_CHCTL_OPENREQUEST)) {
 227                                 if (part->chctl.flags[ch_number] &
 228                                     XPC_CHCTL_OPENREQUEST) {
 229
 230                                         DBUG_ON(ch->delayed_chctl_flags != 0);
 231                                         spin_lock(&part->chctl_lock);
 232                                         part->chctl.flags[ch_number] |=
 233                                             XPC_CHCTL_CLOSEREQUEST;
 234                                         spin_unlock(&part->chctl_lock);
 235                                 }
 236                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 237                                 return;
 238                         }
 239
 240                         XPC_SET_REASON(ch, 0, 0);
 241                         ch->flags &= ~XPC_C_DISCONNECTED;
 242
 243                         atomic_inc(&part->nchannels_active);
 244                         ch->flags |= (XPC_C_CONNECTING | XPC_C_ROPENREQUEST);
 245                 }
 246
 247                 chctl_flags &= ~(XPC_CHCTL_OPENREQUEST | XPC_CHCTL_OPENREPLY);
 248
 249                 /*
 250                  * The meaningful CLOSEREQUEST connection state fields are:
 251                  *      reason = reason connection is to be closed
 252                  */
 253
 254                 ch->flags |= XPC_C_RCLOSEREQUEST;
 255
 256                 if (!(ch->flags & XPC_C_DISCONNECTING)) {
 257                         reason = args->reason;
 258                         if (reason <= xpSuccess || reason > xpUnknownReason)
 259                                 reason = xpUnknownReason;
 260                         else if (reason == xpUnregistering)
 261                                 reason = xpOtherUnregistering;
 262
 263                         XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
 264
 265                         DBUG_ON(chctl_flags & XPC_CHCTL_CLOSEREPLY);
 266                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 267                         return;
 268                 }
 269
 270                 xpc_process_disconnect(ch, &irq_flags);
 271         }
 272
 273         if (chctl_flags & XPC_CHCTL_CLOSEREPLY) {
 274
 275                 dev_dbg(xpc_chan, "XPC_CHCTL_CLOSEREPLY received from partid="
 276                         "%d, channel=%d\n", ch->partid, ch->number);
 277
 278                 if (ch->flags & XPC_C_DISCONNECTED) {
 279                         DBUG_ON(part->act_state != XPC_P_DEACTIVATING);
 280                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 281                         return;
 282                 }
 283
 284                 DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 285
 286                 if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
 287                         if (part->chctl.flags[ch_number] &
 288                             XPC_CHCTL_CLOSEREQUEST) {
 289
 290                                 DBUG_ON(ch->delayed_chctl_flags != 0);
 291                                 spin_lock(&part->chctl_lock);
 292                                 part->chctl.flags[ch_number] |=
 293                                     XPC_CHCTL_CLOSEREPLY;
 294                                 spin_unlock(&part->chctl_lock);
 295                         }
 296                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 297                         return;
 298                 }
 299
 300                 ch->flags |= XPC_C_RCLOSEREPLY;
 301
 302                 if (ch->flags & XPC_C_CLOSEREPLY) {
 303                         /* both sides have finished disconnecting */
 304                         xpc_process_disconnect(ch, &irq_flags);
 305                 }
 306         }
 307
 308         if (chctl_flags & XPC_CHCTL_OPENREQUEST) {
 309
 310                 dev_dbg(xpc_chan, "XPC_CHCTL_OPENREQUEST (msg_size=%d, "
 311                         "local_nentries=%d) received from partid=%d, "
 312                         "channel=%d\n", args->msg_size, args->local_nentries,
 313                         ch->partid, ch->number);
 314
 315                 if (part->act_state == XPC_P_DEACTIVATING ||
 316                     (ch->flags & XPC_C_ROPENREQUEST)) {
 317                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 318                         return;
 319                 }
 320
 321                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_WDISCONNECT)) {
 322                         ch->delayed_chctl_flags |= XPC_CHCTL_OPENREQUEST;
 323                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 324                         return;
 325                 }
 326                 DBUG_ON(!(ch->flags & (XPC_C_DISCONNECTED |
 327                                        XPC_C_OPENREQUEST)));
 328                 DBUG_ON(ch->flags & (XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
 329                                      XPC_C_OPENREPLY | XPC_C_CONNECTED));
 330
 331                 /*
 332                  * The meaningful OPENREQUEST connection state fields are:
 333                  *      msg_size = size of channel's messages in bytes
 334                  *      local_nentries = remote partition's local_nentries
 335                  */
 336                 if (args->msg_size == 0 || args->local_nentries == 0) {
 337                         /* assume OPENREQUEST was delayed by mistake */
 338                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 339                         return;
 340                 }
 341
 342                 ch->flags |= (XPC_C_ROPENREQUEST | XPC_C_CONNECTING);
 343                 ch->remote_nentries = args->local_nentries;
 344
 345                 if (ch->flags & XPC_C_OPENREQUEST) {
 346                         if (args->msg_size != ch->msg_size) {
 347                                 XPC_DISCONNECT_CHANNEL(ch, xpUnequalMsgSizes,
 348                                                        &irq_flags);
 349                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 350                                 return;
 351                         }
 352                 } else {
 353                         ch->msg_size = args->msg_size;
 354
 355                         XPC_SET_REASON(ch, 0, 0);
 356                         ch->flags &= ~XPC_C_DISCONNECTED;
 357
 358                         atomic_inc(&part->nchannels_active);
 359                 }
 360
 361                 xpc_process_connect(ch, &irq_flags);
 362         }
 363
 364         if (chctl_flags & XPC_CHCTL_OPENREPLY) {
 365
 366                 dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY (local_msgqueue_pa="
 367                         "0x%lx, local_nentries=%d, remote_nentries=%d) "
 368                         "received from partid=%d, channel=%d\n",
 369                         (unsigned long)args->local_msgqueue_pa,
 370                         args->local_nentries, args->remote_nentries,
 371                         ch->partid, ch->number);
 372
 373                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
 374                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 375                         return;
 376                 }
 377                 if (!(ch->flags & XPC_C_OPENREQUEST)) {
 378                         XPC_DISCONNECT_CHANNEL(ch, xpOpenCloseError,
 379                                                &irq_flags);
 380                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 381                         return;
 382                 }
 383
 384                 DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
 385                 DBUG_ON(ch->flags & XPC_C_CONNECTED);
 386
 387                 /*
 388                  * The meaningful OPENREPLY connection state fields are:
 389                  *      local_msgqueue_pa = physical address of remote
 390                  *                          partition's local_msgqueue
 391                  *      local_nentries = remote partition's local_nentries
 392                  *      remote_nentries = remote partition's remote_nentries
 393                  */
 394                 DBUG_ON(args->local_msgqueue_pa == 0);
 395                 DBUG_ON(args->local_nentries == 0);
 396                 DBUG_ON(args->remote_nentries == 0);
 397
 398                 ch->flags |= XPC_C_ROPENREPLY;
 399                 ch->remote_msgqueue_pa = args->local_msgqueue_pa;
 400
 401                 if (args->local_nentries < ch->remote_nentries) {
 402                         dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY: new "
 403                                 "remote_nentries=%d, old remote_nentries=%d, "
 404                                 "partid=%d, channel=%d\n",
 405                                 args->local_nentries, ch->remote_nentries,
 406                                 ch->partid, ch->number);
 407
 408                         ch->remote_nentries = args->local_nentries;
 409                 }
 410                 if (args->remote_nentries < ch->local_nentries) {
 411                         dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY: new "
 412                                 "local_nentries=%d, old local_nentries=%d, "
 413                                 "partid=%d, channel=%d\n",
 414                                 args->remote_nentries, ch->local_nentries,
 415                                 ch->partid, ch->number);
 416
 417                         ch->local_nentries = args->remote_nentries;
 418                 }
 419
 420                 xpc_process_connect(ch, &irq_flags);
 421         }
 422
 423         spin_unlock_irqrestore(&ch->lock, irq_flags);
 424 }
 425
 426 /*
 427  * Attempt to establish a channel connection to a remote partition.
 428  */
 429 static enum xp_retval
 430 xpc_connect_channel(struct xpc_channel *ch)
 431 {
 432         unsigned long irq_flags;
 433         struct xpc_registration *registration = &xpc_registrations[ch->number];
 434
 435         if (mutex_trylock(&registration->mutex) == 0)
 436                 return xpRetry;
 437
 438         if (!XPC_CHANNEL_REGISTERED(ch->number)) {
 439                 mutex_unlock(&registration->mutex);
 440                 return xpUnregistered;
 441         }
 442
 443         spin_lock_irqsave(&ch->lock, irq_flags);
 444
 445         DBUG_ON(ch->flags & XPC_C_CONNECTED);
 446         DBUG_ON(ch->flags & XPC_C_OPENREQUEST);
 447
 448         if (ch->flags & XPC_C_DISCONNECTING) {
 449                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 450                 mutex_unlock(&registration->mutex);
 451                 return ch->reason;
 452         }
 453
 454         /* add info from the channel connect registration to the channel */
 455
 456         ch->kthreads_assigned_limit = registration->assigned_limit;
 457         ch->kthreads_idle_limit = registration->idle_limit;
 458         DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
 459         DBUG_ON(atomic_read(&ch->kthreads_idle) != 0);
 460         DBUG_ON(atomic_read(&ch->kthreads_active) != 0);
 461
 462         ch->func = registration->func;
 463         DBUG_ON(registration->func == NULL);
 464         ch->key = registration->key;
 465
 466         ch->local_nentries = registration->nentries;
 467
 468         if (ch->flags & XPC_C_ROPENREQUEST) {
 469                 if (registration->msg_size != ch->msg_size) {
 470                         /* the local and remote sides aren't the same */
 471
 472                         /*
 473                          * Because XPC_DISCONNECT_CHANNEL() can block we're
 474                          * forced to up the registration sema before we unlock
 475                          * the channel lock. But that's okay here because we're
 476                          * done with the part that required the registration
 477                          * sema. XPC_DISCONNECT_CHANNEL() requires that the
 478                          * channel lock be locked and will unlock and relock
 479                          * the channel lock as needed.
 480                          */
 481                         mutex_unlock(&registration->mutex);
 482                         XPC_DISCONNECT_CHANNEL(ch, xpUnequalMsgSizes,
 483                                                &irq_flags);
 484                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 485                         return xpUnequalMsgSizes;
 486                 }
 487         } else {
 488                 ch->msg_size = registration->msg_size;
 489
 490                 XPC_SET_REASON(ch, 0, 0);
 491                 ch->flags &= ~XPC_C_DISCONNECTED;
 492
 493                 atomic_inc(&xpc_partitions[ch->partid].nchannels_active);
 494         }
 495
 496         mutex_unlock(&registration->mutex);
 497
 498         /* initiate the connection */
 499
 500         ch->flags |= (XPC_C_OPENREQUEST | XPC_C_CONNECTING);
 501         xpc_send_chctl_openrequest(ch, &irq_flags);
 502
 503         xpc_process_connect(ch, &irq_flags);
 504
 505         spin_unlock_irqrestore(&ch->lock, irq_flags);
 506
 507         return xpSuccess;
 508 }
 509
 510 void
 511 xpc_process_sent_chctl_flags(struct xpc_partition *part)
 512 {
 513         unsigned long irq_flags;
 514         union xpc_channel_ctl_flags chctl;
 515         struct xpc_channel *ch;
 516         int ch_number;
 517         u32 ch_flags;
 518
 519         chctl.all_flags = xpc_get_chctl_all_flags(part);
 520
 521         /*
 522          * Initiate channel connections for registered channels.
 523          *
 524          * For each connected channel that has pending messages activate idle
 525          * kthreads and/or create new kthreads as needed.
 526          */
 527
 528         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
 529                 ch = &part->channels[ch_number];
 530
 531                 /*
 532                  * Process any open or close related chctl flags, and then deal
 533                  * with connecting or disconnecting the channel as required.
 534                  */
 535
 536                 if (chctl.flags[ch_number] & XPC_OPENCLOSE_CHCTL_FLAGS) {
 537                         xpc_process_openclose_chctl_flags(part, ch_number,
 538                                                         chctl.flags[ch_number]);
 539                 }
 540
 541                 ch_flags = ch->flags;   /* need an atomic snapshot of flags */
 542
 543                 if (ch_flags & XPC_C_DISCONNECTING) {
 544                         spin_lock_irqsave(&ch->lock, irq_flags);
 545                         xpc_process_disconnect(ch, &irq_flags);
 546                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 547                         continue;
 548                 }
 549
 550                 if (part->act_state == XPC_P_DEACTIVATING)
 551                         continue;
 552
 553                 if (!(ch_flags & XPC_C_CONNECTED)) {
 554                         if (!(ch_flags & XPC_C_OPENREQUEST)) {
 555                                 DBUG_ON(ch_flags & XPC_C_SETUP);
 556                                 (void)xpc_connect_channel(ch);
 557                         } else {
 558                                 spin_lock_irqsave(&ch->lock, irq_flags);
 559                                 xpc_process_connect(ch, &irq_flags);
 560                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 561                         }
 562                         continue;
 563                 }
 564
 565                 /*
 566                  * Process any message related chctl flags, this may involve
 567                  * the activation of kthreads to deliver any pending messages
 568                  * sent from the other partition.
 569                  */
 570
 571                 if (chctl.flags[ch_number] & XPC_MSG_CHCTL_FLAGS)
 572                         xpc_process_msg_chctl_flags(part, ch_number);
 573         }
 574 }
 575
 576 /*
 577  * XPC's heartbeat code calls this function to inform XPC that a partition is
 578  * going down.  XPC responds by tearing down the XPartition Communication
 579  * infrastructure used for the just downed partition.
 580  *
 581  * XPC's heartbeat code will never call this function and xpc_partition_up()
 582  * at the same time. Nor will it ever make multiple calls to either function
 583  * at the same time.
 584  */
 585 void
 586 xpc_partition_going_down(struct xpc_partition *part, enum xp_retval reason)
 587 {
 588         unsigned long irq_flags;
 589         int ch_number;
 590         struct xpc_channel *ch;
 591
 592         dev_dbg(xpc_chan, "deactivating partition %d, reason=%d\n",
 593                 XPC_PARTID(part), reason);
 594
 595         if (!xpc_part_ref(part)) {
 596                 /* infrastructure for this partition isn't currently set up */
 597                 return;
 598         }
 599
 600         /* disconnect channels associated with the partition going down */
 601
 602         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
 603                 ch = &part->channels[ch_number];
 604
 605                 xpc_msgqueue_ref(ch);
 606                 spin_lock_irqsave(&ch->lock, irq_flags);
 607
 608                 XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
 609
 610                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 611                 xpc_msgqueue_deref(ch);
 612         }
 613
 614         xpc_wakeup_channel_mgr(part);
 615
 616         xpc_part_deref(part);
 617 }
 618
 619 /*
 620  * Called by XP at the time of channel connection registration to cause
 621  * XPC to establish connections to all currently active partitions.
 622  */
 623 void
 624 xpc_initiate_connect(int ch_number)
 625 {
 626         short partid;
 627         struct xpc_partition *part;
 628         struct xpc_channel *ch;
 629
 630         DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);
 631
 632         for (partid = 0; partid < xp_max_npartitions; partid++) {
 633                 part = &xpc_partitions[partid];
 634
 635                 if (xpc_part_ref(part)) {
 636                         ch = &part->channels[ch_number];
 637
 638                         /*
 639                          * Initiate the establishment of a connection on the
 640                          * newly registered channel to the remote partition.
 641                          */
 642                         xpc_wakeup_channel_mgr(part);
 643                         xpc_part_deref(part);
 644                 }
 645         }
 646 }
 647
 648 void
 649 xpc_connected_callout(struct xpc_channel *ch)
 650 {
 651         /* let the registerer know that a connection has been established */
 652
 653         if (ch->func != NULL) {
 654                 dev_dbg(xpc_chan, "ch->func() called, reason=xpConnected, "
 655                         "partid=%d, channel=%d\n", ch->partid, ch->number);
 656
 657                 ch->func(xpConnected, ch->partid, ch->number,
 658                          (void *)(u64)ch->local_nentries, ch->key);
 659
 660                 dev_dbg(xpc_chan, "ch->func() returned, reason=xpConnected, "
 661                         "partid=%d, channel=%d\n", ch->partid, ch->number);
 662         }
 663 }
 664
 665 /*
 666  * Called by XP at the time of channel connection unregistration to cause
 667  * XPC to teardown all current connections for the specified channel.
 668  *
 669  * Before returning xpc_initiate_disconnect() will wait until all connections
 670  * on the specified channel have been closed/torndown. So the caller can be
 671  * assured that they will not be receiving any more callouts from XPC to the
 672  * function they registered via xpc_connect().
 673  *
 674  * Arguments:
 675  *
 676  *      ch_number - channel # to unregister.
 677  */
 678 void
 679 xpc_initiate_disconnect(int ch_number)
 680 {
 681         unsigned long irq_flags;
 682         short partid;
 683         struct xpc_partition *part;
 684         struct xpc_channel *ch;
 685
 686         DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);
 687
 688         /* initiate the channel disconnect for every active partition */
 689         for (partid = 0; partid < xp_max_npartitions; partid++) {
 690                 part = &xpc_partitions[partid];
 691
 692                 if (xpc_part_ref(part)) {
 693                         ch = &part->channels[ch_number];
 694                         xpc_msgqueue_ref(ch);
 695
 696                         spin_lock_irqsave(&ch->lock, irq_flags);
 697
 698                         if (!(ch->flags & XPC_C_DISCONNECTED)) {
 699                                 ch->flags |= XPC_C_WDISCONNECT;
 700
 701                                 XPC_DISCONNECT_CHANNEL(ch, xpUnregistering,
 702                                                        &irq_flags);
 703                         }
 704
 705                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 706
 707                         xpc_msgqueue_deref(ch);
 708                         xpc_part_deref(part);
 709                 }
 710         }
 711
 712         xpc_disconnect_wait(ch_number);
 713 }
 714
 715 /*
 716  * To disconnect a channel, and reflect it back to all who may be waiting.
 717  *
 718  * An OPEN is not allowed until XPC_C_DISCONNECTING is cleared by
 719  * xpc_process_disconnect(), and if set, XPC_C_WDISCONNECT is cleared by
 720  * xpc_disconnect_wait().
 721  *
 722  * THE CHANNEL IS TO BE LOCKED BY THE CALLER AND WILL REMAIN LOCKED UPON RETURN.
 723  */
 724 void
 725 xpc_disconnect_channel(const int line, struct xpc_channel *ch,
 726                        enum xp_retval reason, unsigned long *irq_flags)
 727 {
 728         u32 channel_was_connected = (ch->flags & XPC_C_CONNECTED);
 729
 730         DBUG_ON(!spin_is_locked(&ch->lock));
 731
 732         if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED))
 733                 return;
 734
 735         DBUG_ON(!(ch->flags & (XPC_C_CONNECTING | XPC_C_CONNECTED)));
 736
 737         dev_dbg(xpc_chan, "reason=%d, line=%d, partid=%d, channel=%d\n",
 738                 reason, line, ch->partid, ch->number);
 739
 740         XPC_SET_REASON(ch, reason, line);
 741
 742         ch->flags |= (XPC_C_CLOSEREQUEST | XPC_C_DISCONNECTING);
 743         /* some of these may not have been set */
 744         ch->flags &= ~(XPC_C_OPENREQUEST | XPC_C_OPENREPLY |
 745                        XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
 746                        XPC_C_CONNECTING | XPC_C_CONNECTED);
 747
 748         xpc_send_chctl_closerequest(ch, irq_flags);
 749
 750         if (channel_was_connected)
 751                 ch->flags |= XPC_C_WASCONNECTED;
 752
 753         spin_unlock_irqrestore(&ch->lock, *irq_flags);
 754
 755         /* wake all idle kthreads so they can exit */
 756         if (atomic_read(&ch->kthreads_idle) > 0) {
 757                 wake_up_all(&ch->idle_wq);
 758
 759         } else if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 760                    !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
 761                 /* start a kthread that will do the xpDisconnecting callout */
 762                 xpc_create_kthreads(ch, 1, 1);
 763         }
 764
 765         /* wake those waiting to allocate an entry from the local msg queue */
 766         if (atomic_read(&ch->n_on_msg_allocate_wq) > 0)
 767                 wake_up(&ch->msg_allocate_wq);
 768
 769         spin_lock_irqsave(&ch->lock, *irq_flags);
 770 }
 771
 772 void
 773 xpc_disconnect_callout(struct xpc_channel *ch, enum xp_retval reason)
 774 {
 775         /*
 776          * Let the channel's registerer know that the channel is being
 777          * disconnected. We don't want to do this if the registerer was never
 778          * informed of a connection being made.
 779          */
 780
 781         if (ch->func != NULL) {
 782                 dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
 783                         "channel=%d\n", reason, ch->partid, ch->number);
 784
 785                 ch->func(reason, ch->partid, ch->number, NULL, ch->key);
 786
 787                 dev_dbg(xpc_chan, "ch->func() returned, reason=%d, partid=%d, "
 788                         "channel=%d\n", reason, ch->partid, ch->number);
 789         }
 790 }
 791
 792 /*
 793  * Wait for a message entry to become available for the specified channel,
 794  * but don't wait any longer than 1 jiffy.
 795  */
 796 enum xp_retval
 797 xpc_allocate_msg_wait(struct xpc_channel *ch)
 798 {
 799         enum xp_retval ret;
 800
 801         if (ch->flags & XPC_C_DISCONNECTING) {
 802                 DBUG_ON(ch->reason == xpInterrupted);
 803                 return ch->reason;
 804         }
 805
 806         atomic_inc(&ch->n_on_msg_allocate_wq);
 807         ret = interruptible_sleep_on_timeout(&ch->msg_allocate_wq, 1);
 808         atomic_dec(&ch->n_on_msg_allocate_wq);
 809
 810         if (ch->flags & XPC_C_DISCONNECTING) {
 811                 ret = ch->reason;
 812                 DBUG_ON(ch->reason == xpInterrupted);
 813         } else if (ret == 0) {
 814                 ret = xpTimeout;
 815         } else {
 816                 ret = xpInterrupted;
 817         }
 818
 819         return ret;
 820 }
 821
 822 /*
 823  * Send a message that contains the user's payload on the specified channel
 824  * connected to the specified partition.
 825  *
 826  * NOTE that this routine can sleep waiting for a message entry to become
 827  * available. To not sleep, pass in the XPC_NOWAIT flag.
 828  *
 829  * Once sent, this routine will not wait for the message to be received, nor
 830  * will notification be given when it does happen.
 831  *
 832  * Arguments:
 833  *
 834  *      partid - ID of partition to which the channel is connected.
 835  *      ch_number - channel # to send message on.
 836  *      flags - see xp.h for valid flags.
 837  *      payload - pointer to the payload which is to be sent.
 838  *      payload_size - size of the payload in bytes.
 839  */
 840 enum xp_retval
 841 xpc_initiate_send(short partid, int ch_number, u32 flags, void *payload,
 842                   u16 payload_size)
 843 {
 844         struct xpc_partition *part = &xpc_partitions[partid];
 845         enum xp_retval ret = xpUnknownReason;
 846
 847         dev_dbg(xpc_chan, "payload=0x%p, partid=%d, channel=%d\n", payload,
 848                 partid, ch_number);
 849
 850         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
 851         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
 852         DBUG_ON(payload == NULL);
 853
 854         if (xpc_part_ref(part)) {
 855                 ret = xpc_send_msg(&part->channels[ch_number], flags, payload,
 856                                    payload_size, 0, NULL, NULL);
 857                 xpc_part_deref(part);
 858         }
 859
 860         return ret;
 861 }
 862
 863 /*
 864  * Send a message that contains the user's payload on the specified channel
 865  * connected to the specified partition.
 866  *
 867  * NOTE that this routine can sleep waiting for a message entry to become
 868  * available. To not sleep, pass in the XPC_NOWAIT flag.
 869  *
 870  * This routine will not wait for the message to be sent or received.
 871  *
 872  * Once the remote end of the channel has received the message, the function
 873  * passed as an argument to xpc_initiate_send_notify() will be called. This
 874  * allows the sender to free up or re-use any buffers referenced by the
 875  * message, but does NOT mean the message has been processed at the remote
 876  * end by a receiver.
 877  *
 878  * If this routine returns an error, the caller's function will NOT be called.
 879  *
 880  * Arguments:
 881  *
 882  *      partid - ID of partition to which the channel is connected.
 883  *      ch_number - channel # to send message on.
 884  *      flags - see xp.h for valid flags.
 885  *      payload - pointer to the payload which is to be sent.
 886  *      payload_size - size of the payload in bytes.
 887  *      func - function to call with asynchronous notification of message
 888  *                receipt. THIS FUNCTION MUST BE NON-BLOCKING.
 889  *      key - user-defined key to be passed to the function when it's called.
 890  */
 891 enum xp_retval
 892 xpc_initiate_send_notify(short partid, int ch_number, u32 flags, void *payload,
 893                          u16 payload_size, xpc_notify_func func, void *key)
 894 {
 895         struct xpc_partition *part = &xpc_partitions[partid];
 896         enum xp_retval ret = xpUnknownReason;
 897
 898         dev_dbg(xpc_chan, "payload=0x%p, partid=%d, channel=%d\n", payload,
 899                 partid, ch_number);
 900
 901         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
 902         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
 903         DBUG_ON(payload == NULL);
 904         DBUG_ON(func == NULL);
 905
 906         if (xpc_part_ref(part)) {
 907                 ret = xpc_send_msg(&part->channels[ch_number], flags, payload,
 908                                    payload_size, XPC_N_CALL, func, key);
 909                 xpc_part_deref(part);
 910         }
 911         return ret;
 912 }
 913
 914 /*
 915  * Deliver a message to its intended recipient.
 916  */
 917 void
 918 xpc_deliver_msg(struct xpc_channel *ch)
 919 {
 920         struct xpc_msg *msg;
 921
 922         msg = xpc_get_deliverable_msg(ch);
 923         if (msg != NULL) {
 924
 925                 /*
 926                  * This ref is taken to protect the payload itself from being
 927                  * freed before the user is finished with it, which the user
 928                  * indicates by calling xpc_initiate_received().
 929                  */
 930                 xpc_msgqueue_ref(ch);
 931
 932                 atomic_inc(&ch->kthreads_active);
 933
 934                 if (ch->func != NULL) {
 935                         dev_dbg(xpc_chan, "ch->func() called, msg=0x%p, "
 936                                 "msg_number=%ld, partid=%d, channel=%d\n",
 937                                 msg, (signed long)msg->number, ch->partid,
 938                                 ch->number);
 939
 940                         /* deliver the message to its intended recipient */
 941                         ch->func(xpMsgReceived, ch->partid, ch->number,
 942                                  &msg->payload, ch->key);
 943
 944                         dev_dbg(xpc_chan, "ch->func() returned, msg=0x%p, "
 945                                 "msg_number=%ld, partid=%d, channel=%d\n",
 946                                 msg, (signed long)msg->number, ch->partid,
 947                                 ch->number);
 948                 }
 949
 950                 atomic_dec(&ch->kthreads_active);
 951         }
 952 }
 953
 954 /*
 955  * Acknowledge receipt of a delivered message.
 956  *
 957  * If a message has XPC_M_INTERRUPT set, send an interrupt to the partition
 958  * that sent the message.
 959  *
 960  * This function, although called by users, does not call xpc_part_ref() to
 961  * ensure that the partition infrastructure is in place. It relies on the
 962  * fact that we called xpc_msgqueue_ref() in xpc_deliver_msg().
 963  *
 964  * Arguments:
 965  *
 966  *      partid - ID of partition to which the channel is connected.
 967  *      ch_number - channel # message received on.
 968  *      payload - pointer to the payload area allocated via
 969  *                      xpc_initiate_send() or xpc_initiate_send_notify().
 970  */
 971 void
 972 xpc_initiate_received(short partid, int ch_number, void *payload)
 973 {
 974         struct xpc_partition *part = &xpc_partitions[partid];
 975         struct xpc_channel *ch;
 976         struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
 977
 978         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
 979         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
 980
 981         ch = &part->channels[ch_number];
 982         xpc_received_msg(ch, msg);
 983
 984         /* the call to xpc_msgqueue_ref() was done by xpc_deliver_msg()  */
 985         xpc_msgqueue_deref(ch);
 986 }