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