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/kernel.h>
  18 #include <linux/init.h>
  19 #include <linux/sched.h>
  20 #include <linux/cache.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/mutex.h>
  23 #include <linux/completion.h>
  24 #include <asm/sn/sn_sal.h>
  25 #include "xpc.h"
  26
  27 /*
  28  * Guarantee that the kzalloc'd memory is cacheline aligned.
  29  */
  30 void *
  31 xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
  32 {
  33         /* see if kzalloc will give us cachline aligned memory by default */
  34         *base = kzalloc(size, flags);
  35         if (*base == NULL)
  36                 return NULL;
  37
  38         if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
  39                 return *base;
  40
  41         kfree(*base);
  42
  43         /* nope, we'll have to do it ourselves */
  44         *base = kzalloc(size + L1_CACHE_BYTES, flags);
  45         if (*base == NULL)
  46                 return NULL;
  47
  48         return (void *)L1_CACHE_ALIGN((u64)*base);
  49 }
  50
  51 /*
  52  * Allocate the local message queue and the notify queue.
  53  */
  54 static enum xp_retval
  55 xpc_allocate_local_msgqueue(struct xpc_channel *ch)
  56 {
  57         unsigned long irq_flags;
  58         int nentries;
  59         size_t nbytes;
  60
  61         for (nentries = ch->local_nentries; nentries > 0; nentries--) {
  62
  63                 nbytes = nentries * ch->msg_size;
  64                 ch->local_msgqueue = xpc_kzalloc_cacheline_aligned(nbytes,
  65                                                                    GFP_KERNEL,
  66                                                       &ch->local_msgqueue_base);
  67                 if (ch->local_msgqueue == NULL)
  68                         continue;
  69
  70                 nbytes = nentries * sizeof(struct xpc_notify);
  71                 ch->notify_queue = kzalloc(nbytes, GFP_KERNEL);
  72                 if (ch->notify_queue == NULL) {
  73                         kfree(ch->local_msgqueue_base);
  74                         ch->local_msgqueue = NULL;
  75                         continue;
  76                 }
  77
  78                 spin_lock_irqsave(&ch->lock, irq_flags);
  79                 if (nentries < ch->local_nentries) {
  80                         dev_dbg(xpc_chan, "nentries=%d local_nentries=%d, "
  81                                 "partid=%d, channel=%d\n", nentries,
  82                                 ch->local_nentries, ch->partid, ch->number);
  83
  84                         ch->local_nentries = nentries;
  85                 }
  86                 spin_unlock_irqrestore(&ch->lock, irq_flags);
  87                 return xpSuccess;
  88         }
  89
  90         dev_dbg(xpc_chan, "can't get memory for local message queue and notify "
  91                 "queue, partid=%d, channel=%d\n", ch->partid, ch->number);
  92         return xpNoMemory;
  93 }
  94
  95 /*
  96  * Allocate the cached remote message queue.
  97  */
  98 static enum xp_retval
  99 xpc_allocate_remote_msgqueue(struct xpc_channel *ch)
 100 {
 101         unsigned long irq_flags;
 102         int nentries;
 103         size_t nbytes;
 104
 105         DBUG_ON(ch->remote_nentries <= 0);
 106
 107         for (nentries = ch->remote_nentries; nentries > 0; nentries--) {
 108
 109                 nbytes = nentries * ch->msg_size;
 110                 ch->remote_msgqueue = xpc_kzalloc_cacheline_aligned(nbytes,
 111                                                                     GFP_KERNEL,
 112                                                      &ch->remote_msgqueue_base);
 113                 if (ch->remote_msgqueue == NULL)
 114                         continue;
 115
 116                 spin_lock_irqsave(&ch->lock, irq_flags);
 117                 if (nentries < ch->remote_nentries) {
 118                         dev_dbg(xpc_chan, "nentries=%d remote_nentries=%d, "
 119                                 "partid=%d, channel=%d\n", nentries,
 120                                 ch->remote_nentries, ch->partid, ch->number);
 121
 122                         ch->remote_nentries = nentries;
 123                 }
 124                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 125                 return xpSuccess;
 126         }
 127
 128         dev_dbg(xpc_chan, "can't get memory for cached remote message queue, "
 129                 "partid=%d, channel=%d\n", ch->partid, ch->number);
 130         return xpNoMemory;
 131 }
 132
 133 /*
 134  * Allocate message queues and other stuff associated with a channel.
 135  *
 136  * Note: Assumes all of the channel sizes are filled in.
 137  */
 138 static enum xp_retval
 139 xpc_allocate_msgqueues(struct xpc_channel *ch)
 140 {
 141         unsigned long irq_flags;
 142         enum xp_retval ret;
 143
 144         DBUG_ON(ch->flags & XPC_C_SETUP);
 145
 146         ret = xpc_allocate_local_msgqueue(ch);
 147         if (ret != xpSuccess)
 148                 return ret;
 149
 150         ret = xpc_allocate_remote_msgqueue(ch);
 151         if (ret != xpSuccess) {
 152                 kfree(ch->local_msgqueue_base);
 153                 ch->local_msgqueue = NULL;
 154                 kfree(ch->notify_queue);
 155                 ch->notify_queue = NULL;
 156                 return ret;
 157         }
 158
 159         spin_lock_irqsave(&ch->lock, irq_flags);
 160         ch->flags |= XPC_C_SETUP;
 161         spin_unlock_irqrestore(&ch->lock, irq_flags);
 162
 163         return xpSuccess;
 164 }
 165
 166 /*
 167  * Process a connect message from a remote partition.
 168  *
 169  * Note: xpc_process_connect() is expecting to be called with the
 170  * spin_lock_irqsave held and will leave it locked upon return.
 171  */
 172 static void
 173 xpc_process_connect(struct xpc_channel *ch, unsigned long *irq_flags)
 174 {
 175         enum xp_retval ret;
 176
 177         DBUG_ON(!spin_is_locked(&ch->lock));
 178
 179         if (!(ch->flags & XPC_C_OPENREQUEST) ||
 180             !(ch->flags & XPC_C_ROPENREQUEST)) {
 181                 /* nothing more to do for now */
 182                 return;
 183         }
 184         DBUG_ON(!(ch->flags & XPC_C_CONNECTING));
 185
 186         if (!(ch->flags & XPC_C_SETUP)) {
 187                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
 188                 ret = xpc_allocate_msgqueues(ch);
 189                 spin_lock_irqsave(&ch->lock, *irq_flags);
 190
 191                 if (ret != xpSuccess)
 192                         XPC_DISCONNECT_CHANNEL(ch, ret, irq_flags);
 193
 194                 if (ch->flags & (XPC_C_CONNECTED | XPC_C_DISCONNECTING))
 195                         return;
 196
 197                 DBUG_ON(!(ch->flags & XPC_C_SETUP));
 198                 DBUG_ON(ch->local_msgqueue == NULL);
 199                 DBUG_ON(ch->remote_msgqueue == NULL);
 200         }
 201
 202         if (!(ch->flags & XPC_C_OPENREPLY)) {
 203                 ch->flags |= XPC_C_OPENREPLY;
 204                 xpc_send_chctl_openreply(ch, irq_flags);
 205         }
 206
 207         if (!(ch->flags & XPC_C_ROPENREPLY))
 208                 return;
 209
 210         DBUG_ON(ch->remote_msgqueue_pa == 0);
 211
 212         ch->flags = (XPC_C_CONNECTED | XPC_C_SETUP);    /* clear all else */
 213
 214         dev_info(xpc_chan, "channel %d to partition %d connected\n",
 215                  ch->number, ch->partid);
 216
 217         spin_unlock_irqrestore(&ch->lock, *irq_flags);
 218         xpc_create_kthreads(ch, 1, 0);
 219         spin_lock_irqsave(&ch->lock, *irq_flags);
 220 }
 221
 222 /*
 223  * Free up message queues and other stuff that were allocated for the specified
 224  * channel.
 225  *
 226  * Note: ch->reason and ch->reason_line are left set for debugging purposes,
 227  * they're cleared when XPC_C_DISCONNECTED is cleared.
 228  */
 229 static void
 230 xpc_free_msgqueues(struct xpc_channel *ch)
 231 {
 232         struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
 233
 234         DBUG_ON(!spin_is_locked(&ch->lock));
 235         DBUG_ON(atomic_read(&ch->n_to_notify) != 0);
 236
 237         ch->remote_msgqueue_pa = 0;
 238         ch->func = NULL;
 239         ch->key = NULL;
 240         ch->msg_size = 0;
 241         ch->local_nentries = 0;
 242         ch->remote_nentries = 0;
 243         ch->kthreads_assigned_limit = 0;
 244         ch->kthreads_idle_limit = 0;
 245
 246         ch_sn2->local_GP->get = 0;
 247         ch_sn2->local_GP->put = 0;
 248         ch_sn2->remote_GP.get = 0;
 249         ch_sn2->remote_GP.put = 0;
 250         ch_sn2->w_local_GP.get = 0;
 251         ch_sn2->w_local_GP.put = 0;
 252         ch_sn2->w_remote_GP.get = 0;
 253         ch_sn2->w_remote_GP.put = 0;
 254         ch_sn2->next_msg_to_pull = 0;
 255
 256         if (ch->flags & XPC_C_SETUP) {
 257                 ch->flags &= ~XPC_C_SETUP;
 258
 259                 dev_dbg(xpc_chan, "ch->flags=0x%x, partid=%d, channel=%d\n",
 260                         ch->flags, ch->partid, ch->number);
 261
 262                 kfree(ch->local_msgqueue_base);
 263                 ch->local_msgqueue = NULL;
 264                 kfree(ch->remote_msgqueue_base);
 265                 ch->remote_msgqueue = NULL;
 266                 kfree(ch->notify_queue);
 267                 ch->notify_queue = NULL;
 268         }
 269 }
 270
 271 /*
 272  * spin_lock_irqsave() is expected to be held on entry.
 273  */
 274 static void
 275 xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
 276 {
 277         struct xpc_partition *part = &xpc_partitions[ch->partid];
 278         u32 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);
 279
 280         DBUG_ON(!spin_is_locked(&ch->lock));
 281
 282         if (!(ch->flags & XPC_C_DISCONNECTING))
 283                 return;
 284
 285         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 286
 287         /* make sure all activity has settled down first */
 288
 289         if (atomic_read(&ch->kthreads_assigned) > 0 ||
 290             atomic_read(&ch->references) > 0) {
 291                 return;
 292         }
 293         DBUG_ON((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 294                 !(ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE));
 295
 296         if (part->act_state == XPC_P_DEACTIVATING) {
 297                 /* can't proceed until the other side disengages from us */
 298                 if (xpc_partition_engaged(ch->partid))
 299                         return;
 300
 301         } else {
 302
 303                 /* as long as the other side is up do the full protocol */
 304
 305                 if (!(ch->flags & XPC_C_RCLOSEREQUEST))
 306                         return;
 307
 308                 if (!(ch->flags & XPC_C_CLOSEREPLY)) {
 309                         ch->flags |= XPC_C_CLOSEREPLY;
 310                         xpc_send_chctl_closereply(ch, irq_flags);
 311                 }
 312
 313                 if (!(ch->flags & XPC_C_RCLOSEREPLY))
 314                         return;
 315         }
 316
 317         /* wake those waiting for notify completion */
 318         if (atomic_read(&ch->n_to_notify) > 0) {
 319                 /* >>> we do callout while holding ch->lock */
 320                 xpc_notify_senders_of_disconnect(ch);
 321         }
 322
 323         /* both sides are disconnected now */
 324
 325         if (ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE) {
 326                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
 327                 xpc_disconnect_callout(ch, xpDisconnected);
 328                 spin_lock_irqsave(&ch->lock, *irq_flags);
 329         }
 330
 331         /* it's now safe to free the channel's message queues */
 332         xpc_free_msgqueues(ch);
 333
 334         /* mark disconnected, clear all other flags except XPC_C_WDISCONNECT */
 335         ch->flags = (XPC_C_DISCONNECTED | (ch->flags & XPC_C_WDISCONNECT));
 336
 337         atomic_dec(&part->nchannels_active);
 338
 339         if (channel_was_connected) {
 340                 dev_info(xpc_chan, "channel %d to partition %d disconnected, "
 341                          "reason=%d\n", ch->number, ch->partid, ch->reason);
 342         }
 343
 344         if (ch->flags & XPC_C_WDISCONNECT) {
 345                 /* we won't lose the CPU since we're holding ch->lock */
 346                 complete(&ch->wdisconnect_wait);
 347         } else if (ch->delayed_chctl_flags) {
 348                 if (part->act_state != XPC_P_DEACTIVATING) {
 349                         /* time to take action on any delayed chctl flags */
 350                         spin_lock(&part->chctl_lock);
 351                         part->chctl.flags[ch->number] |=
 352                             ch->delayed_chctl_flags;
 353                         spin_unlock(&part->chctl_lock);
 354                 }
 355                 ch->delayed_chctl_flags = 0;
 356         }
 357 }
 358
 359 /*
 360  * Process a change in the channel's remote connection state.
 361  */
 362 static void
 363 xpc_process_openclose_chctl_flags(struct xpc_partition *part, int ch_number,
 364                                   u8 chctl_flags)
 365 {
 366         unsigned long irq_flags;
 367         struct xpc_openclose_args *args =
 368             &part->remote_openclose_args[ch_number];
 369         struct xpc_channel *ch = &part->channels[ch_number];
 370         enum xp_retval reason;
 371
 372         spin_lock_irqsave(&ch->lock, irq_flags);
 373
 374 again:
 375
 376         if ((ch->flags & XPC_C_DISCONNECTED) &&
 377             (ch->flags & XPC_C_WDISCONNECT)) {
 378                 /*
 379                  * Delay processing chctl flags until thread waiting disconnect
 380                  * has had a chance to see that the channel is disconnected.
 381                  */
 382                 ch->delayed_chctl_flags |= chctl_flags;
 383                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 384                 return;
 385         }
 386
 387         if (chctl_flags & XPC_CHCTL_CLOSEREQUEST) {
 388
 389                 dev_dbg(xpc_chan, "XPC_CHCTL_CLOSEREQUEST (reason=%d) received "
 390                         "from partid=%d, channel=%d\n", args->reason,
 391                         ch->partid, ch->number);
 392
 393                 /*
 394                  * If RCLOSEREQUEST is set, we're probably waiting for
 395                  * RCLOSEREPLY. We should find it and a ROPENREQUEST packed
 396                  * with this RCLOSEREQUEST in the chctl_flags.
 397                  */
 398
 399                 if (ch->flags & XPC_C_RCLOSEREQUEST) {
 400                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTING));
 401                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 402                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREPLY));
 403                         DBUG_ON(ch->flags & XPC_C_RCLOSEREPLY);
 404
 405                         DBUG_ON(!(chctl_flags & XPC_CHCTL_CLOSEREPLY));
 406                         chctl_flags &= ~XPC_CHCTL_CLOSEREPLY;
 407                         ch->flags |= XPC_C_RCLOSEREPLY;
 408
 409                         /* both sides have finished disconnecting */
 410                         xpc_process_disconnect(ch, &irq_flags);
 411                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 412                         goto again;
 413                 }
 414
 415                 if (ch->flags & XPC_C_DISCONNECTED) {
 416                         if (!(chctl_flags & XPC_CHCTL_OPENREQUEST)) {
 417                                 if (part->chctl.flags[ch_number] &
 418                                     XPC_CHCTL_OPENREQUEST) {
 419
 420                                         DBUG_ON(ch->delayed_chctl_flags != 0);
 421                                         spin_lock(&part->chctl_lock);
 422                                         part->chctl.flags[ch_number] |=
 423                                             XPC_CHCTL_CLOSEREQUEST;
 424                                         spin_unlock(&part->chctl_lock);
 425                                 }
 426                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 427                                 return;
 428                         }
 429
 430                         XPC_SET_REASON(ch, 0, 0);
 431                         ch->flags &= ~XPC_C_DISCONNECTED;
 432
 433                         atomic_inc(&part->nchannels_active);
 434                         ch->flags |= (XPC_C_CONNECTING | XPC_C_ROPENREQUEST);
 435                 }
 436
 437                 chctl_flags &= ~(XPC_CHCTL_OPENREQUEST | XPC_CHCTL_OPENREPLY);
 438
 439                 /*
 440                  * The meaningful CLOSEREQUEST connection state fields are:
 441                  *      reason = reason connection is to be closed
 442                  */
 443
 444                 ch->flags |= XPC_C_RCLOSEREQUEST;
 445
 446                 if (!(ch->flags & XPC_C_DISCONNECTING)) {
 447                         reason = args->reason;
 448                         if (reason <= xpSuccess || reason > xpUnknownReason)
 449                                 reason = xpUnknownReason;
 450                         else if (reason == xpUnregistering)
 451                                 reason = xpOtherUnregistering;
 452
 453                         XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
 454
 455                         DBUG_ON(chctl_flags & XPC_CHCTL_CLOSEREPLY);
 456                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 457                         return;
 458                 }
 459
 460                 xpc_process_disconnect(ch, &irq_flags);
 461         }
 462
 463         if (chctl_flags & XPC_CHCTL_CLOSEREPLY) {
 464
 465                 dev_dbg(xpc_chan, "XPC_CHCTL_CLOSEREPLY received from partid="
 466                         "%d, channel=%d\n", ch->partid, ch->number);
 467
 468                 if (ch->flags & XPC_C_DISCONNECTED) {
 469                         DBUG_ON(part->act_state != XPC_P_DEACTIVATING);
 470                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 471                         return;
 472                 }
 473
 474                 DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 475
 476                 if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
 477                         if (part->chctl.flags[ch_number] &
 478                             XPC_CHCTL_CLOSEREQUEST) {
 479
 480                                 DBUG_ON(ch->delayed_chctl_flags != 0);
 481                                 spin_lock(&part->chctl_lock);
 482                                 part->chctl.flags[ch_number] |=
 483                                     XPC_CHCTL_CLOSEREPLY;
 484                                 spin_unlock(&part->chctl_lock);
 485                         }
 486                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 487                         return;
 488                 }
 489
 490                 ch->flags |= XPC_C_RCLOSEREPLY;
 491
 492                 if (ch->flags & XPC_C_CLOSEREPLY) {
 493                         /* both sides have finished disconnecting */
 494                         xpc_process_disconnect(ch, &irq_flags);
 495                 }
 496         }
 497
 498         if (chctl_flags & XPC_CHCTL_OPENREQUEST) {
 499
 500                 dev_dbg(xpc_chan, "XPC_CHCTL_OPENREQUEST (msg_size=%d, "
 501                         "local_nentries=%d) received from partid=%d, "
 502                         "channel=%d\n", args->msg_size, args->local_nentries,
 503                         ch->partid, ch->number);
 504
 505                 if (part->act_state == XPC_P_DEACTIVATING ||
 506                     (ch->flags & XPC_C_ROPENREQUEST)) {
 507                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 508                         return;
 509                 }
 510
 511                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_WDISCONNECT)) {
 512                         ch->delayed_chctl_flags |= XPC_CHCTL_OPENREQUEST;
 513                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 514                         return;
 515                 }
 516                 DBUG_ON(!(ch->flags & (XPC_C_DISCONNECTED |
 517                                        XPC_C_OPENREQUEST)));
 518                 DBUG_ON(ch->flags & (XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
 519                                      XPC_C_OPENREPLY | XPC_C_CONNECTED));
 520
 521                 /*
 522                  * The meaningful OPENREQUEST connection state fields are:
 523                  *      msg_size = size of channel's messages in bytes
 524                  *      local_nentries = remote partition's local_nentries
 525                  */
 526                 if (args->msg_size == 0 || args->local_nentries == 0) {
 527                         /* assume OPENREQUEST was delayed by mistake */
 528                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 529                         return;
 530                 }
 531
 532                 ch->flags |= (XPC_C_ROPENREQUEST | XPC_C_CONNECTING);
 533                 ch->remote_nentries = args->local_nentries;
 534
 535                 if (ch->flags & XPC_C_OPENREQUEST) {
 536                         if (args->msg_size != ch->msg_size) {
 537                                 XPC_DISCONNECT_CHANNEL(ch, xpUnequalMsgSizes,
 538                                                        &irq_flags);
 539                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 540                                 return;
 541                         }
 542                 } else {
 543                         ch->msg_size = args->msg_size;
 544
 545                         XPC_SET_REASON(ch, 0, 0);
 546                         ch->flags &= ~XPC_C_DISCONNECTED;
 547
 548                         atomic_inc(&part->nchannels_active);
 549                 }
 550
 551                 xpc_process_connect(ch, &irq_flags);
 552         }
 553
 554         if (chctl_flags & XPC_CHCTL_OPENREPLY) {
 555
 556                 dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY (local_msgqueue_pa="
 557                         "0x%lx, local_nentries=%d, remote_nentries=%d) "
 558                         "received from partid=%d, channel=%d\n",
 559                         args->local_msgqueue_pa, args->local_nentries,
 560                         args->remote_nentries, ch->partid, ch->number);
 561
 562                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
 563                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 564                         return;
 565                 }
 566                 if (!(ch->flags & XPC_C_OPENREQUEST)) {
 567                         XPC_DISCONNECT_CHANNEL(ch, xpOpenCloseError,
 568                                                &irq_flags);
 569                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 570                         return;
 571                 }
 572
 573                 DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
 574                 DBUG_ON(ch->flags & XPC_C_CONNECTED);
 575
 576                 /*
 577                  * The meaningful OPENREPLY connection state fields are:
 578                  *      local_msgqueue_pa = physical address of remote
 579                  *                          partition's local_msgqueue
 580                  *      local_nentries = remote partition's local_nentries
 581                  *      remote_nentries = remote partition's remote_nentries
 582                  */
 583                 DBUG_ON(args->local_msgqueue_pa == 0);
 584                 DBUG_ON(args->local_nentries == 0);
 585                 DBUG_ON(args->remote_nentries == 0);
 586
 587                 ch->flags |= XPC_C_ROPENREPLY;
 588                 ch->remote_msgqueue_pa = args->local_msgqueue_pa;
 589
 590                 if (args->local_nentries < ch->remote_nentries) {
 591                         dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY: new "
 592                                 "remote_nentries=%d, old remote_nentries=%d, "
 593                                 "partid=%d, channel=%d\n",
 594                                 args->local_nentries, ch->remote_nentries,
 595                                 ch->partid, ch->number);
 596
 597                         ch->remote_nentries = args->local_nentries;
 598                 }
 599                 if (args->remote_nentries < ch->local_nentries) {
 600                         dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY: new "
 601                                 "local_nentries=%d, old local_nentries=%d, "
 602                                 "partid=%d, channel=%d\n",
 603                                 args->remote_nentries, ch->local_nentries,
 604                                 ch->partid, ch->number);
 605
 606                         ch->local_nentries = args->remote_nentries;
 607                 }
 608
 609                 xpc_process_connect(ch, &irq_flags);
 610         }
 611
 612         spin_unlock_irqrestore(&ch->lock, irq_flags);
 613 }
 614
 615 /*
 616  * Attempt to establish a channel connection to a remote partition.
 617  */
 618 static enum xp_retval
 619 xpc_connect_channel(struct xpc_channel *ch)
 620 {
 621         unsigned long irq_flags;
 622         struct xpc_registration *registration = &xpc_registrations[ch->number];
 623
 624         if (mutex_trylock(&registration->mutex) == 0)
 625                 return xpRetry;
 626
 627         if (!XPC_CHANNEL_REGISTERED(ch->number)) {
 628                 mutex_unlock(&registration->mutex);
 629                 return xpUnregistered;
 630         }
 631
 632         spin_lock_irqsave(&ch->lock, irq_flags);
 633
 634         DBUG_ON(ch->flags & XPC_C_CONNECTED);
 635         DBUG_ON(ch->flags & XPC_C_OPENREQUEST);
 636
 637         if (ch->flags & XPC_C_DISCONNECTING) {
 638                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 639                 mutex_unlock(&registration->mutex);
 640                 return ch->reason;
 641         }
 642
 643         /* add info from the channel connect registration to the channel */
 644
 645         ch->kthreads_assigned_limit = registration->assigned_limit;
 646         ch->kthreads_idle_limit = registration->idle_limit;
 647         DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
 648         DBUG_ON(atomic_read(&ch->kthreads_idle) != 0);
 649         DBUG_ON(atomic_read(&ch->kthreads_active) != 0);
 650
 651         ch->func = registration->func;
 652         DBUG_ON(registration->func == NULL);
 653         ch->key = registration->key;
 654
 655         ch->local_nentries = registration->nentries;
 656
 657         if (ch->flags & XPC_C_ROPENREQUEST) {
 658                 if (registration->msg_size != ch->msg_size) {
 659                         /* the local and remote sides aren't the same */
 660
 661                         /*
 662                          * Because XPC_DISCONNECT_CHANNEL() can block we're
 663                          * forced to up the registration sema before we unlock
 664                          * the channel lock. But that's okay here because we're
 665                          * done with the part that required the registration
 666                          * sema. XPC_DISCONNECT_CHANNEL() requires that the
 667                          * channel lock be locked and will unlock and relock
 668                          * the channel lock as needed.
 669                          */
 670                         mutex_unlock(&registration->mutex);
 671                         XPC_DISCONNECT_CHANNEL(ch, xpUnequalMsgSizes,
 672                                                &irq_flags);
 673                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 674                         return xpUnequalMsgSizes;
 675                 }
 676         } else {
 677                 ch->msg_size = registration->msg_size;
 678
 679                 XPC_SET_REASON(ch, 0, 0);
 680                 ch->flags &= ~XPC_C_DISCONNECTED;
 681
 682                 atomic_inc(&xpc_partitions[ch->partid].nchannels_active);
 683         }
 684
 685         mutex_unlock(&registration->mutex);
 686
 687         /* initiate the connection */
 688
 689         ch->flags |= (XPC_C_OPENREQUEST | XPC_C_CONNECTING);
 690         xpc_send_chctl_openrequest(ch, &irq_flags);
 691
 692         xpc_process_connect(ch, &irq_flags);
 693
 694         spin_unlock_irqrestore(&ch->lock, irq_flags);
 695
 696         return xpSuccess;
 697 }
 698
 699 void
 700 xpc_process_sent_chctl_flags(struct xpc_partition *part)
 701 {
 702         unsigned long irq_flags;
 703         union xpc_channel_ctl_flags chctl;
 704         struct xpc_channel *ch;
 705         int ch_number;
 706         u32 ch_flags;
 707
 708         chctl.all_flags = xpc_get_chctl_all_flags(part);
 709
 710         /*
 711          * Initiate channel connections for registered channels.
 712          *
 713          * For each connected channel that has pending messages activate idle
 714          * kthreads and/or create new kthreads as needed.
 715          */
 716
 717         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
 718                 ch = &part->channels[ch_number];
 719
 720                 /*
 721                  * Process any open or close related chctl flags, and then deal
 722                  * with connecting or disconnecting the channel as required.
 723                  */
 724
 725                 if (chctl.flags[ch_number] & XPC_OPENCLOSE_CHCTL_FLAGS) {
 726                         xpc_process_openclose_chctl_flags(part, ch_number,
 727                                                         chctl.flags[ch_number]);
 728                 }
 729
 730                 ch_flags = ch->flags;   /* need an atomic snapshot of flags */
 731
 732                 if (ch_flags & XPC_C_DISCONNECTING) {
 733                         spin_lock_irqsave(&ch->lock, irq_flags);
 734                         xpc_process_disconnect(ch, &irq_flags);
 735                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 736                         continue;
 737                 }
 738
 739                 if (part->act_state == XPC_P_DEACTIVATING)
 740                         continue;
 741
 742                 if (!(ch_flags & XPC_C_CONNECTED)) {
 743                         if (!(ch_flags & XPC_C_OPENREQUEST)) {
 744                                 DBUG_ON(ch_flags & XPC_C_SETUP);
 745                                 (void)xpc_connect_channel(ch);
 746                         } else {
 747                                 spin_lock_irqsave(&ch->lock, irq_flags);
 748                                 xpc_process_connect(ch, &irq_flags);
 749                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 750                         }
 751                         continue;
 752                 }
 753
 754                 /*
 755                  * Process any message related chctl flags, this may involve
 756                  * the activation of kthreads to deliver any pending messages
 757                  * sent from the other partition.
 758                  */
 759
 760                 if (chctl.flags[ch_number] & XPC_MSG_CHCTL_FLAGS)
 761                         xpc_process_msg_chctl_flags(part, ch_number);
 762         }
 763 }
 764
 765 /*
 766  * XPC's heartbeat code calls this function to inform XPC that a partition is
 767  * going down.  XPC responds by tearing down the XPartition Communication
 768  * infrastructure used for the just downed partition.
 769  *
 770  * XPC's heartbeat code will never call this function and xpc_partition_up()
 771  * at the same time. Nor will it ever make multiple calls to either function
 772  * at the same time.
 773  */
 774 void
 775 xpc_partition_going_down(struct xpc_partition *part, enum xp_retval reason)
 776 {
 777         unsigned long irq_flags;
 778         int ch_number;
 779         struct xpc_channel *ch;
 780
 781         dev_dbg(xpc_chan, "deactivating partition %d, reason=%d\n",
 782                 XPC_PARTID(part), reason);
 783
 784         if (!xpc_part_ref(part)) {
 785                 /* infrastructure for this partition isn't currently set up */
 786                 return;
 787         }
 788
 789         /* disconnect channels associated with the partition going down */
 790
 791         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
 792                 ch = &part->channels[ch_number];
 793
 794                 xpc_msgqueue_ref(ch);
 795                 spin_lock_irqsave(&ch->lock, irq_flags);
 796
 797                 XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
 798
 799                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 800                 xpc_msgqueue_deref(ch);
 801         }
 802
 803         xpc_wakeup_channel_mgr(part);
 804
 805         xpc_part_deref(part);
 806 }
 807
 808 /*
 809  * Called by XP at the time of channel connection registration to cause
 810  * XPC to establish connections to all currently active partitions.
 811  */
 812 void
 813 xpc_initiate_connect(int ch_number)
 814 {
 815         short partid;
 816         struct xpc_partition *part;
 817         struct xpc_channel *ch;
 818
 819         DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);
 820
 821         for (partid = 0; partid < xp_max_npartitions; partid++) {
 822                 part = &xpc_partitions[partid];
 823
 824                 if (xpc_part_ref(part)) {
 825                         ch = &part->channels[ch_number];
 826
 827                         /*
 828                          * Initiate the establishment of a connection on the
 829                          * newly registered channel to the remote partition.
 830                          */
 831                         xpc_wakeup_channel_mgr(part);
 832                         xpc_part_deref(part);
 833                 }
 834         }
 835 }
 836
 837 void
 838 xpc_connected_callout(struct xpc_channel *ch)
 839 {
 840         /* let the registerer know that a connection has been established */
 841
 842         if (ch->func != NULL) {
 843                 dev_dbg(xpc_chan, "ch->func() called, reason=xpConnected, "
 844                         "partid=%d, channel=%d\n", ch->partid, ch->number);
 845
 846                 ch->func(xpConnected, ch->partid, ch->number,
 847                          (void *)(u64)ch->local_nentries, ch->key);
 848
 849                 dev_dbg(xpc_chan, "ch->func() returned, reason=xpConnected, "
 850                         "partid=%d, channel=%d\n", ch->partid, ch->number);
 851         }
 852 }
 853
 854 /*
 855  * Called by XP at the time of channel connection unregistration to cause
 856  * XPC to teardown all current connections for the specified channel.
 857  *
 858  * Before returning xpc_initiate_disconnect() will wait until all connections
 859  * on the specified channel have been closed/torndown. So the caller can be
 860  * assured that they will not be receiving any more callouts from XPC to the
 861  * function they registered via xpc_connect().
 862  *
 863  * Arguments:
 864  *
 865  *      ch_number - channel # to unregister.
 866  */
 867 void
 868 xpc_initiate_disconnect(int ch_number)
 869 {
 870         unsigned long irq_flags;
 871         short partid;
 872         struct xpc_partition *part;
 873         struct xpc_channel *ch;
 874
 875         DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);
 876
 877         /* initiate the channel disconnect for every active partition */
 878         for (partid = 0; partid < xp_max_npartitions; partid++) {
 879                 part = &xpc_partitions[partid];
 880
 881                 if (xpc_part_ref(part)) {
 882                         ch = &part->channels[ch_number];
 883                         xpc_msgqueue_ref(ch);
 884
 885                         spin_lock_irqsave(&ch->lock, irq_flags);
 886
 887                         if (!(ch->flags & XPC_C_DISCONNECTED)) {
 888                                 ch->flags |= XPC_C_WDISCONNECT;
 889
 890                                 XPC_DISCONNECT_CHANNEL(ch, xpUnregistering,
 891                                                        &irq_flags);
 892                         }
 893
 894                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 895
 896                         xpc_msgqueue_deref(ch);
 897                         xpc_part_deref(part);
 898                 }
 899         }
 900
 901         xpc_disconnect_wait(ch_number);
 902 }
 903
 904 /*
 905  * To disconnect a channel, and reflect it back to all who may be waiting.
 906  *
 907  * An OPEN is not allowed until XPC_C_DISCONNECTING is cleared by
 908  * xpc_process_disconnect(), and if set, XPC_C_WDISCONNECT is cleared by
 909  * xpc_disconnect_wait().
 910  *
 911  * THE CHANNEL IS TO BE LOCKED BY THE CALLER AND WILL REMAIN LOCKED UPON RETURN.
 912  */
 913 void
 914 xpc_disconnect_channel(const int line, struct xpc_channel *ch,
 915                        enum xp_retval reason, unsigned long *irq_flags)
 916 {
 917         u32 channel_was_connected = (ch->flags & XPC_C_CONNECTED);
 918
 919         DBUG_ON(!spin_is_locked(&ch->lock));
 920
 921         if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED))
 922                 return;
 923
 924         DBUG_ON(!(ch->flags & (XPC_C_CONNECTING | XPC_C_CONNECTED)));
 925
 926         dev_dbg(xpc_chan, "reason=%d, line=%d, partid=%d, channel=%d\n",
 927                 reason, line, ch->partid, ch->number);
 928
 929         XPC_SET_REASON(ch, reason, line);
 930
 931         ch->flags |= (XPC_C_CLOSEREQUEST | XPC_C_DISCONNECTING);
 932         /* some of these may not have been set */
 933         ch->flags &= ~(XPC_C_OPENREQUEST | XPC_C_OPENREPLY |
 934                        XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
 935                        XPC_C_CONNECTING | XPC_C_CONNECTED);
 936
 937         xpc_send_chctl_closerequest(ch, irq_flags);
 938
 939         if (channel_was_connected)
 940                 ch->flags |= XPC_C_WASCONNECTED;
 941
 942         spin_unlock_irqrestore(&ch->lock, *irq_flags);
 943
 944         /* wake all idle kthreads so they can exit */
 945         if (atomic_read(&ch->kthreads_idle) > 0) {
 946                 wake_up_all(&ch->idle_wq);
 947
 948         } else if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 949                    !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
 950                 /* start a kthread that will do the xpDisconnecting callout */
 951                 xpc_create_kthreads(ch, 1, 1);
 952         }
 953
 954         /* wake those waiting to allocate an entry from the local msg queue */
 955         if (atomic_read(&ch->n_on_msg_allocate_wq) > 0)
 956                 wake_up(&ch->msg_allocate_wq);
 957
 958         spin_lock_irqsave(&ch->lock, *irq_flags);
 959 }
 960
 961 void
 962 xpc_disconnect_callout(struct xpc_channel *ch, enum xp_retval reason)
 963 {
 964         /*
 965          * Let the channel's registerer know that the channel is being
 966          * disconnected. We don't want to do this if the registerer was never
 967          * informed of a connection being made.
 968          */
 969
 970         if (ch->func != NULL) {
 971                 dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
 972                         "channel=%d\n", reason, ch->partid, ch->number);
 973
 974                 ch->func(reason, ch->partid, ch->number, NULL, ch->key);
 975
 976                 dev_dbg(xpc_chan, "ch->func() returned, reason=%d, partid=%d, "
 977                         "channel=%d\n", reason, ch->partid, ch->number);
 978         }
 979 }
 980
 981 /*
 982  * Wait for a message entry to become available for the specified channel,
 983  * but don't wait any longer than 1 jiffy.
 984  */
 985 enum xp_retval
 986 xpc_allocate_msg_wait(struct xpc_channel *ch)
 987 {
 988         enum xp_retval ret;
 989
 990         if (ch->flags & XPC_C_DISCONNECTING) {
 991                 DBUG_ON(ch->reason == xpInterrupted);
 992                 return ch->reason;
 993         }
 994
 995         atomic_inc(&ch->n_on_msg_allocate_wq);
 996         ret = interruptible_sleep_on_timeout(&ch->msg_allocate_wq, 1);
 997         atomic_dec(&ch->n_on_msg_allocate_wq);
 998
 999         if (ch->flags & XPC_C_DISCONNECTING) {
1000                 ret = ch->reason;
1001                 DBUG_ON(ch->reason == xpInterrupted);
1002         } else if (ret == 0) {
1003                 ret = xpTimeout;
1004         } else {
1005                 ret = xpInterrupted;
1006         }
1007
1008         return ret;
1009 }
1010
1011 /*
1012  * Send a message that contains the user's payload on the specified channel
1013  * connected to the specified partition.
1014  *
1015  * NOTE that this routine can sleep waiting for a message entry to become
1016  * available. To not sleep, pass in the XPC_NOWAIT flag.
1017  *
1018  * Once sent, this routine will not wait for the message to be received, nor
1019  * will notification be given when it does happen.
1020  *
1021  * Arguments:
1022  *
1023  *      partid - ID of partition to which the channel is connected.
1024  *      ch_number - channel # to send message on.
1025  *      flags - see xp.h for valid flags.
1026  *      payload - pointer to the payload which is to be sent.
1027  *      payload_size - size of the payload in bytes.
1028  */
1029 enum xp_retval
1030 xpc_initiate_send(short partid, int ch_number, u32 flags, void *payload,
1031                   u16 payload_size)
1032 {
1033         struct xpc_partition *part = &xpc_partitions[partid];
1034         enum xp_retval ret = xpUnknownReason;
1035
1036         dev_dbg(xpc_chan, "payload=0x%p, partid=%d, channel=%d\n", payload,
1037                 partid, ch_number);
1038
1039         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
1040         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
1041         DBUG_ON(payload == NULL);
1042
1043         if (xpc_part_ref(part)) {
1044                 ret = xpc_send_msg(&part->channels[ch_number], flags, payload,
1045                                    payload_size, 0, NULL, NULL);
1046                 xpc_part_deref(part);
1047         }
1048
1049         return ret;
1050 }
1051
1052 /*
1053  * Send a message that contains the user's payload on the specified channel
1054  * connected to the specified partition.
1055  *
1056  * NOTE that this routine can sleep waiting for a message entry to become
1057  * available. To not sleep, pass in the XPC_NOWAIT flag.
1058  *
1059  * This routine will not wait for the message to be sent or received.
1060  *
1061  * Once the remote end of the channel has received the message, the function
1062  * passed as an argument to xpc_initiate_send_notify() will be called. This
1063  * allows the sender to free up or re-use any buffers referenced by the
1064  * message, but does NOT mean the message has been processed at the remote
1065  * end by a receiver.
1066  *
1067  * If this routine returns an error, the caller's function will NOT be called.
1068  *
1069  * Arguments:
1070  *
1071  *      partid - ID of partition to which the channel is connected.
1072  *      ch_number - channel # to send message on.
1073  *      flags - see xp.h for valid flags.
1074  *      payload - pointer to the payload which is to be sent.
1075  *      payload_size - size of the payload in bytes.
1076  *      func - function to call with asynchronous notification of message
1077  *                receipt. THIS FUNCTION MUST BE NON-BLOCKING.
1078  *      key - user-defined key to be passed to the function when it's called.
1079  */
1080 enum xp_retval
1081 xpc_initiate_send_notify(short partid, int ch_number, u32 flags, void *payload,
1082                          u16 payload_size, xpc_notify_func func, void *key)
1083 {
1084         struct xpc_partition *part = &xpc_partitions[partid];
1085         enum xp_retval ret = xpUnknownReason;
1086
1087         dev_dbg(xpc_chan, "payload=0x%p, partid=%d, channel=%d\n", payload,
1088                 partid, ch_number);
1089
1090         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
1091         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
1092         DBUG_ON(payload == NULL);
1093         DBUG_ON(func == NULL);
1094
1095         if (xpc_part_ref(part)) {
1096                 ret = xpc_send_msg(&part->channels[ch_number], flags, payload,
1097                                    payload_size, XPC_N_CALL, func, key);
1098                 xpc_part_deref(part);
1099         }
1100         return ret;
1101 }
1102
1103 /*
1104  * Deliver a message to its intended recipient.
1105  */
1106 void
1107 xpc_deliver_msg(struct xpc_channel *ch)
1108 {
1109         struct xpc_msg *msg;
1110
1111         msg = xpc_get_deliverable_msg(ch);
1112         if (msg != NULL) {
1113
1114                 /*
1115                  * This ref is taken to protect the payload itself from being
1116                  * freed before the user is finished with it, which the user
1117                  * indicates by calling xpc_initiate_received().
1118                  */
1119                 xpc_msgqueue_ref(ch);
1120
1121                 atomic_inc(&ch->kthreads_active);
1122
1123                 if (ch->func != NULL) {
1124                         dev_dbg(xpc_chan, "ch->func() called, msg=0x%p, "
1125                                 "msg_number=%ld, partid=%d, channel=%d\n",
1126                                 (void *)msg, msg->number, ch->partid,
1127                                 ch->number);
1128
1129                         /* deliver the message to its intended recipient */
1130                         ch->func(xpMsgReceived, ch->partid, ch->number,
1131                                  &msg->payload, ch->key);
1132
1133                         dev_dbg(xpc_chan, "ch->func() returned, msg=0x%p, "
1134                                 "msg_number=%ld, partid=%d, channel=%d\n",
1135                                 (void *)msg, msg->number, ch->partid,
1136                                 ch->number);
1137                 }
1138
1139                 atomic_dec(&ch->kthreads_active);
1140         }
1141 }
1142
1143 /*
1144  * Acknowledge receipt of a delivered message.
1145  *
1146  * If a message has XPC_M_INTERRUPT set, send an interrupt to the partition
1147  * that sent the message.
1148  *
1149  * This function, although called by users, does not call xpc_part_ref() to
1150  * ensure that the partition infrastructure is in place. It relies on the
1151  * fact that we called xpc_msgqueue_ref() in xpc_deliver_msg().
1152  *
1153  * Arguments:
1154  *
1155  *      partid - ID of partition to which the channel is connected.
1156  *      ch_number - channel # message received on.
1157  *      payload - pointer to the payload area allocated via
1158  *                      xpc_initiate_send() or xpc_initiate_send_notify().
1159  */
1160 void
1161 xpc_initiate_received(short partid, int ch_number, void *payload)
1162 {
1163         struct xpc_partition *part = &xpc_partitions[partid];
1164         struct xpc_channel *ch;
1165         struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
1166
1167         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
1168         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
1169
1170         ch = &part->channels[ch_number];
1171         xpc_received_msg(ch, msg);
1172
1173         /* the call to xpc_msgqueue_ref() was done by xpc_deliver_msg()  */
1174         xpc_msgqueue_deref(ch);
1175 }