arch/ia64/sn/kernel/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) 2004-2006 Silicon Graphics, Inc.  All Rights Reserved.
   7  */
   8
   9
  10 /*
  11  * Cross Partition Communication (XPC) channel support.
  12  *
  13  *      This is the part of XPC that manages the channels and
  14  *      sends/receives messages across them to/from other partitions.
  15  *
  16  */
  17
  18
  19 #include <linux/kernel.h>
  20 #include <linux/init.h>
  21 #include <linux/sched.h>
  22 #include <linux/cache.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/mutex.h>
  25 #include <linux/completion.h>
  26 #include <asm/sn/bte.h>
  27 #include <asm/sn/sn_sal.h>
  28 #include <asm/sn/xpc.h>
  29
  30
  31 /*
  32  * Guarantee that the kzalloc'd memory is cacheline aligned.
  33  */
  34 static void *
  35 xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
  36 {
  37         /* see if kzalloc will give us cachline aligned memory by default */
  38         *base = kzalloc(size, flags);
  39         if (*base == NULL) {
  40                 return NULL;
  41         }
  42         if ((u64) *base == L1_CACHE_ALIGN((u64) *base)) {
  43                 return *base;
  44         }
  45         kfree(*base);
  46
  47         /* nope, we'll have to do it ourselves */
  48         *base = kzalloc(size + L1_CACHE_BYTES, flags);
  49         if (*base == NULL) {
  50                 return NULL;
  51         }
  52         return (void *) L1_CACHE_ALIGN((u64) *base);
  53 }
  54
  55
  56 /*
  57  * Set up the initial values for the XPartition Communication channels.
  58  */
  59 static void
  60 xpc_initialize_channels(struct xpc_partition *part, partid_t partid)
  61 {
  62         int ch_number;
  63         struct xpc_channel *ch;
  64
  65
  66         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
  67                 ch = &part->channels[ch_number];
  68
  69                 ch->partid = partid;
  70                 ch->number = ch_number;
  71                 ch->flags = XPC_C_DISCONNECTED;
  72
  73                 ch->local_GP = &part->local_GPs[ch_number];
  74                 ch->local_openclose_args =
  75                                         &part->local_openclose_args[ch_number];
  76
  77                 atomic_set(&ch->kthreads_assigned, 0);
  78                 atomic_set(&ch->kthreads_idle, 0);
  79                 atomic_set(&ch->kthreads_active, 0);
  80
  81                 atomic_set(&ch->references, 0);
  82                 atomic_set(&ch->n_to_notify, 0);
  83
  84                 spin_lock_init(&ch->lock);
  85                 mutex_init(&ch->msg_to_pull_mutex);
  86                 init_completion(&ch->wdisconnect_wait);
  87
  88                 atomic_set(&ch->n_on_msg_allocate_wq, 0);
  89                 init_waitqueue_head(&ch->msg_allocate_wq);
  90                 init_waitqueue_head(&ch->idle_wq);
  91         }
  92 }
  93
  94
  95 /*
  96  * Setup the infrastructure necessary to support XPartition Communication
  97  * between the specified remote partition and the local one.
  98  */
  99 enum xpc_retval
 100 xpc_setup_infrastructure(struct xpc_partition *part)
 101 {
 102         int ret, cpuid;
 103         struct timer_list *timer;
 104         partid_t partid = XPC_PARTID(part);
 105
 106
 107         /*
 108          * Zero out MOST of the entry for this partition. Only the fields
 109          * starting with `nchannels' will be zeroed. The preceding fields must
 110          * remain `viable' across partition ups and downs, since they may be
 111          * referenced during this memset() operation.
 112          */
 113         memset(&part->nchannels, 0, sizeof(struct xpc_partition) -
 114                                 offsetof(struct xpc_partition, nchannels));
 115
 116         /*
 117          * Allocate all of the channel structures as a contiguous chunk of
 118          * memory.
 119          */
 120         part->channels = kzalloc(sizeof(struct xpc_channel) * XPC_NCHANNELS,
 121                                                                 GFP_KERNEL);
 122         if (part->channels == NULL) {
 123                 dev_err(xpc_chan, "can't get memory for channels\n");
 124                 return xpcNoMemory;
 125         }
 126
 127         part->nchannels = XPC_NCHANNELS;
 128
 129
 130         /* allocate all the required GET/PUT values */
 131
 132         part->local_GPs = xpc_kzalloc_cacheline_aligned(XPC_GP_SIZE,
 133                                         GFP_KERNEL, &part->local_GPs_base);
 134         if (part->local_GPs == NULL) {
 135                 kfree(part->channels);
 136                 part->channels = NULL;
 137                 dev_err(xpc_chan, "can't get memory for local get/put "
 138                         "values\n");
 139                 return xpcNoMemory;
 140         }
 141
 142         part->remote_GPs = xpc_kzalloc_cacheline_aligned(XPC_GP_SIZE,
 143                                         GFP_KERNEL, &part->remote_GPs_base);
 144         if (part->remote_GPs == NULL) {
 145                 dev_err(xpc_chan, "can't get memory for remote get/put "
 146                         "values\n");
 147                 kfree(part->local_GPs_base);
 148                 part->local_GPs = NULL;
 149                 kfree(part->channels);
 150                 part->channels = NULL;
 151                 return xpcNoMemory;
 152         }
 153
 154
 155         /* allocate all the required open and close args */
 156
 157         part->local_openclose_args = xpc_kzalloc_cacheline_aligned(
 158                                         XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
 159                                         &part->local_openclose_args_base);
 160         if (part->local_openclose_args == NULL) {
 161                 dev_err(xpc_chan, "can't get memory for local connect args\n");
 162                 kfree(part->remote_GPs_base);
 163                 part->remote_GPs = NULL;
 164                 kfree(part->local_GPs_base);
 165                 part->local_GPs = NULL;
 166                 kfree(part->channels);
 167                 part->channels = NULL;
 168                 return xpcNoMemory;
 169         }
 170
 171         part->remote_openclose_args = xpc_kzalloc_cacheline_aligned(
 172                                         XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
 173                                         &part->remote_openclose_args_base);
 174         if (part->remote_openclose_args == NULL) {
 175                 dev_err(xpc_chan, "can't get memory for remote connect args\n");
 176                 kfree(part->local_openclose_args_base);
 177                 part->local_openclose_args = NULL;
 178                 kfree(part->remote_GPs_base);
 179                 part->remote_GPs = NULL;
 180                 kfree(part->local_GPs_base);
 181                 part->local_GPs = NULL;
 182                 kfree(part->channels);
 183                 part->channels = NULL;
 184                 return xpcNoMemory;
 185         }
 186
 187
 188         xpc_initialize_channels(part, partid);
 189
 190         atomic_set(&part->nchannels_active, 0);
 191         atomic_set(&part->nchannels_engaged, 0);
 192
 193
 194         /* local_IPI_amo were set to 0 by an earlier memset() */
 195
 196         /* Initialize this partitions AMO_t structure */
 197         part->local_IPI_amo_va = xpc_IPI_init(partid);
 198
 199         spin_lock_init(&part->IPI_lock);
 200
 201         atomic_set(&part->channel_mgr_requests, 1);
 202         init_waitqueue_head(&part->channel_mgr_wq);
 203
 204         sprintf(part->IPI_owner, "xpc%02d", partid);
 205         ret = request_irq(SGI_XPC_NOTIFY, xpc_notify_IRQ_handler, IRQF_SHARED,
 206                                 part->IPI_owner, (void *) (u64) partid);
 207         if (ret != 0) {
 208                 dev_err(xpc_chan, "can't register NOTIFY IRQ handler, "
 209                         "errno=%d\n", -ret);
 210                 kfree(part->remote_openclose_args_base);
 211                 part->remote_openclose_args = NULL;
 212                 kfree(part->local_openclose_args_base);
 213                 part->local_openclose_args = NULL;
 214                 kfree(part->remote_GPs_base);
 215                 part->remote_GPs = NULL;
 216                 kfree(part->local_GPs_base);
 217                 part->local_GPs = NULL;
 218                 kfree(part->channels);
 219                 part->channels = NULL;
 220                 return xpcLackOfResources;
 221         }
 222
 223         /* Setup a timer to check for dropped IPIs */
 224         timer = &part->dropped_IPI_timer;
 225         init_timer(timer);
 226         timer->function = (void (*)(unsigned long)) xpc_dropped_IPI_check;
 227         timer->data = (unsigned long) part;
 228         timer->expires = jiffies + XPC_P_DROPPED_IPI_WAIT;
 229         add_timer(timer);
 230
 231         /*
 232          * With the setting of the partition setup_state to XPC_P_SETUP, we're
 233          * declaring that this partition is ready to go.
 234          */
 235         part->setup_state = XPC_P_SETUP;
 236
 237
 238         /*
 239          * Setup the per partition specific variables required by the
 240          * remote partition to establish channel connections with us.
 241          *
 242          * The setting of the magic # indicates that these per partition
 243          * specific variables are ready to be used.
 244          */
 245         xpc_vars_part[partid].GPs_pa = __pa(part->local_GPs);
 246         xpc_vars_part[partid].openclose_args_pa =
 247                                         __pa(part->local_openclose_args);
 248         xpc_vars_part[partid].IPI_amo_pa = __pa(part->local_IPI_amo_va);
 249         cpuid = raw_smp_processor_id(); /* any CPU in this partition will do */
 250         xpc_vars_part[partid].IPI_nasid = cpuid_to_nasid(cpuid);
 251         xpc_vars_part[partid].IPI_phys_cpuid = cpu_physical_id(cpuid);
 252         xpc_vars_part[partid].nchannels = part->nchannels;
 253         xpc_vars_part[partid].magic = XPC_VP_MAGIC1;
 254
 255         return xpcSuccess;
 256 }
 257
 258
 259 /*
 260  * Create a wrapper that hides the underlying mechanism for pulling a cacheline
 261  * (or multiple cachelines) from a remote partition.
 262  *
 263  * src must be a cacheline aligned physical address on the remote partition.
 264  * dst must be a cacheline aligned virtual address on this partition.
 265  * cnt must be an cacheline sized
 266  */
 267 static enum xpc_retval
 268 xpc_pull_remote_cachelines(struct xpc_partition *part, void *dst,
 269                                 const void *src, size_t cnt)
 270 {
 271         bte_result_t bte_ret;
 272
 273
 274         DBUG_ON((u64) src != L1_CACHE_ALIGN((u64) src));
 275         DBUG_ON((u64) dst != L1_CACHE_ALIGN((u64) dst));
 276         DBUG_ON(cnt != L1_CACHE_ALIGN(cnt));
 277
 278         if (part->act_state == XPC_P_DEACTIVATING) {
 279                 return part->reason;
 280         }
 281
 282         bte_ret = xp_bte_copy((u64) src, (u64) dst, (u64) cnt,
 283                                         (BTE_NORMAL | BTE_WACQUIRE), NULL);
 284         if (bte_ret == BTE_SUCCESS) {
 285                 return xpcSuccess;
 286         }
 287
 288         dev_dbg(xpc_chan, "xp_bte_copy() from partition %d failed, ret=%d\n",
 289                 XPC_PARTID(part), bte_ret);
 290
 291         return xpc_map_bte_errors(bte_ret);
 292 }
 293
 294
 295 /*
 296  * Pull the remote per partititon specific variables from the specified
 297  * partition.
 298  */
 299 enum xpc_retval
 300 xpc_pull_remote_vars_part(struct xpc_partition *part)
 301 {
 302         u8 buffer[L1_CACHE_BYTES * 2];
 303         struct xpc_vars_part *pulled_entry_cacheline =
 304                         (struct xpc_vars_part *) L1_CACHE_ALIGN((u64) buffer);
 305         struct xpc_vars_part *pulled_entry;
 306         u64 remote_entry_cacheline_pa, remote_entry_pa;
 307         partid_t partid = XPC_PARTID(part);
 308         enum xpc_retval ret;
 309
 310
 311         /* pull the cacheline that contains the variables we're interested in */
 312
 313         DBUG_ON(part->remote_vars_part_pa !=
 314                                 L1_CACHE_ALIGN(part->remote_vars_part_pa));
 315         DBUG_ON(sizeof(struct xpc_vars_part) != L1_CACHE_BYTES / 2);
 316
 317         remote_entry_pa = part->remote_vars_part_pa +
 318                         sn_partition_id * sizeof(struct xpc_vars_part);
 319
 320         remote_entry_cacheline_pa = (remote_entry_pa & ~(L1_CACHE_BYTES - 1));
 321
 322         pulled_entry = (struct xpc_vars_part *) ((u64) pulled_entry_cacheline +
 323                                 (remote_entry_pa & (L1_CACHE_BYTES - 1)));
 324
 325         ret = xpc_pull_remote_cachelines(part, pulled_entry_cacheline,
 326                                         (void *) remote_entry_cacheline_pa,
 327                                         L1_CACHE_BYTES);
 328         if (ret != xpcSuccess) {
 329                 dev_dbg(xpc_chan, "failed to pull XPC vars_part from "
 330                         "partition %d, ret=%d\n", partid, ret);
 331                 return ret;
 332         }
 333
 334
 335         /* see if they've been set up yet */
 336
 337         if (pulled_entry->magic != XPC_VP_MAGIC1 &&
 338                                 pulled_entry->magic != XPC_VP_MAGIC2) {
 339
 340                 if (pulled_entry->magic != 0) {
 341                         dev_dbg(xpc_chan, "partition %d's XPC vars_part for "
 342                                 "partition %d has bad magic value (=0x%lx)\n",
 343                                 partid, sn_partition_id, pulled_entry->magic);
 344                         return xpcBadMagic;
 345                 }
 346
 347                 /* they've not been initialized yet */
 348                 return xpcRetry;
 349         }
 350
 351         if (xpc_vars_part[partid].magic == XPC_VP_MAGIC1) {
 352
 353                 /* validate the variables */
 354
 355                 if (pulled_entry->GPs_pa == 0 ||
 356                                 pulled_entry->openclose_args_pa == 0 ||
 357                                         pulled_entry->IPI_amo_pa == 0) {
 358
 359                         dev_err(xpc_chan, "partition %d's XPC vars_part for "
 360                                 "partition %d are not valid\n", partid,
 361                                 sn_partition_id);
 362                         return xpcInvalidAddress;
 363                 }
 364
 365                 /* the variables we imported look to be valid */
 366
 367                 part->remote_GPs_pa = pulled_entry->GPs_pa;
 368                 part->remote_openclose_args_pa =
 369                                         pulled_entry->openclose_args_pa;
 370                 part->remote_IPI_amo_va =
 371                                       (AMO_t *) __va(pulled_entry->IPI_amo_pa);
 372                 part->remote_IPI_nasid = pulled_entry->IPI_nasid;
 373                 part->remote_IPI_phys_cpuid = pulled_entry->IPI_phys_cpuid;
 374
 375                 if (part->nchannels > pulled_entry->nchannels) {
 376                         part->nchannels = pulled_entry->nchannels;
 377                 }
 378
 379                 /* let the other side know that we've pulled their variables */
 380
 381                 xpc_vars_part[partid].magic = XPC_VP_MAGIC2;
 382         }
 383
 384         if (pulled_entry->magic == XPC_VP_MAGIC1) {
 385                 return xpcRetry;
 386         }
 387
 388         return xpcSuccess;
 389 }
 390
 391
 392 /*
 393  * Get the IPI flags and pull the openclose args and/or remote GPs as needed.
 394  */
 395 static u64
 396 xpc_get_IPI_flags(struct xpc_partition *part)
 397 {
 398         unsigned long irq_flags;
 399         u64 IPI_amo;
 400         enum xpc_retval ret;
 401
 402
 403         /*
 404          * See if there are any IPI flags to be handled.
 405          */
 406
 407         spin_lock_irqsave(&part->IPI_lock, irq_flags);
 408         if ((IPI_amo = part->local_IPI_amo) != 0) {
 409                 part->local_IPI_amo = 0;
 410         }
 411         spin_unlock_irqrestore(&part->IPI_lock, irq_flags);
 412
 413
 414         if (XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(IPI_amo)) {
 415                 ret = xpc_pull_remote_cachelines(part,
 416                                         part->remote_openclose_args,
 417                                         (void *) part->remote_openclose_args_pa,
 418                                         XPC_OPENCLOSE_ARGS_SIZE);
 419                 if (ret != xpcSuccess) {
 420                         XPC_DEACTIVATE_PARTITION(part, ret);
 421
 422                         dev_dbg(xpc_chan, "failed to pull openclose args from "
 423                                 "partition %d, ret=%d\n", XPC_PARTID(part),
 424                                 ret);
 425
 426                         /* don't bother processing IPIs anymore */
 427                         IPI_amo = 0;
 428                 }
 429         }
 430
 431         if (XPC_ANY_MSG_IPI_FLAGS_SET(IPI_amo)) {
 432                 ret = xpc_pull_remote_cachelines(part, part->remote_GPs,
 433                                                 (void *) part->remote_GPs_pa,
 434                                                 XPC_GP_SIZE);
 435                 if (ret != xpcSuccess) {
 436                         XPC_DEACTIVATE_PARTITION(part, ret);
 437
 438                         dev_dbg(xpc_chan, "failed to pull GPs from partition "
 439                                 "%d, ret=%d\n", XPC_PARTID(part), ret);
 440
 441                         /* don't bother processing IPIs anymore */
 442                         IPI_amo = 0;
 443                 }
 444         }
 445
 446         return IPI_amo;
 447 }
 448
 449
 450 /*
 451  * Allocate the local message queue and the notify queue.
 452  */
 453 static enum xpc_retval
 454 xpc_allocate_local_msgqueue(struct xpc_channel *ch)
 455 {
 456         unsigned long irq_flags;
 457         int nentries;
 458         size_t nbytes;
 459
 460
 461         // >>> may want to check for ch->flags & XPC_C_DISCONNECTING between
 462         // >>> iterations of the for-loop, bail if set?
 463
 464         // >>> should we impose a minumum #of entries? like 4 or 8?
 465         for (nentries = ch->local_nentries; nentries > 0; nentries--) {
 466
 467                 nbytes = nentries * ch->msg_size;
 468                 ch->local_msgqueue = xpc_kzalloc_cacheline_aligned(nbytes,
 469                                                 GFP_KERNEL,
 470                                                 &ch->local_msgqueue_base);
 471                 if (ch->local_msgqueue == NULL) {
 472                         continue;
 473                 }
 474
 475                 nbytes = nentries * sizeof(struct xpc_notify);
 476                 ch->notify_queue = kzalloc(nbytes, GFP_KERNEL);
 477                 if (ch->notify_queue == NULL) {
 478                         kfree(ch->local_msgqueue_base);
 479                         ch->local_msgqueue = NULL;
 480                         continue;
 481                 }
 482
 483                 spin_lock_irqsave(&ch->lock, irq_flags);
 484                 if (nentries < ch->local_nentries) {
 485                         dev_dbg(xpc_chan, "nentries=%d local_nentries=%d, "
 486                                 "partid=%d, channel=%d\n", nentries,
 487                                 ch->local_nentries, ch->partid, ch->number);
 488
 489                         ch->local_nentries = nentries;
 490                 }
 491                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 492                 return xpcSuccess;
 493         }
 494
 495         dev_dbg(xpc_chan, "can't get memory for local message queue and notify "
 496                 "queue, partid=%d, channel=%d\n", ch->partid, ch->number);
 497         return xpcNoMemory;
 498 }
 499
 500
 501 /*
 502  * Allocate the cached remote message queue.
 503  */
 504 static enum xpc_retval
 505 xpc_allocate_remote_msgqueue(struct xpc_channel *ch)
 506 {
 507         unsigned long irq_flags;
 508         int nentries;
 509         size_t nbytes;
 510
 511
 512         DBUG_ON(ch->remote_nentries <= 0);
 513
 514         // >>> may want to check for ch->flags & XPC_C_DISCONNECTING between
 515         // >>> iterations of the for-loop, bail if set?
 516
 517         // >>> should we impose a minumum #of entries? like 4 or 8?
 518         for (nentries = ch->remote_nentries; nentries > 0; nentries--) {
 519
 520                 nbytes = nentries * ch->msg_size;
 521                 ch->remote_msgqueue = xpc_kzalloc_cacheline_aligned(nbytes,
 522                                                 GFP_KERNEL,
 523                                                 &ch->remote_msgqueue_base);
 524                 if (ch->remote_msgqueue == NULL) {
 525                         continue;
 526                 }
 527
 528                 spin_lock_irqsave(&ch->lock, irq_flags);
 529                 if (nentries < ch->remote_nentries) {
 530                         dev_dbg(xpc_chan, "nentries=%d remote_nentries=%d, "
 531                                 "partid=%d, channel=%d\n", nentries,
 532                                 ch->remote_nentries, ch->partid, ch->number);
 533
 534                         ch->remote_nentries = nentries;
 535                 }
 536                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 537                 return xpcSuccess;
 538         }
 539
 540         dev_dbg(xpc_chan, "can't get memory for cached remote message queue, "
 541                 "partid=%d, channel=%d\n", ch->partid, ch->number);
 542         return xpcNoMemory;
 543 }
 544
 545
 546 /*
 547  * Allocate message queues and other stuff associated with a channel.
 548  *
 549  * Note: Assumes all of the channel sizes are filled in.
 550  */
 551 static enum xpc_retval
 552 xpc_allocate_msgqueues(struct xpc_channel *ch)
 553 {
 554         unsigned long irq_flags;
 555         enum xpc_retval ret;
 556
 557
 558         DBUG_ON(ch->flags & XPC_C_SETUP);
 559
 560         if ((ret = xpc_allocate_local_msgqueue(ch)) != xpcSuccess) {
 561                 return ret;
 562         }
 563
 564         if ((ret = xpc_allocate_remote_msgqueue(ch)) != xpcSuccess) {
 565                 kfree(ch->local_msgqueue_base);
 566                 ch->local_msgqueue = NULL;
 567                 kfree(ch->notify_queue);
 568                 ch->notify_queue = NULL;
 569                 return ret;
 570         }
 571
 572         spin_lock_irqsave(&ch->lock, irq_flags);
 573         ch->flags |= XPC_C_SETUP;
 574         spin_unlock_irqrestore(&ch->lock, irq_flags);
 575
 576         return xpcSuccess;
 577 }
 578
 579
 580 /*
 581  * Process a connect message from a remote partition.
 582  *
 583  * Note: xpc_process_connect() is expecting to be called with the
 584  * spin_lock_irqsave held and will leave it locked upon return.
 585  */
 586 static void
 587 xpc_process_connect(struct xpc_channel *ch, unsigned long *irq_flags)
 588 {
 589         enum xpc_retval ret;
 590
 591
 592         DBUG_ON(!spin_is_locked(&ch->lock));
 593
 594         if (!(ch->flags & XPC_C_OPENREQUEST) ||
 595                                 !(ch->flags & XPC_C_ROPENREQUEST)) {
 596                 /* nothing more to do for now */
 597                 return;
 598         }
 599         DBUG_ON(!(ch->flags & XPC_C_CONNECTING));
 600
 601         if (!(ch->flags & XPC_C_SETUP)) {
 602                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
 603                 ret = xpc_allocate_msgqueues(ch);
 604                 spin_lock_irqsave(&ch->lock, *irq_flags);
 605
 606                 if (ret != xpcSuccess) {
 607                         XPC_DISCONNECT_CHANNEL(ch, ret, irq_flags);
 608                 }
 609                 if (ch->flags & (XPC_C_CONNECTED | XPC_C_DISCONNECTING)) {
 610                         return;
 611                 }
 612
 613                 DBUG_ON(!(ch->flags & XPC_C_SETUP));
 614                 DBUG_ON(ch->local_msgqueue == NULL);
 615                 DBUG_ON(ch->remote_msgqueue == NULL);
 616         }
 617
 618         if (!(ch->flags & XPC_C_OPENREPLY)) {
 619                 ch->flags |= XPC_C_OPENREPLY;
 620                 xpc_IPI_send_openreply(ch, irq_flags);
 621         }
 622
 623         if (!(ch->flags & XPC_C_ROPENREPLY)) {
 624                 return;
 625         }
 626
 627         DBUG_ON(ch->remote_msgqueue_pa == 0);
 628
 629         ch->flags = (XPC_C_CONNECTED | XPC_C_SETUP);    /* clear all else */
 630
 631         dev_info(xpc_chan, "channel %d to partition %d connected\n",
 632                 ch->number, ch->partid);
 633
 634         spin_unlock_irqrestore(&ch->lock, *irq_flags);
 635         xpc_create_kthreads(ch, 1, 0);
 636         spin_lock_irqsave(&ch->lock, *irq_flags);
 637 }
 638
 639
 640 /*
 641  * Notify those who wanted to be notified upon delivery of their message.
 642  */
 643 static void
 644 xpc_notify_senders(struct xpc_channel *ch, enum xpc_retval reason, s64 put)
 645 {
 646         struct xpc_notify *notify;
 647         u8 notify_type;
 648         s64 get = ch->w_remote_GP.get - 1;
 649
 650
 651         while (++get < put && atomic_read(&ch->n_to_notify) > 0) {
 652
 653                 notify = &ch->notify_queue[get % ch->local_nentries];
 654
 655                 /*
 656                  * See if the notify entry indicates it was associated with
 657                  * a message who's sender wants to be notified. It is possible
 658                  * that it is, but someone else is doing or has done the
 659                  * notification.
 660                  */
 661                 notify_type = notify->type;
 662                 if (notify_type == 0 ||
 663                                 cmpxchg(&notify->type, notify_type, 0) !=
 664                                                                 notify_type) {
 665                         continue;
 666                 }
 667
 668                 DBUG_ON(notify_type != XPC_N_CALL);
 669
 670                 atomic_dec(&ch->n_to_notify);
 671
 672                 if (notify->func != NULL) {
 673                         dev_dbg(xpc_chan, "notify->func() called, notify=0x%p, "
 674                                 "msg_number=%ld, partid=%d, channel=%d\n",
 675                                 (void *) notify, get, ch->partid, ch->number);
 676
 677                         notify->func(reason, ch->partid, ch->number,
 678                                                                 notify->key);
 679
 680                         dev_dbg(xpc_chan, "notify->func() returned, "
 681                                 "notify=0x%p, msg_number=%ld, partid=%d, "
 682                                 "channel=%d\n", (void *) notify, get,
 683                                 ch->partid, ch->number);
 684                 }
 685         }
 686 }
 687
 688
 689 /*
 690  * Free up message queues and other stuff that were allocated for the specified
 691  * channel.
 692  *
 693  * Note: ch->reason and ch->reason_line are left set for debugging purposes,
 694  * they're cleared when XPC_C_DISCONNECTED is cleared.
 695  */
 696 static void
 697 xpc_free_msgqueues(struct xpc_channel *ch)
 698 {
 699         DBUG_ON(!spin_is_locked(&ch->lock));
 700         DBUG_ON(atomic_read(&ch->n_to_notify) != 0);
 701
 702         ch->remote_msgqueue_pa = 0;
 703         ch->func = NULL;
 704         ch->key = NULL;
 705         ch->msg_size = 0;
 706         ch->local_nentries = 0;
 707         ch->remote_nentries = 0;
 708         ch->kthreads_assigned_limit = 0;
 709         ch->kthreads_idle_limit = 0;
 710
 711         ch->local_GP->get = 0;
 712         ch->local_GP->put = 0;
 713         ch->remote_GP.get = 0;
 714         ch->remote_GP.put = 0;
 715         ch->w_local_GP.get = 0;
 716         ch->w_local_GP.put = 0;
 717         ch->w_remote_GP.get = 0;
 718         ch->w_remote_GP.put = 0;
 719         ch->next_msg_to_pull = 0;
 720
 721         if (ch->flags & XPC_C_SETUP) {
 722                 ch->flags &= ~XPC_C_SETUP;
 723
 724                 dev_dbg(xpc_chan, "ch->flags=0x%x, partid=%d, channel=%d\n",
 725                         ch->flags, ch->partid, ch->number);
 726
 727                 kfree(ch->local_msgqueue_base);
 728                 ch->local_msgqueue = NULL;
 729                 kfree(ch->remote_msgqueue_base);
 730                 ch->remote_msgqueue = NULL;
 731                 kfree(ch->notify_queue);
 732                 ch->notify_queue = NULL;
 733         }
 734 }
 735
 736
 737 /*
 738  * spin_lock_irqsave() is expected to be held on entry.
 739  */
 740 static void
 741 xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
 742 {
 743         struct xpc_partition *part = &xpc_partitions[ch->partid];
 744         u32 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);
 745
 746
 747         DBUG_ON(!spin_is_locked(&ch->lock));
 748
 749         if (!(ch->flags & XPC_C_DISCONNECTING)) {
 750                 return;
 751         }
 752
 753         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 754
 755         /* make sure all activity has settled down first */
 756
 757         if (atomic_read(&ch->kthreads_assigned) > 0 ||
 758                                 atomic_read(&ch->references) > 0) {
 759                 return;
 760         }
 761         DBUG_ON((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 762                         !(ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE));
 763
 764         if (part->act_state == XPC_P_DEACTIVATING) {
 765                 /* can't proceed until the other side disengages from us */
 766                 if (xpc_partition_engaged(1UL << ch->partid)) {
 767                         return;
 768                 }
 769
 770         } else {
 771
 772                 /* as long as the other side is up do the full protocol */
 773
 774                 if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
 775                         return;
 776                 }
 777
 778                 if (!(ch->flags & XPC_C_CLOSEREPLY)) {
 779                         ch->flags |= XPC_C_CLOSEREPLY;
 780                         xpc_IPI_send_closereply(ch, irq_flags);
 781                 }
 782
 783                 if (!(ch->flags & XPC_C_RCLOSEREPLY)) {
 784                         return;
 785                 }
 786         }
 787
 788         /* wake those waiting for notify completion */
 789         if (atomic_read(&ch->n_to_notify) > 0) {
 790                 /* >>> we do callout while holding ch->lock */
 791                 xpc_notify_senders(ch, ch->reason, ch->w_local_GP.put);
 792         }
 793
 794         /* both sides are disconnected now */
 795
 796         if (ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE) {
 797                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
 798                 xpc_disconnect_callout(ch, xpcDisconnected);
 799                 spin_lock_irqsave(&ch->lock, *irq_flags);
 800         }
 801
 802         /* it's now safe to free the channel's message queues */
 803         xpc_free_msgqueues(ch);
 804
 805         /* mark disconnected, clear all other flags except XPC_C_WDISCONNECT */
 806         ch->flags = (XPC_C_DISCONNECTED | (ch->flags & XPC_C_WDISCONNECT));
 807
 808         atomic_dec(&part->nchannels_active);
 809
 810         if (channel_was_connected) {
 811                 dev_info(xpc_chan, "channel %d to partition %d disconnected, "
 812                         "reason=%d\n", ch->number, ch->partid, ch->reason);
 813         }
 814
 815         if (ch->flags & XPC_C_WDISCONNECT) {
 816                 /* we won't lose the CPU since we're holding ch->lock */
 817                 complete(&ch->wdisconnect_wait);
 818         } else if (ch->delayed_IPI_flags) {
 819                 if (part->act_state != XPC_P_DEACTIVATING) {
 820                         /* time to take action on any delayed IPI flags */
 821                         spin_lock(&part->IPI_lock);
 822                         XPC_SET_IPI_FLAGS(part->local_IPI_amo, ch->number,
 823                                                         ch->delayed_IPI_flags);
 824                         spin_unlock(&part->IPI_lock);
 825                 }
 826                 ch->delayed_IPI_flags = 0;
 827         }
 828 }
 829
 830
 831 /*
 832  * Process a change in the channel's remote connection state.
 833  */
 834 static void
 835 xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
 836                                 u8 IPI_flags)
 837 {
 838         unsigned long irq_flags;
 839         struct xpc_openclose_args *args =
 840                                 &part->remote_openclose_args[ch_number];
 841         struct xpc_channel *ch = &part->channels[ch_number];
 842         enum xpc_retval reason;
 843
 844
 845
 846         spin_lock_irqsave(&ch->lock, irq_flags);
 847
 848 again:
 849
 850         if ((ch->flags & XPC_C_DISCONNECTED) &&
 851                                         (ch->flags & XPC_C_WDISCONNECT)) {
 852                 /*
 853                  * Delay processing IPI flags until thread waiting disconnect
 854                  * has had a chance to see that the channel is disconnected.
 855                  */
 856                 ch->delayed_IPI_flags |= IPI_flags;
 857                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 858                 return;
 859         }
 860
 861
 862         if (IPI_flags & XPC_IPI_CLOSEREQUEST) {
 863
 864                 dev_dbg(xpc_chan, "XPC_IPI_CLOSEREQUEST (reason=%d) received "
 865                         "from partid=%d, channel=%d\n", args->reason,
 866                         ch->partid, ch->number);
 867
 868                 /*
 869                  * If RCLOSEREQUEST is set, we're probably waiting for
 870                  * RCLOSEREPLY. We should find it and a ROPENREQUEST packed
 871                  * with this RCLOSEREQUEST in the IPI_flags.
 872                  */
 873
 874                 if (ch->flags & XPC_C_RCLOSEREQUEST) {
 875                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTING));
 876                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 877                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREPLY));
 878                         DBUG_ON(ch->flags & XPC_C_RCLOSEREPLY);
 879
 880                         DBUG_ON(!(IPI_flags & XPC_IPI_CLOSEREPLY));
 881                         IPI_flags &= ~XPC_IPI_CLOSEREPLY;
 882                         ch->flags |= XPC_C_RCLOSEREPLY;
 883
 884                         /* both sides have finished disconnecting */
 885                         xpc_process_disconnect(ch, &irq_flags);
 886                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 887                         goto again;
 888                 }
 889
 890                 if (ch->flags & XPC_C_DISCONNECTED) {
 891                         if (!(IPI_flags & XPC_IPI_OPENREQUEST)) {
 892                                 if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo,
 893                                          ch_number) & XPC_IPI_OPENREQUEST)) {
 894
 895                                         DBUG_ON(ch->delayed_IPI_flags != 0);
 896                                         spin_lock(&part->IPI_lock);
 897                                         XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 898                                                         ch_number,
 899                                                         XPC_IPI_CLOSEREQUEST);
 900                                         spin_unlock(&part->IPI_lock);
 901                                 }
 902                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 903                                 return;
 904                         }
 905
 906                         XPC_SET_REASON(ch, 0, 0);
 907                         ch->flags &= ~XPC_C_DISCONNECTED;
 908
 909                         atomic_inc(&part->nchannels_active);
 910                         ch->flags |= (XPC_C_CONNECTING | XPC_C_ROPENREQUEST);
 911                 }
 912
 913                 IPI_flags &= ~(XPC_IPI_OPENREQUEST | XPC_IPI_OPENREPLY);
 914
 915                 /*
 916                  * The meaningful CLOSEREQUEST connection state fields are:
 917                  *      reason = reason connection is to be closed
 918                  */
 919
 920                 ch->flags |= XPC_C_RCLOSEREQUEST;
 921
 922                 if (!(ch->flags & XPC_C_DISCONNECTING)) {
 923                         reason = args->reason;
 924                         if (reason <= xpcSuccess || reason > xpcUnknownReason) {
 925                                 reason = xpcUnknownReason;
 926                         } else if (reason == xpcUnregistering) {
 927                                 reason = xpcOtherUnregistering;
 928                         }
 929
 930                         XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
 931
 932                         DBUG_ON(IPI_flags & XPC_IPI_CLOSEREPLY);
 933                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 934                         return;
 935                 }
 936
 937                 xpc_process_disconnect(ch, &irq_flags);
 938         }
 939
 940
 941         if (IPI_flags & XPC_IPI_CLOSEREPLY) {
 942
 943                 dev_dbg(xpc_chan, "XPC_IPI_CLOSEREPLY received from partid=%d,"
 944                         " channel=%d\n", ch->partid, ch->number);
 945
 946                 if (ch->flags & XPC_C_DISCONNECTED) {
 947                         DBUG_ON(part->act_state != XPC_P_DEACTIVATING);
 948                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 949                         return;
 950                 }
 951
 952                 DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 953
 954                 if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
 955                         if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo, ch_number)
 956                                                 & XPC_IPI_CLOSEREQUEST)) {
 957
 958                                 DBUG_ON(ch->delayed_IPI_flags != 0);
 959                                 spin_lock(&part->IPI_lock);
 960                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 961                                                 ch_number, XPC_IPI_CLOSEREPLY);
 962                                 spin_unlock(&part->IPI_lock);
 963                         }
 964                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 965                         return;
 966                 }
 967
 968                 ch->flags |= XPC_C_RCLOSEREPLY;
 969
 970                 if (ch->flags & XPC_C_CLOSEREPLY) {
 971                         /* both sides have finished disconnecting */
 972                         xpc_process_disconnect(ch, &irq_flags);
 973                 }
 974         }
 975
 976
 977         if (IPI_flags & XPC_IPI_OPENREQUEST) {
 978
 979                 dev_dbg(xpc_chan, "XPC_IPI_OPENREQUEST (msg_size=%d, "
 980                         "local_nentries=%d) received from partid=%d, "
 981                         "channel=%d\n", args->msg_size, args->local_nentries,
 982                         ch->partid, ch->number);
 983
 984                 if (part->act_state == XPC_P_DEACTIVATING ||
 985                                         (ch->flags & XPC_C_ROPENREQUEST)) {
 986                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 987                         return;
 988                 }
 989
 990                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_WDISCONNECT)) {
 991                         ch->delayed_IPI_flags |= XPC_IPI_OPENREQUEST;
 992                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 993                         return;
 994                 }
 995                 DBUG_ON(!(ch->flags & (XPC_C_DISCONNECTED |
 996                                                         XPC_C_OPENREQUEST)));
 997                 DBUG_ON(ch->flags & (XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
 998                                         XPC_C_OPENREPLY | XPC_C_CONNECTED));
 999
1000                 /*
1001                  * The meaningful OPENREQUEST connection state fields are:
1002                  *      msg_size = size of channel's messages in bytes
1003                  *      local_nentries = remote partition's local_nentries
1004                  */
1005                 if (args->msg_size == 0 || args->local_nentries == 0) {
1006                         /* assume OPENREQUEST was delayed by mistake */
1007                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1008                         return;
1009                 }
1010
1011                 ch->flags |= (XPC_C_ROPENREQUEST | XPC_C_CONNECTING);
1012                 ch->remote_nentries = args->local_nentries;
1013
1014
1015                 if (ch->flags & XPC_C_OPENREQUEST) {
1016                         if (args->msg_size != ch->msg_size) {
1017                                 XPC_DISCONNECT_CHANNEL(ch, xpcUnequalMsgSizes,
1018                                                                 &irq_flags);
1019                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
1020                                 return;
1021                         }
1022                 } else {
1023                         ch->msg_size = args->msg_size;
1024
1025                         XPC_SET_REASON(ch, 0, 0);
1026                         ch->flags &= ~XPC_C_DISCONNECTED;
1027
1028                         atomic_inc(&part->nchannels_active);
1029                 }
1030
1031                 xpc_process_connect(ch, &irq_flags);
1032         }
1033
1034
1035         if (IPI_flags & XPC_IPI_OPENREPLY) {
1036
1037                 dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY (local_msgqueue_pa=0x%lx, "
1038                         "local_nentries=%d, remote_nentries=%d) received from "
1039                         "partid=%d, channel=%d\n", args->local_msgqueue_pa,
1040                         args->local_nentries, args->remote_nentries,
1041                         ch->partid, ch->number);
1042
1043                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
1044                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1045                         return;
1046                 }
1047                 if (!(ch->flags & XPC_C_OPENREQUEST)) {
1048                         XPC_DISCONNECT_CHANNEL(ch, xpcOpenCloseError,
1049                                                                 &irq_flags);
1050                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1051                         return;
1052                 }
1053
1054                 DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
1055                 DBUG_ON(ch->flags & XPC_C_CONNECTED);
1056
1057                 /*
1058                  * The meaningful OPENREPLY connection state fields are:
1059                  *      local_msgqueue_pa = physical address of remote
1060                  *                          partition's local_msgqueue
1061                  *      local_nentries = remote partition's local_nentries
1062                  *      remote_nentries = remote partition's remote_nentries
1063                  */
1064                 DBUG_ON(args->local_msgqueue_pa == 0);
1065                 DBUG_ON(args->local_nentries == 0);
1066                 DBUG_ON(args->remote_nentries == 0);
1067
1068                 ch->flags |= XPC_C_ROPENREPLY;
1069                 ch->remote_msgqueue_pa = args->local_msgqueue_pa;
1070
1071                 if (args->local_nentries < ch->remote_nentries) {
1072                         dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY: new "
1073                                 "remote_nentries=%d, old remote_nentries=%d, "
1074                                 "partid=%d, channel=%d\n",
1075                                 args->local_nentries, ch->remote_nentries,
1076                                 ch->partid, ch->number);
1077
1078                         ch->remote_nentries = args->local_nentries;
1079                 }
1080                 if (args->remote_nentries < ch->local_nentries) {
1081                         dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY: new "
1082                                 "local_nentries=%d, old local_nentries=%d, "
1083                                 "partid=%d, channel=%d\n",
1084                                 args->remote_nentries, ch->local_nentries,
1085                                 ch->partid, ch->number);
1086
1087                         ch->local_nentries = args->remote_nentries;
1088                 }
1089
1090                 xpc_process_connect(ch, &irq_flags);
1091         }
1092
1093         spin_unlock_irqrestore(&ch->lock, irq_flags);
1094 }
1095
1096
1097 /*
1098  * Attempt to establish a channel connection to a remote partition.
1099  */
1100 static enum xpc_retval
1101 xpc_connect_channel(struct xpc_channel *ch)
1102 {
1103         unsigned long irq_flags;
1104         struct xpc_registration *registration = &xpc_registrations[ch->number];
1105
1106
1107         if (mutex_trylock(&registration->mutex) == 0) {
1108                 return xpcRetry;
1109         }
1110
1111         if (!XPC_CHANNEL_REGISTERED(ch->number)) {
1112                 mutex_unlock(&registration->mutex);
1113                 return xpcUnregistered;
1114         }
1115
1116         spin_lock_irqsave(&ch->lock, irq_flags);
1117
1118         DBUG_ON(ch->flags & XPC_C_CONNECTED);
1119         DBUG_ON(ch->flags & XPC_C_OPENREQUEST);
1120
1121         if (ch->flags & XPC_C_DISCONNECTING) {
1122                 spin_unlock_irqrestore(&ch->lock, irq_flags);
1123                 mutex_unlock(&registration->mutex);
1124                 return ch->reason;
1125         }
1126
1127
1128         /* add info from the channel connect registration to the channel */
1129
1130         ch->kthreads_assigned_limit = registration->assigned_limit;
1131         ch->kthreads_idle_limit = registration->idle_limit;
1132         DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
1133         DBUG_ON(atomic_read(&ch->kthreads_idle) != 0);
1134         DBUG_ON(atomic_read(&ch->kthreads_active) != 0);
1135
1136         ch->func = registration->func;
1137         DBUG_ON(registration->func == NULL);
1138         ch->key = registration->key;
1139
1140         ch->local_nentries = registration->nentries;
1141
1142         if (ch->flags & XPC_C_ROPENREQUEST) {
1143                 if (registration->msg_size != ch->msg_size) {
1144                         /* the local and remote sides aren't the same */
1145
1146                         /*
1147                          * Because XPC_DISCONNECT_CHANNEL() can block we're
1148                          * forced to up the registration sema before we unlock
1149                          * the channel lock. But that's okay here because we're
1150                          * done with the part that required the registration
1151                          * sema. XPC_DISCONNECT_CHANNEL() requires that the
1152                          * channel lock be locked and will unlock and relock
1153                          * the channel lock as needed.
1154                          */
1155                         mutex_unlock(&registration->mutex);
1156                         XPC_DISCONNECT_CHANNEL(ch, xpcUnequalMsgSizes,
1157                                                                 &irq_flags);
1158                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1159                         return xpcUnequalMsgSizes;
1160                 }
1161         } else {
1162                 ch->msg_size = registration->msg_size;
1163
1164                 XPC_SET_REASON(ch, 0, 0);
1165                 ch->flags &= ~XPC_C_DISCONNECTED;
1166
1167                 atomic_inc(&xpc_partitions[ch->partid].nchannels_active);
1168         }
1169
1170         mutex_unlock(&registration->mutex);
1171
1172
1173         /* initiate the connection */
1174
1175         ch->flags |= (XPC_C_OPENREQUEST | XPC_C_CONNECTING);
1176         xpc_IPI_send_openrequest(ch, &irq_flags);
1177
1178         xpc_process_connect(ch, &irq_flags);
1179
1180         spin_unlock_irqrestore(&ch->lock, irq_flags);
1181
1182         return xpcSuccess;
1183 }
1184
1185
1186 /*
1187  * Clear some of the msg flags in the local message queue.
1188  */
1189 static inline void
1190 xpc_clear_local_msgqueue_flags(struct xpc_channel *ch)
1191 {
1192         struct xpc_msg *msg;
1193         s64 get;
1194
1195
1196         get = ch->w_remote_GP.get;
1197         do {
1198                 msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
1199                                 (get % ch->local_nentries) * ch->msg_size);
1200                 msg->flags = 0;
1201         } while (++get < (volatile s64) ch->remote_GP.get);
1202 }
1203
1204
1205 /*
1206  * Clear some of the msg flags in the remote message queue.
1207  */
1208 static inline void
1209 xpc_clear_remote_msgqueue_flags(struct xpc_channel *ch)
1210 {
1211         struct xpc_msg *msg;
1212         s64 put;
1213
1214
1215         put = ch->w_remote_GP.put;
1216         do {
1217                 msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
1218                                 (put % ch->remote_nentries) * ch->msg_size);
1219                 msg->flags = 0;
1220         } while (++put < (volatile s64) ch->remote_GP.put);
1221 }
1222
1223
1224 static void
1225 xpc_process_msg_IPI(struct xpc_partition *part, int ch_number)
1226 {
1227         struct xpc_channel *ch = &part->channels[ch_number];
1228         int nmsgs_sent;
1229
1230
1231         ch->remote_GP = part->remote_GPs[ch_number];
1232
1233
1234         /* See what, if anything, has changed for each connected channel */
1235
1236         xpc_msgqueue_ref(ch);
1237
1238         if (ch->w_remote_GP.get == ch->remote_GP.get &&
1239                                 ch->w_remote_GP.put == ch->remote_GP.put) {
1240                 /* nothing changed since GPs were last pulled */
1241                 xpc_msgqueue_deref(ch);
1242                 return;
1243         }
1244
1245         if (!(ch->flags & XPC_C_CONNECTED)){
1246                 xpc_msgqueue_deref(ch);
1247                 return;
1248         }
1249
1250
1251         /*
1252          * First check to see if messages recently sent by us have been
1253          * received by the other side. (The remote GET value will have
1254          * changed since we last looked at it.)
1255          */
1256
1257         if (ch->w_remote_GP.get != ch->remote_GP.get) {
1258
1259                 /*
1260                  * We need to notify any senders that want to be notified
1261                  * that their sent messages have been received by their
1262                  * intended recipients. We need to do this before updating
1263                  * w_remote_GP.get so that we don't allocate the same message
1264                  * queue entries prematurely (see xpc_allocate_msg()).
1265                  */
1266                 if (atomic_read(&ch->n_to_notify) > 0) {
1267                         /*
1268                          * Notify senders that messages sent have been
1269                          * received and delivered by the other side.
1270                          */
1271                         xpc_notify_senders(ch, xpcMsgDelivered,
1272                                                         ch->remote_GP.get);
1273                 }
1274
1275                 /*
1276                  * Clear msg->flags in previously sent messages, so that
1277                  * they're ready for xpc_allocate_msg().
1278                  */
1279                 xpc_clear_local_msgqueue_flags(ch);
1280
1281                 ch->w_remote_GP.get = ch->remote_GP.get;
1282
1283                 dev_dbg(xpc_chan, "w_remote_GP.get changed to %ld, partid=%d, "
1284                         "channel=%d\n", ch->w_remote_GP.get, ch->partid,
1285                         ch->number);
1286
1287                 /*
1288                  * If anyone was waiting for message queue entries to become
1289                  * available, wake them up.
1290                  */
1291                 if (atomic_read(&ch->n_on_msg_allocate_wq) > 0) {
1292                         wake_up(&ch->msg_allocate_wq);
1293                 }
1294         }
1295
1296
1297         /*
1298          * Now check for newly sent messages by the other side. (The remote
1299          * PUT value will have changed since we last looked at it.)
1300          */
1301
1302         if (ch->w_remote_GP.put != ch->remote_GP.put) {
1303                 /*
1304                  * Clear msg->flags in previously received messages, so that
1305                  * they're ready for xpc_get_deliverable_msg().
1306                  */
1307                 xpc_clear_remote_msgqueue_flags(ch);
1308
1309                 ch->w_remote_GP.put = ch->remote_GP.put;
1310
1311                 dev_dbg(xpc_chan, "w_remote_GP.put changed to %ld, partid=%d, "
1312                         "channel=%d\n", ch->w_remote_GP.put, ch->partid,
1313                         ch->number);
1314
1315                 nmsgs_sent = ch->w_remote_GP.put - ch->w_local_GP.get;
1316                 if (nmsgs_sent > 0) {
1317                         dev_dbg(xpc_chan, "msgs waiting to be copied and "
1318                                 "delivered=%d, partid=%d, channel=%d\n",
1319                                 nmsgs_sent, ch->partid, ch->number);
1320
1321                         if (ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) {
1322                                 xpc_activate_kthreads(ch, nmsgs_sent);
1323                         }
1324                 }
1325         }
1326
1327         xpc_msgqueue_deref(ch);
1328 }
1329
1330
1331 void
1332 xpc_process_channel_activity(struct xpc_partition *part)
1333 {
1334         unsigned long irq_flags;
1335         u64 IPI_amo, IPI_flags;
1336         struct xpc_channel *ch;
1337         int ch_number;
1338         u32 ch_flags;
1339
1340
1341         IPI_amo = xpc_get_IPI_flags(part);
1342
1343         /*
1344          * Initiate channel connections for registered channels.
1345          *
1346          * For each connected channel that has pending messages activate idle
1347          * kthreads and/or create new kthreads as needed.
1348          */
1349
1350         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
1351                 ch = &part->channels[ch_number];
1352
1353
1354                 /*
1355                  * Process any open or close related IPI flags, and then deal
1356                  * with connecting or disconnecting the channel as required.
1357                  */
1358
1359                 IPI_flags = XPC_GET_IPI_FLAGS(IPI_amo, ch_number);
1360
1361                 if (XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(IPI_flags)) {
1362                         xpc_process_openclose_IPI(part, ch_number, IPI_flags);
1363                 }
1364
1365                 ch_flags = ch->flags;   /* need an atomic snapshot of flags */
1366
1367                 if (ch_flags & XPC_C_DISCONNECTING) {
1368                         spin_lock_irqsave(&ch->lock, irq_flags);
1369                         xpc_process_disconnect(ch, &irq_flags);
1370                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1371                         continue;
1372                 }
1373
1374                 if (part->act_state == XPC_P_DEACTIVATING) {
1375                         continue;
1376                 }
1377
1378                 if (!(ch_flags & XPC_C_CONNECTED)) {
1379                         if (!(ch_flags & XPC_C_OPENREQUEST)) {
1380                                 DBUG_ON(ch_flags & XPC_C_SETUP);
1381                                 (void) xpc_connect_channel(ch);
1382                         } else {
1383                                 spin_lock_irqsave(&ch->lock, irq_flags);
1384                                 xpc_process_connect(ch, &irq_flags);
1385                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
1386                         }
1387                         continue;
1388                 }
1389
1390
1391                 /*
1392                  * Process any message related IPI flags, this may involve the
1393                  * activation of kthreads to deliver any pending messages sent
1394                  * from the other partition.
1395                  */
1396
1397                 if (XPC_ANY_MSG_IPI_FLAGS_SET(IPI_flags)) {
1398                         xpc_process_msg_IPI(part, ch_number);
1399                 }
1400         }
1401 }
1402
1403
1404 /*
1405  * XPC's heartbeat code calls this function to inform XPC that a partition is
1406  * going down.  XPC responds by tearing down the XPartition Communication
1407  * infrastructure used for the just downed partition.
1408  *
1409  * XPC's heartbeat code will never call this function and xpc_partition_up()
1410  * at the same time. Nor will it ever make multiple calls to either function
1411  * at the same time.
1412  */
1413 void
1414 xpc_partition_going_down(struct xpc_partition *part, enum xpc_retval reason)
1415 {
1416         unsigned long irq_flags;
1417         int ch_number;
1418         struct xpc_channel *ch;
1419
1420
1421         dev_dbg(xpc_chan, "deactivating partition %d, reason=%d\n",
1422                 XPC_PARTID(part), reason);
1423
1424         if (!xpc_part_ref(part)) {
1425                 /* infrastructure for this partition isn't currently set up */
1426                 return;
1427         }
1428
1429
1430         /* disconnect channels associated with the partition going down */
1431
1432         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
1433                 ch = &part->channels[ch_number];
1434
1435                 xpc_msgqueue_ref(ch);
1436                 spin_lock_irqsave(&ch->lock, irq_flags);
1437
1438                 XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
1439
1440                 spin_unlock_irqrestore(&ch->lock, irq_flags);
1441                 xpc_msgqueue_deref(ch);
1442         }
1443
1444         xpc_wakeup_channel_mgr(part);
1445
1446         xpc_part_deref(part);
1447 }
1448
1449
1450 /*
1451  * Teardown the infrastructure necessary to support XPartition Communication
1452  * between the specified remote partition and the local one.
1453  */
1454 void
1455 xpc_teardown_infrastructure(struct xpc_partition *part)
1456 {
1457         partid_t partid = XPC_PARTID(part);
1458
1459
1460         /*
1461          * We start off by making this partition inaccessible to local
1462          * processes by marking it as no longer setup. Then we make it
1463          * inaccessible to remote processes by clearing the XPC per partition
1464          * specific variable's magic # (which indicates that these variables
1465          * are no longer valid) and by ignoring all XPC notify IPIs sent to
1466          * this partition.
1467          */
1468
1469         DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
1470         DBUG_ON(atomic_read(&part->nchannels_active) != 0);
1471         DBUG_ON(part->setup_state != XPC_P_SETUP);
1472         part->setup_state = XPC_P_WTEARDOWN;
1473
1474         xpc_vars_part[partid].magic = 0;
1475
1476
1477         free_irq(SGI_XPC_NOTIFY, (void *) (u64) partid);
1478
1479
1480         /*
1481          * Before proceding with the teardown we have to wait until all
1482          * existing references cease.
1483          */
1484         wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
1485
1486
1487         /* now we can begin tearing down the infrastructure */
1488
1489         part->setup_state = XPC_P_TORNDOWN;
1490
1491         /* in case we've still got outstanding timers registered... */
1492         del_timer_sync(&part->dropped_IPI_timer);
1493
1494         kfree(part->remote_openclose_args_base);
1495         part->remote_openclose_args = NULL;
1496         kfree(part->local_openclose_args_base);
1497         part->local_openclose_args = NULL;
1498         kfree(part->remote_GPs_base);
1499         part->remote_GPs = NULL;
1500         kfree(part->local_GPs_base);
1501         part->local_GPs = NULL;
1502         kfree(part->channels);
1503         part->channels = NULL;
1504         part->local_IPI_amo_va = NULL;
1505 }
1506
1507
1508 /*
1509  * Called by XP at the time of channel connection registration to cause
1510  * XPC to establish connections to all currently active partitions.
1511  */
1512 void
1513 xpc_initiate_connect(int ch_number)
1514 {
1515         partid_t partid;
1516         struct xpc_partition *part;
1517         struct xpc_channel *ch;
1518
1519
1520         DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);
1521
1522         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1523                 part = &xpc_partitions[partid];
1524
1525                 if (xpc_part_ref(part)) {
1526                         ch = &part->channels[ch_number];
1527
1528                         /*
1529                          * Initiate the establishment of a connection on the
1530                          * newly registered channel to the remote partition.
1531                          */
1532                         xpc_wakeup_channel_mgr(part);
1533                         xpc_part_deref(part);
1534                 }
1535         }
1536 }
1537
1538
1539 void
1540 xpc_connected_callout(struct xpc_channel *ch)
1541 {
1542         /* let the registerer know that a connection has been established */
1543
1544         if (ch->func != NULL) {
1545                 dev_dbg(xpc_chan, "ch->func() called, reason=xpcConnected, "
1546                         "partid=%d, channel=%d\n", ch->partid, ch->number);
1547
1548                 ch->func(xpcConnected, ch->partid, ch->number,
1549                                 (void *) (u64) ch->local_nentries, ch->key);
1550
1551                 dev_dbg(xpc_chan, "ch->func() returned, reason=xpcConnected, "
1552                         "partid=%d, channel=%d\n", ch->partid, ch->number);
1553         }
1554 }
1555
1556
1557 /*
1558  * Called by XP at the time of channel connection unregistration to cause
1559  * XPC to teardown all current connections for the specified channel.
1560  *
1561  * Before returning xpc_initiate_disconnect() will wait until all connections
1562  * on the specified channel have been closed/torndown. So the caller can be
1563  * assured that they will not be receiving any more callouts from XPC to the
1564  * function they registered via xpc_connect().
1565  *
1566  * Arguments:
1567  *
1568  *      ch_number - channel # to unregister.
1569  */
1570 void
1571 xpc_initiate_disconnect(int ch_number)
1572 {
1573         unsigned long irq_flags;
1574         partid_t partid;
1575         struct xpc_partition *part;
1576         struct xpc_channel *ch;
1577
1578
1579         DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);
1580
1581         /* initiate the channel disconnect for every active partition */
1582         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1583                 part = &xpc_partitions[partid];
1584
1585                 if (xpc_part_ref(part)) {
1586                         ch = &part->channels[ch_number];
1587                         xpc_msgqueue_ref(ch);
1588
1589                         spin_lock_irqsave(&ch->lock, irq_flags);
1590
1591                         if (!(ch->flags & XPC_C_DISCONNECTED)) {
1592                                 ch->flags |= XPC_C_WDISCONNECT;
1593
1594                                 XPC_DISCONNECT_CHANNEL(ch, xpcUnregistering,
1595                                                                 &irq_flags);
1596                         }
1597
1598                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1599
1600                         xpc_msgqueue_deref(ch);
1601                         xpc_part_deref(part);
1602                 }
1603         }
1604
1605         xpc_disconnect_wait(ch_number);
1606 }
1607
1608
1609 /*
1610  * To disconnect a channel, and reflect it back to all who may be waiting.
1611  *
1612  * An OPEN is not allowed until XPC_C_DISCONNECTING is cleared by
1613  * xpc_process_disconnect(), and if set, XPC_C_WDISCONNECT is cleared by
1614  * xpc_disconnect_wait().
1615  *
1616  * THE CHANNEL IS TO BE LOCKED BY THE CALLER AND WILL REMAIN LOCKED UPON RETURN.
1617  */
1618 void
1619 xpc_disconnect_channel(const int line, struct xpc_channel *ch,
1620                         enum xpc_retval reason, unsigned long *irq_flags)
1621 {
1622         u32 channel_was_connected = (ch->flags & XPC_C_CONNECTED);
1623
1624
1625         DBUG_ON(!spin_is_locked(&ch->lock));
1626
1627         if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
1628                 return;
1629         }
1630         DBUG_ON(!(ch->flags & (XPC_C_CONNECTING | XPC_C_CONNECTED)));
1631
1632         dev_dbg(xpc_chan, "reason=%d, line=%d, partid=%d, channel=%d\n",
1633                 reason, line, ch->partid, ch->number);
1634
1635         XPC_SET_REASON(ch, reason, line);
1636
1637         ch->flags |= (XPC_C_CLOSEREQUEST | XPC_C_DISCONNECTING);
1638         /* some of these may not have been set */
1639         ch->flags &= ~(XPC_C_OPENREQUEST | XPC_C_OPENREPLY |
1640                         XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
1641                         XPC_C_CONNECTING | XPC_C_CONNECTED);
1642
1643         xpc_IPI_send_closerequest(ch, irq_flags);
1644
1645         if (channel_was_connected) {
1646                 ch->flags |= XPC_C_WASCONNECTED;
1647         }
1648
1649         spin_unlock_irqrestore(&ch->lock, *irq_flags);
1650
1651         /* wake all idle kthreads so they can exit */
1652         if (atomic_read(&ch->kthreads_idle) > 0) {
1653                 wake_up_all(&ch->idle_wq);
1654
1655         } else if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
1656                         !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
1657                 /* start a kthread that will do the xpcDisconnecting callout */
1658                 xpc_create_kthreads(ch, 1, 1);
1659         }
1660
1661         /* wake those waiting to allocate an entry from the local msg queue */
1662         if (atomic_read(&ch->n_on_msg_allocate_wq) > 0) {
1663                 wake_up(&ch->msg_allocate_wq);
1664         }
1665
1666         spin_lock_irqsave(&ch->lock, *irq_flags);
1667 }
1668
1669
1670 void
1671 xpc_disconnect_callout(struct xpc_channel *ch, enum xpc_retval reason)
1672 {
1673         /*
1674          * Let the channel's registerer know that the channel is being
1675          * disconnected. We don't want to do this if the registerer was never
1676          * informed of a connection being made.
1677          */
1678
1679         if (ch->func != NULL) {
1680                 dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
1681                         "channel=%d\n", reason, ch->partid, ch->number);
1682
1683                 ch->func(reason, ch->partid, ch->number, NULL, ch->key);
1684
1685                 dev_dbg(xpc_chan, "ch->func() returned, reason=%d, partid=%d, "
1686                         "channel=%d\n", reason, ch->partid, ch->number);
1687         }
1688 }
1689
1690
1691 /*
1692  * Wait for a message entry to become available for the specified channel,
1693  * but don't wait any longer than 1 jiffy.
1694  */
1695 static enum xpc_retval
1696 xpc_allocate_msg_wait(struct xpc_channel *ch)
1697 {
1698         enum xpc_retval ret;
1699
1700
1701         if (ch->flags & XPC_C_DISCONNECTING) {
1702                 DBUG_ON(ch->reason == xpcInterrupted);  // >>> Is this true?
1703                 return ch->reason;
1704         }
1705
1706         atomic_inc(&ch->n_on_msg_allocate_wq);
1707         ret = interruptible_sleep_on_timeout(&ch->msg_allocate_wq, 1);
1708         atomic_dec(&ch->n_on_msg_allocate_wq);
1709
1710         if (ch->flags & XPC_C_DISCONNECTING) {
1711                 ret = ch->reason;
1712                 DBUG_ON(ch->reason == xpcInterrupted);  // >>> Is this true?
1713         } else if (ret == 0) {
1714                 ret = xpcTimeout;
1715         } else {
1716                 ret = xpcInterrupted;
1717         }
1718
1719         return ret;
1720 }
1721
1722
1723 /*
1724  * Allocate an entry for a message from the message queue associated with the
1725  * specified channel.
1726  */
1727 static enum xpc_retval
1728 xpc_allocate_msg(struct xpc_channel *ch, u32 flags,
1729                         struct xpc_msg **address_of_msg)
1730 {
1731         struct xpc_msg *msg;
1732         enum xpc_retval ret;
1733         s64 put;
1734
1735
1736         /* this reference will be dropped in xpc_send_msg() */
1737         xpc_msgqueue_ref(ch);
1738
1739         if (ch->flags & XPC_C_DISCONNECTING) {
1740                 xpc_msgqueue_deref(ch);
1741                 return ch->reason;
1742         }
1743         if (!(ch->flags & XPC_C_CONNECTED)) {
1744                 xpc_msgqueue_deref(ch);
1745                 return xpcNotConnected;
1746         }
1747
1748
1749         /*
1750          * Get the next available message entry from the local message queue.
1751          * If none are available, we'll make sure that we grab the latest
1752          * GP values.
1753          */
1754         ret = xpcTimeout;
1755
1756         while (1) {
1757
1758                 put = (volatile s64) ch->w_local_GP.put;
1759                 if (put - (volatile s64) ch->w_remote_GP.get <
1760                                                         ch->local_nentries) {
1761
1762                         /* There are available message entries. We need to try
1763                          * to secure one for ourselves. We'll do this by trying
1764                          * to increment w_local_GP.put as long as someone else
1765                          * doesn't beat us to it. If they do, we'll have to
1766                          * try again.
1767                          */
1768                         if (cmpxchg(&ch->w_local_GP.put, put, put + 1) ==
1769                                                                         put) {
1770                                 /* we got the entry referenced by put */
1771                                 break;
1772                         }
1773                         continue;       /* try again */
1774                 }
1775
1776
1777                 /*
1778                  * There aren't any available msg entries at this time.
1779                  *
1780                  * In waiting for a message entry to become available,
1781                  * we set a timeout in case the other side is not
1782                  * sending completion IPIs. This lets us fake an IPI
1783                  * that will cause the IPI handler to fetch the latest
1784                  * GP values as if an IPI was sent by the other side.
1785                  */
1786                 if (ret == xpcTimeout) {
1787                         xpc_IPI_send_local_msgrequest(ch);
1788                 }
1789
1790                 if (flags & XPC_NOWAIT) {
1791                         xpc_msgqueue_deref(ch);
1792                         return xpcNoWait;
1793                 }
1794
1795                 ret = xpc_allocate_msg_wait(ch);
1796                 if (ret != xpcInterrupted && ret != xpcTimeout) {
1797                         xpc_msgqueue_deref(ch);
1798                         return ret;
1799                 }
1800         }
1801
1802
1803         /* get the message's address and initialize it */
1804         msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
1805                                 (put % ch->local_nentries) * ch->msg_size);
1806
1807
1808         DBUG_ON(msg->flags != 0);
1809         msg->number = put;
1810
1811         dev_dbg(xpc_chan, "w_local_GP.put changed to %ld; msg=0x%p, "
1812                 "msg_number=%ld, partid=%d, channel=%d\n", put + 1,
1813                 (void *) msg, msg->number, ch->partid, ch->number);
1814
1815         *address_of_msg = msg;
1816
1817         return xpcSuccess;
1818 }
1819
1820
1821 /*
1822  * Allocate an entry for a message from the message queue associated with the
1823  * specified channel. NOTE that this routine can sleep waiting for a message
1824  * entry to become available. To not sleep, pass in the XPC_NOWAIT flag.
1825  *
1826  * Arguments:
1827  *
1828  *      partid - ID of partition to which the channel is connected.
1829  *      ch_number - channel #.
1830  *      flags - see xpc.h for valid flags.
1831  *      payload - address of the allocated payload area pointer (filled in on
1832  *                return) in which the user-defined message is constructed.
1833  */
1834 enum xpc_retval
1835 xpc_initiate_allocate(partid_t partid, int ch_number, u32 flags, void **payload)
1836 {
1837         struct xpc_partition *part = &xpc_partitions[partid];
1838         enum xpc_retval ret = xpcUnknownReason;
1839         struct xpc_msg *msg = NULL;
1840
1841
1842         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
1843         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
1844
1845         *payload = NULL;
1846
1847         if (xpc_part_ref(part)) {
1848                 ret = xpc_allocate_msg(&part->channels[ch_number], flags, &msg);
1849                 xpc_part_deref(part);
1850
1851                 if (msg != NULL) {
1852                         *payload = &msg->payload;
1853                 }
1854         }
1855
1856         return ret;
1857 }
1858
1859
1860 /*
1861  * Now we actually send the messages that are ready to be sent by advancing
1862  * the local message queue's Put value and then send an IPI to the recipient
1863  * partition.
1864  */
1865 static void
1866 xpc_send_msgs(struct xpc_channel *ch, s64 initial_put)
1867 {
1868         struct xpc_msg *msg;
1869         s64 put = initial_put + 1;
1870         int send_IPI = 0;
1871
1872
1873         while (1) {
1874
1875                 while (1) {
1876                         if (put == (volatile s64) ch->w_local_GP.put) {
1877                                 break;
1878                         }
1879
1880                         msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
1881                                (put % ch->local_nentries) * ch->msg_size);
1882
1883                         if (!(msg->flags & XPC_M_READY)) {
1884                                 break;
1885                         }
1886
1887                         put++;
1888                 }
1889
1890                 if (put == initial_put) {
1891                         /* nothing's changed */
1892                         break;
1893                 }
1894
1895                 if (cmpxchg_rel(&ch->local_GP->put, initial_put, put) !=
1896                                                                 initial_put) {
1897                         /* someone else beat us to it */
1898                         DBUG_ON((volatile s64) ch->local_GP->put < initial_put);
1899                         break;
1900                 }
1901
1902                 /* we just set the new value of local_GP->put */
1903
1904                 dev_dbg(xpc_chan, "local_GP->put changed to %ld, partid=%d, "
1905                         "channel=%d\n", put, ch->partid, ch->number);
1906
1907                 send_IPI = 1;
1908
1909                 /*
1910                  * We need to ensure that the message referenced by
1911                  * local_GP->put is not XPC_M_READY or that local_GP->put
1912                  * equals w_local_GP.put, so we'll go have a look.
1913                  */
1914                 initial_put = put;
1915         }
1916
1917         if (send_IPI) {
1918                 xpc_IPI_send_msgrequest(ch);
1919         }
1920 }
1921
1922
1923 /*
1924  * Common code that does the actual sending of the message by advancing the
1925  * local message queue's Put value and sends an IPI to the partition the
1926  * message is being sent to.
1927  */
1928 static enum xpc_retval
1929 xpc_send_msg(struct xpc_channel *ch, struct xpc_msg *msg, u8 notify_type,
1930                         xpc_notify_func func, void *key)
1931 {
1932         enum xpc_retval ret = xpcSuccess;
1933         struct xpc_notify *notify = notify;
1934         s64 put, msg_number = msg->number;
1935
1936
1937         DBUG_ON(notify_type == XPC_N_CALL && func == NULL);
1938         DBUG_ON((((u64) msg - (u64) ch->local_msgqueue) / ch->msg_size) !=
1939                                         msg_number % ch->local_nentries);
1940         DBUG_ON(msg->flags & XPC_M_READY);
1941
1942         if (ch->flags & XPC_C_DISCONNECTING) {
1943                 /* drop the reference grabbed in xpc_allocate_msg() */
1944                 xpc_msgqueue_deref(ch);
1945                 return ch->reason;
1946         }
1947
1948         if (notify_type != 0) {
1949                 /*
1950                  * Tell the remote side to send an ACK interrupt when the
1951                  * message has been delivered.
1952                  */
1953                 msg->flags |= XPC_M_INTERRUPT;
1954
1955                 atomic_inc(&ch->n_to_notify);
1956
1957                 notify = &ch->notify_queue[msg_number % ch->local_nentries];
1958                 notify->func = func;
1959                 notify->key = key;
1960                 notify->type = notify_type;
1961
1962                 // >>> is a mb() needed here?
1963
1964                 if (ch->flags & XPC_C_DISCONNECTING) {
1965                         /*
1966                          * An error occurred between our last error check and
1967                          * this one. We will try to clear the type field from
1968                          * the notify entry. If we succeed then
1969                          * xpc_disconnect_channel() didn't already process
1970                          * the notify entry.
1971                          */
1972                         if (cmpxchg(&notify->type, notify_type, 0) ==
1973                                                                 notify_type) {
1974                                 atomic_dec(&ch->n_to_notify);
1975                                 ret = ch->reason;
1976                         }
1977
1978                         /* drop the reference grabbed in xpc_allocate_msg() */
1979                         xpc_msgqueue_deref(ch);
1980                         return ret;
1981                 }
1982         }
1983
1984         msg->flags |= XPC_M_READY;
1985
1986         /*
1987          * The preceding store of msg->flags must occur before the following
1988          * load of ch->local_GP->put.
1989          */
1990         mb();
1991
1992         /* see if the message is next in line to be sent, if so send it */
1993
1994         put = ch->local_GP->put;
1995         if (put == msg_number) {
1996                 xpc_send_msgs(ch, put);
1997         }
1998
1999         /* drop the reference grabbed in xpc_allocate_msg() */
2000         xpc_msgqueue_deref(ch);
2001         return ret;
2002 }
2003
2004
2005 /*
2006  * Send a message previously allocated using xpc_initiate_allocate() on the
2007  * specified channel connected to the specified partition.
2008  *
2009  * This routine will not wait for the message to be received, nor will
2010  * notification be given when it does happen. Once this routine has returned
2011  * the message entry allocated via xpc_initiate_allocate() is no longer
2012  * accessable to the caller.
2013  *
2014  * This routine, although called by users, does not call xpc_part_ref() to
2015  * ensure that the partition infrastructure is in place. It relies on the
2016  * fact that we called xpc_msgqueue_ref() in xpc_allocate_msg().
2017  *
2018  * Arguments:
2019  *
2020  *      partid - ID of partition to which the channel is connected.
2021  *      ch_number - channel # to send message on.
2022  *      payload - pointer to the payload area allocated via
2023  *                      xpc_initiate_allocate().
2024  */
2025 enum xpc_retval
2026 xpc_initiate_send(partid_t partid, int ch_number, void *payload)
2027 {
2028         struct xpc_partition *part = &xpc_partitions[partid];
2029         struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
2030         enum xpc_retval ret;
2031
2032
2033         dev_dbg(xpc_chan, "msg=0x%p, partid=%d, channel=%d\n", (void *) msg,
2034                 partid, ch_number);
2035
2036         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
2037         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
2038         DBUG_ON(msg == NULL);
2039
2040         ret = xpc_send_msg(&part->channels[ch_number], msg, 0, NULL, NULL);
2041
2042         return ret;
2043 }
2044
2045
2046 /*
2047  * Send a message previously allocated using xpc_initiate_allocate on the
2048  * specified channel connected to the specified partition.
2049  *
2050  * This routine will not wait for the message to be sent. Once this routine
2051  * has returned the message entry allocated via xpc_initiate_allocate() is no
2052  * longer accessable to the caller.
2053  *
2054  * Once the remote end of the channel has received the message, the function
2055  * passed as an argument to xpc_initiate_send_notify() will be called. This
2056  * allows the sender to free up or re-use any buffers referenced by the
2057  * message, but does NOT mean the message has been processed at the remote
2058  * end by a receiver.
2059  *
2060  * If this routine returns an error, the caller's function will NOT be called.
2061  *
2062  * This routine, although called by users, does not call xpc_part_ref() to
2063  * ensure that the partition infrastructure is in place. It relies on the
2064  * fact that we called xpc_msgqueue_ref() in xpc_allocate_msg().
2065  *
2066  * Arguments:
2067  *
2068  *      partid - ID of partition to which the channel is connected.
2069  *      ch_number - channel # to send message on.
2070  *      payload - pointer to the payload area allocated via
2071  *                      xpc_initiate_allocate().
2072  *      func - function to call with asynchronous notification of message
2073  *                receipt. THIS FUNCTION MUST BE NON-BLOCKING.
2074  *      key - user-defined key to be passed to the function when it's called.
2075  */
2076 enum xpc_retval
2077 xpc_initiate_send_notify(partid_t partid, int ch_number, void *payload,
2078                                 xpc_notify_func func, void *key)
2079 {
2080         struct xpc_partition *part = &xpc_partitions[partid];
2081         struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
2082         enum xpc_retval ret;
2083
2084
2085         dev_dbg(xpc_chan, "msg=0x%p, partid=%d, channel=%d\n", (void *) msg,
2086                 partid, ch_number);
2087
2088         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
2089         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
2090         DBUG_ON(msg == NULL);
2091         DBUG_ON(func == NULL);
2092
2093         ret = xpc_send_msg(&part->channels[ch_number], msg, XPC_N_CALL,
2094                                                                 func, key);
2095         return ret;
2096 }
2097
2098
2099 static struct xpc_msg *
2100 xpc_pull_remote_msg(struct xpc_channel *ch, s64 get)
2101 {
2102         struct xpc_partition *part = &xpc_partitions[ch->partid];
2103         struct xpc_msg *remote_msg, *msg;
2104         u32 msg_index, nmsgs;
2105         u64 msg_offset;
2106         enum xpc_retval ret;
2107
2108
2109         if (mutex_lock_interruptible(&ch->msg_to_pull_mutex) != 0) {
2110                 /* we were interrupted by a signal */
2111                 return NULL;
2112         }
2113
2114         while (get >= ch->next_msg_to_pull) {
2115
2116                 /* pull as many messages as are ready and able to be pulled */
2117
2118                 msg_index = ch->next_msg_to_pull % ch->remote_nentries;
2119
2120                 DBUG_ON(ch->next_msg_to_pull >=
2121                                         (volatile s64) ch->w_remote_GP.put);
2122                 nmsgs =  (volatile s64) ch->w_remote_GP.put -
2123                                                 ch->next_msg_to_pull;
2124                 if (msg_index + nmsgs > ch->remote_nentries) {
2125                         /* ignore the ones that wrap the msg queue for now */
2126                         nmsgs = ch->remote_nentries - msg_index;
2127                 }
2128
2129                 msg_offset = msg_index * ch->msg_size;
2130                 msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
2131                                                                 msg_offset);
2132                 remote_msg = (struct xpc_msg *) (ch->remote_msgqueue_pa +
2133                                                                 msg_offset);
2134
2135                 if ((ret = xpc_pull_remote_cachelines(part, msg, remote_msg,
2136                                 nmsgs * ch->msg_size)) != xpcSuccess) {
2137
2138                         dev_dbg(xpc_chan, "failed to pull %d msgs starting with"
2139                                 " msg %ld from partition %d, channel=%d, "
2140                                 "ret=%d\n", nmsgs, ch->next_msg_to_pull,
2141                                 ch->partid, ch->number, ret);
2142
2143                         XPC_DEACTIVATE_PARTITION(part, ret);
2144
2145                         mutex_unlock(&ch->msg_to_pull_mutex);
2146                         return NULL;
2147                 }
2148
2149                 mb();   /* >>> this may not be needed, we're not sure */
2150
2151                 ch->next_msg_to_pull += nmsgs;
2152         }
2153
2154         mutex_unlock(&ch->msg_to_pull_mutex);
2155
2156         /* return the message we were looking for */
2157         msg_offset = (get % ch->remote_nentries) * ch->msg_size;
2158         msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue + msg_offset);
2159
2160         return msg;
2161 }
2162
2163
2164 /*
2165  * Get a message to be delivered.
2166  */
2167 static struct xpc_msg *
2168 xpc_get_deliverable_msg(struct xpc_channel *ch)
2169 {
2170         struct xpc_msg *msg = NULL;
2171         s64 get;
2172
2173
2174         do {
2175                 if ((volatile u32) ch->flags & XPC_C_DISCONNECTING) {
2176                         break;
2177                 }
2178
2179                 get = (volatile s64) ch->w_local_GP.get;
2180                 if (get == (volatile s64) ch->w_remote_GP.put) {
2181                         break;
2182                 }
2183
2184                 /* There are messages waiting to be pulled and delivered.
2185                  * We need to try to secure one for ourselves. We'll do this
2186                  * by trying to increment w_local_GP.get and hope that no one
2187                  * else beats us to it. If they do, we'll we'll simply have
2188                  * to try again for the next one.
2189                  */
2190
2191                 if (cmpxchg(&ch->w_local_GP.get, get, get + 1) == get) {
2192                         /* we got the entry referenced by get */
2193
2194                         dev_dbg(xpc_chan, "w_local_GP.get changed to %ld, "
2195                                 "partid=%d, channel=%d\n", get + 1,
2196                                 ch->partid, ch->number);
2197
2198                         /* pull the message from the remote partition */
2199
2200                         msg = xpc_pull_remote_msg(ch, get);
2201
2202                         DBUG_ON(msg != NULL && msg->number != get);
2203                         DBUG_ON(msg != NULL && (msg->flags & XPC_M_DONE));
2204                         DBUG_ON(msg != NULL && !(msg->flags & XPC_M_READY));
2205
2206                         break;
2207                 }
2208
2209         } while (1);
2210
2211         return msg;
2212 }
2213
2214
2215 /*
2216  * Deliver a message to its intended recipient.
2217  */
2218 void
2219 xpc_deliver_msg(struct xpc_channel *ch)
2220 {
2221         struct xpc_msg *msg;
2222
2223
2224         if ((msg = xpc_get_deliverable_msg(ch)) != NULL) {
2225
2226                 /*
2227                  * This ref is taken to protect the payload itself from being
2228                  * freed before the user is finished with it, which the user
2229                  * indicates by calling xpc_initiate_received().
2230                  */
2231                 xpc_msgqueue_ref(ch);
2232
2233                 atomic_inc(&ch->kthreads_active);
2234
2235                 if (ch->func != NULL) {
2236                         dev_dbg(xpc_chan, "ch->func() called, msg=0x%p, "
2237                                 "msg_number=%ld, partid=%d, channel=%d\n",
2238                                 (void *) msg, msg->number, ch->partid,
2239                                 ch->number);
2240
2241                         /* deliver the message to its intended recipient */
2242                         ch->func(xpcMsgReceived, ch->partid, ch->number,
2243                                         &msg->payload, ch->key);
2244
2245                         dev_dbg(xpc_chan, "ch->func() returned, msg=0x%p, "
2246                                 "msg_number=%ld, partid=%d, channel=%d\n",
2247                                 (void *) msg, msg->number, ch->partid,
2248                                 ch->number);
2249                 }
2250
2251                 atomic_dec(&ch->kthreads_active);
2252         }
2253 }
2254
2255
2256 /*
2257  * Now we actually acknowledge the messages that have been delivered and ack'd
2258  * by advancing the cached remote message queue's Get value and if requested
2259  * send an IPI to the message sender's partition.
2260  */
2261 static void
2262 xpc_acknowledge_msgs(struct xpc_channel *ch, s64 initial_get, u8 msg_flags)
2263 {
2264         struct xpc_msg *msg;
2265         s64 get = initial_get + 1;
2266         int send_IPI = 0;
2267
2268
2269         while (1) {
2270
2271                 while (1) {
2272                         if (get == (volatile s64) ch->w_local_GP.get) {
2273                                 break;
2274                         }
2275
2276                         msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
2277                                (get % ch->remote_nentries) * ch->msg_size);
2278
2279                         if (!(msg->flags & XPC_M_DONE)) {
2280                                 break;
2281                         }
2282
2283                         msg_flags |= msg->flags;
2284                         get++;
2285                 }
2286
2287                 if (get == initial_get) {
2288                         /* nothing's changed */
2289                         break;
2290                 }
2291
2292                 if (cmpxchg_rel(&ch->local_GP->get, initial_get, get) !=
2293                                                                 initial_get) {
2294                         /* someone else beat us to it */
2295                         DBUG_ON((volatile s64) ch->local_GP->get <=
2296                                                                 initial_get);
2297                         break;
2298                 }
2299
2300                 /* we just set the new value of local_GP->get */
2301
2302                 dev_dbg(xpc_chan, "local_GP->get changed to %ld, partid=%d, "
2303                         "channel=%d\n", get, ch->partid, ch->number);
2304
2305                 send_IPI = (msg_flags & XPC_M_INTERRUPT);
2306
2307                 /*
2308                  * We need to ensure that the message referenced by
2309                  * local_GP->get is not XPC_M_DONE or that local_GP->get
2310                  * equals w_local_GP.get, so we'll go have a look.
2311                  */
2312                 initial_get = get;
2313         }
2314
2315         if (send_IPI) {
2316                 xpc_IPI_send_msgrequest(ch);
2317         }
2318 }
2319
2320
2321 /*
2322  * Acknowledge receipt of a delivered message.
2323  *
2324  * If a message has XPC_M_INTERRUPT set, send an interrupt to the partition
2325  * that sent the message.
2326  *
2327  * This function, although called by users, does not call xpc_part_ref() to
2328  * ensure that the partition infrastructure is in place. It relies on the
2329  * fact that we called xpc_msgqueue_ref() in xpc_deliver_msg().
2330  *
2331  * Arguments:
2332  *
2333  *      partid - ID of partition to which the channel is connected.
2334  *      ch_number - channel # message received on.
2335  *      payload - pointer to the payload area allocated via
2336  *                      xpc_initiate_allocate().
2337  */
2338 void
2339 xpc_initiate_received(partid_t partid, int ch_number, void *payload)
2340 {
2341         struct xpc_partition *part = &xpc_partitions[partid];
2342         struct xpc_channel *ch;
2343         struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
2344         s64 get, msg_number = msg->number;
2345
2346
2347         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
2348         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
2349
2350         ch = &part->channels[ch_number];
2351
2352         dev_dbg(xpc_chan, "msg=0x%p, msg_number=%ld, partid=%d, channel=%d\n",
2353                 (void *) msg, msg_number, ch->partid, ch->number);
2354
2355         DBUG_ON((((u64) msg - (u64) ch->remote_msgqueue) / ch->msg_size) !=
2356                                         msg_number % ch->remote_nentries);
2357         DBUG_ON(msg->flags & XPC_M_DONE);
2358
2359         msg->flags |= XPC_M_DONE;
2360
2361         /*
2362          * The preceding store of msg->flags must occur before the following
2363          * load of ch->local_GP->get.
2364          */
2365         mb();
2366
2367         /*
2368          * See if this message is next in line to be acknowledged as having
2369          * been delivered.
2370          */
2371         get = ch->local_GP->get;
2372         if (get == msg_number) {
2373                 xpc_acknowledge_msgs(ch, get, msg->flags);
2374         }
2375
2376         /* the call to xpc_msgqueue_ref() was done by xpc_deliver_msg()  */
2377         xpc_msgqueue_deref(ch);
2378 }
2379