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/slab.h>
  25 #include <linux/mutex.h>
  26 #include <linux/completion.h>
  27 #include <asm/sn/bte.h>
  28 #include <asm/sn/sn_sal.h>
  29 #include <asm/sn/xpc.h>
  30
  31
  32 /*
  33  * Set up the initial values for the XPartition Communication channels.
  34  */
  35 static void
  36 xpc_initialize_channels(struct xpc_partition *part, partid_t partid)
  37 {
  38         int ch_number;
  39         struct xpc_channel *ch;
  40
  41
  42         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
  43                 ch = &part->channels[ch_number];
  44
  45                 ch->partid = partid;
  46                 ch->number = ch_number;
  47                 ch->flags = XPC_C_DISCONNECTED;
  48
  49                 ch->local_GP = &part->local_GPs[ch_number];
  50                 ch->local_openclose_args =
  51                                         &part->local_openclose_args[ch_number];
  52
  53                 atomic_set(&ch->kthreads_assigned, 0);
  54                 atomic_set(&ch->kthreads_idle, 0);
  55                 atomic_set(&ch->kthreads_active, 0);
  56
  57                 atomic_set(&ch->references, 0);
  58                 atomic_set(&ch->n_to_notify, 0);
  59
  60                 spin_lock_init(&ch->lock);
  61                 mutex_init(&ch->msg_to_pull_mutex);
  62                 init_completion(&ch->wdisconnect_wait);
  63
  64                 atomic_set(&ch->n_on_msg_allocate_wq, 0);
  65                 init_waitqueue_head(&ch->msg_allocate_wq);
  66                 init_waitqueue_head(&ch->idle_wq);
  67         }
  68 }
  69
  70
  71 /*
  72  * Setup the infrastructure necessary to support XPartition Communication
  73  * between the specified remote partition and the local one.
  74  */
  75 enum xpc_retval
  76 xpc_setup_infrastructure(struct xpc_partition *part)
  77 {
  78         int ret, cpuid;
  79         struct timer_list *timer;
  80         partid_t partid = XPC_PARTID(part);
  81
  82
  83         /*
  84          * Zero out MOST of the entry for this partition. Only the fields
  85          * starting with `nchannels' will be zeroed. The preceding fields must
  86          * remain `viable' across partition ups and downs, since they may be
  87          * referenced during this memset() operation.
  88          */
  89         memset(&part->nchannels, 0, sizeof(struct xpc_partition) -
  90                                 offsetof(struct xpc_partition, nchannels));
  91
  92         /*
  93          * Allocate all of the channel structures as a contiguous chunk of
  94          * memory.
  95          */
  96         part->channels = kmalloc(sizeof(struct xpc_channel) * XPC_NCHANNELS,
  97                                                                 GFP_KERNEL);
  98         if (part->channels == NULL) {
  99                 dev_err(xpc_chan, "can't get memory for channels\n");
 100                 return xpcNoMemory;
 101         }
 102         memset(part->channels, 0, sizeof(struct xpc_channel) * XPC_NCHANNELS);
 103
 104         part->nchannels = XPC_NCHANNELS;
 105
 106
 107         /* allocate all the required GET/PUT values */
 108
 109         part->local_GPs = xpc_kmalloc_cacheline_aligned(XPC_GP_SIZE,
 110                                         GFP_KERNEL, &part->local_GPs_base);
 111         if (part->local_GPs == NULL) {
 112                 kfree(part->channels);
 113                 part->channels = NULL;
 114                 dev_err(xpc_chan, "can't get memory for local get/put "
 115                         "values\n");
 116                 return xpcNoMemory;
 117         }
 118         memset(part->local_GPs, 0, XPC_GP_SIZE);
 119
 120         part->remote_GPs = xpc_kmalloc_cacheline_aligned(XPC_GP_SIZE,
 121                                         GFP_KERNEL, &part->remote_GPs_base);
 122         if (part->remote_GPs == NULL) {
 123                 kfree(part->channels);
 124                 part->channels = NULL;
 125                 kfree(part->local_GPs_base);
 126                 part->local_GPs = NULL;
 127                 dev_err(xpc_chan, "can't get memory for remote get/put "
 128                         "values\n");
 129                 return xpcNoMemory;
 130         }
 131         memset(part->remote_GPs, 0, XPC_GP_SIZE);
 132
 133
 134         /* allocate all the required open and close args */
 135
 136         part->local_openclose_args = xpc_kmalloc_cacheline_aligned(
 137                                         XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
 138                                         &part->local_openclose_args_base);
 139         if (part->local_openclose_args == NULL) {
 140                 kfree(part->channels);
 141                 part->channels = NULL;
 142                 kfree(part->local_GPs_base);
 143                 part->local_GPs = NULL;
 144                 kfree(part->remote_GPs_base);
 145                 part->remote_GPs = NULL;
 146                 dev_err(xpc_chan, "can't get memory for local connect args\n");
 147                 return xpcNoMemory;
 148         }
 149         memset(part->local_openclose_args, 0, XPC_OPENCLOSE_ARGS_SIZE);
 150
 151         part->remote_openclose_args = xpc_kmalloc_cacheline_aligned(
 152                                         XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
 153                                         &part->remote_openclose_args_base);
 154         if (part->remote_openclose_args == NULL) {
 155                 kfree(part->channels);
 156                 part->channels = NULL;
 157                 kfree(part->local_GPs_base);
 158                 part->local_GPs = NULL;
 159                 kfree(part->remote_GPs_base);
 160                 part->remote_GPs = NULL;
 161                 kfree(part->local_openclose_args_base);
 162                 part->local_openclose_args = NULL;
 163                 dev_err(xpc_chan, "can't get memory for remote connect args\n");
 164                 return xpcNoMemory;
 165         }
 166         memset(part->remote_openclose_args, 0, XPC_OPENCLOSE_ARGS_SIZE);
 167
 168
 169         xpc_initialize_channels(part, partid);
 170
 171         atomic_set(&part->nchannels_active, 0);
 172         atomic_set(&part->nchannels_engaged, 0);
 173
 174
 175         /* local_IPI_amo were set to 0 by an earlier memset() */
 176
 177         /* Initialize this partitions AMO_t structure */
 178         part->local_IPI_amo_va = xpc_IPI_init(partid);
 179
 180         spin_lock_init(&part->IPI_lock);
 181
 182         atomic_set(&part->channel_mgr_requests, 1);
 183         init_waitqueue_head(&part->channel_mgr_wq);
 184
 185         sprintf(part->IPI_owner, "xpc%02d", partid);
 186         ret = request_irq(SGI_XPC_NOTIFY, xpc_notify_IRQ_handler, SA_SHIRQ,
 187                                 part->IPI_owner, (void *) (u64) partid);
 188         if (ret != 0) {
 189                 kfree(part->channels);
 190                 part->channels = NULL;
 191                 kfree(part->local_GPs_base);
 192                 part->local_GPs = NULL;
 193                 kfree(part->remote_GPs_base);
 194                 part->remote_GPs = NULL;
 195                 kfree(part->local_openclose_args_base);
 196                 part->local_openclose_args = NULL;
 197                 kfree(part->remote_openclose_args_base);
 198                 part->remote_openclose_args = NULL;
 199                 dev_err(xpc_chan, "can't register NOTIFY IRQ handler, "
 200                         "errno=%d\n", -ret);
 201                 return xpcLackOfResources;
 202         }
 203
 204         /* Setup a timer to check for dropped IPIs */
 205         timer = &part->dropped_IPI_timer;
 206         init_timer(timer);
 207         timer->function = (void (*)(unsigned long)) xpc_dropped_IPI_check;
 208         timer->data = (unsigned long) part;
 209         timer->expires = jiffies + XPC_P_DROPPED_IPI_WAIT;
 210         add_timer(timer);
 211
 212         /*
 213          * With the setting of the partition setup_state to XPC_P_SETUP, we're
 214          * declaring that this partition is ready to go.
 215          */
 216         part->setup_state = XPC_P_SETUP;
 217
 218
 219         /*
 220          * Setup the per partition specific variables required by the
 221          * remote partition to establish channel connections with us.
 222          *
 223          * The setting of the magic # indicates that these per partition
 224          * specific variables are ready to be used.
 225          */
 226         xpc_vars_part[partid].GPs_pa = __pa(part->local_GPs);
 227         xpc_vars_part[partid].openclose_args_pa =
 228                                         __pa(part->local_openclose_args);
 229         xpc_vars_part[partid].IPI_amo_pa = __pa(part->local_IPI_amo_va);
 230         cpuid = raw_smp_processor_id(); /* any CPU in this partition will do */
 231         xpc_vars_part[partid].IPI_nasid = cpuid_to_nasid(cpuid);
 232         xpc_vars_part[partid].IPI_phys_cpuid = cpu_physical_id(cpuid);
 233         xpc_vars_part[partid].nchannels = part->nchannels;
 234         xpc_vars_part[partid].magic = XPC_VP_MAGIC1;
 235
 236         return xpcSuccess;
 237 }
 238
 239
 240 /*
 241  * Create a wrapper that hides the underlying mechanism for pulling a cacheline
 242  * (or multiple cachelines) from a remote partition.
 243  *
 244  * src must be a cacheline aligned physical address on the remote partition.
 245  * dst must be a cacheline aligned virtual address on this partition.
 246  * cnt must be an cacheline sized
 247  */
 248 static enum xpc_retval
 249 xpc_pull_remote_cachelines(struct xpc_partition *part, void *dst,
 250                                 const void *src, size_t cnt)
 251 {
 252         bte_result_t bte_ret;
 253
 254
 255         DBUG_ON((u64) src != L1_CACHE_ALIGN((u64) src));
 256         DBUG_ON((u64) dst != L1_CACHE_ALIGN((u64) dst));
 257         DBUG_ON(cnt != L1_CACHE_ALIGN(cnt));
 258
 259         if (part->act_state == XPC_P_DEACTIVATING) {
 260                 return part->reason;
 261         }
 262
 263         bte_ret = xp_bte_copy((u64) src, (u64) ia64_tpa((u64) dst),
 264                                 (u64) cnt, (BTE_NORMAL | BTE_WACQUIRE), NULL);
 265         if (bte_ret == BTE_SUCCESS) {
 266                 return xpcSuccess;
 267         }
 268
 269         dev_dbg(xpc_chan, "xp_bte_copy() from partition %d failed, ret=%d\n",
 270                 XPC_PARTID(part), bte_ret);
 271
 272         return xpc_map_bte_errors(bte_ret);
 273 }
 274
 275
 276 /*
 277  * Pull the remote per partititon specific variables from the specified
 278  * partition.
 279  */
 280 enum xpc_retval
 281 xpc_pull_remote_vars_part(struct xpc_partition *part)
 282 {
 283         u8 buffer[L1_CACHE_BYTES * 2];
 284         struct xpc_vars_part *pulled_entry_cacheline =
 285                         (struct xpc_vars_part *) L1_CACHE_ALIGN((u64) buffer);
 286         struct xpc_vars_part *pulled_entry;
 287         u64 remote_entry_cacheline_pa, remote_entry_pa;
 288         partid_t partid = XPC_PARTID(part);
 289         enum xpc_retval ret;
 290
 291
 292         /* pull the cacheline that contains the variables we're interested in */
 293
 294         DBUG_ON(part->remote_vars_part_pa !=
 295                                 L1_CACHE_ALIGN(part->remote_vars_part_pa));
 296         DBUG_ON(sizeof(struct xpc_vars_part) != L1_CACHE_BYTES / 2);
 297
 298         remote_entry_pa = part->remote_vars_part_pa +
 299                         sn_partition_id * sizeof(struct xpc_vars_part);
 300
 301         remote_entry_cacheline_pa = (remote_entry_pa & ~(L1_CACHE_BYTES - 1));
 302
 303         pulled_entry = (struct xpc_vars_part *) ((u64) pulled_entry_cacheline +
 304                                 (remote_entry_pa & (L1_CACHE_BYTES - 1)));
 305
 306         ret = xpc_pull_remote_cachelines(part, pulled_entry_cacheline,
 307                                         (void *) remote_entry_cacheline_pa,
 308                                         L1_CACHE_BYTES);
 309         if (ret != xpcSuccess) {
 310                 dev_dbg(xpc_chan, "failed to pull XPC vars_part from "
 311                         "partition %d, ret=%d\n", partid, ret);
 312                 return ret;
 313         }
 314
 315
 316         /* see if they've been set up yet */
 317
 318         if (pulled_entry->magic != XPC_VP_MAGIC1 &&
 319                                 pulled_entry->magic != XPC_VP_MAGIC2) {
 320
 321                 if (pulled_entry->magic != 0) {
 322                         dev_dbg(xpc_chan, "partition %d's XPC vars_part for "
 323                                 "partition %d has bad magic value (=0x%lx)\n",
 324                                 partid, sn_partition_id, pulled_entry->magic);
 325                         return xpcBadMagic;
 326                 }
 327
 328                 /* they've not been initialized yet */
 329                 return xpcRetry;
 330         }
 331
 332         if (xpc_vars_part[partid].magic == XPC_VP_MAGIC1) {
 333
 334                 /* validate the variables */
 335
 336                 if (pulled_entry->GPs_pa == 0 ||
 337                                 pulled_entry->openclose_args_pa == 0 ||
 338                                         pulled_entry->IPI_amo_pa == 0) {
 339
 340                         dev_err(xpc_chan, "partition %d's XPC vars_part for "
 341                                 "partition %d are not valid\n", partid,
 342                                 sn_partition_id);
 343                         return xpcInvalidAddress;
 344                 }
 345
 346                 /* the variables we imported look to be valid */
 347
 348                 part->remote_GPs_pa = pulled_entry->GPs_pa;
 349                 part->remote_openclose_args_pa =
 350                                         pulled_entry->openclose_args_pa;
 351                 part->remote_IPI_amo_va =
 352                                       (AMO_t *) __va(pulled_entry->IPI_amo_pa);
 353                 part->remote_IPI_nasid = pulled_entry->IPI_nasid;
 354                 part->remote_IPI_phys_cpuid = pulled_entry->IPI_phys_cpuid;
 355
 356                 if (part->nchannels > pulled_entry->nchannels) {
 357                         part->nchannels = pulled_entry->nchannels;
 358                 }
 359
 360                 /* let the other side know that we've pulled their variables */
 361
 362                 xpc_vars_part[partid].magic = XPC_VP_MAGIC2;
 363         }
 364
 365         if (pulled_entry->magic == XPC_VP_MAGIC1) {
 366                 return xpcRetry;
 367         }
 368
 369         return xpcSuccess;
 370 }
 371
 372
 373 /*
 374  * Get the IPI flags and pull the openclose args and/or remote GPs as needed.
 375  */
 376 static u64
 377 xpc_get_IPI_flags(struct xpc_partition *part)
 378 {
 379         unsigned long irq_flags;
 380         u64 IPI_amo;
 381         enum xpc_retval ret;
 382
 383
 384         /*
 385          * See if there are any IPI flags to be handled.
 386          */
 387
 388         spin_lock_irqsave(&part->IPI_lock, irq_flags);
 389         if ((IPI_amo = part->local_IPI_amo) != 0) {
 390                 part->local_IPI_amo = 0;
 391         }
 392         spin_unlock_irqrestore(&part->IPI_lock, irq_flags);
 393
 394
 395         if (XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(IPI_amo)) {
 396                 ret = xpc_pull_remote_cachelines(part,
 397                                         part->remote_openclose_args,
 398                                         (void *) part->remote_openclose_args_pa,
 399                                         XPC_OPENCLOSE_ARGS_SIZE);
 400                 if (ret != xpcSuccess) {
 401                         XPC_DEACTIVATE_PARTITION(part, ret);
 402
 403                         dev_dbg(xpc_chan, "failed to pull openclose args from "
 404                                 "partition %d, ret=%d\n", XPC_PARTID(part),
 405                                 ret);
 406
 407                         /* don't bother processing IPIs anymore */
 408                         IPI_amo = 0;
 409                 }
 410         }
 411
 412         if (XPC_ANY_MSG_IPI_FLAGS_SET(IPI_amo)) {
 413                 ret = xpc_pull_remote_cachelines(part, part->remote_GPs,
 414                                                 (void *) part->remote_GPs_pa,
 415                                                 XPC_GP_SIZE);
 416                 if (ret != xpcSuccess) {
 417                         XPC_DEACTIVATE_PARTITION(part, ret);
 418
 419                         dev_dbg(xpc_chan, "failed to pull GPs from partition "
 420                                 "%d, ret=%d\n", XPC_PARTID(part), ret);
 421
 422                         /* don't bother processing IPIs anymore */
 423                         IPI_amo = 0;
 424                 }
 425         }
 426
 427         return IPI_amo;
 428 }
 429
 430
 431 /*
 432  * Allocate the local message queue and the notify queue.
 433  */
 434 static enum xpc_retval
 435 xpc_allocate_local_msgqueue(struct xpc_channel *ch)
 436 {
 437         unsigned long irq_flags;
 438         int nentries;
 439         size_t nbytes;
 440
 441
 442         // >>> may want to check for ch->flags & XPC_C_DISCONNECTING between
 443         // >>> iterations of the for-loop, bail if set?
 444
 445         // >>> should we impose a minumum #of entries? like 4 or 8?
 446         for (nentries = ch->local_nentries; nentries > 0; nentries--) {
 447
 448                 nbytes = nentries * ch->msg_size;
 449                 ch->local_msgqueue = xpc_kmalloc_cacheline_aligned(nbytes,
 450                                                 GFP_KERNEL,
 451                                                 &ch->local_msgqueue_base);
 452                 if (ch->local_msgqueue == NULL) {
 453                         continue;
 454                 }
 455                 memset(ch->local_msgqueue, 0, nbytes);
 456
 457                 nbytes = nentries * sizeof(struct xpc_notify);
 458                 ch->notify_queue = kmalloc(nbytes, GFP_KERNEL);
 459                 if (ch->notify_queue == NULL) {
 460                         kfree(ch->local_msgqueue_base);
 461                         ch->local_msgqueue = NULL;
 462                         continue;
 463                 }
 464                 memset(ch->notify_queue, 0, nbytes);
 465
 466                 spin_lock_irqsave(&ch->lock, irq_flags);
 467                 if (nentries < ch->local_nentries) {
 468                         dev_dbg(xpc_chan, "nentries=%d local_nentries=%d, "
 469                                 "partid=%d, channel=%d\n", nentries,
 470                                 ch->local_nentries, ch->partid, ch->number);
 471
 472                         ch->local_nentries = nentries;
 473                 }
 474                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 475                 return xpcSuccess;
 476         }
 477
 478         dev_dbg(xpc_chan, "can't get memory for local message queue and notify "
 479                 "queue, partid=%d, channel=%d\n", ch->partid, ch->number);
 480         return xpcNoMemory;
 481 }
 482
 483
 484 /*
 485  * Allocate the cached remote message queue.
 486  */
 487 static enum xpc_retval
 488 xpc_allocate_remote_msgqueue(struct xpc_channel *ch)
 489 {
 490         unsigned long irq_flags;
 491         int nentries;
 492         size_t nbytes;
 493
 494
 495         DBUG_ON(ch->remote_nentries <= 0);
 496
 497         // >>> may want to check for ch->flags & XPC_C_DISCONNECTING between
 498         // >>> iterations of the for-loop, bail if set?
 499
 500         // >>> should we impose a minumum #of entries? like 4 or 8?
 501         for (nentries = ch->remote_nentries; nentries > 0; nentries--) {
 502
 503                 nbytes = nentries * ch->msg_size;
 504                 ch->remote_msgqueue = xpc_kmalloc_cacheline_aligned(nbytes,
 505                                                 GFP_KERNEL,
 506                                                 &ch->remote_msgqueue_base);
 507                 if (ch->remote_msgqueue == NULL) {
 508                         continue;
 509                 }
 510                 memset(ch->remote_msgqueue, 0, nbytes);
 511
 512                 spin_lock_irqsave(&ch->lock, irq_flags);
 513                 if (nentries < ch->remote_nentries) {
 514                         dev_dbg(xpc_chan, "nentries=%d remote_nentries=%d, "
 515                                 "partid=%d, channel=%d\n", nentries,
 516                                 ch->remote_nentries, ch->partid, ch->number);
 517
 518                         ch->remote_nentries = nentries;
 519                 }
 520                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 521                 return xpcSuccess;
 522         }
 523
 524         dev_dbg(xpc_chan, "can't get memory for cached remote message queue, "
 525                 "partid=%d, channel=%d\n", ch->partid, ch->number);
 526         return xpcNoMemory;
 527 }
 528
 529
 530 /*
 531  * Allocate message queues and other stuff associated with a channel.
 532  *
 533  * Note: Assumes all of the channel sizes are filled in.
 534  */
 535 static enum xpc_retval
 536 xpc_allocate_msgqueues(struct xpc_channel *ch)
 537 {
 538         unsigned long irq_flags;
 539         enum xpc_retval ret;
 540
 541
 542         DBUG_ON(ch->flags & XPC_C_SETUP);
 543
 544         if ((ret = xpc_allocate_local_msgqueue(ch)) != xpcSuccess) {
 545                 return ret;
 546         }
 547
 548         if ((ret = xpc_allocate_remote_msgqueue(ch)) != xpcSuccess) {
 549                 kfree(ch->local_msgqueue_base);
 550                 ch->local_msgqueue = NULL;
 551                 kfree(ch->notify_queue);
 552                 ch->notify_queue = NULL;
 553                 return ret;
 554         }
 555
 556         spin_lock_irqsave(&ch->lock, irq_flags);
 557         ch->flags |= XPC_C_SETUP;
 558         spin_unlock_irqrestore(&ch->lock, irq_flags);
 559
 560         return xpcSuccess;
 561 }
 562
 563
 564 /*
 565  * Process a connect message from a remote partition.
 566  *
 567  * Note: xpc_process_connect() is expecting to be called with the
 568  * spin_lock_irqsave held and will leave it locked upon return.
 569  */
 570 static void
 571 xpc_process_connect(struct xpc_channel *ch, unsigned long *irq_flags)
 572 {
 573         enum xpc_retval ret;
 574
 575
 576         DBUG_ON(!spin_is_locked(&ch->lock));
 577
 578         if (!(ch->flags & XPC_C_OPENREQUEST) ||
 579                                 !(ch->flags & XPC_C_ROPENREQUEST)) {
 580                 /* nothing more to do for now */
 581                 return;
 582         }
 583         DBUG_ON(!(ch->flags & XPC_C_CONNECTING));
 584
 585         if (!(ch->flags & XPC_C_SETUP)) {
 586                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
 587                 ret = xpc_allocate_msgqueues(ch);
 588                 spin_lock_irqsave(&ch->lock, *irq_flags);
 589
 590                 if (ret != xpcSuccess) {
 591                         XPC_DISCONNECT_CHANNEL(ch, ret, irq_flags);
 592                 }
 593                 if (ch->flags & (XPC_C_CONNECTED | XPC_C_DISCONNECTING)) {
 594                         return;
 595                 }
 596
 597                 DBUG_ON(!(ch->flags & XPC_C_SETUP));
 598                 DBUG_ON(ch->local_msgqueue == NULL);
 599                 DBUG_ON(ch->remote_msgqueue == NULL);
 600         }
 601
 602         if (!(ch->flags & XPC_C_OPENREPLY)) {
 603                 ch->flags |= XPC_C_OPENREPLY;
 604                 xpc_IPI_send_openreply(ch, irq_flags);
 605         }
 606
 607         if (!(ch->flags & XPC_C_ROPENREPLY)) {
 608                 return;
 609         }
 610
 611         DBUG_ON(ch->remote_msgqueue_pa == 0);
 612
 613         ch->flags = (XPC_C_CONNECTED | XPC_C_SETUP);    /* clear all else */
 614
 615         dev_info(xpc_chan, "channel %d to partition %d connected\n",
 616                 ch->number, ch->partid);
 617
 618         spin_unlock_irqrestore(&ch->lock, *irq_flags);
 619         xpc_create_kthreads(ch, 1);
 620         spin_lock_irqsave(&ch->lock, *irq_flags);
 621 }
 622
 623
 624 /*
 625  * Notify those who wanted to be notified upon delivery of their message.
 626  */
 627 static void
 628 xpc_notify_senders(struct xpc_channel *ch, enum xpc_retval reason, s64 put)
 629 {
 630         struct xpc_notify *notify;
 631         u8 notify_type;
 632         s64 get = ch->w_remote_GP.get - 1;
 633
 634
 635         while (++get < put && atomic_read(&ch->n_to_notify) > 0) {
 636
 637                 notify = &ch->notify_queue[get % ch->local_nentries];
 638
 639                 /*
 640                  * See if the notify entry indicates it was associated with
 641                  * a message who's sender wants to be notified. It is possible
 642                  * that it is, but someone else is doing or has done the
 643                  * notification.
 644                  */
 645                 notify_type = notify->type;
 646                 if (notify_type == 0 ||
 647                                 cmpxchg(&notify->type, notify_type, 0) !=
 648                                                                 notify_type) {
 649                         continue;
 650                 }
 651
 652                 DBUG_ON(notify_type != XPC_N_CALL);
 653
 654                 atomic_dec(&ch->n_to_notify);
 655
 656                 if (notify->func != NULL) {
 657                         dev_dbg(xpc_chan, "notify->func() called, notify=0x%p, "
 658                                 "msg_number=%ld, partid=%d, channel=%d\n",
 659                                 (void *) notify, get, ch->partid, ch->number);
 660
 661                         notify->func(reason, ch->partid, ch->number,
 662                                                                 notify->key);
 663
 664                         dev_dbg(xpc_chan, "notify->func() returned, "
 665                                 "notify=0x%p, msg_number=%ld, partid=%d, "
 666                                 "channel=%d\n", (void *) notify, get,
 667                                 ch->partid, ch->number);
 668                 }
 669         }
 670 }
 671
 672
 673 /*
 674  * Free up message queues and other stuff that were allocated for the specified
 675  * channel.
 676  *
 677  * Note: ch->reason and ch->reason_line are left set for debugging purposes,
 678  * they're cleared when XPC_C_DISCONNECTED is cleared.
 679  */
 680 static void
 681 xpc_free_msgqueues(struct xpc_channel *ch)
 682 {
 683         DBUG_ON(!spin_is_locked(&ch->lock));
 684         DBUG_ON(atomic_read(&ch->n_to_notify) != 0);
 685
 686         ch->remote_msgqueue_pa = 0;
 687         ch->func = NULL;
 688         ch->key = NULL;
 689         ch->msg_size = 0;
 690         ch->local_nentries = 0;
 691         ch->remote_nentries = 0;
 692         ch->kthreads_assigned_limit = 0;
 693         ch->kthreads_idle_limit = 0;
 694
 695         ch->local_GP->get = 0;
 696         ch->local_GP->put = 0;
 697         ch->remote_GP.get = 0;
 698         ch->remote_GP.put = 0;
 699         ch->w_local_GP.get = 0;
 700         ch->w_local_GP.put = 0;
 701         ch->w_remote_GP.get = 0;
 702         ch->w_remote_GP.put = 0;
 703         ch->next_msg_to_pull = 0;
 704
 705         if (ch->flags & XPC_C_SETUP) {
 706                 ch->flags &= ~XPC_C_SETUP;
 707
 708                 dev_dbg(xpc_chan, "ch->flags=0x%x, partid=%d, channel=%d\n",
 709                         ch->flags, ch->partid, ch->number);
 710
 711                 kfree(ch->local_msgqueue_base);
 712                 ch->local_msgqueue = NULL;
 713                 kfree(ch->remote_msgqueue_base);
 714                 ch->remote_msgqueue = NULL;
 715                 kfree(ch->notify_queue);
 716                 ch->notify_queue = NULL;
 717         }
 718 }
 719
 720
 721 /*
 722  * spin_lock_irqsave() is expected to be held on entry.
 723  */
 724 static void
 725 xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
 726 {
 727         struct xpc_partition *part = &xpc_partitions[ch->partid];
 728         u32 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);
 729
 730
 731         DBUG_ON(!spin_is_locked(&ch->lock));
 732
 733         if (!(ch->flags & XPC_C_DISCONNECTING)) {
 734                 return;
 735         }
 736
 737         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 738
 739         /* make sure all activity has settled down first */
 740
 741         if (atomic_read(&ch->references) > 0 ||
 742                         ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 743                         !(ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE))) {
 744                 return;
 745         }
 746         DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
 747
 748         if (part->act_state == XPC_P_DEACTIVATING) {
 749                 /* can't proceed until the other side disengages from us */
 750                 if (xpc_partition_engaged(1UL << ch->partid)) {
 751                         return;
 752                 }
 753
 754         } else {
 755
 756                 /* as long as the other side is up do the full protocol */
 757
 758                 if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
 759                         return;
 760                 }
 761
 762                 if (!(ch->flags & XPC_C_CLOSEREPLY)) {
 763                         ch->flags |= XPC_C_CLOSEREPLY;
 764                         xpc_IPI_send_closereply(ch, irq_flags);
 765                 }
 766
 767                 if (!(ch->flags & XPC_C_RCLOSEREPLY)) {
 768                         return;
 769                 }
 770         }
 771
 772         /* wake those waiting for notify completion */
 773         if (atomic_read(&ch->n_to_notify) > 0) {
 774                 /* >>> we do callout while holding ch->lock */
 775                 xpc_notify_senders(ch, ch->reason, ch->w_local_GP.put);
 776         }
 777
 778         /* both sides are disconnected now */
 779
 780         if (ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE) {
 781                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
 782                 xpc_disconnect_callout(ch, xpcDisconnected);
 783                 spin_lock_irqsave(&ch->lock, *irq_flags);
 784         }
 785
 786         /* it's now safe to free the channel's message queues */
 787         xpc_free_msgqueues(ch);
 788
 789         /* mark disconnected, clear all other flags except XPC_C_WDISCONNECT */
 790         ch->flags = (XPC_C_DISCONNECTED | (ch->flags & XPC_C_WDISCONNECT));
 791
 792         atomic_dec(&part->nchannels_active);
 793
 794         if (channel_was_connected) {
 795                 dev_info(xpc_chan, "channel %d to partition %d disconnected, "
 796                         "reason=%d\n", ch->number, ch->partid, ch->reason);
 797         }
 798
 799         if (ch->flags & XPC_C_WDISCONNECT) {
 800                 /* we won't lose the CPU since we're holding ch->lock */
 801                 complete(&ch->wdisconnect_wait);
 802         } else if (ch->delayed_IPI_flags) {
 803                 if (part->act_state != XPC_P_DEACTIVATING) {
 804                         /* time to take action on any delayed IPI flags */
 805                         spin_lock(&part->IPI_lock);
 806                         XPC_SET_IPI_FLAGS(part->local_IPI_amo, ch->number,
 807                                                         ch->delayed_IPI_flags);
 808                         spin_unlock(&part->IPI_lock);
 809                 }
 810                 ch->delayed_IPI_flags = 0;
 811         }
 812 }
 813
 814
 815 /*
 816  * Process a change in the channel's remote connection state.
 817  */
 818 static void
 819 xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
 820                                 u8 IPI_flags)
 821 {
 822         unsigned long irq_flags;
 823         struct xpc_openclose_args *args =
 824                                 &part->remote_openclose_args[ch_number];
 825         struct xpc_channel *ch = &part->channels[ch_number];
 826         enum xpc_retval reason;
 827
 828
 829
 830         spin_lock_irqsave(&ch->lock, irq_flags);
 831
 832 again:
 833
 834         if ((ch->flags & XPC_C_DISCONNECTED) &&
 835                                         (ch->flags & XPC_C_WDISCONNECT)) {
 836                 /*
 837                  * Delay processing IPI flags until thread waiting disconnect
 838                  * has had a chance to see that the channel is disconnected.
 839                  */
 840                 ch->delayed_IPI_flags |= IPI_flags;
 841                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 842                 return;
 843         }
 844
 845
 846         if (IPI_flags & XPC_IPI_CLOSEREQUEST) {
 847
 848                 dev_dbg(xpc_chan, "XPC_IPI_CLOSEREQUEST (reason=%d) received "
 849                         "from partid=%d, channel=%d\n", args->reason,
 850                         ch->partid, ch->number);
 851
 852                 /*
 853                  * If RCLOSEREQUEST is set, we're probably waiting for
 854                  * RCLOSEREPLY. We should find it and a ROPENREQUEST packed
 855                  * with this RCLOSEREQUEST in the IPI_flags.
 856                  */
 857
 858                 if (ch->flags & XPC_C_RCLOSEREQUEST) {
 859                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTING));
 860                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 861                         DBUG_ON(!(ch->flags & XPC_C_CLOSEREPLY));
 862                         DBUG_ON(ch->flags & XPC_C_RCLOSEREPLY);
 863
 864                         DBUG_ON(!(IPI_flags & XPC_IPI_CLOSEREPLY));
 865                         IPI_flags &= ~XPC_IPI_CLOSEREPLY;
 866                         ch->flags |= XPC_C_RCLOSEREPLY;
 867
 868                         /* both sides have finished disconnecting */
 869                         xpc_process_disconnect(ch, &irq_flags);
 870                         DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 871                         goto again;
 872                 }
 873
 874                 if (ch->flags & XPC_C_DISCONNECTED) {
 875                         if (!(IPI_flags & XPC_IPI_OPENREQUEST)) {
 876                                 if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo,
 877                                          ch_number) & XPC_IPI_OPENREQUEST)) {
 878
 879                                         DBUG_ON(ch->delayed_IPI_flags != 0);
 880                                         spin_lock(&part->IPI_lock);
 881                                         XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 882                                                         ch_number,
 883                                                         XPC_IPI_CLOSEREQUEST);
 884                                         spin_unlock(&part->IPI_lock);
 885                                 }
 886                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 887                                 return;
 888                         }
 889
 890                         XPC_SET_REASON(ch, 0, 0);
 891                         ch->flags &= ~XPC_C_DISCONNECTED;
 892
 893                         atomic_inc(&part->nchannels_active);
 894                         ch->flags |= (XPC_C_CONNECTING | XPC_C_ROPENREQUEST);
 895                 }
 896
 897                 IPI_flags &= ~(XPC_IPI_OPENREQUEST | XPC_IPI_OPENREPLY);
 898
 899                 /*
 900                  * The meaningful CLOSEREQUEST connection state fields are:
 901                  *      reason = reason connection is to be closed
 902                  */
 903
 904                 ch->flags |= XPC_C_RCLOSEREQUEST;
 905
 906                 if (!(ch->flags & XPC_C_DISCONNECTING)) {
 907                         reason = args->reason;
 908                         if (reason <= xpcSuccess || reason > xpcUnknownReason) {
 909                                 reason = xpcUnknownReason;
 910                         } else if (reason == xpcUnregistering) {
 911                                 reason = xpcOtherUnregistering;
 912                         }
 913
 914                         XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
 915
 916                         DBUG_ON(IPI_flags & XPC_IPI_CLOSEREPLY);
 917                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 918                         return;
 919                 }
 920
 921                 xpc_process_disconnect(ch, &irq_flags);
 922         }
 923
 924
 925         if (IPI_flags & XPC_IPI_CLOSEREPLY) {
 926
 927                 dev_dbg(xpc_chan, "XPC_IPI_CLOSEREPLY received from partid=%d,"
 928                         " channel=%d\n", ch->partid, ch->number);
 929
 930                 if (ch->flags & XPC_C_DISCONNECTED) {
 931                         DBUG_ON(part->act_state != XPC_P_DEACTIVATING);
 932                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 933                         return;
 934                 }
 935
 936                 DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
 937
 938                 if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
 939                         if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo, ch_number)
 940                                                 & XPC_IPI_CLOSEREQUEST)) {
 941
 942                                 DBUG_ON(ch->delayed_IPI_flags != 0);
 943                                 spin_lock(&part->IPI_lock);
 944                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 945                                                 ch_number, XPC_IPI_CLOSEREPLY);
 946                                 spin_unlock(&part->IPI_lock);
 947                         }
 948                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 949                         return;
 950                 }
 951
 952                 ch->flags |= XPC_C_RCLOSEREPLY;
 953
 954                 if (ch->flags & XPC_C_CLOSEREPLY) {
 955                         /* both sides have finished disconnecting */
 956                         xpc_process_disconnect(ch, &irq_flags);
 957                 }
 958         }
 959
 960
 961         if (IPI_flags & XPC_IPI_OPENREQUEST) {
 962
 963                 dev_dbg(xpc_chan, "XPC_IPI_OPENREQUEST (msg_size=%d, "
 964                         "local_nentries=%d) received from partid=%d, "
 965                         "channel=%d\n", args->msg_size, args->local_nentries,
 966                         ch->partid, ch->number);
 967
 968                 if (part->act_state == XPC_P_DEACTIVATING ||
 969                                         (ch->flags & XPC_C_ROPENREQUEST)) {
 970                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 971                         return;
 972                 }
 973
 974                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_WDISCONNECT)) {
 975                         ch->delayed_IPI_flags |= XPC_IPI_OPENREQUEST;
 976                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 977                         return;
 978                 }
 979                 DBUG_ON(!(ch->flags & (XPC_C_DISCONNECTED |
 980                                                         XPC_C_OPENREQUEST)));
 981                 DBUG_ON(ch->flags & (XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
 982                                         XPC_C_OPENREPLY | XPC_C_CONNECTED));
 983
 984                 /*
 985                  * The meaningful OPENREQUEST connection state fields are:
 986                  *      msg_size = size of channel's messages in bytes
 987                  *      local_nentries = remote partition's local_nentries
 988                  */
 989                 if (args->msg_size == 0 || args->local_nentries == 0) {
 990                         /* assume OPENREQUEST was delayed by mistake */
 991                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 992                         return;
 993                 }
 994
 995                 ch->flags |= (XPC_C_ROPENREQUEST | XPC_C_CONNECTING);
 996                 ch->remote_nentries = args->local_nentries;
 997
 998
 999                 if (ch->flags & XPC_C_OPENREQUEST) {
1000                         if (args->msg_size != ch->msg_size) {
1001                                 XPC_DISCONNECT_CHANNEL(ch, xpcUnequalMsgSizes,
1002                                                                 &irq_flags);
1003                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
1004                                 return;
1005                         }
1006                 } else {
1007                         ch->msg_size = args->msg_size;
1008
1009                         XPC_SET_REASON(ch, 0, 0);
1010                         ch->flags &= ~XPC_C_DISCONNECTED;
1011
1012                         atomic_inc(&part->nchannels_active);
1013                 }
1014
1015                 xpc_process_connect(ch, &irq_flags);
1016         }
1017
1018
1019         if (IPI_flags & XPC_IPI_OPENREPLY) {
1020
1021                 dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY (local_msgqueue_pa=0x%lx, "
1022                         "local_nentries=%d, remote_nentries=%d) received from "
1023                         "partid=%d, channel=%d\n", args->local_msgqueue_pa,
1024                         args->local_nentries, args->remote_nentries,
1025                         ch->partid, ch->number);
1026
1027                 if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
1028                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1029                         return;
1030                 }
1031                 if (!(ch->flags & XPC_C_OPENREQUEST)) {
1032                         XPC_DISCONNECT_CHANNEL(ch, xpcOpenCloseError,
1033                                                                 &irq_flags);
1034                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1035                         return;
1036                 }
1037
1038                 DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
1039                 DBUG_ON(ch->flags & XPC_C_CONNECTED);
1040
1041                 /*
1042                  * The meaningful OPENREPLY connection state fields are:
1043                  *      local_msgqueue_pa = physical address of remote
1044                  *                          partition's local_msgqueue
1045                  *      local_nentries = remote partition's local_nentries
1046                  *      remote_nentries = remote partition's remote_nentries
1047                  */
1048                 DBUG_ON(args->local_msgqueue_pa == 0);
1049                 DBUG_ON(args->local_nentries == 0);
1050                 DBUG_ON(args->remote_nentries == 0);
1051
1052                 ch->flags |= XPC_C_ROPENREPLY;
1053                 ch->remote_msgqueue_pa = args->local_msgqueue_pa;
1054
1055                 if (args->local_nentries < ch->remote_nentries) {
1056                         dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY: new "
1057                                 "remote_nentries=%d, old remote_nentries=%d, "
1058                                 "partid=%d, channel=%d\n",
1059                                 args->local_nentries, ch->remote_nentries,
1060                                 ch->partid, ch->number);
1061
1062                         ch->remote_nentries = args->local_nentries;
1063                 }
1064                 if (args->remote_nentries < ch->local_nentries) {
1065                         dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY: new "
1066                                 "local_nentries=%d, old local_nentries=%d, "
1067                                 "partid=%d, channel=%d\n",
1068                                 args->remote_nentries, ch->local_nentries,
1069                                 ch->partid, ch->number);
1070
1071                         ch->local_nentries = args->remote_nentries;
1072                 }
1073
1074                 xpc_process_connect(ch, &irq_flags);
1075         }
1076
1077         spin_unlock_irqrestore(&ch->lock, irq_flags);
1078 }
1079
1080
1081 /*
1082  * Attempt to establish a channel connection to a remote partition.
1083  */
1084 static enum xpc_retval
1085 xpc_connect_channel(struct xpc_channel *ch)
1086 {
1087         unsigned long irq_flags;
1088         struct xpc_registration *registration = &xpc_registrations[ch->number];
1089
1090
1091         if (mutex_trylock(&registration->mutex) == 0) {
1092                 return xpcRetry;
1093         }
1094
1095         if (!XPC_CHANNEL_REGISTERED(ch->number)) {
1096                 mutex_unlock(&registration->mutex);
1097                 return xpcUnregistered;
1098         }
1099
1100         spin_lock_irqsave(&ch->lock, irq_flags);
1101
1102         DBUG_ON(ch->flags & XPC_C_CONNECTED);
1103         DBUG_ON(ch->flags & XPC_C_OPENREQUEST);
1104
1105         if (ch->flags & XPC_C_DISCONNECTING) {
1106                 spin_unlock_irqrestore(&ch->lock, irq_flags);
1107                 mutex_unlock(&registration->mutex);
1108                 return ch->reason;
1109         }
1110
1111
1112         /* add info from the channel connect registration to the channel */
1113
1114         ch->kthreads_assigned_limit = registration->assigned_limit;
1115         ch->kthreads_idle_limit = registration->idle_limit;
1116         DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
1117         DBUG_ON(atomic_read(&ch->kthreads_idle) != 0);
1118         DBUG_ON(atomic_read(&ch->kthreads_active) != 0);
1119
1120         ch->func = registration->func;
1121         DBUG_ON(registration->func == NULL);
1122         ch->key = registration->key;
1123
1124         ch->local_nentries = registration->nentries;
1125
1126         if (ch->flags & XPC_C_ROPENREQUEST) {
1127                 if (registration->msg_size != ch->msg_size) {
1128                         /* the local and remote sides aren't the same */
1129
1130                         /*
1131                          * Because XPC_DISCONNECT_CHANNEL() can block we're
1132                          * forced to up the registration sema before we unlock
1133                          * the channel lock. But that's okay here because we're
1134                          * done with the part that required the registration
1135                          * sema. XPC_DISCONNECT_CHANNEL() requires that the
1136                          * channel lock be locked and will unlock and relock
1137                          * the channel lock as needed.
1138                          */
1139                         mutex_unlock(&registration->mutex);
1140                         XPC_DISCONNECT_CHANNEL(ch, xpcUnequalMsgSizes,
1141                                                                 &irq_flags);
1142                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1143                         return xpcUnequalMsgSizes;
1144                 }
1145         } else {
1146                 ch->msg_size = registration->msg_size;
1147
1148                 XPC_SET_REASON(ch, 0, 0);
1149                 ch->flags &= ~XPC_C_DISCONNECTED;
1150
1151                 atomic_inc(&xpc_partitions[ch->partid].nchannels_active);
1152         }
1153
1154         mutex_unlock(&registration->mutex);
1155
1156
1157         /* initiate the connection */
1158
1159         ch->flags |= (XPC_C_OPENREQUEST | XPC_C_CONNECTING);
1160         xpc_IPI_send_openrequest(ch, &irq_flags);
1161
1162         xpc_process_connect(ch, &irq_flags);
1163
1164         spin_unlock_irqrestore(&ch->lock, irq_flags);
1165
1166         return xpcSuccess;
1167 }
1168
1169
1170 /*
1171  * Clear some of the msg flags in the local message queue.
1172  */
1173 static inline void
1174 xpc_clear_local_msgqueue_flags(struct xpc_channel *ch)
1175 {
1176         struct xpc_msg *msg;
1177         s64 get;
1178
1179
1180         get = ch->w_remote_GP.get;
1181         do {
1182                 msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
1183                                 (get % ch->local_nentries) * ch->msg_size);
1184                 msg->flags = 0;
1185         } while (++get < (volatile s64) ch->remote_GP.get);
1186 }
1187
1188
1189 /*
1190  * Clear some of the msg flags in the remote message queue.
1191  */
1192 static inline void
1193 xpc_clear_remote_msgqueue_flags(struct xpc_channel *ch)
1194 {
1195         struct xpc_msg *msg;
1196         s64 put;
1197
1198
1199         put = ch->w_remote_GP.put;
1200         do {
1201                 msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
1202                                 (put % ch->remote_nentries) * ch->msg_size);
1203                 msg->flags = 0;
1204         } while (++put < (volatile s64) ch->remote_GP.put);
1205 }
1206
1207
1208 static void
1209 xpc_process_msg_IPI(struct xpc_partition *part, int ch_number)
1210 {
1211         struct xpc_channel *ch = &part->channels[ch_number];
1212         int nmsgs_sent;
1213
1214
1215         ch->remote_GP = part->remote_GPs[ch_number];
1216
1217
1218         /* See what, if anything, has changed for each connected channel */
1219
1220         xpc_msgqueue_ref(ch);
1221
1222         if (ch->w_remote_GP.get == ch->remote_GP.get &&
1223                                 ch->w_remote_GP.put == ch->remote_GP.put) {
1224                 /* nothing changed since GPs were last pulled */
1225                 xpc_msgqueue_deref(ch);
1226                 return;
1227         }
1228
1229         if (!(ch->flags & XPC_C_CONNECTED)){
1230                 xpc_msgqueue_deref(ch);
1231                 return;
1232         }
1233
1234
1235         /*
1236          * First check to see if messages recently sent by us have been
1237          * received by the other side. (The remote GET value will have
1238          * changed since we last looked at it.)
1239          */
1240
1241         if (ch->w_remote_GP.get != ch->remote_GP.get) {
1242
1243                 /*
1244                  * We need to notify any senders that want to be notified
1245                  * that their sent messages have been received by their
1246                  * intended recipients. We need to do this before updating
1247                  * w_remote_GP.get so that we don't allocate the same message
1248                  * queue entries prematurely (see xpc_allocate_msg()).
1249                  */
1250                 if (atomic_read(&ch->n_to_notify) > 0) {
1251                         /*
1252                          * Notify senders that messages sent have been
1253                          * received and delivered by the other side.
1254                          */
1255                         xpc_notify_senders(ch, xpcMsgDelivered,
1256                                                         ch->remote_GP.get);
1257                 }
1258
1259                 /*
1260                  * Clear msg->flags in previously sent messages, so that
1261                  * they're ready for xpc_allocate_msg().
1262                  */
1263                 xpc_clear_local_msgqueue_flags(ch);
1264
1265                 ch->w_remote_GP.get = ch->remote_GP.get;
1266
1267                 dev_dbg(xpc_chan, "w_remote_GP.get changed to %ld, partid=%d, "
1268                         "channel=%d\n", ch->w_remote_GP.get, ch->partid,
1269                         ch->number);
1270
1271                 /*
1272                  * If anyone was waiting for message queue entries to become
1273                  * available, wake them up.
1274                  */
1275                 if (atomic_read(&ch->n_on_msg_allocate_wq) > 0) {
1276                         wake_up(&ch->msg_allocate_wq);
1277                 }
1278         }
1279
1280
1281         /*
1282          * Now check for newly sent messages by the other side. (The remote
1283          * PUT value will have changed since we last looked at it.)
1284          */
1285
1286         if (ch->w_remote_GP.put != ch->remote_GP.put) {
1287                 /*
1288                  * Clear msg->flags in previously received messages, so that
1289                  * they're ready for xpc_get_deliverable_msg().
1290                  */
1291                 xpc_clear_remote_msgqueue_flags(ch);
1292
1293                 ch->w_remote_GP.put = ch->remote_GP.put;
1294
1295                 dev_dbg(xpc_chan, "w_remote_GP.put changed to %ld, partid=%d, "
1296                         "channel=%d\n", ch->w_remote_GP.put, ch->partid,
1297                         ch->number);
1298
1299                 nmsgs_sent = ch->w_remote_GP.put - ch->w_local_GP.get;
1300                 if (nmsgs_sent > 0) {
1301                         dev_dbg(xpc_chan, "msgs waiting to be copied and "
1302                                 "delivered=%d, partid=%d, channel=%d\n",
1303                                 nmsgs_sent, ch->partid, ch->number);
1304
1305                         if (ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) {
1306                                 xpc_activate_kthreads(ch, nmsgs_sent);
1307                         }
1308                 }
1309         }
1310
1311         xpc_msgqueue_deref(ch);
1312 }
1313
1314
1315 void
1316 xpc_process_channel_activity(struct xpc_partition *part)
1317 {
1318         unsigned long irq_flags;
1319         u64 IPI_amo, IPI_flags;
1320         struct xpc_channel *ch;
1321         int ch_number;
1322         u32 ch_flags;
1323
1324
1325         IPI_amo = xpc_get_IPI_flags(part);
1326
1327         /*
1328          * Initiate channel connections for registered channels.
1329          *
1330          * For each connected channel that has pending messages activate idle
1331          * kthreads and/or create new kthreads as needed.
1332          */
1333
1334         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
1335                 ch = &part->channels[ch_number];
1336
1337
1338                 /*
1339                  * Process any open or close related IPI flags, and then deal
1340                  * with connecting or disconnecting the channel as required.
1341                  */
1342
1343                 IPI_flags = XPC_GET_IPI_FLAGS(IPI_amo, ch_number);
1344
1345                 if (XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(IPI_flags)) {
1346                         xpc_process_openclose_IPI(part, ch_number, IPI_flags);
1347                 }
1348
1349                 ch_flags = ch->flags;   /* need an atomic snapshot of flags */
1350
1351                 if (ch_flags & XPC_C_DISCONNECTING) {
1352                         spin_lock_irqsave(&ch->lock, irq_flags);
1353                         xpc_process_disconnect(ch, &irq_flags);
1354                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1355                         continue;
1356                 }
1357
1358                 if (part->act_state == XPC_P_DEACTIVATING) {
1359                         continue;
1360                 }
1361
1362                 if (!(ch_flags & XPC_C_CONNECTED)) {
1363                         if (!(ch_flags & XPC_C_OPENREQUEST)) {
1364                                 DBUG_ON(ch_flags & XPC_C_SETUP);
1365                                 (void) xpc_connect_channel(ch);
1366                         } else {
1367                                 spin_lock_irqsave(&ch->lock, irq_flags);
1368                                 xpc_process_connect(ch, &irq_flags);
1369                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
1370                         }
1371                         continue;
1372                 }
1373
1374
1375                 /*
1376                  * Process any message related IPI flags, this may involve the
1377                  * activation of kthreads to deliver any pending messages sent
1378                  * from the other partition.
1379                  */
1380
1381                 if (XPC_ANY_MSG_IPI_FLAGS_SET(IPI_flags)) {
1382                         xpc_process_msg_IPI(part, ch_number);
1383                 }
1384         }
1385 }
1386
1387
1388 /*
1389  * XPC's heartbeat code calls this function to inform XPC that a partition is
1390  * going down.  XPC responds by tearing down the XPartition Communication
1391  * infrastructure used for the just downed partition.
1392  *
1393  * XPC's heartbeat code will never call this function and xpc_partition_up()
1394  * at the same time. Nor will it ever make multiple calls to either function
1395  * at the same time.
1396  */
1397 void
1398 xpc_partition_going_down(struct xpc_partition *part, enum xpc_retval reason)
1399 {
1400         unsigned long irq_flags;
1401         int ch_number;
1402         struct xpc_channel *ch;
1403
1404
1405         dev_dbg(xpc_chan, "deactivating partition %d, reason=%d\n",
1406                 XPC_PARTID(part), reason);
1407
1408         if (!xpc_part_ref(part)) {
1409                 /* infrastructure for this partition isn't currently set up */
1410                 return;
1411         }
1412
1413
1414         /* disconnect channels associated with the partition going down */
1415
1416         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
1417                 ch = &part->channels[ch_number];
1418
1419                 xpc_msgqueue_ref(ch);
1420                 spin_lock_irqsave(&ch->lock, irq_flags);
1421
1422                 XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
1423
1424                 spin_unlock_irqrestore(&ch->lock, irq_flags);
1425                 xpc_msgqueue_deref(ch);
1426         }
1427
1428         xpc_wakeup_channel_mgr(part);
1429
1430         xpc_part_deref(part);
1431 }
1432
1433
1434 /*
1435  * Teardown the infrastructure necessary to support XPartition Communication
1436  * between the specified remote partition and the local one.
1437  */
1438 void
1439 xpc_teardown_infrastructure(struct xpc_partition *part)
1440 {
1441         partid_t partid = XPC_PARTID(part);
1442
1443
1444         /*
1445          * We start off by making this partition inaccessible to local
1446          * processes by marking it as no longer setup. Then we make it
1447          * inaccessible to remote processes by clearing the XPC per partition
1448          * specific variable's magic # (which indicates that these variables
1449          * are no longer valid) and by ignoring all XPC notify IPIs sent to
1450          * this partition.
1451          */
1452
1453         DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
1454         DBUG_ON(atomic_read(&part->nchannels_active) != 0);
1455         DBUG_ON(part->setup_state != XPC_P_SETUP);
1456         part->setup_state = XPC_P_WTEARDOWN;
1457
1458         xpc_vars_part[partid].magic = 0;
1459
1460
1461         free_irq(SGI_XPC_NOTIFY, (void *) (u64) partid);
1462
1463
1464         /*
1465          * Before proceding with the teardown we have to wait until all
1466          * existing references cease.
1467          */
1468         wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
1469
1470
1471         /* now we can begin tearing down the infrastructure */
1472
1473         part->setup_state = XPC_P_TORNDOWN;
1474
1475         /* in case we've still got outstanding timers registered... */
1476         del_timer_sync(&part->dropped_IPI_timer);
1477
1478         kfree(part->remote_openclose_args_base);
1479         part->remote_openclose_args = NULL;
1480         kfree(part->local_openclose_args_base);
1481         part->local_openclose_args = NULL;
1482         kfree(part->remote_GPs_base);
1483         part->remote_GPs = NULL;
1484         kfree(part->local_GPs_base);
1485         part->local_GPs = NULL;
1486         kfree(part->channels);
1487         part->channels = NULL;
1488         part->local_IPI_amo_va = NULL;
1489 }
1490
1491
1492 /*
1493  * Called by XP at the time of channel connection registration to cause
1494  * XPC to establish connections to all currently active partitions.
1495  */
1496 void
1497 xpc_initiate_connect(int ch_number)
1498 {
1499         partid_t partid;
1500         struct xpc_partition *part;
1501         struct xpc_channel *ch;
1502
1503
1504         DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);
1505
1506         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1507                 part = &xpc_partitions[partid];
1508
1509                 if (xpc_part_ref(part)) {
1510                         ch = &part->channels[ch_number];
1511
1512                         /*
1513                          * Initiate the establishment of a connection on the
1514                          * newly registered channel to the remote partition.
1515                          */
1516                         xpc_wakeup_channel_mgr(part);
1517                         xpc_part_deref(part);
1518                 }
1519         }
1520 }
1521
1522
1523 void
1524 xpc_connected_callout(struct xpc_channel *ch)
1525 {
1526         /* let the registerer know that a connection has been established */
1527
1528         if (ch->func != NULL) {
1529                 dev_dbg(xpc_chan, "ch->func() called, reason=xpcConnected, "
1530                         "partid=%d, channel=%d\n", ch->partid, ch->number);
1531
1532                 ch->func(xpcConnected, ch->partid, ch->number,
1533                                 (void *) (u64) ch->local_nentries, ch->key);
1534
1535                 dev_dbg(xpc_chan, "ch->func() returned, reason=xpcConnected, "
1536                         "partid=%d, channel=%d\n", ch->partid, ch->number);
1537         }
1538 }
1539
1540
1541 /*
1542  * Called by XP at the time of channel connection unregistration to cause
1543  * XPC to teardown all current connections for the specified channel.
1544  *
1545  * Before returning xpc_initiate_disconnect() will wait until all connections
1546  * on the specified channel have been closed/torndown. So the caller can be
1547  * assured that they will not be receiving any more callouts from XPC to the
1548  * function they registered via xpc_connect().
1549  *
1550  * Arguments:
1551  *
1552  *      ch_number - channel # to unregister.
1553  */
1554 void
1555 xpc_initiate_disconnect(int ch_number)
1556 {
1557         unsigned long irq_flags;
1558         partid_t partid;
1559         struct xpc_partition *part;
1560         struct xpc_channel *ch;
1561
1562
1563         DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);
1564
1565         /* initiate the channel disconnect for every active partition */
1566         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1567                 part = &xpc_partitions[partid];
1568
1569                 if (xpc_part_ref(part)) {
1570                         ch = &part->channels[ch_number];
1571                         xpc_msgqueue_ref(ch);
1572
1573                         spin_lock_irqsave(&ch->lock, irq_flags);
1574
1575                         if (!(ch->flags & XPC_C_DISCONNECTED)) {
1576                                 ch->flags |= XPC_C_WDISCONNECT;
1577
1578                                 XPC_DISCONNECT_CHANNEL(ch, xpcUnregistering,
1579                                                                 &irq_flags);
1580                         }
1581
1582                         spin_unlock_irqrestore(&ch->lock, irq_flags);
1583
1584                         xpc_msgqueue_deref(ch);
1585                         xpc_part_deref(part);
1586                 }
1587         }
1588
1589         xpc_disconnect_wait(ch_number);
1590 }
1591
1592
1593 /*
1594  * To disconnect a channel, and reflect it back to all who may be waiting.
1595  *
1596  * An OPEN is not allowed until XPC_C_DISCONNECTING is cleared by
1597  * xpc_process_disconnect(), and if set, XPC_C_WDISCONNECT is cleared by
1598  * xpc_disconnect_wait().
1599  *
1600  * THE CHANNEL IS TO BE LOCKED BY THE CALLER AND WILL REMAIN LOCKED UPON RETURN.
1601  */
1602 void
1603 xpc_disconnect_channel(const int line, struct xpc_channel *ch,
1604                         enum xpc_retval reason, unsigned long *irq_flags)
1605 {
1606         u32 channel_was_connected = (ch->flags & XPC_C_CONNECTED);
1607
1608
1609         DBUG_ON(!spin_is_locked(&ch->lock));
1610
1611         if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
1612                 return;
1613         }
1614         DBUG_ON(!(ch->flags & (XPC_C_CONNECTING | XPC_C_CONNECTED)));
1615
1616         dev_dbg(xpc_chan, "reason=%d, line=%d, partid=%d, channel=%d\n",
1617                 reason, line, ch->partid, ch->number);
1618
1619         XPC_SET_REASON(ch, reason, line);
1620
1621         ch->flags |= (XPC_C_CLOSEREQUEST | XPC_C_DISCONNECTING);
1622         /* some of these may not have been set */
1623         ch->flags &= ~(XPC_C_OPENREQUEST | XPC_C_OPENREPLY |
1624                         XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
1625                         XPC_C_CONNECTING | XPC_C_CONNECTED);
1626
1627         xpc_IPI_send_closerequest(ch, irq_flags);
1628
1629         if (channel_was_connected) {
1630                 ch->flags |= XPC_C_WASCONNECTED;
1631         }
1632
1633         spin_unlock_irqrestore(&ch->lock, *irq_flags);
1634
1635         /* wake all idle kthreads so they can exit */
1636         if (atomic_read(&ch->kthreads_idle) > 0) {
1637                 wake_up_all(&ch->idle_wq);
1638         }
1639
1640         /* wake those waiting to allocate an entry from the local msg queue */
1641         if (atomic_read(&ch->n_on_msg_allocate_wq) > 0) {
1642                 wake_up(&ch->msg_allocate_wq);
1643         }
1644
1645         spin_lock_irqsave(&ch->lock, *irq_flags);
1646 }
1647
1648
1649 void
1650 xpc_disconnect_callout(struct xpc_channel *ch, enum xpc_retval reason)
1651 {
1652         /*
1653          * Let the channel's registerer know that the channel is being
1654          * disconnected. We don't want to do this if the registerer was never
1655          * informed of a connection being made.
1656          */
1657
1658         if (ch->func != NULL) {
1659                 dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
1660                         "channel=%d\n", reason, ch->partid, ch->number);
1661
1662                 ch->func(reason, ch->partid, ch->number, NULL, ch->key);
1663
1664                 dev_dbg(xpc_chan, "ch->func() returned, reason=%d, partid=%d, "
1665                         "channel=%d\n", reason, ch->partid, ch->number);
1666         }
1667 }
1668
1669
1670 /*
1671  * Wait for a message entry to become available for the specified channel,
1672  * but don't wait any longer than 1 jiffy.
1673  */
1674 static enum xpc_retval
1675 xpc_allocate_msg_wait(struct xpc_channel *ch)
1676 {
1677         enum xpc_retval ret;
1678
1679
1680         if (ch->flags & XPC_C_DISCONNECTING) {
1681                 DBUG_ON(ch->reason == xpcInterrupted);  // >>> Is this true?
1682                 return ch->reason;
1683         }
1684
1685         atomic_inc(&ch->n_on_msg_allocate_wq);
1686         ret = interruptible_sleep_on_timeout(&ch->msg_allocate_wq, 1);
1687         atomic_dec(&ch->n_on_msg_allocate_wq);
1688
1689         if (ch->flags & XPC_C_DISCONNECTING) {
1690                 ret = ch->reason;
1691                 DBUG_ON(ch->reason == xpcInterrupted);  // >>> Is this true?
1692         } else if (ret == 0) {
1693                 ret = xpcTimeout;
1694         } else {
1695                 ret = xpcInterrupted;
1696         }
1697
1698         return ret;
1699 }
1700
1701
1702 /*
1703  * Allocate an entry for a message from the message queue associated with the
1704  * specified channel.
1705  */
1706 static enum xpc_retval
1707 xpc_allocate_msg(struct xpc_channel *ch, u32 flags,
1708                         struct xpc_msg **address_of_msg)
1709 {
1710         struct xpc_msg *msg;
1711         enum xpc_retval ret;
1712         s64 put;
1713
1714
1715         /* this reference will be dropped in xpc_send_msg() */
1716         xpc_msgqueue_ref(ch);
1717
1718         if (ch->flags & XPC_C_DISCONNECTING) {
1719                 xpc_msgqueue_deref(ch);
1720                 return ch->reason;
1721         }
1722         if (!(ch->flags & XPC_C_CONNECTED)) {
1723                 xpc_msgqueue_deref(ch);
1724                 return xpcNotConnected;
1725         }
1726
1727
1728         /*
1729          * Get the next available message entry from the local message queue.
1730          * If none are available, we'll make sure that we grab the latest
1731          * GP values.
1732          */
1733         ret = xpcTimeout;
1734
1735         while (1) {
1736
1737                 put = (volatile s64) ch->w_local_GP.put;
1738                 if (put - (volatile s64) ch->w_remote_GP.get <
1739                                                         ch->local_nentries) {
1740
1741                         /* There are available message entries. We need to try
1742                          * to secure one for ourselves. We'll do this by trying
1743                          * to increment w_local_GP.put as long as someone else
1744                          * doesn't beat us to it. If they do, we'll have to
1745                          * try again.
1746                          */
1747                         if (cmpxchg(&ch->w_local_GP.put, put, put + 1) ==
1748                                                                         put) {
1749                                 /* we got the entry referenced by put */
1750                                 break;
1751                         }
1752                         continue;       /* try again */
1753                 }
1754
1755
1756                 /*
1757                  * There aren't any available msg entries at this time.
1758                  *
1759                  * In waiting for a message entry to become available,
1760                  * we set a timeout in case the other side is not
1761                  * sending completion IPIs. This lets us fake an IPI
1762                  * that will cause the IPI handler to fetch the latest
1763                  * GP values as if an IPI was sent by the other side.
1764                  */
1765                 if (ret == xpcTimeout) {
1766                         xpc_IPI_send_local_msgrequest(ch);
1767                 }
1768
1769                 if (flags & XPC_NOWAIT) {
1770                         xpc_msgqueue_deref(ch);
1771                         return xpcNoWait;
1772                 }
1773
1774                 ret = xpc_allocate_msg_wait(ch);
1775                 if (ret != xpcInterrupted && ret != xpcTimeout) {
1776                         xpc_msgqueue_deref(ch);
1777                         return ret;
1778                 }
1779         }
1780
1781
1782         /* get the message's address and initialize it */
1783         msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
1784                                 (put % ch->local_nentries) * ch->msg_size);
1785
1786
1787         DBUG_ON(msg->flags != 0);
1788         msg->number = put;
1789
1790         dev_dbg(xpc_chan, "w_local_GP.put changed to %ld; msg=0x%p, "
1791                 "msg_number=%ld, partid=%d, channel=%d\n", put + 1,
1792                 (void *) msg, msg->number, ch->partid, ch->number);
1793
1794         *address_of_msg = msg;
1795
1796         return xpcSuccess;
1797 }
1798
1799
1800 /*
1801  * Allocate an entry for a message from the message queue associated with the
1802  * specified channel. NOTE that this routine can sleep waiting for a message
1803  * entry to become available. To not sleep, pass in the XPC_NOWAIT flag.
1804  *
1805  * Arguments:
1806  *
1807  *      partid - ID of partition to which the channel is connected.
1808  *      ch_number - channel #.
1809  *      flags - see xpc.h for valid flags.
1810  *      payload - address of the allocated payload area pointer (filled in on
1811  *                return) in which the user-defined message is constructed.
1812  */
1813 enum xpc_retval
1814 xpc_initiate_allocate(partid_t partid, int ch_number, u32 flags, void **payload)
1815 {
1816         struct xpc_partition *part = &xpc_partitions[partid];
1817         enum xpc_retval ret = xpcUnknownReason;
1818         struct xpc_msg *msg;
1819
1820
1821         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
1822         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
1823
1824         *payload = NULL;
1825
1826         if (xpc_part_ref(part)) {
1827                 ret = xpc_allocate_msg(&part->channels[ch_number], flags, &msg);
1828                 xpc_part_deref(part);
1829
1830                 if (msg != NULL) {
1831                         *payload = &msg->payload;
1832                 }
1833         }
1834
1835         return ret;
1836 }
1837
1838
1839 /*
1840  * Now we actually send the messages that are ready to be sent by advancing
1841  * the local message queue's Put value and then send an IPI to the recipient
1842  * partition.
1843  */
1844 static void
1845 xpc_send_msgs(struct xpc_channel *ch, s64 initial_put)
1846 {
1847         struct xpc_msg *msg;
1848         s64 put = initial_put + 1;
1849         int send_IPI = 0;
1850
1851
1852         while (1) {
1853
1854                 while (1) {
1855                         if (put == (volatile s64) ch->w_local_GP.put) {
1856                                 break;
1857                         }
1858
1859                         msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
1860                                (put % ch->local_nentries) * ch->msg_size);
1861
1862                         if (!(msg->flags & XPC_M_READY)) {
1863                                 break;
1864                         }
1865
1866                         put++;
1867                 }
1868
1869                 if (put == initial_put) {
1870                         /* nothing's changed */
1871                         break;
1872                 }
1873
1874                 if (cmpxchg_rel(&ch->local_GP->put, initial_put, put) !=
1875                                                                 initial_put) {
1876                         /* someone else beat us to it */
1877                         DBUG_ON((volatile s64) ch->local_GP->put < initial_put);
1878                         break;
1879                 }
1880
1881                 /* we just set the new value of local_GP->put */
1882
1883                 dev_dbg(xpc_chan, "local_GP->put changed to %ld, partid=%d, "
1884                         "channel=%d\n", put, ch->partid, ch->number);
1885
1886                 send_IPI = 1;
1887
1888                 /*
1889                  * We need to ensure that the message referenced by
1890                  * local_GP->put is not XPC_M_READY or that local_GP->put
1891                  * equals w_local_GP.put, so we'll go have a look.
1892                  */
1893                 initial_put = put;
1894         }
1895
1896         if (send_IPI) {
1897                 xpc_IPI_send_msgrequest(ch);
1898         }
1899 }
1900
1901
1902 /*
1903  * Common code that does the actual sending of the message by advancing the
1904  * local message queue's Put value and sends an IPI to the partition the
1905  * message is being sent to.
1906  */
1907 static enum xpc_retval
1908 xpc_send_msg(struct xpc_channel *ch, struct xpc_msg *msg, u8 notify_type,
1909                         xpc_notify_func func, void *key)
1910 {
1911         enum xpc_retval ret = xpcSuccess;
1912         struct xpc_notify *notify = notify;
1913         s64 put, msg_number = msg->number;
1914
1915
1916         DBUG_ON(notify_type == XPC_N_CALL && func == NULL);
1917         DBUG_ON((((u64) msg - (u64) ch->local_msgqueue) / ch->msg_size) !=
1918                                         msg_number % ch->local_nentries);
1919         DBUG_ON(msg->flags & XPC_M_READY);
1920
1921         if (ch->flags & XPC_C_DISCONNECTING) {
1922                 /* drop the reference grabbed in xpc_allocate_msg() */
1923                 xpc_msgqueue_deref(ch);
1924                 return ch->reason;
1925         }
1926
1927         if (notify_type != 0) {
1928                 /*
1929                  * Tell the remote side to send an ACK interrupt when the
1930                  * message has been delivered.
1931                  */
1932                 msg->flags |= XPC_M_INTERRUPT;
1933
1934                 atomic_inc(&ch->n_to_notify);
1935
1936                 notify = &ch->notify_queue[msg_number % ch->local_nentries];
1937                 notify->func = func;
1938                 notify->key = key;
1939                 notify->type = notify_type;
1940
1941                 // >>> is a mb() needed here?
1942
1943                 if (ch->flags & XPC_C_DISCONNECTING) {
1944                         /*
1945                          * An error occurred between our last error check and
1946                          * this one. We will try to clear the type field from
1947                          * the notify entry. If we succeed then
1948                          * xpc_disconnect_channel() didn't already process
1949                          * the notify entry.
1950                          */
1951                         if (cmpxchg(&notify->type, notify_type, 0) ==
1952                                                                 notify_type) {
1953                                 atomic_dec(&ch->n_to_notify);
1954                                 ret = ch->reason;
1955                         }
1956
1957                         /* drop the reference grabbed in xpc_allocate_msg() */
1958                         xpc_msgqueue_deref(ch);
1959                         return ret;
1960                 }
1961         }
1962
1963         msg->flags |= XPC_M_READY;
1964
1965         /*
1966          * The preceding store of msg->flags must occur before the following
1967          * load of ch->local_GP->put.
1968          */
1969         mb();
1970
1971         /* see if the message is next in line to be sent, if so send it */
1972
1973         put = ch->local_GP->put;
1974         if (put == msg_number) {
1975                 xpc_send_msgs(ch, put);
1976         }
1977
1978         /* drop the reference grabbed in xpc_allocate_msg() */
1979         xpc_msgqueue_deref(ch);
1980         return ret;
1981 }
1982
1983
1984 /*
1985  * Send a message previously allocated using xpc_initiate_allocate() on the
1986  * specified channel connected to the specified partition.
1987  *
1988  * This routine will not wait for the message to be received, nor will
1989  * notification be given when it does happen. Once this routine has returned
1990  * the message entry allocated via xpc_initiate_allocate() is no longer
1991  * accessable to the caller.
1992  *
1993  * This routine, although called by users, does not call xpc_part_ref() to
1994  * ensure that the partition infrastructure is in place. It relies on the
1995  * fact that we called xpc_msgqueue_ref() in xpc_allocate_msg().
1996  *
1997  * Arguments:
1998  *
1999  *      partid - ID of partition to which the channel is connected.
2000  *      ch_number - channel # to send message on.
2001  *      payload - pointer to the payload area allocated via
2002  *                      xpc_initiate_allocate().
2003  */
2004 enum xpc_retval
2005 xpc_initiate_send(partid_t partid, int ch_number, void *payload)
2006 {
2007         struct xpc_partition *part = &xpc_partitions[partid];
2008         struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
2009         enum xpc_retval ret;
2010
2011
2012         dev_dbg(xpc_chan, "msg=0x%p, partid=%d, channel=%d\n", (void *) msg,
2013                 partid, ch_number);
2014
2015         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
2016         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
2017         DBUG_ON(msg == NULL);
2018
2019         ret = xpc_send_msg(&part->channels[ch_number], msg, 0, NULL, NULL);
2020
2021         return ret;
2022 }
2023
2024
2025 /*
2026  * Send a message previously allocated using xpc_initiate_allocate on the
2027  * specified channel connected to the specified partition.
2028  *
2029  * This routine will not wait for the message to be sent. Once this routine
2030  * has returned the message entry allocated via xpc_initiate_allocate() is no
2031  * longer accessable to the caller.
2032  *
2033  * Once the remote end of the channel has received the message, the function
2034  * passed as an argument to xpc_initiate_send_notify() will be called. This
2035  * allows the sender to free up or re-use any buffers referenced by the
2036  * message, but does NOT mean the message has been processed at the remote
2037  * end by a receiver.
2038  *
2039  * If this routine returns an error, the caller's function will NOT be called.
2040  *
2041  * This routine, although called by users, does not call xpc_part_ref() to
2042  * ensure that the partition infrastructure is in place. It relies on the
2043  * fact that we called xpc_msgqueue_ref() in xpc_allocate_msg().
2044  *
2045  * Arguments:
2046  *
2047  *      partid - ID of partition to which the channel is connected.
2048  *      ch_number - channel # to send message on.
2049  *      payload - pointer to the payload area allocated via
2050  *                      xpc_initiate_allocate().
2051  *      func - function to call with asynchronous notification of message
2052  *                receipt. THIS FUNCTION MUST BE NON-BLOCKING.
2053  *      key - user-defined key to be passed to the function when it's called.
2054  */
2055 enum xpc_retval
2056 xpc_initiate_send_notify(partid_t partid, int ch_number, void *payload,
2057                                 xpc_notify_func func, void *key)
2058 {
2059         struct xpc_partition *part = &xpc_partitions[partid];
2060         struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
2061         enum xpc_retval ret;
2062
2063
2064         dev_dbg(xpc_chan, "msg=0x%p, partid=%d, channel=%d\n", (void *) msg,
2065                 partid, ch_number);
2066
2067         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
2068         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
2069         DBUG_ON(msg == NULL);
2070         DBUG_ON(func == NULL);
2071
2072         ret = xpc_send_msg(&part->channels[ch_number], msg, XPC_N_CALL,
2073                                                                 func, key);
2074         return ret;
2075 }
2076
2077
2078 static struct xpc_msg *
2079 xpc_pull_remote_msg(struct xpc_channel *ch, s64 get)
2080 {
2081         struct xpc_partition *part = &xpc_partitions[ch->partid];
2082         struct xpc_msg *remote_msg, *msg;
2083         u32 msg_index, nmsgs;
2084         u64 msg_offset;
2085         enum xpc_retval ret;
2086
2087
2088         if (mutex_lock_interruptible(&ch->msg_to_pull_mutex) != 0) {
2089                 /* we were interrupted by a signal */
2090                 return NULL;
2091         }
2092
2093         while (get >= ch->next_msg_to_pull) {
2094
2095                 /* pull as many messages as are ready and able to be pulled */
2096
2097                 msg_index = ch->next_msg_to_pull % ch->remote_nentries;
2098
2099                 DBUG_ON(ch->next_msg_to_pull >=
2100                                         (volatile s64) ch->w_remote_GP.put);
2101                 nmsgs =  (volatile s64) ch->w_remote_GP.put -
2102                                                 ch->next_msg_to_pull;
2103                 if (msg_index + nmsgs > ch->remote_nentries) {
2104                         /* ignore the ones that wrap the msg queue for now */
2105                         nmsgs = ch->remote_nentries - msg_index;
2106                 }
2107
2108                 msg_offset = msg_index * ch->msg_size;
2109                 msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
2110                                                                 msg_offset);
2111                 remote_msg = (struct xpc_msg *) (ch->remote_msgqueue_pa +
2112                                                                 msg_offset);
2113
2114                 if ((ret = xpc_pull_remote_cachelines(part, msg, remote_msg,
2115                                 nmsgs * ch->msg_size)) != xpcSuccess) {
2116
2117                         dev_dbg(xpc_chan, "failed to pull %d msgs starting with"
2118                                 " msg %ld from partition %d, channel=%d, "
2119                                 "ret=%d\n", nmsgs, ch->next_msg_to_pull,
2120                                 ch->partid, ch->number, ret);
2121
2122                         XPC_DEACTIVATE_PARTITION(part, ret);
2123
2124                         mutex_unlock(&ch->msg_to_pull_mutex);
2125                         return NULL;
2126                 }
2127
2128                 mb();   /* >>> this may not be needed, we're not sure */
2129
2130                 ch->next_msg_to_pull += nmsgs;
2131         }
2132
2133         mutex_unlock(&ch->msg_to_pull_mutex);
2134
2135         /* return the message we were looking for */
2136         msg_offset = (get % ch->remote_nentries) * ch->msg_size;
2137         msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue + msg_offset);
2138
2139         return msg;
2140 }
2141
2142
2143 /*
2144  * Get a message to be delivered.
2145  */
2146 static struct xpc_msg *
2147 xpc_get_deliverable_msg(struct xpc_channel *ch)
2148 {
2149         struct xpc_msg *msg = NULL;
2150         s64 get;
2151
2152
2153         do {
2154                 if ((volatile u32) ch->flags & XPC_C_DISCONNECTING) {
2155                         break;
2156                 }
2157
2158                 get = (volatile s64) ch->w_local_GP.get;
2159                 if (get == (volatile s64) ch->w_remote_GP.put) {
2160                         break;
2161                 }
2162
2163                 /* There are messages waiting to be pulled and delivered.
2164                  * We need to try to secure one for ourselves. We'll do this
2165                  * by trying to increment w_local_GP.get and hope that no one
2166                  * else beats us to it. If they do, we'll we'll simply have
2167                  * to try again for the next one.
2168                  */
2169
2170                 if (cmpxchg(&ch->w_local_GP.get, get, get + 1) == get) {
2171                         /* we got the entry referenced by get */
2172
2173                         dev_dbg(xpc_chan, "w_local_GP.get changed to %ld, "
2174                                 "partid=%d, channel=%d\n", get + 1,
2175                                 ch->partid, ch->number);
2176
2177                         /* pull the message from the remote partition */
2178
2179                         msg = xpc_pull_remote_msg(ch, get);
2180
2181                         DBUG_ON(msg != NULL && msg->number != get);
2182                         DBUG_ON(msg != NULL && (msg->flags & XPC_M_DONE));
2183                         DBUG_ON(msg != NULL && !(msg->flags & XPC_M_READY));
2184
2185                         break;
2186                 }
2187
2188         } while (1);
2189
2190         return msg;
2191 }
2192
2193
2194 /*
2195  * Deliver a message to its intended recipient.
2196  */
2197 void
2198 xpc_deliver_msg(struct xpc_channel *ch)
2199 {
2200         struct xpc_msg *msg;
2201
2202
2203         if ((msg = xpc_get_deliverable_msg(ch)) != NULL) {
2204
2205                 /*
2206                  * This ref is taken to protect the payload itself from being
2207                  * freed before the user is finished with it, which the user
2208                  * indicates by calling xpc_initiate_received().
2209                  */
2210                 xpc_msgqueue_ref(ch);
2211
2212                 atomic_inc(&ch->kthreads_active);
2213
2214                 if (ch->func != NULL) {
2215                         dev_dbg(xpc_chan, "ch->func() called, msg=0x%p, "
2216                                 "msg_number=%ld, partid=%d, channel=%d\n",
2217                                 (void *) msg, msg->number, ch->partid,
2218                                 ch->number);
2219
2220                         /* deliver the message to its intended recipient */
2221                         ch->func(xpcMsgReceived, ch->partid, ch->number,
2222                                         &msg->payload, ch->key);
2223
2224                         dev_dbg(xpc_chan, "ch->func() returned, msg=0x%p, "
2225                                 "msg_number=%ld, partid=%d, channel=%d\n",
2226                                 (void *) msg, msg->number, ch->partid,
2227                                 ch->number);
2228                 }
2229
2230                 atomic_dec(&ch->kthreads_active);
2231         }
2232 }
2233
2234
2235 /*
2236  * Now we actually acknowledge the messages that have been delivered and ack'd
2237  * by advancing the cached remote message queue's Get value and if requested
2238  * send an IPI to the message sender's partition.
2239  */
2240 static void
2241 xpc_acknowledge_msgs(struct xpc_channel *ch, s64 initial_get, u8 msg_flags)
2242 {
2243         struct xpc_msg *msg;
2244         s64 get = initial_get + 1;
2245         int send_IPI = 0;
2246
2247
2248         while (1) {
2249
2250                 while (1) {
2251                         if (get == (volatile s64) ch->w_local_GP.get) {
2252                                 break;
2253                         }
2254
2255                         msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
2256                                (get % ch->remote_nentries) * ch->msg_size);
2257
2258                         if (!(msg->flags & XPC_M_DONE)) {
2259                                 break;
2260                         }
2261
2262                         msg_flags |= msg->flags;
2263                         get++;
2264                 }
2265
2266                 if (get == initial_get) {
2267                         /* nothing's changed */
2268                         break;
2269                 }
2270
2271                 if (cmpxchg_rel(&ch->local_GP->get, initial_get, get) !=
2272                                                                 initial_get) {
2273                         /* someone else beat us to it */
2274                         DBUG_ON((volatile s64) ch->local_GP->get <=
2275                                                                 initial_get);
2276                         break;
2277                 }
2278
2279                 /* we just set the new value of local_GP->get */
2280
2281                 dev_dbg(xpc_chan, "local_GP->get changed to %ld, partid=%d, "
2282                         "channel=%d\n", get, ch->partid, ch->number);
2283
2284                 send_IPI = (msg_flags & XPC_M_INTERRUPT);
2285
2286                 /*
2287                  * We need to ensure that the message referenced by
2288                  * local_GP->get is not XPC_M_DONE or that local_GP->get
2289                  * equals w_local_GP.get, so we'll go have a look.
2290                  */
2291                 initial_get = get;
2292         }
2293
2294         if (send_IPI) {
2295                 xpc_IPI_send_msgrequest(ch);
2296         }
2297 }
2298
2299
2300 /*
2301  * Acknowledge receipt of a delivered message.
2302  *
2303  * If a message has XPC_M_INTERRUPT set, send an interrupt to the partition
2304  * that sent the message.
2305  *
2306  * This function, although called by users, does not call xpc_part_ref() to
2307  * ensure that the partition infrastructure is in place. It relies on the
2308  * fact that we called xpc_msgqueue_ref() in xpc_deliver_msg().
2309  *
2310  * Arguments:
2311  *
2312  *      partid - ID of partition to which the channel is connected.
2313  *      ch_number - channel # message received on.
2314  *      payload - pointer to the payload area allocated via
2315  *                      xpc_initiate_allocate().
2316  */
2317 void
2318 xpc_initiate_received(partid_t partid, int ch_number, void *payload)
2319 {
2320         struct xpc_partition *part = &xpc_partitions[partid];
2321         struct xpc_channel *ch;
2322         struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
2323         s64 get, msg_number = msg->number;
2324
2325
2326         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
2327         DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
2328
2329         ch = &part->channels[ch_number];
2330
2331         dev_dbg(xpc_chan, "msg=0x%p, msg_number=%ld, partid=%d, channel=%d\n",
2332                 (void *) msg, msg_number, ch->partid, ch->number);
2333
2334         DBUG_ON((((u64) msg - (u64) ch->remote_msgqueue) / ch->msg_size) !=
2335                                         msg_number % ch->remote_nentries);
2336         DBUG_ON(msg->flags & XPC_M_DONE);
2337
2338         msg->flags |= XPC_M_DONE;
2339
2340         /*
2341          * The preceding store of msg->flags must occur before the following
2342          * load of ch->local_GP->get.
2343          */
2344         mb();
2345
2346         /*
2347          * See if this message is next in line to be acknowledged as having
2348          * been delivered.
2349          */
2350         get = ch->local_GP->get;
2351         if (get == msg_number) {
2352                 xpc_acknowledge_msgs(ch, get, msg->flags);
2353         }
2354
2355         /* the call to xpc_msgqueue_ref() was done by xpc_deliver_msg()  */
2356         xpc_msgqueue_deref(ch);
2357 }
2358