net/sunrpc/sched.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/net/sunrpc/sched.c
   4  *
   5  * Scheduling for synchronous and asynchronous RPC requests.
   6  *
   7  * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
   8  *
   9  * TCP NFS related read + write fixes
  10  * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
  11  */
  12
  13 #include <linux/module.h>
  14
  15 #include <linux/sched.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/slab.h>
  18 #include <linux/mempool.h>
  19 #include <linux/smp.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/mutex.h>
  22 #include <linux/freezer.h>
  23 #include <linux/sched/mm.h>
  24
  25 #include <linux/sunrpc/clnt.h>
  26
  27 #include "sunrpc.h"
  28
  29 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  30 #define RPCDBG_FACILITY         RPCDBG_SCHED
  31 #endif
  32
  33 #define CREATE_TRACE_POINTS
  34 #include <trace/events/sunrpc.h>
  35
  36 /*
  37  * RPC slabs and memory pools
  38  */
  39 #define RPC_BUFFER_MAXSIZE      (2048)
  40 #define RPC_BUFFER_POOLSIZE     (8)
  41 #define RPC_TASK_POOLSIZE       (8)
  42 static struct kmem_cache        *rpc_task_slabp __read_mostly;
  43 static struct kmem_cache        *rpc_buffer_slabp __read_mostly;
  44 static mempool_t        *rpc_task_mempool __read_mostly;
  45 static mempool_t        *rpc_buffer_mempool __read_mostly;
  46
  47 static void                     rpc_async_schedule(struct work_struct *);
  48 static void                      rpc_release_task(struct rpc_task *task);
  49 static void __rpc_queue_timer_fn(struct timer_list *t);
  50
  51 /*
  52  * RPC tasks sit here while waiting for conditions to improve.
  53  */
  54 static struct rpc_wait_queue delay_queue;
  55
  56 /*
  57  * rpciod-related stuff
  58  */
  59 struct workqueue_struct *rpciod_workqueue __read_mostly;
  60 struct workqueue_struct *xprtiod_workqueue __read_mostly;
  61
  62 unsigned long
  63 rpc_task_timeout(const struct rpc_task *task)
  64 {
  65         unsigned long timeout = READ_ONCE(task->tk_timeout);
  66
  67         if (timeout != 0) {
  68                 unsigned long now = jiffies;
  69                 if (time_before(now, timeout))
  70                         return timeout - now;
  71         }
  72         return 0;
  73 }
  74 EXPORT_SYMBOL_GPL(rpc_task_timeout);
  75
  76 /*
  77  * Disable the timer for a given RPC task. Should be called with
  78  * queue->lock and bh_disabled in order to avoid races within
  79  * rpc_run_timer().
  80  */
  81 static void
  82 __rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
  83 {
  84         if (list_empty(&task->u.tk_wait.timer_list))
  85                 return;
  86         dprintk("RPC: %5u disabling timer\n", task->tk_pid);
  87         task->tk_timeout = 0;
  88         list_del(&task->u.tk_wait.timer_list);
  89         if (list_empty(&queue->timer_list.list))
  90                 del_timer(&queue->timer_list.timer);
  91 }
  92
  93 static void
  94 rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
  95 {
  96         timer_reduce(&queue->timer_list.timer, expires);
  97 }
  98
  99 /*
 100  * Set up a timer for the current task.
 101  */
 102 static void
 103 __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task,
 104                 unsigned long timeout)
 105 {
 106         dprintk("RPC: %5u setting alarm for %u ms\n",
 107                 task->tk_pid, jiffies_to_msecs(timeout - jiffies));
 108
 109         task->tk_timeout = timeout;
 110         rpc_set_queue_timer(queue, timeout);
 111         list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
 112 }
 113
 114 static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 115 {
 116         if (queue->priority != priority) {
 117                 queue->priority = priority;
 118                 queue->nr = 1U << priority;
 119         }
 120 }
 121
 122 static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 123 {
 124         rpc_set_waitqueue_priority(queue, queue->maxpriority);
 125 }
 126
 127 /*
 128  * Add a request to a queue list
 129  */
 130 static void
 131 __rpc_list_enqueue_task(struct list_head *q, struct rpc_task *task)
 132 {
 133         struct rpc_task *t;
 134
 135         list_for_each_entry(t, q, u.tk_wait.list) {
 136                 if (t->tk_owner == task->tk_owner) {
 137                         list_add_tail(&task->u.tk_wait.links,
 138                                         &t->u.tk_wait.links);
 139                         /* Cache the queue head in task->u.tk_wait.list */
 140                         task->u.tk_wait.list.next = q;
 141                         task->u.tk_wait.list.prev = NULL;
 142                         return;
 143                 }
 144         }
 145         INIT_LIST_HEAD(&task->u.tk_wait.links);
 146         list_add_tail(&task->u.tk_wait.list, q);
 147 }
 148
 149 /*
 150  * Remove request from a queue list
 151  */
 152 static void
 153 __rpc_list_dequeue_task(struct rpc_task *task)
 154 {
 155         struct list_head *q;
 156         struct rpc_task *t;
 157
 158         if (task->u.tk_wait.list.prev == NULL) {
 159                 list_del(&task->u.tk_wait.links);
 160                 return;
 161         }
 162         if (!list_empty(&task->u.tk_wait.links)) {
 163                 t = list_first_entry(&task->u.tk_wait.links,
 164                                 struct rpc_task,
 165                                 u.tk_wait.links);
 166                 /* Assume __rpc_list_enqueue_task() cached the queue head */
 167                 q = t->u.tk_wait.list.next;
 168                 list_add_tail(&t->u.tk_wait.list, q);
 169                 list_del(&task->u.tk_wait.links);
 170         }
 171         list_del(&task->u.tk_wait.list);
 172 }
 173
 174 /*
 175  * Add new request to a priority queue.
 176  */
 177 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
 178                 struct rpc_task *task,
 179                 unsigned char queue_priority)
 180 {
 181         if (unlikely(queue_priority > queue->maxpriority))
 182                 queue_priority = queue->maxpriority;
 183         __rpc_list_enqueue_task(&queue->tasks[queue_priority], task);
 184 }
 185
 186 /*
 187  * Add new request to wait queue.
 188  *
 189  * Swapper tasks always get inserted at the head of the queue.
 190  * This should avoid many nasty memory deadlocks and hopefully
 191  * improve overall performance.
 192  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
 193  */
 194 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
 195                 struct rpc_task *task,
 196                 unsigned char queue_priority)
 197 {
 198         WARN_ON_ONCE(RPC_IS_QUEUED(task));
 199         if (RPC_IS_QUEUED(task))
 200                 return;
 201
 202         INIT_LIST_HEAD(&task->u.tk_wait.timer_list);
 203         if (RPC_IS_PRIORITY(queue))
 204                 __rpc_add_wait_queue_priority(queue, task, queue_priority);
 205         else if (RPC_IS_SWAPPER(task))
 206                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
 207         else
 208                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
 209         task->tk_waitqueue = queue;
 210         queue->qlen++;
 211         /* barrier matches the read in rpc_wake_up_task_queue_locked() */
 212         smp_wmb();
 213         rpc_set_queued(task);
 214
 215         dprintk("RPC: %5u added to queue %p \"%s\"\n",
 216                         task->tk_pid, queue, rpc_qname(queue));
 217 }
 218
 219 /*
 220  * Remove request from a priority queue.
 221  */
 222 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 223 {
 224         __rpc_list_dequeue_task(task);
 225 }
 226
 227 /*
 228  * Remove request from queue.
 229  * Note: must be called with spin lock held.
 230  */
 231 static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
 232 {
 233         __rpc_disable_timer(queue, task);
 234         if (RPC_IS_PRIORITY(queue))
 235                 __rpc_remove_wait_queue_priority(task);
 236         else
 237                 list_del(&task->u.tk_wait.list);
 238         queue->qlen--;
 239         dprintk("RPC: %5u removed from queue %p \"%s\"\n",
 240                         task->tk_pid, queue, rpc_qname(queue));
 241 }
 242
 243 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
 244 {
 245         int i;
 246
 247         spin_lock_init(&queue->lock);
 248         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 249                 INIT_LIST_HEAD(&queue->tasks[i]);
 250         queue->maxpriority = nr_queues - 1;
 251         rpc_reset_waitqueue_priority(queue);
 252         queue->qlen = 0;
 253         timer_setup(&queue->timer_list.timer,
 254                         __rpc_queue_timer_fn,
 255                         TIMER_DEFERRABLE);
 256         INIT_LIST_HEAD(&queue->timer_list.list);
 257         rpc_assign_waitqueue_name(queue, qname);
 258 }
 259
 260 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 261 {
 262         __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
 263 }
 264 EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
 265
 266 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 267 {
 268         __rpc_init_priority_wait_queue(queue, qname, 1);
 269 }
 270 EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
 271
 272 void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
 273 {
 274         del_timer_sync(&queue->timer_list.timer);
 275 }
 276 EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
 277
 278 static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode)
 279 {
 280         freezable_schedule_unsafe();
 281         if (signal_pending_state(mode, current))
 282                 return -ERESTARTSYS;
 283         return 0;
 284 }
 285
 286 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) || IS_ENABLED(CONFIG_TRACEPOINTS)
 287 static void rpc_task_set_debuginfo(struct rpc_task *task)
 288 {
 289         static atomic_t rpc_pid;
 290
 291         task->tk_pid = atomic_inc_return(&rpc_pid);
 292 }
 293 #else
 294 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
 295 {
 296 }
 297 #endif
 298
 299 static void rpc_set_active(struct rpc_task *task)
 300 {
 301         rpc_task_set_debuginfo(task);
 302         set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 303         trace_rpc_task_begin(task, NULL);
 304 }
 305
 306 /*
 307  * Mark an RPC call as having completed by clearing the 'active' bit
 308  * and then waking up all tasks that were sleeping.
 309  */
 310 static int rpc_complete_task(struct rpc_task *task)
 311 {
 312         void *m = &task->tk_runstate;
 313         wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
 314         struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
 315         unsigned long flags;
 316         int ret;
 317
 318         trace_rpc_task_complete(task, NULL);
 319
 320         spin_lock_irqsave(&wq->lock, flags);
 321         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 322         ret = atomic_dec_and_test(&task->tk_count);
 323         if (waitqueue_active(wq))
 324                 __wake_up_locked_key(wq, TASK_NORMAL, &k);
 325         spin_unlock_irqrestore(&wq->lock, flags);
 326         return ret;
 327 }
 328
 329 /*
 330  * Allow callers to wait for completion of an RPC call
 331  *
 332  * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
 333  * to enforce taking of the wq->lock and hence avoid races with
 334  * rpc_complete_task().
 335  */
 336 int __rpc_wait_for_completion_task(struct rpc_task *task, wait_bit_action_f *action)
 337 {
 338         if (action == NULL)
 339                 action = rpc_wait_bit_killable;
 340         return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 341                         action, TASK_KILLABLE);
 342 }
 343 EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
 344
 345 /*
 346  * Make an RPC task runnable.
 347  *
 348  * Note: If the task is ASYNC, and is being made runnable after sitting on an
 349  * rpc_wait_queue, this must be called with the queue spinlock held to protect
 350  * the wait queue operation.
 351  * Note the ordering of rpc_test_and_set_running() and rpc_clear_queued(),
 352  * which is needed to ensure that __rpc_execute() doesn't loop (due to the
 353  * lockless RPC_IS_QUEUED() test) before we've had a chance to test
 354  * the RPC_TASK_RUNNING flag.
 355  */
 356 static void rpc_make_runnable(struct workqueue_struct *wq,
 357                 struct rpc_task *task)
 358 {
 359         bool need_wakeup = !rpc_test_and_set_running(task);
 360
 361         rpc_clear_queued(task);
 362         if (!need_wakeup)
 363                 return;
 364         if (RPC_IS_ASYNC(task)) {
 365                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
 366                 queue_work(wq, &task->u.tk_work);
 367         } else
 368                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 369 }
 370
 371 /*
 372  * Prepare for sleeping on a wait queue.
 373  * By always appending tasks to the list we ensure FIFO behavior.
 374  * NB: An RPC task will only receive interrupt-driven events as long
 375  * as it's on a wait queue.
 376  */
 377 static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
 378                 struct rpc_task *task,
 379                 unsigned char queue_priority)
 380 {
 381         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
 382                         task->tk_pid, rpc_qname(q), jiffies);
 383
 384         trace_rpc_task_sleep(task, q);
 385
 386         __rpc_add_wait_queue(q, task, queue_priority);
 387
 388 }
 389
 390 static void __rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
 391                 struct rpc_task *task, unsigned long timeout,
 392                 unsigned char queue_priority)
 393 {
 394         if (time_is_after_jiffies(timeout)) {
 395                 __rpc_sleep_on_priority(q, task, queue_priority);
 396                 __rpc_add_timer(q, task, timeout);
 397         } else
 398                 task->tk_status = -ETIMEDOUT;
 399 }
 400
 401 static void rpc_set_tk_callback(struct rpc_task *task, rpc_action action)
 402 {
 403         if (action && !WARN_ON_ONCE(task->tk_callback != NULL))
 404                 task->tk_callback = action;
 405 }
 406
 407 static bool rpc_sleep_check_activated(struct rpc_task *task)
 408 {
 409         /* We shouldn't ever put an inactive task to sleep */
 410         if (WARN_ON_ONCE(!RPC_IS_ACTIVATED(task))) {
 411                 task->tk_status = -EIO;
 412                 rpc_put_task_async(task);
 413                 return false;
 414         }
 415         return true;
 416 }
 417
 418 void rpc_sleep_on_timeout(struct rpc_wait_queue *q, struct rpc_task *task,
 419                                 rpc_action action, unsigned long timeout)
 420 {
 421         if (!rpc_sleep_check_activated(task))
 422                 return;
 423
 424         rpc_set_tk_callback(task, action);
 425
 426         /*
 427          * Protect the queue operations.
 428          */
 429         spin_lock_bh(&q->lock);
 430         __rpc_sleep_on_priority_timeout(q, task, timeout, task->tk_priority);
 431         spin_unlock_bh(&q->lock);
 432 }
 433 EXPORT_SYMBOL_GPL(rpc_sleep_on_timeout);
 434
 435 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 436                                 rpc_action action)
 437 {
 438         if (!rpc_sleep_check_activated(task))
 439                 return;
 440
 441         rpc_set_tk_callback(task, action);
 442
 443         WARN_ON_ONCE(task->tk_timeout != 0);
 444         /*
 445          * Protect the queue operations.
 446          */
 447         spin_lock_bh(&q->lock);
 448         __rpc_sleep_on_priority(q, task, task->tk_priority);
 449         spin_unlock_bh(&q->lock);
 450 }
 451 EXPORT_SYMBOL_GPL(rpc_sleep_on);
 452
 453 void rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
 454                 struct rpc_task *task, unsigned long timeout, int priority)
 455 {
 456         if (!rpc_sleep_check_activated(task))
 457                 return;
 458
 459         priority -= RPC_PRIORITY_LOW;
 460         /*
 461          * Protect the queue operations.
 462          */
 463         spin_lock_bh(&q->lock);
 464         __rpc_sleep_on_priority_timeout(q, task, timeout, priority);
 465         spin_unlock_bh(&q->lock);
 466 }
 467 EXPORT_SYMBOL_GPL(rpc_sleep_on_priority_timeout);
 468
 469 void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
 470                 int priority)
 471 {
 472         if (!rpc_sleep_check_activated(task))
 473                 return;
 474
 475         WARN_ON_ONCE(task->tk_timeout != 0);
 476         priority -= RPC_PRIORITY_LOW;
 477         /*
 478          * Protect the queue operations.
 479          */
 480         spin_lock_bh(&q->lock);
 481         __rpc_sleep_on_priority(q, task, priority);
 482         spin_unlock_bh(&q->lock);
 483 }
 484 EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
 485
 486 /**
 487  * __rpc_do_wake_up_task_on_wq - wake up a single rpc_task
 488  * @wq: workqueue on which to run task
 489  * @queue: wait queue
 490  * @task: task to be woken up
 491  *
 492  * Caller must hold queue->lock, and have cleared the task queued flag.
 493  */
 494 static void __rpc_do_wake_up_task_on_wq(struct workqueue_struct *wq,
 495                 struct rpc_wait_queue *queue,
 496                 struct rpc_task *task)
 497 {
 498         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
 499                         task->tk_pid, jiffies);
 500
 501         /* Has the task been executed yet? If not, we cannot wake it up! */
 502         if (!RPC_IS_ACTIVATED(task)) {
 503                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 504                 return;
 505         }
 506
 507         trace_rpc_task_wakeup(task, queue);
 508
 509         __rpc_remove_wait_queue(queue, task);
 510
 511         rpc_make_runnable(wq, task);
 512
 513         dprintk("RPC:       __rpc_wake_up_task done\n");
 514 }
 515
 516 /*
 517  * Wake up a queued task while the queue lock is being held
 518  */
 519 static struct rpc_task *
 520 rpc_wake_up_task_on_wq_queue_action_locked(struct workqueue_struct *wq,
 521                 struct rpc_wait_queue *queue, struct rpc_task *task,
 522                 bool (*action)(struct rpc_task *, void *), void *data)
 523 {
 524         if (RPC_IS_QUEUED(task)) {
 525                 smp_rmb();
 526                 if (task->tk_waitqueue == queue) {
 527                         if (action == NULL || action(task, data)) {
 528                                 __rpc_do_wake_up_task_on_wq(wq, queue, task);
 529                                 return task;
 530                         }
 531                 }
 532         }
 533         return NULL;
 534 }
 535
 536 static void
 537 rpc_wake_up_task_on_wq_queue_locked(struct workqueue_struct *wq,
 538                 struct rpc_wait_queue *queue, struct rpc_task *task)
 539 {
 540         rpc_wake_up_task_on_wq_queue_action_locked(wq, queue, task, NULL, NULL);
 541 }
 542
 543 /*
 544  * Wake up a queued task while the queue lock is being held
 545  */
 546 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
 547 {
 548         rpc_wake_up_task_on_wq_queue_locked(rpciod_workqueue, queue, task);
 549 }
 550
 551 /*
 552  * Wake up a task on a specific queue
 553  */
 554 void rpc_wake_up_queued_task_on_wq(struct workqueue_struct *wq,
 555                 struct rpc_wait_queue *queue,
 556                 struct rpc_task *task)
 557 {
 558         if (!RPC_IS_QUEUED(task))
 559                 return;
 560         spin_lock_bh(&queue->lock);
 561         rpc_wake_up_task_on_wq_queue_locked(wq, queue, task);
 562         spin_unlock_bh(&queue->lock);
 563 }
 564
 565 /*
 566  * Wake up a task on a specific queue
 567  */
 568 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 569 {
 570         if (!RPC_IS_QUEUED(task))
 571                 return;
 572         spin_lock_bh(&queue->lock);
 573         rpc_wake_up_task_queue_locked(queue, task);
 574         spin_unlock_bh(&queue->lock);
 575 }
 576 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
 577
 578 static bool rpc_task_action_set_status(struct rpc_task *task, void *status)
 579 {
 580         task->tk_status = *(int *)status;
 581         return true;
 582 }
 583
 584 static void
 585 rpc_wake_up_task_queue_set_status_locked(struct rpc_wait_queue *queue,
 586                 struct rpc_task *task, int status)
 587 {
 588         rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
 589                         task, rpc_task_action_set_status, &status);
 590 }
 591
 592 /**
 593  * rpc_wake_up_queued_task_set_status - wake up a task and set task->tk_status
 594  * @queue: pointer to rpc_wait_queue
 595  * @task: pointer to rpc_task
 596  * @status: integer error value
 597  *
 598  * If @task is queued on @queue, then it is woken up, and @task->tk_status is
 599  * set to the value of @status.
 600  */
 601 void
 602 rpc_wake_up_queued_task_set_status(struct rpc_wait_queue *queue,
 603                 struct rpc_task *task, int status)
 604 {
 605         if (!RPC_IS_QUEUED(task))
 606                 return;
 607         spin_lock_bh(&queue->lock);
 608         rpc_wake_up_task_queue_set_status_locked(queue, task, status);
 609         spin_unlock_bh(&queue->lock);
 610 }
 611
 612 /*
 613  * Wake up the next task on a priority queue.
 614  */
 615 static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
 616 {
 617         struct list_head *q;
 618         struct rpc_task *task;
 619
 620         /*
 621          * Service a batch of tasks from a single owner.
 622          */
 623         q = &queue->tasks[queue->priority];
 624         if (!list_empty(q) && --queue->nr) {
 625                 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
 626                 goto out;
 627         }
 628
 629         /*
 630          * Service the next queue.
 631          */
 632         do {
 633                 if (q == &queue->tasks[0])
 634                         q = &queue->tasks[queue->maxpriority];
 635                 else
 636                         q = q - 1;
 637                 if (!list_empty(q)) {
 638                         task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
 639                         goto new_queue;
 640                 }
 641         } while (q != &queue->tasks[queue->priority]);
 642
 643         rpc_reset_waitqueue_priority(queue);
 644         return NULL;
 645
 646 new_queue:
 647         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 648 out:
 649         return task;
 650 }
 651
 652 static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
 653 {
 654         if (RPC_IS_PRIORITY(queue))
 655                 return __rpc_find_next_queued_priority(queue);
 656         if (!list_empty(&queue->tasks[0]))
 657                 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
 658         return NULL;
 659 }
 660
 661 /*
 662  * Wake up the first task on the wait queue.
 663  */
 664 struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq,
 665                 struct rpc_wait_queue *queue,
 666                 bool (*func)(struct rpc_task *, void *), void *data)
 667 {
 668         struct rpc_task *task = NULL;
 669
 670         dprintk("RPC:       wake_up_first(%p \"%s\")\n",
 671                         queue, rpc_qname(queue));
 672         spin_lock_bh(&queue->lock);
 673         task = __rpc_find_next_queued(queue);
 674         if (task != NULL)
 675                 task = rpc_wake_up_task_on_wq_queue_action_locked(wq, queue,
 676                                 task, func, data);
 677         spin_unlock_bh(&queue->lock);
 678
 679         return task;
 680 }
 681
 682 /*
 683  * Wake up the first task on the wait queue.
 684  */
 685 struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
 686                 bool (*func)(struct rpc_task *, void *), void *data)
 687 {
 688         return rpc_wake_up_first_on_wq(rpciod_workqueue, queue, func, data);
 689 }
 690 EXPORT_SYMBOL_GPL(rpc_wake_up_first);
 691
 692 static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
 693 {
 694         return true;
 695 }
 696
 697 /*
 698  * Wake up the next task on the wait queue.
 699 */
 700 struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
 701 {
 702         return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
 703 }
 704 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
 705
 706 /**
 707  * rpc_wake_up - wake up all rpc_tasks
 708  * @queue: rpc_wait_queue on which the tasks are sleeping
 709  *
 710  * Grabs queue->lock
 711  */
 712 void rpc_wake_up(struct rpc_wait_queue *queue)
 713 {
 714         struct list_head *head;
 715
 716         spin_lock_bh(&queue->lock);
 717         head = &queue->tasks[queue->maxpriority];
 718         for (;;) {
 719                 while (!list_empty(head)) {
 720                         struct rpc_task *task;
 721                         task = list_first_entry(head,
 722                                         struct rpc_task,
 723                                         u.tk_wait.list);
 724                         rpc_wake_up_task_queue_locked(queue, task);
 725                 }
 726                 if (head == &queue->tasks[0])
 727                         break;
 728                 head--;
 729         }
 730         spin_unlock_bh(&queue->lock);
 731 }
 732 EXPORT_SYMBOL_GPL(rpc_wake_up);
 733
 734 /**
 735  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 736  * @queue: rpc_wait_queue on which the tasks are sleeping
 737  * @status: status value to set
 738  *
 739  * Grabs queue->lock
 740  */
 741 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 742 {
 743         struct list_head *head;
 744
 745         spin_lock_bh(&queue->lock);
 746         head = &queue->tasks[queue->maxpriority];
 747         for (;;) {
 748                 while (!list_empty(head)) {
 749                         struct rpc_task *task;
 750                         task = list_first_entry(head,
 751                                         struct rpc_task,
 752                                         u.tk_wait.list);
 753                         task->tk_status = status;
 754                         rpc_wake_up_task_queue_locked(queue, task);
 755                 }
 756                 if (head == &queue->tasks[0])
 757                         break;
 758                 head--;
 759         }
 760         spin_unlock_bh(&queue->lock);
 761 }
 762 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
 763
 764 static void __rpc_queue_timer_fn(struct timer_list *t)
 765 {
 766         struct rpc_wait_queue *queue = from_timer(queue, t, timer_list.timer);
 767         struct rpc_task *task, *n;
 768         unsigned long expires, now, timeo;
 769
 770         spin_lock(&queue->lock);
 771         expires = now = jiffies;
 772         list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
 773                 timeo = task->tk_timeout;
 774                 if (time_after_eq(now, timeo)) {
 775                         dprintk("RPC: %5u timeout\n", task->tk_pid);
 776                         task->tk_status = -ETIMEDOUT;
 777                         rpc_wake_up_task_queue_locked(queue, task);
 778                         continue;
 779                 }
 780                 if (expires == now || time_after(expires, timeo))
 781                         expires = timeo;
 782         }
 783         if (!list_empty(&queue->timer_list.list))
 784                 rpc_set_queue_timer(queue, expires);
 785         spin_unlock(&queue->lock);
 786 }
 787
 788 static void __rpc_atrun(struct rpc_task *task)
 789 {
 790         if (task->tk_status == -ETIMEDOUT)
 791                 task->tk_status = 0;
 792 }
 793
 794 /*
 795  * Run a task at a later time
 796  */
 797 void rpc_delay(struct rpc_task *task, unsigned long delay)
 798 {
 799         rpc_sleep_on_timeout(&delay_queue, task, __rpc_atrun, jiffies + delay);
 800 }
 801 EXPORT_SYMBOL_GPL(rpc_delay);
 802
 803 /*
 804  * Helper to call task->tk_ops->rpc_call_prepare
 805  */
 806 void rpc_prepare_task(struct rpc_task *task)
 807 {
 808         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 809 }
 810
 811 static void
 812 rpc_init_task_statistics(struct rpc_task *task)
 813 {
 814         /* Initialize retry counters */
 815         task->tk_garb_retry = 2;
 816         task->tk_cred_retry = 2;
 817         task->tk_rebind_retry = 2;
 818
 819         /* starting timestamp */
 820         task->tk_start = ktime_get();
 821 }
 822
 823 static void
 824 rpc_reset_task_statistics(struct rpc_task *task)
 825 {
 826         task->tk_timeouts = 0;
 827         task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_SENT);
 828         rpc_init_task_statistics(task);
 829 }
 830
 831 /*
 832  * Helper that calls task->tk_ops->rpc_call_done if it exists
 833  */
 834 void rpc_exit_task(struct rpc_task *task)
 835 {
 836         task->tk_action = NULL;
 837         if (task->tk_ops->rpc_call_done != NULL) {
 838                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
 839                 if (task->tk_action != NULL) {
 840                         /* Always release the RPC slot and buffer memory */
 841                         xprt_release(task);
 842                         rpc_reset_task_statistics(task);
 843                 }
 844         }
 845 }
 846
 847 void rpc_signal_task(struct rpc_task *task)
 848 {
 849         struct rpc_wait_queue *queue;
 850
 851         if (!RPC_IS_ACTIVATED(task))
 852                 return;
 853         set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
 854         smp_mb__after_atomic();
 855         queue = READ_ONCE(task->tk_waitqueue);
 856         if (queue)
 857                 rpc_wake_up_queued_task_set_status(queue, task, -ERESTARTSYS);
 858 }
 859
 860 void rpc_exit(struct rpc_task *task, int status)
 861 {
 862         task->tk_status = status;
 863         task->tk_action = rpc_exit_task;
 864         rpc_wake_up_queued_task(task->tk_waitqueue, task);
 865 }
 866 EXPORT_SYMBOL_GPL(rpc_exit);
 867
 868 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
 869 {
 870         if (ops->rpc_release != NULL)
 871                 ops->rpc_release(calldata);
 872 }
 873
 874 /*
 875  * This is the RPC `scheduler' (or rather, the finite state machine).
 876  */
 877 static void __rpc_execute(struct rpc_task *task)
 878 {
 879         struct rpc_wait_queue *queue;
 880         int task_is_async = RPC_IS_ASYNC(task);
 881         int status = 0;
 882
 883         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
 884                         task->tk_pid, task->tk_flags);
 885
 886         WARN_ON_ONCE(RPC_IS_QUEUED(task));
 887         if (RPC_IS_QUEUED(task))
 888                 return;
 889
 890         for (;;) {
 891                 void (*do_action)(struct rpc_task *);
 892
 893                 /*
 894                  * Perform the next FSM step or a pending callback.
 895                  *
 896                  * tk_action may be NULL if the task has been killed.
 897                  * In particular, note that rpc_killall_tasks may
 898                  * do this at any time, so beware when dereferencing.
 899                  */
 900                 do_action = task->tk_action;
 901                 if (task->tk_callback) {
 902                         do_action = task->tk_callback;
 903                         task->tk_callback = NULL;
 904                 }
 905                 if (!do_action)
 906                         break;
 907                 trace_rpc_task_run_action(task, do_action);
 908                 do_action(task);
 909
 910                 /*
 911                  * Lockless check for whether task is sleeping or not.
 912                  */
 913                 if (!RPC_IS_QUEUED(task))
 914                         continue;
 915
 916                 /*
 917                  * Signalled tasks should exit rather than sleep.
 918                  */
 919                 if (RPC_SIGNALLED(task))
 920                         rpc_exit(task, -ERESTARTSYS);
 921
 922                 /*
 923                  * The queue->lock protects against races with
 924                  * rpc_make_runnable().
 925                  *
 926                  * Note that once we clear RPC_TASK_RUNNING on an asynchronous
 927                  * rpc_task, rpc_make_runnable() can assign it to a
 928                  * different workqueue. We therefore cannot assume that the
 929                  * rpc_task pointer may still be dereferenced.
 930                  */
 931                 queue = task->tk_waitqueue;
 932                 spin_lock_bh(&queue->lock);
 933                 if (!RPC_IS_QUEUED(task)) {
 934                         spin_unlock_bh(&queue->lock);
 935                         continue;
 936                 }
 937                 rpc_clear_running(task);
 938                 spin_unlock_bh(&queue->lock);
 939                 if (task_is_async)
 940                         return;
 941
 942                 /* sync task: sleep here */
 943                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
 944                 status = out_of_line_wait_on_bit(&task->tk_runstate,
 945                                 RPC_TASK_QUEUED, rpc_wait_bit_killable,
 946                                 TASK_KILLABLE);
 947                 if (status < 0) {
 948                         /*
 949                          * When a sync task receives a signal, it exits with
 950                          * -ERESTARTSYS. In order to catch any callbacks that
 951                          * clean up after sleeping on some queue, we don't
 952                          * break the loop here, but go around once more.
 953                          */
 954                         dprintk("RPC: %5u got signal\n", task->tk_pid);
 955                         set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
 956                         rpc_exit(task, -ERESTARTSYS);
 957                 }
 958                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
 959         }
 960
 961         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
 962                         task->tk_status);
 963         /* Release all resources associated with the task */
 964         rpc_release_task(task);
 965 }
 966
 967 /*
 968  * User-visible entry point to the scheduler.
 969  *
 970  * This may be called recursively if e.g. an async NFS task updates
 971  * the attributes and finds that dirty pages must be flushed.
 972  * NOTE: Upon exit of this function the task is guaranteed to be
 973  *       released. In particular note that tk_release() will have
 974  *       been called, so your task memory may have been freed.
 975  */
 976 void rpc_execute(struct rpc_task *task)
 977 {
 978         bool is_async = RPC_IS_ASYNC(task);
 979
 980         rpc_set_active(task);
 981         rpc_make_runnable(rpciod_workqueue, task);
 982         if (!is_async)
 983                 __rpc_execute(task);
 984 }
 985
 986 static void rpc_async_schedule(struct work_struct *work)
 987 {
 988         unsigned int pflags = memalloc_nofs_save();
 989
 990         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
 991         memalloc_nofs_restore(pflags);
 992 }
 993
 994 /**
 995  * rpc_malloc - allocate RPC buffer resources
 996  * @task: RPC task
 997  *
 998  * A single memory region is allocated, which is split between the
 999  * RPC call and RPC reply that this task is being used for. When
1000  * this RPC is retired, the memory is released by calling rpc_free.
1001  *
1002  * To prevent rpciod from hanging, this allocator never sleeps,
1003  * returning -ENOMEM and suppressing warning if the request cannot
1004  * be serviced immediately. The caller can arrange to sleep in a
1005  * way that is safe for rpciod.
1006  *
1007  * Most requests are 'small' (under 2KiB) and can be serviced from a
1008  * mempool, ensuring that NFS reads and writes can always proceed,
1009  * and that there is good locality of reference for these buffers.
1010  */
1011 int rpc_malloc(struct rpc_task *task)
1012 {
1013         struct rpc_rqst *rqst = task->tk_rqstp;
1014         size_t size = rqst->rq_callsize + rqst->rq_rcvsize;
1015         struct rpc_buffer *buf;
1016         gfp_t gfp = GFP_NOFS;
1017
1018         if (RPC_IS_SWAPPER(task))
1019                 gfp = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN;
1020
1021         size += sizeof(struct rpc_buffer);
1022         if (size <= RPC_BUFFER_MAXSIZE)
1023                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
1024         else
1025                 buf = kmalloc(size, gfp);
1026
1027         if (!buf)
1028                 return -ENOMEM;
1029
1030         buf->len = size;
1031         dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
1032                         task->tk_pid, size, buf);
1033         rqst->rq_buffer = buf->data;
1034         rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_callsize;
1035         return 0;
1036 }
1037 EXPORT_SYMBOL_GPL(rpc_malloc);
1038
1039 /**
1040  * rpc_free - free RPC buffer resources allocated via rpc_malloc
1041  * @task: RPC task
1042  *
1043  */
1044 void rpc_free(struct rpc_task *task)
1045 {
1046         void *buffer = task->tk_rqstp->rq_buffer;
1047         size_t size;
1048         struct rpc_buffer *buf;
1049
1050         buf = container_of(buffer, struct rpc_buffer, data);
1051         size = buf->len;
1052
1053         dprintk("RPC:       freeing buffer of size %zu at %p\n",
1054                         size, buf);
1055
1056         if (size <= RPC_BUFFER_MAXSIZE)
1057                 mempool_free(buf, rpc_buffer_mempool);
1058         else
1059                 kfree(buf);
1060 }
1061 EXPORT_SYMBOL_GPL(rpc_free);
1062
1063 /*
1064  * Creation and deletion of RPC task structures
1065  */
1066 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
1067 {
1068         memset(task, 0, sizeof(*task));
1069         atomic_set(&task->tk_count, 1);
1070         task->tk_flags  = task_setup_data->flags;
1071         task->tk_ops = task_setup_data->callback_ops;
1072         task->tk_calldata = task_setup_data->callback_data;
1073         INIT_LIST_HEAD(&task->tk_task);
1074
1075         task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
1076         task->tk_owner = current->tgid;
1077
1078         /* Initialize workqueue for async tasks */
1079         task->tk_workqueue = task_setup_data->workqueue;
1080
1081         task->tk_xprt = xprt_get(task_setup_data->rpc_xprt);
1082
1083         task->tk_op_cred = get_rpccred(task_setup_data->rpc_op_cred);
1084
1085         if (task->tk_ops->rpc_call_prepare != NULL)
1086                 task->tk_action = rpc_prepare_task;
1087
1088         rpc_init_task_statistics(task);
1089
1090         dprintk("RPC:       new task initialized, procpid %u\n",
1091                                 task_pid_nr(current));
1092 }
1093
1094 static struct rpc_task *
1095 rpc_alloc_task(void)
1096 {
1097         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
1098 }
1099
1100 /*
1101  * Create a new task for the specified client.
1102  */
1103 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
1104 {
1105         struct rpc_task *task = setup_data->task;
1106         unsigned short flags = 0;
1107
1108         if (task == NULL) {
1109                 task = rpc_alloc_task();
1110                 flags = RPC_TASK_DYNAMIC;
1111         }
1112
1113         rpc_init_task(task, setup_data);
1114         task->tk_flags |= flags;
1115         dprintk("RPC:       allocated task %p\n", task);
1116         return task;
1117 }
1118
1119 /*
1120  * rpc_free_task - release rpc task and perform cleanups
1121  *
1122  * Note that we free up the rpc_task _after_ rpc_release_calldata()
1123  * in order to work around a workqueue dependency issue.
1124  *
1125  * Tejun Heo states:
1126  * "Workqueue currently considers two work items to be the same if they're
1127  * on the same address and won't execute them concurrently - ie. it
1128  * makes a work item which is queued again while being executed wait
1129  * for the previous execution to complete.
1130  *
1131  * If a work function frees the work item, and then waits for an event
1132  * which should be performed by another work item and *that* work item
1133  * recycles the freed work item, it can create a false dependency loop.
1134  * There really is no reliable way to detect this short of verifying
1135  * every memory free."
1136  *
1137  */
1138 static void rpc_free_task(struct rpc_task *task)
1139 {
1140         unsigned short tk_flags = task->tk_flags;
1141
1142         put_rpccred(task->tk_op_cred);
1143         rpc_release_calldata(task->tk_ops, task->tk_calldata);
1144
1145         if (tk_flags & RPC_TASK_DYNAMIC) {
1146                 dprintk("RPC: %5u freeing task\n", task->tk_pid);
1147                 mempool_free(task, rpc_task_mempool);
1148         }
1149 }
1150
1151 static void rpc_async_release(struct work_struct *work)
1152 {
1153         unsigned int pflags = memalloc_nofs_save();
1154
1155         rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
1156         memalloc_nofs_restore(pflags);
1157 }
1158
1159 static void rpc_release_resources_task(struct rpc_task *task)
1160 {
1161         xprt_release(task);
1162         if (task->tk_msg.rpc_cred) {
1163                 put_cred(task->tk_msg.rpc_cred);
1164                 task->tk_msg.rpc_cred = NULL;
1165         }
1166         rpc_task_release_client(task);
1167 }
1168
1169 static void rpc_final_put_task(struct rpc_task *task,
1170                 struct workqueue_struct *q)
1171 {
1172         if (q != NULL) {
1173                 INIT_WORK(&task->u.tk_work, rpc_async_release);
1174                 queue_work(q, &task->u.tk_work);
1175         } else
1176                 rpc_free_task(task);
1177 }
1178
1179 static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1180 {
1181         if (atomic_dec_and_test(&task->tk_count)) {
1182                 rpc_release_resources_task(task);
1183                 rpc_final_put_task(task, q);
1184         }
1185 }
1186
1187 void rpc_put_task(struct rpc_task *task)
1188 {
1189         rpc_do_put_task(task, NULL);
1190 }
1191 EXPORT_SYMBOL_GPL(rpc_put_task);
1192
1193 void rpc_put_task_async(struct rpc_task *task)
1194 {
1195         rpc_do_put_task(task, task->tk_workqueue);
1196 }
1197 EXPORT_SYMBOL_GPL(rpc_put_task_async);
1198
1199 static void rpc_release_task(struct rpc_task *task)
1200 {
1201         dprintk("RPC: %5u release task\n", task->tk_pid);
1202
1203         WARN_ON_ONCE(RPC_IS_QUEUED(task));
1204
1205         rpc_release_resources_task(task);
1206
1207         /*
1208          * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1209          * so it should be safe to use task->tk_count as a test for whether
1210          * or not any other processes still hold references to our rpc_task.
1211          */
1212         if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1213                 /* Wake up anyone who may be waiting for task completion */
1214                 if (!rpc_complete_task(task))
1215                         return;
1216         } else {
1217                 if (!atomic_dec_and_test(&task->tk_count))
1218                         return;
1219         }
1220         rpc_final_put_task(task, task->tk_workqueue);
1221 }
1222
1223 int rpciod_up(void)
1224 {
1225         return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1226 }
1227
1228 void rpciod_down(void)
1229 {
1230         module_put(THIS_MODULE);
1231 }
1232
1233 /*
1234  * Start up the rpciod workqueue.
1235  */
1236 static int rpciod_start(void)
1237 {
1238         struct workqueue_struct *wq;
1239
1240         /*
1241          * Create the rpciod thread and wait for it to start.
1242          */
1243         dprintk("RPC:       creating workqueue rpciod\n");
1244         wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
1245         if (!wq)
1246                 goto out_failed;
1247         rpciod_workqueue = wq;
1248         /* Note: highpri because network receive is latency sensitive */
1249         wq = alloc_workqueue("xprtiod", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_HIGHPRI, 0);
1250         if (!wq)
1251                 goto free_rpciod;
1252         xprtiod_workqueue = wq;
1253         return 1;
1254 free_rpciod:
1255         wq = rpciod_workqueue;
1256         rpciod_workqueue = NULL;
1257         destroy_workqueue(wq);
1258 out_failed:
1259         return 0;
1260 }
1261
1262 static void rpciod_stop(void)
1263 {
1264         struct workqueue_struct *wq = NULL;
1265
1266         if (rpciod_workqueue == NULL)
1267                 return;
1268         dprintk("RPC:       destroying workqueue rpciod\n");
1269
1270         wq = rpciod_workqueue;
1271         rpciod_workqueue = NULL;
1272         destroy_workqueue(wq);
1273         wq = xprtiod_workqueue;
1274         xprtiod_workqueue = NULL;
1275         destroy_workqueue(wq);
1276 }
1277
1278 void
1279 rpc_destroy_mempool(void)
1280 {
1281         rpciod_stop();
1282         mempool_destroy(rpc_buffer_mempool);
1283         mempool_destroy(rpc_task_mempool);
1284         kmem_cache_destroy(rpc_task_slabp);
1285         kmem_cache_destroy(rpc_buffer_slabp);
1286         rpc_destroy_wait_queue(&delay_queue);
1287 }
1288
1289 int
1290 rpc_init_mempool(void)
1291 {
1292         /*
1293          * The following is not strictly a mempool initialisation,
1294          * but there is no harm in doing it here
1295          */
1296         rpc_init_wait_queue(&delay_queue, "delayq");
1297         if (!rpciod_start())
1298                 goto err_nomem;
1299
1300         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1301                                              sizeof(struct rpc_task),
1302                                              0, SLAB_HWCACHE_ALIGN,
1303                                              NULL);
1304         if (!rpc_task_slabp)
1305                 goto err_nomem;
1306         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1307                                              RPC_BUFFER_MAXSIZE,
1308                                              0, SLAB_HWCACHE_ALIGN,
1309                                              NULL);
1310         if (!rpc_buffer_slabp)
1311                 goto err_nomem;
1312         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1313                                                     rpc_task_slabp);
1314         if (!rpc_task_mempool)
1315                 goto err_nomem;
1316         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1317                                                       rpc_buffer_slabp);
1318         if (!rpc_buffer_mempool)
1319                 goto err_nomem;
1320         return 0;
1321 err_nomem:
1322         rpc_destroy_mempool();
1323         return -ENOMEM;
1324 }