net/sunrpc/sched.c

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