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
  23 #include <linux/sunrpc/clnt.h>
  24
  25 #include "sunrpc.h"
  26
  27 #ifdef RPC_DEBUG
  28 #define RPCDBG_FACILITY         RPCDBG_SCHED
  29 #endif
  30
  31 /*
  32  * RPC slabs and memory pools
  33  */
  34 #define RPC_BUFFER_MAXSIZE      (2048)
  35 #define RPC_BUFFER_POOLSIZE     (8)
  36 #define RPC_TASK_POOLSIZE       (8)
  37 static struct kmem_cache        *rpc_task_slabp __read_mostly;
  38 static struct kmem_cache        *rpc_buffer_slabp __read_mostly;
  39 static mempool_t        *rpc_task_mempool __read_mostly;
  40 static mempool_t        *rpc_buffer_mempool __read_mostly;
  41
  42 static void                     rpc_async_schedule(struct work_struct *);
  43 static void                      rpc_release_task(struct rpc_task *task);
  44 static void __rpc_queue_timer_fn(unsigned long ptr);
  45
  46 /*
  47  * RPC tasks sit here while waiting for conditions to improve.
  48  */
  49 static struct rpc_wait_queue delay_queue;
  50
  51 /*
  52  * rpciod-related stuff
  53  */
  54 struct workqueue_struct *rpciod_workqueue;
  55
  56 /*
  57  * Disable the timer for a given RPC task. Should be called with
  58  * queue->lock and bh_disabled in order to avoid races within
  59  * rpc_run_timer().
  60  */
  61 static void
  62 __rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
  63 {
  64         if (task->tk_timeout == 0)
  65                 return;
  66         dprintk("RPC: %5u disabling timer\n", task->tk_pid);
  67         task->tk_timeout = 0;
  68         list_del(&task->u.tk_wait.timer_list);
  69         if (list_empty(&queue->timer_list.list))
  70                 del_timer(&queue->timer_list.timer);
  71 }
  72
  73 static void
  74 rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
  75 {
  76         queue->timer_list.expires = expires;
  77         mod_timer(&queue->timer_list.timer, expires);
  78 }
  79
  80 /*
  81  * Set up a timer for the current task.
  82  */
  83 static void
  84 __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
  85 {
  86         if (!task->tk_timeout)
  87                 return;
  88
  89         dprintk("RPC: %5u setting alarm for %lu ms\n",
  90                         task->tk_pid, task->tk_timeout * 1000 / HZ);
  91
  92         task->u.tk_wait.expires = jiffies + task->tk_timeout;
  93         if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
  94                 rpc_set_queue_timer(queue, task->u.tk_wait.expires);
  95         list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
  96 }
  97
  98 /*
  99  * Add new request to a priority queue.
 100  */
 101 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
 102                 struct rpc_task *task,
 103                 unsigned char queue_priority)
 104 {
 105         struct list_head *q;
 106         struct rpc_task *t;
 107
 108         INIT_LIST_HEAD(&task->u.tk_wait.links);
 109         q = &queue->tasks[queue_priority];
 110         if (unlikely(queue_priority > queue->maxpriority))
 111                 q = &queue->tasks[queue->maxpriority];
 112         list_for_each_entry(t, q, u.tk_wait.list) {
 113                 if (t->tk_owner == task->tk_owner) {
 114                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
 115                         return;
 116                 }
 117         }
 118         list_add_tail(&task->u.tk_wait.list, q);
 119 }
 120
 121 /*
 122  * Add new request to wait queue.
 123  *
 124  * Swapper tasks always get inserted at the head of the queue.
 125  * This should avoid many nasty memory deadlocks and hopefully
 126  * improve overall performance.
 127  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
 128  */
 129 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
 130                 struct rpc_task *task,
 131                 unsigned char queue_priority)
 132 {
 133         BUG_ON (RPC_IS_QUEUED(task));
 134
 135         if (RPC_IS_PRIORITY(queue))
 136                 __rpc_add_wait_queue_priority(queue, task, queue_priority);
 137         else if (RPC_IS_SWAPPER(task))
 138                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
 139         else
 140                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
 141         task->tk_waitqueue = queue;
 142         queue->qlen++;
 143         rpc_set_queued(task);
 144
 145         dprintk("RPC: %5u added to queue %p \"%s\"\n",
 146                         task->tk_pid, queue, rpc_qname(queue));
 147 }
 148
 149 /*
 150  * Remove request from a priority queue.
 151  */
 152 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 153 {
 154         struct rpc_task *t;
 155
 156         if (!list_empty(&task->u.tk_wait.links)) {
 157                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
 158                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
 159                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
 160         }
 161 }
 162
 163 /*
 164  * Remove request from queue.
 165  * Note: must be called with spin lock held.
 166  */
 167 static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
 168 {
 169         __rpc_disable_timer(queue, task);
 170         if (RPC_IS_PRIORITY(queue))
 171                 __rpc_remove_wait_queue_priority(task);
 172         list_del(&task->u.tk_wait.list);
 173         queue->qlen--;
 174         dprintk("RPC: %5u removed from queue %p \"%s\"\n",
 175                         task->tk_pid, queue, rpc_qname(queue));
 176 }
 177
 178 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 179 {
 180         queue->priority = priority;
 181         queue->count = 1 << (priority * 2);
 182 }
 183
 184 static inline void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
 185 {
 186         queue->owner = pid;
 187         queue->nr = RPC_BATCH_COUNT;
 188 }
 189
 190 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 191 {
 192         rpc_set_waitqueue_priority(queue, queue->maxpriority);
 193         rpc_set_waitqueue_owner(queue, 0);
 194 }
 195
 196 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
 197 {
 198         int i;
 199
 200         spin_lock_init(&queue->lock);
 201         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 202                 INIT_LIST_HEAD(&queue->tasks[i]);
 203         queue->maxpriority = nr_queues - 1;
 204         rpc_reset_waitqueue_priority(queue);
 205         queue->qlen = 0;
 206         setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
 207         INIT_LIST_HEAD(&queue->timer_list.list);
 208 #ifdef RPC_DEBUG
 209         queue->name = qname;
 210 #endif
 211 }
 212
 213 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 214 {
 215         __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
 216 }
 217 EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
 218
 219 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 220 {
 221         __rpc_init_priority_wait_queue(queue, qname, 1);
 222 }
 223 EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
 224
 225 void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
 226 {
 227         del_timer_sync(&queue->timer_list.timer);
 228 }
 229 EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
 230
 231 static int rpc_wait_bit_killable(void *word)
 232 {
 233         if (fatal_signal_pending(current))
 234                 return -ERESTARTSYS;
 235         freezable_schedule();
 236         return 0;
 237 }
 238
 239 #ifdef RPC_DEBUG
 240 static void rpc_task_set_debuginfo(struct rpc_task *task)
 241 {
 242         static atomic_t rpc_pid;
 243
 244         task->tk_pid = atomic_inc_return(&rpc_pid);
 245 }
 246 #else
 247 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
 248 {
 249 }
 250 #endif
 251
 252 static void rpc_set_active(struct rpc_task *task)
 253 {
 254         rpc_task_set_debuginfo(task);
 255         set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 256 }
 257
 258 /*
 259  * Mark an RPC call as having completed by clearing the 'active' bit
 260  * and then waking up all tasks that were sleeping.
 261  */
 262 static int rpc_complete_task(struct rpc_task *task)
 263 {
 264         void *m = &task->tk_runstate;
 265         wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
 266         struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
 267         unsigned long flags;
 268         int ret;
 269
 270         spin_lock_irqsave(&wq->lock, flags);
 271         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 272         ret = atomic_dec_and_test(&task->tk_count);
 273         if (waitqueue_active(wq))
 274                 __wake_up_locked_key(wq, TASK_NORMAL, &k);
 275         spin_unlock_irqrestore(&wq->lock, flags);
 276         return ret;
 277 }
 278
 279 /*
 280  * Allow callers to wait for completion of an RPC call
 281  *
 282  * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
 283  * to enforce taking of the wq->lock and hence avoid races with
 284  * rpc_complete_task().
 285  */
 286 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
 287 {
 288         if (action == NULL)
 289                 action = rpc_wait_bit_killable;
 290         return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 291                         action, TASK_KILLABLE);
 292 }
 293 EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
 294
 295 /*
 296  * Make an RPC task runnable.
 297  *
 298  * Note: If the task is ASYNC, this must be called with
 299  * the spinlock held to protect the wait queue operation.
 300  */
 301 static void rpc_make_runnable(struct rpc_task *task)
 302 {
 303         rpc_clear_queued(task);
 304         if (rpc_test_and_set_running(task))
 305                 return;
 306         if (RPC_IS_ASYNC(task)) {
 307                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
 308                 queue_work(rpciod_workqueue, &task->u.tk_work);
 309         } else
 310                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 311 }
 312
 313 /*
 314  * Prepare for sleeping on a wait queue.
 315  * By always appending tasks to the list we ensure FIFO behavior.
 316  * NB: An RPC task will only receive interrupt-driven events as long
 317  * as it's on a wait queue.
 318  */
 319 static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
 320                 struct rpc_task *task,
 321                 rpc_action action,
 322                 unsigned char queue_priority)
 323 {
 324         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
 325                         task->tk_pid, rpc_qname(q), jiffies);
 326
 327         __rpc_add_wait_queue(q, task, queue_priority);
 328
 329         BUG_ON(task->tk_callback != NULL);
 330         task->tk_callback = action;
 331         __rpc_add_timer(q, task);
 332 }
 333
 334 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 335                                 rpc_action action)
 336 {
 337         /* We shouldn't ever put an inactive task to sleep */
 338         BUG_ON(!RPC_IS_ACTIVATED(task));
 339
 340         /*
 341          * Protect the queue operations.
 342          */
 343         spin_lock_bh(&q->lock);
 344         __rpc_sleep_on_priority(q, task, action, task->tk_priority);
 345         spin_unlock_bh(&q->lock);
 346 }
 347 EXPORT_SYMBOL_GPL(rpc_sleep_on);
 348
 349 void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
 350                 rpc_action action, int priority)
 351 {
 352         /* We shouldn't ever put an inactive task to sleep */
 353         BUG_ON(!RPC_IS_ACTIVATED(task));
 354
 355         /*
 356          * Protect the queue operations.
 357          */
 358         spin_lock_bh(&q->lock);
 359         __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
 360         spin_unlock_bh(&q->lock);
 361 }
 362
 363 /**
 364  * __rpc_do_wake_up_task - wake up a single rpc_task
 365  * @queue: wait queue
 366  * @task: task to be woken up
 367  *
 368  * Caller must hold queue->lock, and have cleared the task queued flag.
 369  */
 370 static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 371 {
 372         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
 373                         task->tk_pid, jiffies);
 374
 375         /* Has the task been executed yet? If not, we cannot wake it up! */
 376         if (!RPC_IS_ACTIVATED(task)) {
 377                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 378                 return;
 379         }
 380
 381         __rpc_remove_wait_queue(queue, task);
 382
 383         rpc_make_runnable(task);
 384
 385         dprintk("RPC:       __rpc_wake_up_task done\n");
 386 }
 387
 388 /*
 389  * Wake up a queued task while the queue lock is being held
 390  */
 391 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
 392 {
 393         if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
 394                 __rpc_do_wake_up_task(queue, task);
 395 }
 396
 397 /*
 398  * Tests whether rpc queue is empty
 399  */
 400 int rpc_queue_empty(struct rpc_wait_queue *queue)
 401 {
 402         int res;
 403
 404         spin_lock_bh(&queue->lock);
 405         res = queue->qlen;
 406         spin_unlock_bh(&queue->lock);
 407         return res == 0;
 408 }
 409 EXPORT_SYMBOL_GPL(rpc_queue_empty);
 410
 411 /*
 412  * Wake up a task on a specific queue
 413  */
 414 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 415 {
 416         spin_lock_bh(&queue->lock);
 417         rpc_wake_up_task_queue_locked(queue, task);
 418         spin_unlock_bh(&queue->lock);
 419 }
 420 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
 421
 422 /*
 423  * Wake up the next task on a priority queue.
 424  */
 425 static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
 426 {
 427         struct list_head *q;
 428         struct rpc_task *task;
 429
 430         /*
 431          * Service a batch of tasks from a single owner.
 432          */
 433         q = &queue->tasks[queue->priority];
 434         if (!list_empty(q)) {
 435                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 436                 if (queue->owner == task->tk_owner) {
 437                         if (--queue->nr)
 438                                 goto out;
 439                         list_move_tail(&task->u.tk_wait.list, q);
 440                 }
 441                 /*
 442                  * Check if we need to switch queues.
 443                  */
 444                 if (--queue->count)
 445                         goto new_owner;
 446         }
 447
 448         /*
 449          * Service the next queue.
 450          */
 451         do {
 452                 if (q == &queue->tasks[0])
 453                         q = &queue->tasks[queue->maxpriority];
 454                 else
 455                         q = q - 1;
 456                 if (!list_empty(q)) {
 457                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 458                         goto new_queue;
 459                 }
 460         } while (q != &queue->tasks[queue->priority]);
 461
 462         rpc_reset_waitqueue_priority(queue);
 463         return NULL;
 464
 465 new_queue:
 466         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 467 new_owner:
 468         rpc_set_waitqueue_owner(queue, task->tk_owner);
 469 out:
 470         return task;
 471 }
 472
 473 static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
 474 {
 475         if (RPC_IS_PRIORITY(queue))
 476                 return __rpc_find_next_queued_priority(queue);
 477         if (!list_empty(&queue->tasks[0]))
 478                 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
 479         return NULL;
 480 }
 481
 482 /*
 483  * Wake up the first task on the wait queue.
 484  */
 485 struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
 486                 bool (*func)(struct rpc_task *, void *), void *data)
 487 {
 488         struct rpc_task *task = NULL;
 489
 490         dprintk("RPC:       wake_up_first(%p \"%s\")\n",
 491                         queue, rpc_qname(queue));
 492         spin_lock_bh(&queue->lock);
 493         task = __rpc_find_next_queued(queue);
 494         if (task != NULL) {
 495                 if (func(task, data))
 496                         rpc_wake_up_task_queue_locked(queue, task);
 497                 else
 498                         task = NULL;
 499         }
 500         spin_unlock_bh(&queue->lock);
 501
 502         return task;
 503 }
 504 EXPORT_SYMBOL_GPL(rpc_wake_up_first);
 505
 506 static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
 507 {
 508         return true;
 509 }
 510
 511 /*
 512  * Wake up the next task on the wait queue.
 513 */
 514 struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
 515 {
 516         return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
 517 }
 518 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
 519
 520 /**
 521  * rpc_wake_up - wake up all rpc_tasks
 522  * @queue: rpc_wait_queue on which the tasks are sleeping
 523  *
 524  * Grabs queue->lock
 525  */
 526 void rpc_wake_up(struct rpc_wait_queue *queue)
 527 {
 528         struct rpc_task *task, *next;
 529         struct list_head *head;
 530
 531         spin_lock_bh(&queue->lock);
 532         head = &queue->tasks[queue->maxpriority];
 533         for (;;) {
 534                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
 535                         rpc_wake_up_task_queue_locked(queue, task);
 536                 if (head == &queue->tasks[0])
 537                         break;
 538                 head--;
 539         }
 540         spin_unlock_bh(&queue->lock);
 541 }
 542 EXPORT_SYMBOL_GPL(rpc_wake_up);
 543
 544 /**
 545  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 546  * @queue: rpc_wait_queue on which the tasks are sleeping
 547  * @status: status value to set
 548  *
 549  * Grabs queue->lock
 550  */
 551 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 552 {
 553         struct rpc_task *task, *next;
 554         struct list_head *head;
 555
 556         spin_lock_bh(&queue->lock);
 557         head = &queue->tasks[queue->maxpriority];
 558         for (;;) {
 559                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
 560                         task->tk_status = status;
 561                         rpc_wake_up_task_queue_locked(queue, task);
 562                 }
 563                 if (head == &queue->tasks[0])
 564                         break;
 565                 head--;
 566         }
 567         spin_unlock_bh(&queue->lock);
 568 }
 569 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
 570
 571 static void __rpc_queue_timer_fn(unsigned long ptr)
 572 {
 573         struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
 574         struct rpc_task *task, *n;
 575         unsigned long expires, now, timeo;
 576
 577         spin_lock(&queue->lock);
 578         expires = now = jiffies;
 579         list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
 580                 timeo = task->u.tk_wait.expires;
 581                 if (time_after_eq(now, timeo)) {
 582                         dprintk("RPC: %5u timeout\n", task->tk_pid);
 583                         task->tk_status = -ETIMEDOUT;
 584                         rpc_wake_up_task_queue_locked(queue, task);
 585                         continue;
 586                 }
 587                 if (expires == now || time_after(expires, timeo))
 588                         expires = timeo;
 589         }
 590         if (!list_empty(&queue->timer_list.list))
 591                 rpc_set_queue_timer(queue, expires);
 592         spin_unlock(&queue->lock);
 593 }
 594
 595 static void __rpc_atrun(struct rpc_task *task)
 596 {
 597         task->tk_status = 0;
 598 }
 599
 600 /*
 601  * Run a task at a later time
 602  */
 603 void rpc_delay(struct rpc_task *task, unsigned long delay)
 604 {
 605         task->tk_timeout = delay;
 606         rpc_sleep_on(&delay_queue, task, __rpc_atrun);
 607 }
 608 EXPORT_SYMBOL_GPL(rpc_delay);
 609
 610 /*
 611  * Helper to call task->tk_ops->rpc_call_prepare
 612  */
 613 void rpc_prepare_task(struct rpc_task *task)
 614 {
 615         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 616 }
 617
 618 static void
 619 rpc_init_task_statistics(struct rpc_task *task)
 620 {
 621         /* Initialize retry counters */
 622         task->tk_garb_retry = 2;
 623         task->tk_cred_retry = 2;
 624         task->tk_rebind_retry = 2;
 625
 626         /* starting timestamp */
 627         task->tk_start = ktime_get();
 628 }
 629
 630 static void
 631 rpc_reset_task_statistics(struct rpc_task *task)
 632 {
 633         task->tk_timeouts = 0;
 634         task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
 635
 636         rpc_init_task_statistics(task);
 637 }
 638
 639 /*
 640  * Helper that calls task->tk_ops->rpc_call_done if it exists
 641  */
 642 void rpc_exit_task(struct rpc_task *task)
 643 {
 644         task->tk_action = NULL;
 645         if (task->tk_ops->rpc_call_done != NULL) {
 646                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
 647                 if (task->tk_action != NULL) {
 648                         WARN_ON(RPC_ASSASSINATED(task));
 649                         /* Always release the RPC slot and buffer memory */
 650                         xprt_release(task);
 651                         rpc_reset_task_statistics(task);
 652                 }
 653         }
 654 }
 655
 656 void rpc_exit(struct rpc_task *task, int status)
 657 {
 658         task->tk_status = status;
 659         task->tk_action = rpc_exit_task;
 660         if (RPC_IS_QUEUED(task))
 661                 rpc_wake_up_queued_task(task->tk_waitqueue, task);
 662 }
 663 EXPORT_SYMBOL_GPL(rpc_exit);
 664
 665 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
 666 {
 667         if (ops->rpc_release != NULL)
 668                 ops->rpc_release(calldata);
 669 }
 670
 671 /*
 672  * This is the RPC `scheduler' (or rather, the finite state machine).
 673  */
 674 static void __rpc_execute(struct rpc_task *task)
 675 {
 676         struct rpc_wait_queue *queue;
 677         int task_is_async = RPC_IS_ASYNC(task);
 678         int status = 0;
 679
 680         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
 681                         task->tk_pid, task->tk_flags);
 682
 683         BUG_ON(RPC_IS_QUEUED(task));
 684
 685         for (;;) {
 686                 void (*do_action)(struct rpc_task *);
 687
 688                 /*
 689                  * Execute any pending callback first.
 690                  */
 691                 do_action = task->tk_callback;
 692                 task->tk_callback = NULL;
 693                 if (do_action == NULL) {
 694                         /*
 695                          * Perform the next FSM step.
 696                          * tk_action may be NULL if the task has been killed.
 697                          * In particular, note that rpc_killall_tasks may
 698                          * do this at any time, so beware when dereferencing.
 699                          */
 700                         do_action = task->tk_action;
 701                         if (do_action == NULL)
 702                                 break;
 703                 }
 704                 do_action(task);
 705
 706                 /*
 707                  * Lockless check for whether task is sleeping or not.
 708                  */
 709                 if (!RPC_IS_QUEUED(task))
 710                         continue;
 711                 /*
 712                  * The queue->lock protects against races with
 713                  * rpc_make_runnable().
 714                  *
 715                  * Note that once we clear RPC_TASK_RUNNING on an asynchronous
 716                  * rpc_task, rpc_make_runnable() can assign it to a
 717                  * different workqueue. We therefore cannot assume that the
 718                  * rpc_task pointer may still be dereferenced.
 719                  */
 720                 queue = task->tk_waitqueue;
 721                 spin_lock_bh(&queue->lock);
 722                 if (!RPC_IS_QUEUED(task)) {
 723                         spin_unlock_bh(&queue->lock);
 724                         continue;
 725                 }
 726                 rpc_clear_running(task);
 727                 spin_unlock_bh(&queue->lock);
 728                 if (task_is_async)
 729                         return;
 730
 731                 /* sync task: sleep here */
 732                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
 733                 status = out_of_line_wait_on_bit(&task->tk_runstate,
 734                                 RPC_TASK_QUEUED, rpc_wait_bit_killable,
 735                                 TASK_KILLABLE);
 736                 if (status == -ERESTARTSYS) {
 737                         /*
 738                          * When a sync task receives a signal, it exits with
 739                          * -ERESTARTSYS. In order to catch any callbacks that
 740                          * clean up after sleeping on some queue, we don't
 741                          * break the loop here, but go around once more.
 742                          */
 743                         dprintk("RPC: %5u got signal\n", task->tk_pid);
 744                         task->tk_flags |= RPC_TASK_KILLED;
 745                         rpc_exit(task, -ERESTARTSYS);
 746                 }
 747                 rpc_set_running(task);
 748                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
 749         }
 750
 751         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
 752                         task->tk_status);
 753         /* Release all resources associated with the task */
 754         rpc_release_task(task);
 755 }
 756
 757 /*
 758  * User-visible entry point to the scheduler.
 759  *
 760  * This may be called recursively if e.g. an async NFS task updates
 761  * the attributes and finds that dirty pages must be flushed.
 762  * NOTE: Upon exit of this function the task is guaranteed to be
 763  *       released. In particular note that tk_release() will have
 764  *       been called, so your task memory may have been freed.
 765  */
 766 void rpc_execute(struct rpc_task *task)
 767 {
 768         rpc_set_active(task);
 769         rpc_make_runnable(task);
 770         if (!RPC_IS_ASYNC(task))
 771                 __rpc_execute(task);
 772 }
 773
 774 static void rpc_async_schedule(struct work_struct *work)
 775 {
 776         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
 777 }
 778
 779 /**
 780  * rpc_malloc - allocate an RPC buffer
 781  * @task: RPC task that will use this buffer
 782  * @size: requested byte size
 783  *
 784  * To prevent rpciod from hanging, this allocator never sleeps,
 785  * returning NULL if the request cannot be serviced immediately.
 786  * The caller can arrange to sleep in a way that is safe for rpciod.
 787  *
 788  * Most requests are 'small' (under 2KiB) and can be serviced from a
 789  * mempool, ensuring that NFS reads and writes can always proceed,
 790  * and that there is good locality of reference for these buffers.
 791  *
 792  * In order to avoid memory starvation triggering more writebacks of
 793  * NFS requests, we avoid using GFP_KERNEL.
 794  */
 795 void *rpc_malloc(struct rpc_task *task, size_t size)
 796 {
 797         struct rpc_buffer *buf;
 798         gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
 799
 800         size += sizeof(struct rpc_buffer);
 801         if (size <= RPC_BUFFER_MAXSIZE)
 802                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
 803         else
 804                 buf = kmalloc(size, gfp);
 805
 806         if (!buf)
 807                 return NULL;
 808
 809         buf->len = size;
 810         dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
 811                         task->tk_pid, size, buf);
 812         return &buf->data;
 813 }
 814 EXPORT_SYMBOL_GPL(rpc_malloc);
 815
 816 /**
 817  * rpc_free - free buffer allocated via rpc_malloc
 818  * @buffer: buffer to free
 819  *
 820  */
 821 void rpc_free(void *buffer)
 822 {
 823         size_t size;
 824         struct rpc_buffer *buf;
 825
 826         if (!buffer)
 827                 return;
 828
 829         buf = container_of(buffer, struct rpc_buffer, data);
 830         size = buf->len;
 831
 832         dprintk("RPC:       freeing buffer of size %zu at %p\n",
 833                         size, buf);
 834
 835         if (size <= RPC_BUFFER_MAXSIZE)
 836                 mempool_free(buf, rpc_buffer_mempool);
 837         else
 838                 kfree(buf);
 839 }
 840 EXPORT_SYMBOL_GPL(rpc_free);
 841
 842 /*
 843  * Creation and deletion of RPC task structures
 844  */
 845 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
 846 {
 847         memset(task, 0, sizeof(*task));
 848         atomic_set(&task->tk_count, 1);
 849         task->tk_flags  = task_setup_data->flags;
 850         task->tk_ops = task_setup_data->callback_ops;
 851         task->tk_calldata = task_setup_data->callback_data;
 852         INIT_LIST_HEAD(&task->tk_task);
 853
 854         task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
 855         task->tk_owner = current->tgid;
 856
 857         /* Initialize workqueue for async tasks */
 858         task->tk_workqueue = task_setup_data->workqueue;
 859
 860         if (task->tk_ops->rpc_call_prepare != NULL)
 861                 task->tk_action = rpc_prepare_task;
 862
 863         rpc_init_task_statistics(task);
 864
 865         dprintk("RPC:       new task initialized, procpid %u\n",
 866                                 task_pid_nr(current));
 867 }
 868
 869 static struct rpc_task *
 870 rpc_alloc_task(void)
 871 {
 872         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 873 }
 874
 875 /*
 876  * Create a new task for the specified client.
 877  */
 878 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
 879 {
 880         struct rpc_task *task = setup_data->task;
 881         unsigned short flags = 0;
 882
 883         if (task == NULL) {
 884                 task = rpc_alloc_task();
 885                 if (task == NULL) {
 886                         rpc_release_calldata(setup_data->callback_ops,
 887                                         setup_data->callback_data);
 888                         return ERR_PTR(-ENOMEM);
 889                 }
 890                 flags = RPC_TASK_DYNAMIC;
 891         }
 892
 893         rpc_init_task(task, setup_data);
 894         task->tk_flags |= flags;
 895         dprintk("RPC:       allocated task %p\n", task);
 896         return task;
 897 }
 898
 899 static void rpc_free_task(struct rpc_task *task)
 900 {
 901         const struct rpc_call_ops *tk_ops = task->tk_ops;
 902         void *calldata = task->tk_calldata;
 903
 904         if (task->tk_flags & RPC_TASK_DYNAMIC) {
 905                 dprintk("RPC: %5u freeing task\n", task->tk_pid);
 906                 mempool_free(task, rpc_task_mempool);
 907         }
 908         rpc_release_calldata(tk_ops, calldata);
 909 }
 910
 911 static void rpc_async_release(struct work_struct *work)
 912 {
 913         rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
 914 }
 915
 916 static void rpc_release_resources_task(struct rpc_task *task)
 917 {
 918         if (task->tk_rqstp)
 919                 xprt_release(task);
 920         if (task->tk_msg.rpc_cred) {
 921                 put_rpccred(task->tk_msg.rpc_cred);
 922                 task->tk_msg.rpc_cred = NULL;
 923         }
 924         rpc_task_release_client(task);
 925 }
 926
 927 static void rpc_final_put_task(struct rpc_task *task,
 928                 struct workqueue_struct *q)
 929 {
 930         if (q != NULL) {
 931                 INIT_WORK(&task->u.tk_work, rpc_async_release);
 932                 queue_work(q, &task->u.tk_work);
 933         } else
 934                 rpc_free_task(task);
 935 }
 936
 937 static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
 938 {
 939         if (atomic_dec_and_test(&task->tk_count)) {
 940                 rpc_release_resources_task(task);
 941                 rpc_final_put_task(task, q);
 942         }
 943 }
 944
 945 void rpc_put_task(struct rpc_task *task)
 946 {
 947         rpc_do_put_task(task, NULL);
 948 }
 949 EXPORT_SYMBOL_GPL(rpc_put_task);
 950
 951 void rpc_put_task_async(struct rpc_task *task)
 952 {
 953         rpc_do_put_task(task, task->tk_workqueue);
 954 }
 955 EXPORT_SYMBOL_GPL(rpc_put_task_async);
 956
 957 static void rpc_release_task(struct rpc_task *task)
 958 {
 959         dprintk("RPC: %5u release task\n", task->tk_pid);
 960
 961         BUG_ON (RPC_IS_QUEUED(task));
 962
 963         rpc_release_resources_task(task);
 964
 965         /*
 966          * Note: at this point we have been removed from rpc_clnt->cl_tasks,
 967          * so it should be safe to use task->tk_count as a test for whether
 968          * or not any other processes still hold references to our rpc_task.
 969          */
 970         if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
 971                 /* Wake up anyone who may be waiting for task completion */
 972                 if (!rpc_complete_task(task))
 973                         return;
 974         } else {
 975                 if (!atomic_dec_and_test(&task->tk_count))
 976                         return;
 977         }
 978         rpc_final_put_task(task, task->tk_workqueue);
 979 }
 980
 981 int rpciod_up(void)
 982 {
 983         return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
 984 }
 985
 986 void rpciod_down(void)
 987 {
 988         module_put(THIS_MODULE);
 989 }
 990
 991 /*
 992  * Start up the rpciod workqueue.
 993  */
 994 static int rpciod_start(void)
 995 {
 996         struct workqueue_struct *wq;
 997
 998         /*
 999          * Create the rpciod thread and wait for it to start.
1000          */
1001         dprintk("RPC:       creating workqueue rpciod\n");
1002         wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 0);
1003         rpciod_workqueue = wq;
1004         return rpciod_workqueue != NULL;
1005 }
1006
1007 static void rpciod_stop(void)
1008 {
1009         struct workqueue_struct *wq = NULL;
1010
1011         if (rpciod_workqueue == NULL)
1012                 return;
1013         dprintk("RPC:       destroying workqueue rpciod\n");
1014
1015         wq = rpciod_workqueue;
1016         rpciod_workqueue = NULL;
1017         destroy_workqueue(wq);
1018 }
1019
1020 void
1021 rpc_destroy_mempool(void)
1022 {
1023         rpciod_stop();
1024         if (rpc_buffer_mempool)
1025                 mempool_destroy(rpc_buffer_mempool);
1026         if (rpc_task_mempool)
1027                 mempool_destroy(rpc_task_mempool);
1028         if (rpc_task_slabp)
1029                 kmem_cache_destroy(rpc_task_slabp);
1030         if (rpc_buffer_slabp)
1031                 kmem_cache_destroy(rpc_buffer_slabp);
1032         rpc_destroy_wait_queue(&delay_queue);
1033 }
1034
1035 int
1036 rpc_init_mempool(void)
1037 {
1038         /*
1039          * The following is not strictly a mempool initialisation,
1040          * but there is no harm in doing it here
1041          */
1042         rpc_init_wait_queue(&delay_queue, "delayq");
1043         if (!rpciod_start())
1044                 goto err_nomem;
1045
1046         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1047                                              sizeof(struct rpc_task),
1048                                              0, SLAB_HWCACHE_ALIGN,
1049                                              NULL);
1050         if (!rpc_task_slabp)
1051                 goto err_nomem;
1052         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1053                                              RPC_BUFFER_MAXSIZE,
1054                                              0, SLAB_HWCACHE_ALIGN,
1055                                              NULL);
1056         if (!rpc_buffer_slabp)
1057                 goto err_nomem;
1058         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1059                                                     rpc_task_slabp);
1060         if (!rpc_task_mempool)
1061                 goto err_nomem;
1062         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1063                                                       rpc_buffer_slabp);
1064         if (!rpc_buffer_mempool)
1065                 goto err_nomem;
1066         return 0;
1067 err_nomem:
1068         rpc_destroy_mempool();
1069         return -ENOMEM;
1070 }