linux/net/sunrpc/sched.c
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   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#define CREATE_TRACE_POINTS
  32#include <trace/events/sunrpc.h>
  33
  34/*
  35 * RPC slabs and memory pools
  36 */
  37#define RPC_BUFFER_MAXSIZE      (2048)
  38#define RPC_BUFFER_POOLSIZE     (8)
  39#define RPC_TASK_POOLSIZE       (8)
  40static struct kmem_cache        *rpc_task_slabp __read_mostly;
  41static struct kmem_cache        *rpc_buffer_slabp __read_mostly;
  42static mempool_t        *rpc_task_mempool __read_mostly;
  43static mempool_t        *rpc_buffer_mempool __read_mostly;
  44
  45static void                     rpc_async_schedule(struct work_struct *);
  46static void                      rpc_release_task(struct rpc_task *task);
  47static void __rpc_queue_timer_fn(unsigned long ptr);
  48
  49/*
  50 * RPC tasks sit here while waiting for conditions to improve.
  51 */
  52static struct rpc_wait_queue delay_queue;
  53
  54/*
  55 * rpciod-related stuff
  56 */
  57struct workqueue_struct *rpciod_workqueue;
  58
  59/*
  60 * Disable the timer for a given RPC task. Should be called with
  61 * queue->lock and bh_disabled in order to avoid races within
  62 * rpc_run_timer().
  63 */
  64static void
  65__rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
  66{
  67        if (task->tk_timeout == 0)
  68                return;
  69        dprintk("RPC: %5u disabling timer\n", task->tk_pid);
  70        task->tk_timeout = 0;
  71        list_del(&task->u.tk_wait.timer_list);
  72        if (list_empty(&queue->timer_list.list))
  73                del_timer(&queue->timer_list.timer);
  74}
  75
  76static void
  77rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
  78{
  79        queue->timer_list.expires = expires;
  80        mod_timer(&queue->timer_list.timer, expires);
  81}
  82
  83/*
  84 * Set up a timer for the current task.
  85 */
  86static void
  87__rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
  88{
  89        if (!task->tk_timeout)
  90                return;
  91
  92        dprintk("RPC: %5u setting alarm for %lu ms\n",
  93                        task->tk_pid, task->tk_timeout * 1000 / HZ);
  94
  95        task->u.tk_wait.expires = jiffies + task->tk_timeout;
  96        if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
  97                rpc_set_queue_timer(queue, task->u.tk_wait.expires);
  98        list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
  99}
 100
 101/*
 102 * Add new request to a priority queue.
 103 */
 104static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
 105                struct rpc_task *task,
 106                unsigned char queue_priority)
 107{
 108        struct list_head *q;
 109        struct rpc_task *t;
 110
 111        INIT_LIST_HEAD(&task->u.tk_wait.links);
 112        q = &queue->tasks[queue_priority];
 113        if (unlikely(queue_priority > queue->maxpriority))
 114                q = &queue->tasks[queue->maxpriority];
 115        list_for_each_entry(t, q, u.tk_wait.list) {
 116                if (t->tk_owner == task->tk_owner) {
 117                        list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
 118                        return;
 119                }
 120        }
 121        list_add_tail(&task->u.tk_wait.list, q);
 122}
 123
 124/*
 125 * Add new request to wait queue.
 126 *
 127 * Swapper tasks always get inserted at the head of the queue.
 128 * This should avoid many nasty memory deadlocks and hopefully
 129 * improve overall performance.
 130 * Everyone else gets appended to the queue to ensure proper FIFO behavior.
 131 */
 132static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
 133                struct rpc_task *task,
 134                unsigned char queue_priority)
 135{
 136        BUG_ON (RPC_IS_QUEUED(task));
 137
 138        if (RPC_IS_PRIORITY(queue))
 139                __rpc_add_wait_queue_priority(queue, task, queue_priority);
 140        else if (RPC_IS_SWAPPER(task))
 141                list_add(&task->u.tk_wait.list, &queue->tasks[0]);
 142        else
 143                list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
 144        task->tk_waitqueue = queue;
 145        queue->qlen++;
 146        rpc_set_queued(task);
 147
 148        dprintk("RPC: %5u added to queue %p \"%s\"\n",
 149                        task->tk_pid, queue, rpc_qname(queue));
 150}
 151
 152/*
 153 * Remove request from a priority queue.
 154 */
 155static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 156{
 157        struct rpc_task *t;
 158
 159        if (!list_empty(&task->u.tk_wait.links)) {
 160                t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
 161                list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
 162                list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
 163        }
 164}
 165
 166/*
 167 * Remove request from queue.
 168 * Note: must be called with spin lock held.
 169 */
 170static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
 171{
 172        __rpc_disable_timer(queue, task);
 173        if (RPC_IS_PRIORITY(queue))
 174                __rpc_remove_wait_queue_priority(task);
 175        list_del(&task->u.tk_wait.list);
 176        queue->qlen--;
 177        dprintk("RPC: %5u removed from queue %p \"%s\"\n",
 178                        task->tk_pid, queue, rpc_qname(queue));
 179}
 180
 181static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 182{
 183        queue->priority = priority;
 184        queue->count = 1 << (priority * 2);
 185}
 186
 187static inline void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
 188{
 189        queue->owner = pid;
 190        queue->nr = RPC_BATCH_COUNT;
 191}
 192
 193static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 194{
 195        rpc_set_waitqueue_priority(queue, queue->maxpriority);
 196        rpc_set_waitqueue_owner(queue, 0);
 197}
 198
 199static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
 200{
 201        int i;
 202
 203        spin_lock_init(&queue->lock);
 204        for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 205                INIT_LIST_HEAD(&queue->tasks[i]);
 206        queue->maxpriority = nr_queues - 1;
 207        rpc_reset_waitqueue_priority(queue);
 208        queue->qlen = 0;
 209        setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
 210        INIT_LIST_HEAD(&queue->timer_list.list);
 211        rpc_assign_waitqueue_name(queue, qname);
 212}
 213
 214void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 215{
 216        __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
 217}
 218EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
 219
 220void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 221{
 222        __rpc_init_priority_wait_queue(queue, qname, 1);
 223}
 224EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
 225
 226void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
 227{
 228        del_timer_sync(&queue->timer_list.timer);
 229}
 230EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
 231
 232static int rpc_wait_bit_killable(void *word)
 233{
 234        if (fatal_signal_pending(current))
 235                return -ERESTARTSYS;
 236        freezable_schedule();
 237        return 0;
 238}
 239
 240#ifdef RPC_DEBUG
 241static void rpc_task_set_debuginfo(struct rpc_task *task)
 242{
 243        static atomic_t rpc_pid;
 244
 245        task->tk_pid = atomic_inc_return(&rpc_pid);
 246}
 247#else
 248static inline void rpc_task_set_debuginfo(struct rpc_task *task)
 249{
 250}
 251#endif
 252
 253static void rpc_set_active(struct rpc_task *task)
 254{
 255        trace_rpc_task_begin(task->tk_client, task, NULL);
 256
 257        rpc_task_set_debuginfo(task);
 258        set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 259}
 260
 261/*
 262 * Mark an RPC call as having completed by clearing the 'active' bit
 263 * and then waking up all tasks that were sleeping.
 264 */
 265static int rpc_complete_task(struct rpc_task *task)
 266{
 267        void *m = &task->tk_runstate;
 268        wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
 269        struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
 270        unsigned long flags;
 271        int ret;
 272
 273        trace_rpc_task_complete(task->tk_client, task, NULL);
 274
 275        spin_lock_irqsave(&wq->lock, flags);
 276        clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 277        ret = atomic_dec_and_test(&task->tk_count);
 278        if (waitqueue_active(wq))
 279                __wake_up_locked_key(wq, TASK_NORMAL, &k);
 280        spin_unlock_irqrestore(&wq->lock, flags);
 281        return ret;
 282}
 283
 284/*
 285 * Allow callers to wait for completion of an RPC call
 286 *
 287 * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
 288 * to enforce taking of the wq->lock and hence avoid races with
 289 * rpc_complete_task().
 290 */
 291int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
 292{
 293        if (action == NULL)
 294                action = rpc_wait_bit_killable;
 295        return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 296                        action, TASK_KILLABLE);
 297}
 298EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
 299
 300/*
 301 * Make an RPC task runnable.
 302 *
 303 * Note: If the task is ASYNC, and is being made runnable after sitting on an
 304 * rpc_wait_queue, this must be called with the queue spinlock held to protect
 305 * the wait queue operation.
 306 */
 307static void rpc_make_runnable(struct rpc_task *task)
 308{
 309        rpc_clear_queued(task);
 310        if (rpc_test_and_set_running(task))
 311                return;
 312        if (RPC_IS_ASYNC(task)) {
 313                INIT_WORK(&task->u.tk_work, rpc_async_schedule);
 314                queue_work(rpciod_workqueue, &task->u.tk_work);
 315        } else
 316                wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 317}
 318
 319/*
 320 * Prepare for sleeping on a wait queue.
 321 * By always appending tasks to the list we ensure FIFO behavior.
 322 * NB: An RPC task will only receive interrupt-driven events as long
 323 * as it's on a wait queue.
 324 */
 325static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
 326                struct rpc_task *task,
 327                rpc_action action,
 328                unsigned char queue_priority)
 329{
 330        dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
 331                        task->tk_pid, rpc_qname(q), jiffies);
 332
 333        trace_rpc_task_sleep(task->tk_client, task, q);
 334
 335        __rpc_add_wait_queue(q, task, queue_priority);
 336
 337        BUG_ON(task->tk_callback != NULL);
 338        task->tk_callback = action;
 339        __rpc_add_timer(q, task);
 340}
 341
 342void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 343                                rpc_action action)
 344{
 345        /* We shouldn't ever put an inactive task to sleep */
 346        BUG_ON(!RPC_IS_ACTIVATED(task));
 347
 348        /*
 349         * Protect the queue operations.
 350         */
 351        spin_lock_bh(&q->lock);
 352        __rpc_sleep_on_priority(q, task, action, task->tk_priority);
 353        spin_unlock_bh(&q->lock);
 354}
 355EXPORT_SYMBOL_GPL(rpc_sleep_on);
 356
 357void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
 358                rpc_action action, int priority)
 359{
 360        /* We shouldn't ever put an inactive task to sleep */
 361        BUG_ON(!RPC_IS_ACTIVATED(task));
 362
 363        /*
 364         * Protect the queue operations.
 365         */
 366        spin_lock_bh(&q->lock);
 367        __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
 368        spin_unlock_bh(&q->lock);
 369}
 370
 371/**
 372 * __rpc_do_wake_up_task - wake up a single rpc_task
 373 * @queue: wait queue
 374 * @task: task to be woken up
 375 *
 376 * Caller must hold queue->lock, and have cleared the task queued flag.
 377 */
 378static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 379{
 380        dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
 381                        task->tk_pid, jiffies);
 382
 383        /* Has the task been executed yet? If not, we cannot wake it up! */
 384        if (!RPC_IS_ACTIVATED(task)) {
 385                printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 386                return;
 387        }
 388
 389        trace_rpc_task_wakeup(task->tk_client, task, queue);
 390
 391        __rpc_remove_wait_queue(queue, task);
 392
 393        rpc_make_runnable(task);
 394
 395        dprintk("RPC:       __rpc_wake_up_task done\n");
 396}
 397
 398/*
 399 * Wake up a queued task while the queue lock is being held
 400 */
 401static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
 402{
 403        if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
 404                __rpc_do_wake_up_task(queue, task);
 405}
 406
 407/*
 408 * Tests whether rpc queue is empty
 409 */
 410int rpc_queue_empty(struct rpc_wait_queue *queue)
 411{
 412        int res;
 413
 414        spin_lock_bh(&queue->lock);
 415        res = queue->qlen;
 416        spin_unlock_bh(&queue->lock);
 417        return res == 0;
 418}
 419EXPORT_SYMBOL_GPL(rpc_queue_empty);
 420
 421/*
 422 * Wake up a task on a specific queue
 423 */
 424void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 425{
 426        spin_lock_bh(&queue->lock);
 427        rpc_wake_up_task_queue_locked(queue, task);
 428        spin_unlock_bh(&queue->lock);
 429}
 430EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
 431
 432/*
 433 * Wake up the next task on a priority queue.
 434 */
 435static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
 436{
 437        struct list_head *q;
 438        struct rpc_task *task;
 439
 440        /*
 441         * Service a batch of tasks from a single owner.
 442         */
 443        q = &queue->tasks[queue->priority];
 444        if (!list_empty(q)) {
 445                task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 446                if (queue->owner == task->tk_owner) {
 447                        if (--queue->nr)
 448                                goto out;
 449                        list_move_tail(&task->u.tk_wait.list, q);
 450                }
 451                /*
 452                 * Check if we need to switch queues.
 453                 */
 454                if (--queue->count)
 455                        goto new_owner;
 456        }
 457
 458        /*
 459         * Service the next queue.
 460         */
 461        do {
 462                if (q == &queue->tasks[0])
 463                        q = &queue->tasks[queue->maxpriority];
 464                else
 465                        q = q - 1;
 466                if (!list_empty(q)) {
 467                        task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 468                        goto new_queue;
 469                }
 470        } while (q != &queue->tasks[queue->priority]);
 471
 472        rpc_reset_waitqueue_priority(queue);
 473        return NULL;
 474
 475new_queue:
 476        rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 477new_owner:
 478        rpc_set_waitqueue_owner(queue, task->tk_owner);
 479out:
 480        return task;
 481}
 482
 483static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
 484{
 485        if (RPC_IS_PRIORITY(queue))
 486                return __rpc_find_next_queued_priority(queue);
 487        if (!list_empty(&queue->tasks[0]))
 488                return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
 489        return NULL;
 490}
 491
 492/*
 493 * Wake up the first task on the wait queue.
 494 */
 495struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
 496                bool (*func)(struct rpc_task *, void *), void *data)
 497{
 498        struct rpc_task *task = NULL;
 499
 500        dprintk("RPC:       wake_up_first(%p \"%s\")\n",
 501                        queue, rpc_qname(queue));
 502        spin_lock_bh(&queue->lock);
 503        task = __rpc_find_next_queued(queue);
 504        if (task != NULL) {
 505                if (func(task, data))
 506                        rpc_wake_up_task_queue_locked(queue, task);
 507                else
 508                        task = NULL;
 509        }
 510        spin_unlock_bh(&queue->lock);
 511
 512        return task;
 513}
 514EXPORT_SYMBOL_GPL(rpc_wake_up_first);
 515
 516static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
 517{
 518        return true;
 519}
 520
 521/*
 522 * Wake up the next task on the wait queue.
 523*/
 524struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
 525{
 526        return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
 527}
 528EXPORT_SYMBOL_GPL(rpc_wake_up_next);
 529
 530/**
 531 * rpc_wake_up - wake up all rpc_tasks
 532 * @queue: rpc_wait_queue on which the tasks are sleeping
 533 *
 534 * Grabs queue->lock
 535 */
 536void rpc_wake_up(struct rpc_wait_queue *queue)
 537{
 538        struct list_head *head;
 539
 540        spin_lock_bh(&queue->lock);
 541        head = &queue->tasks[queue->maxpriority];
 542        for (;;) {
 543                while (!list_empty(head)) {
 544                        struct rpc_task *task;
 545                        task = list_first_entry(head,
 546                                        struct rpc_task,
 547                                        u.tk_wait.list);
 548                        rpc_wake_up_task_queue_locked(queue, task);
 549                }
 550                if (head == &queue->tasks[0])
 551                        break;
 552                head--;
 553        }
 554        spin_unlock_bh(&queue->lock);
 555}
 556EXPORT_SYMBOL_GPL(rpc_wake_up);
 557
 558/**
 559 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 560 * @queue: rpc_wait_queue on which the tasks are sleeping
 561 * @status: status value to set
 562 *
 563 * Grabs queue->lock
 564 */
 565void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 566{
 567        struct list_head *head;
 568
 569        spin_lock_bh(&queue->lock);
 570        head = &queue->tasks[queue->maxpriority];
 571        for (;;) {
 572                while (!list_empty(head)) {
 573                        struct rpc_task *task;
 574                        task = list_first_entry(head,
 575                                        struct rpc_task,
 576                                        u.tk_wait.list);
 577                        task->tk_status = status;
 578                        rpc_wake_up_task_queue_locked(queue, task);
 579                }
 580                if (head == &queue->tasks[0])
 581                        break;
 582                head--;
 583        }
 584        spin_unlock_bh(&queue->lock);
 585}
 586EXPORT_SYMBOL_GPL(rpc_wake_up_status);
 587
 588static void __rpc_queue_timer_fn(unsigned long ptr)
 589{
 590        struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
 591        struct rpc_task *task, *n;
 592        unsigned long expires, now, timeo;
 593
 594        spin_lock(&queue->lock);
 595        expires = now = jiffies;
 596        list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
 597                timeo = task->u.tk_wait.expires;
 598                if (time_after_eq(now, timeo)) {
 599                        dprintk("RPC: %5u timeout\n", task->tk_pid);
 600                        task->tk_status = -ETIMEDOUT;
 601                        rpc_wake_up_task_queue_locked(queue, task);
 602                        continue;
 603                }
 604                if (expires == now || time_after(expires, timeo))
 605                        expires = timeo;
 606        }
 607        if (!list_empty(&queue->timer_list.list))
 608                rpc_set_queue_timer(queue, expires);
 609        spin_unlock(&queue->lock);
 610}
 611
 612static void __rpc_atrun(struct rpc_task *task)
 613{
 614        task->tk_status = 0;
 615}
 616
 617/*
 618 * Run a task at a later time
 619 */
 620void rpc_delay(struct rpc_task *task, unsigned long delay)
 621{
 622        task->tk_timeout = delay;
 623        rpc_sleep_on(&delay_queue, task, __rpc_atrun);
 624}
 625EXPORT_SYMBOL_GPL(rpc_delay);
 626
 627/*
 628 * Helper to call task->tk_ops->rpc_call_prepare
 629 */
 630void rpc_prepare_task(struct rpc_task *task)
 631{
 632        task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 633}
 634
 635static void
 636rpc_init_task_statistics(struct rpc_task *task)
 637{
 638        /* Initialize retry counters */
 639        task->tk_garb_retry = 2;
 640        task->tk_cred_retry = 2;
 641        task->tk_rebind_retry = 2;
 642
 643        /* starting timestamp */
 644        task->tk_start = ktime_get();
 645}
 646
 647static void
 648rpc_reset_task_statistics(struct rpc_task *task)
 649{
 650        task->tk_timeouts = 0;
 651        task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
 652
 653        rpc_init_task_statistics(task);
 654}
 655
 656/*
 657 * Helper that calls task->tk_ops->rpc_call_done if it exists
 658 */
 659void rpc_exit_task(struct rpc_task *task)
 660{
 661        task->tk_action = NULL;
 662        if (task->tk_ops->rpc_call_done != NULL) {
 663                task->tk_ops->rpc_call_done(task, task->tk_calldata);
 664                if (task->tk_action != NULL) {
 665                        WARN_ON(RPC_ASSASSINATED(task));
 666                        /* Always release the RPC slot and buffer memory */
 667                        xprt_release(task);
 668                        rpc_reset_task_statistics(task);
 669                }
 670        }
 671}
 672
 673void rpc_exit(struct rpc_task *task, int status)
 674{
 675        task->tk_status = status;
 676        task->tk_action = rpc_exit_task;
 677        if (RPC_IS_QUEUED(task))
 678                rpc_wake_up_queued_task(task->tk_waitqueue, task);
 679}
 680EXPORT_SYMBOL_GPL(rpc_exit);
 681
 682void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
 683{
 684        if (ops->rpc_release != NULL)
 685                ops->rpc_release(calldata);
 686}
 687
 688/*
 689 * This is the RPC `scheduler' (or rather, the finite state machine).
 690 */
 691static void __rpc_execute(struct rpc_task *task)
 692{
 693        struct rpc_wait_queue *queue;
 694        int task_is_async = RPC_IS_ASYNC(task);
 695        int status = 0;
 696
 697        dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
 698                        task->tk_pid, task->tk_flags);
 699
 700        BUG_ON(RPC_IS_QUEUED(task));
 701
 702        for (;;) {
 703                void (*do_action)(struct rpc_task *);
 704
 705                /*
 706                 * Execute any pending callback first.
 707                 */
 708                do_action = task->tk_callback;
 709                task->tk_callback = NULL;
 710                if (do_action == NULL) {
 711                        /*
 712                         * Perform the next FSM step.
 713                         * tk_action may be NULL if the task has been killed.
 714                         * In particular, note that rpc_killall_tasks may
 715                         * do this at any time, so beware when dereferencing.
 716                         */
 717                        do_action = task->tk_action;
 718                        if (do_action == NULL)
 719                                break;
 720                }
 721                trace_rpc_task_run_action(task->tk_client, task, task->tk_action);
 722                do_action(task);
 723
 724                /*
 725                 * Lockless check for whether task is sleeping or not.
 726                 */
 727                if (!RPC_IS_QUEUED(task))
 728                        continue;
 729                /*
 730                 * The queue->lock protects against races with
 731                 * rpc_make_runnable().
 732                 *
 733                 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
 734                 * rpc_task, rpc_make_runnable() can assign it to a
 735                 * different workqueue. We therefore cannot assume that the
 736                 * rpc_task pointer may still be dereferenced.
 737                 */
 738                queue = task->tk_waitqueue;
 739                spin_lock_bh(&queue->lock);
 740                if (!RPC_IS_QUEUED(task)) {
 741                        spin_unlock_bh(&queue->lock);
 742                        continue;
 743                }
 744                rpc_clear_running(task);
 745                spin_unlock_bh(&queue->lock);
 746                if (task_is_async)
 747                        return;
 748
 749                /* sync task: sleep here */
 750                dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
 751                status = out_of_line_wait_on_bit(&task->tk_runstate,
 752                                RPC_TASK_QUEUED, rpc_wait_bit_killable,
 753                                TASK_KILLABLE);
 754                if (status == -ERESTARTSYS) {
 755                        /*
 756                         * When a sync task receives a signal, it exits with
 757                         * -ERESTARTSYS. In order to catch any callbacks that
 758                         * clean up after sleeping on some queue, we don't
 759                         * break the loop here, but go around once more.
 760                         */
 761                        dprintk("RPC: %5u got signal\n", task->tk_pid);
 762                        task->tk_flags |= RPC_TASK_KILLED;
 763                        rpc_exit(task, -ERESTARTSYS);
 764                }
 765                rpc_set_running(task);
 766                dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
 767        }
 768
 769        dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
 770                        task->tk_status);
 771        /* Release all resources associated with the task */
 772        rpc_release_task(task);
 773}
 774
 775/*
 776 * User-visible entry point to the scheduler.
 777 *
 778 * This may be called recursively if e.g. an async NFS task updates
 779 * the attributes and finds that dirty pages must be flushed.
 780 * NOTE: Upon exit of this function the task is guaranteed to be
 781 *       released. In particular note that tk_release() will have
 782 *       been called, so your task memory may have been freed.
 783 */
 784void rpc_execute(struct rpc_task *task)
 785{
 786        rpc_set_active(task);
 787        rpc_make_runnable(task);
 788        if (!RPC_IS_ASYNC(task))
 789                __rpc_execute(task);
 790}
 791
 792static void rpc_async_schedule(struct work_struct *work)
 793{
 794        current->flags |= PF_FSTRANS;
 795        __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
 796        current->flags &= ~PF_FSTRANS;
 797}
 798
 799/**
 800 * rpc_malloc - allocate an RPC buffer
 801 * @task: RPC task that will use this buffer
 802 * @size: requested byte size
 803 *
 804 * To prevent rpciod from hanging, this allocator never sleeps,
 805 * returning NULL if the request cannot be serviced immediately.
 806 * The caller can arrange to sleep in a way that is safe for rpciod.
 807 *
 808 * Most requests are 'small' (under 2KiB) and can be serviced from a
 809 * mempool, ensuring that NFS reads and writes can always proceed,
 810 * and that there is good locality of reference for these buffers.
 811 *
 812 * In order to avoid memory starvation triggering more writebacks of
 813 * NFS requests, we avoid using GFP_KERNEL.
 814 */
 815void *rpc_malloc(struct rpc_task *task, size_t size)
 816{
 817        struct rpc_buffer *buf;
 818        gfp_t gfp = GFP_NOWAIT;
 819
 820        if (RPC_IS_SWAPPER(task))
 821                gfp |= __GFP_MEMALLOC;
 822
 823        size += sizeof(struct rpc_buffer);
 824        if (size <= RPC_BUFFER_MAXSIZE)
 825                buf = mempool_alloc(rpc_buffer_mempool, gfp);
 826        else
 827                buf = kmalloc(size, gfp);
 828
 829        if (!buf)
 830                return NULL;
 831
 832        buf->len = size;
 833        dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
 834                        task->tk_pid, size, buf);
 835        return &buf->data;
 836}
 837EXPORT_SYMBOL_GPL(rpc_malloc);
 838
 839/**
 840 * rpc_free - free buffer allocated via rpc_malloc
 841 * @buffer: buffer to free
 842 *
 843 */
 844void rpc_free(void *buffer)
 845{
 846        size_t size;
 847        struct rpc_buffer *buf;
 848
 849        if (!buffer)
 850                return;
 851
 852        buf = container_of(buffer, struct rpc_buffer, data);
 853        size = buf->len;
 854
 855        dprintk("RPC:       freeing buffer of size %zu at %p\n",
 856                        size, buf);
 857
 858        if (size <= RPC_BUFFER_MAXSIZE)
 859                mempool_free(buf, rpc_buffer_mempool);
 860        else
 861                kfree(buf);
 862}
 863EXPORT_SYMBOL_GPL(rpc_free);
 864
 865/*
 866 * Creation and deletion of RPC task structures
 867 */
 868static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
 869{
 870        memset(task, 0, sizeof(*task));
 871        atomic_set(&task->tk_count, 1);
 872        task->tk_flags  = task_setup_data->flags;
 873        task->tk_ops = task_setup_data->callback_ops;
 874        task->tk_calldata = task_setup_data->callback_data;
 875        INIT_LIST_HEAD(&task->tk_task);
 876
 877        task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
 878        task->tk_owner = current->tgid;
 879
 880        /* Initialize workqueue for async tasks */
 881        task->tk_workqueue = task_setup_data->workqueue;
 882
 883        if (task->tk_ops->rpc_call_prepare != NULL)
 884                task->tk_action = rpc_prepare_task;
 885
 886        rpc_init_task_statistics(task);
 887
 888        dprintk("RPC:       new task initialized, procpid %u\n",
 889                                task_pid_nr(current));
 890}
 891
 892static struct rpc_task *
 893rpc_alloc_task(void)
 894{
 895        return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO);
 896}
 897
 898/*
 899 * Create a new task for the specified client.
 900 */
 901struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
 902{
 903        struct rpc_task *task = setup_data->task;
 904        unsigned short flags = 0;
 905
 906        if (task == NULL) {
 907                task = rpc_alloc_task();
 908                if (task == NULL) {
 909                        rpc_release_calldata(setup_data->callback_ops,
 910                                        setup_data->callback_data);
 911                        return ERR_PTR(-ENOMEM);
 912                }
 913                flags = RPC_TASK_DYNAMIC;
 914        }
 915
 916        rpc_init_task(task, setup_data);
 917        task->tk_flags |= flags;
 918        dprintk("RPC:       allocated task %p\n", task);
 919        return task;
 920}
 921
 922static void rpc_free_task(struct rpc_task *task)
 923{
 924        const struct rpc_call_ops *tk_ops = task->tk_ops;
 925        void *calldata = task->tk_calldata;
 926
 927        if (task->tk_flags & RPC_TASK_DYNAMIC) {
 928                dprintk("RPC: %5u freeing task\n", task->tk_pid);
 929                mempool_free(task, rpc_task_mempool);
 930        }
 931        rpc_release_calldata(tk_ops, calldata);
 932}
 933
 934static void rpc_async_release(struct work_struct *work)
 935{
 936        rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
 937}
 938
 939static void rpc_release_resources_task(struct rpc_task *task)
 940{
 941        if (task->tk_rqstp)
 942                xprt_release(task);
 943        if (task->tk_msg.rpc_cred) {
 944                put_rpccred(task->tk_msg.rpc_cred);
 945                task->tk_msg.rpc_cred = NULL;
 946        }
 947        rpc_task_release_client(task);
 948}
 949
 950static void rpc_final_put_task(struct rpc_task *task,
 951                struct workqueue_struct *q)
 952{
 953        if (q != NULL) {
 954                INIT_WORK(&task->u.tk_work, rpc_async_release);
 955                queue_work(q, &task->u.tk_work);
 956        } else
 957                rpc_free_task(task);
 958}
 959
 960static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
 961{
 962        if (atomic_dec_and_test(&task->tk_count)) {
 963                rpc_release_resources_task(task);
 964                rpc_final_put_task(task, q);
 965        }
 966}
 967
 968void rpc_put_task(struct rpc_task *task)
 969{
 970        rpc_do_put_task(task, NULL);
 971}
 972EXPORT_SYMBOL_GPL(rpc_put_task);
 973
 974void rpc_put_task_async(struct rpc_task *task)
 975{
 976        rpc_do_put_task(task, task->tk_workqueue);
 977}
 978EXPORT_SYMBOL_GPL(rpc_put_task_async);
 979
 980static void rpc_release_task(struct rpc_task *task)
 981{
 982        dprintk("RPC: %5u release task\n", task->tk_pid);
 983
 984        BUG_ON (RPC_IS_QUEUED(task));
 985
 986        rpc_release_resources_task(task);
 987
 988        /*
 989         * Note: at this point we have been removed from rpc_clnt->cl_tasks,
 990         * so it should be safe to use task->tk_count as a test for whether
 991         * or not any other processes still hold references to our rpc_task.
 992         */
 993        if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
 994                /* Wake up anyone who may be waiting for task completion */
 995                if (!rpc_complete_task(task))
 996                        return;
 997        } else {
 998                if (!atomic_dec_and_test(&task->tk_count))
 999                        return;
1000        }
1001        rpc_final_put_task(task, task->tk_workqueue);
1002}
1003
1004int rpciod_up(void)
1005{
1006        return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1007}
1008
1009void rpciod_down(void)
1010{
1011        module_put(THIS_MODULE);
1012}
1013
1014/*
1015 * Start up the rpciod workqueue.
1016 */
1017static int rpciod_start(void)
1018{
1019        struct workqueue_struct *wq;
1020
1021        /*
1022         * Create the rpciod thread and wait for it to start.
1023         */
1024        dprintk("RPC:       creating workqueue rpciod\n");
1025        wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 0);
1026        rpciod_workqueue = wq;
1027        return rpciod_workqueue != NULL;
1028}
1029
1030static void rpciod_stop(void)
1031{
1032        struct workqueue_struct *wq = NULL;
1033
1034        if (rpciod_workqueue == NULL)
1035                return;
1036        dprintk("RPC:       destroying workqueue rpciod\n");
1037
1038        wq = rpciod_workqueue;
1039        rpciod_workqueue = NULL;
1040        destroy_workqueue(wq);
1041}
1042
1043void
1044rpc_destroy_mempool(void)
1045{
1046        rpciod_stop();
1047        if (rpc_buffer_mempool)
1048                mempool_destroy(rpc_buffer_mempool);
1049        if (rpc_task_mempool)
1050                mempool_destroy(rpc_task_mempool);
1051        if (rpc_task_slabp)
1052                kmem_cache_destroy(rpc_task_slabp);
1053        if (rpc_buffer_slabp)
1054                kmem_cache_destroy(rpc_buffer_slabp);
1055        rpc_destroy_wait_queue(&delay_queue);
1056}
1057
1058int
1059rpc_init_mempool(void)
1060{
1061        /*
1062         * The following is not strictly a mempool initialisation,
1063         * but there is no harm in doing it here
1064         */
1065        rpc_init_wait_queue(&delay_queue, "delayq");
1066        if (!rpciod_start())
1067                goto err_nomem;
1068
1069        rpc_task_slabp = kmem_cache_create("rpc_tasks",
1070                                             sizeof(struct rpc_task),
1071                                             0, SLAB_HWCACHE_ALIGN,
1072                                             NULL);
1073        if (!rpc_task_slabp)
1074                goto err_nomem;
1075        rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1076                                             RPC_BUFFER_MAXSIZE,
1077                                             0, SLAB_HWCACHE_ALIGN,
1078                                             NULL);
1079        if (!rpc_buffer_slabp)
1080                goto err_nomem;
1081        rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1082                                                    rpc_task_slabp);
1083        if (!rpc_task_mempool)
1084                goto err_nomem;
1085        rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1086                                                      rpc_buffer_slabp);
1087        if (!rpc_buffer_mempool)
1088                goto err_nomem;
1089        return 0;
1090err_nomem:
1091        rpc_destroy_mempool();
1092        return -ENOMEM;
1093}
1094
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