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