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/smp_lock.h>
  20#include <linux/spinlock.h>
  21#include <linux/mutex.h>
  22
  23#include <linux/sunrpc/clnt.h>
  24
  25#ifdef RPC_DEBUG
  26#define RPCDBG_FACILITY         RPCDBG_SCHED
  27#define RPC_TASK_MAGIC_ID       0xf00baa
  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}
 212
 213void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 214{
 215        __rpc_init_priority_wait_queue(queue, qname, 1);
 216}
 217EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
 218
 219void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
 220{
 221        del_timer_sync(&queue->timer_list.timer);
 222}
 223EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
 224
 225static int rpc_wait_bit_killable(void *word)
 226{
 227        if (fatal_signal_pending(current))
 228                return -ERESTARTSYS;
 229        schedule();
 230        return 0;
 231}
 232
 233#ifdef RPC_DEBUG
 234static void rpc_task_set_debuginfo(struct rpc_task *task)
 235{
 236        static atomic_t rpc_pid;
 237
 238        task->tk_magic = RPC_TASK_MAGIC_ID;
 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#ifdef RPC_DEBUG
 362        BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 363#endif
 364        /* Has the task been executed yet? If not, we cannot wake it up! */
 365        if (!RPC_IS_ACTIVATED(task)) {
 366                printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 367                return;
 368        }
 369
 370        __rpc_remove_wait_queue(queue, task);
 371
 372        rpc_make_runnable(task);
 373
 374        dprintk("RPC:       __rpc_wake_up_task done\n");
 375}
 376
 377/*
 378 * Wake up a queued task while the queue lock is being held
 379 */
 380static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
 381{
 382        if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
 383                __rpc_do_wake_up_task(queue, task);
 384}
 385
 386/*
 387 * Wake up a task on a specific queue
 388 */
 389void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 390{
 391        spin_lock_bh(&queue->lock);
 392        rpc_wake_up_task_queue_locked(queue, task);
 393        spin_unlock_bh(&queue->lock);
 394}
 395EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
 396
 397/*
 398 * Wake up the specified task
 399 */
 400static void rpc_wake_up_task(struct rpc_task *task)
 401{
 402        rpc_wake_up_queued_task(task->tk_waitqueue, task);
 403}
 404
 405/*
 406 * Wake up the next task on a priority queue.
 407 */
 408static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
 409{
 410        struct list_head *q;
 411        struct rpc_task *task;
 412
 413        /*
 414         * Service a batch of tasks from a single owner.
 415         */
 416        q = &queue->tasks[queue->priority];
 417        if (!list_empty(q)) {
 418                task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 419                if (queue->owner == task->tk_owner) {
 420                        if (--queue->nr)
 421                                goto out;
 422                        list_move_tail(&task->u.tk_wait.list, q);
 423                }
 424                /*
 425                 * Check if we need to switch queues.
 426                 */
 427                if (--queue->count)
 428                        goto new_owner;
 429        }
 430
 431        /*
 432         * Service the next queue.
 433         */
 434        do {
 435                if (q == &queue->tasks[0])
 436                        q = &queue->tasks[queue->maxpriority];
 437                else
 438                        q = q - 1;
 439                if (!list_empty(q)) {
 440                        task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 441                        goto new_queue;
 442                }
 443        } while (q != &queue->tasks[queue->priority]);
 444
 445        rpc_reset_waitqueue_priority(queue);
 446        return NULL;
 447
 448new_queue:
 449        rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 450new_owner:
 451        rpc_set_waitqueue_owner(queue, task->tk_owner);
 452out:
 453        rpc_wake_up_task_queue_locked(queue, task);
 454        return task;
 455}
 456
 457/*
 458 * Wake up the next task on the wait queue.
 459 */
 460struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
 461{
 462        struct rpc_task *task = NULL;
 463
 464        dprintk("RPC:       wake_up_next(%p \"%s\")\n",
 465                        queue, rpc_qname(queue));
 466        spin_lock_bh(&queue->lock);
 467        if (RPC_IS_PRIORITY(queue))
 468                task = __rpc_wake_up_next_priority(queue);
 469        else {
 470                task_for_first(task, &queue->tasks[0])
 471                        rpc_wake_up_task_queue_locked(queue, task);
 472        }
 473        spin_unlock_bh(&queue->lock);
 474
 475        return task;
 476}
 477EXPORT_SYMBOL_GPL(rpc_wake_up_next);
 478
 479/**
 480 * rpc_wake_up - wake up all rpc_tasks
 481 * @queue: rpc_wait_queue on which the tasks are sleeping
 482 *
 483 * Grabs queue->lock
 484 */
 485void rpc_wake_up(struct rpc_wait_queue *queue)
 486{
 487        struct rpc_task *task, *next;
 488        struct list_head *head;
 489
 490        spin_lock_bh(&queue->lock);
 491        head = &queue->tasks[queue->maxpriority];
 492        for (;;) {
 493                list_for_each_entry_safe(task, next, head, u.tk_wait.list)
 494                        rpc_wake_up_task_queue_locked(queue, task);
 495                if (head == &queue->tasks[0])
 496                        break;
 497                head--;
 498        }
 499        spin_unlock_bh(&queue->lock);
 500}
 501EXPORT_SYMBOL_GPL(rpc_wake_up);
 502
 503/**
 504 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 505 * @queue: rpc_wait_queue on which the tasks are sleeping
 506 * @status: status value to set
 507 *
 508 * Grabs queue->lock
 509 */
 510void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 511{
 512        struct rpc_task *task, *next;
 513        struct list_head *head;
 514
 515        spin_lock_bh(&queue->lock);
 516        head = &queue->tasks[queue->maxpriority];
 517        for (;;) {
 518                list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
 519                        task->tk_status = status;
 520                        rpc_wake_up_task_queue_locked(queue, task);
 521                }
 522                if (head == &queue->tasks[0])
 523                        break;
 524                head--;
 525        }
 526        spin_unlock_bh(&queue->lock);
 527}
 528EXPORT_SYMBOL_GPL(rpc_wake_up_status);
 529
 530static void __rpc_queue_timer_fn(unsigned long ptr)
 531{
 532        struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
 533        struct rpc_task *task, *n;
 534        unsigned long expires, now, timeo;
 535
 536        spin_lock(&queue->lock);
 537        expires = now = jiffies;
 538        list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
 539                timeo = task->u.tk_wait.expires;
 540                if (time_after_eq(now, timeo)) {
 541                        dprintk("RPC: %5u timeout\n", task->tk_pid);
 542                        task->tk_status = -ETIMEDOUT;
 543                        rpc_wake_up_task_queue_locked(queue, task);
 544                        continue;
 545                }
 546                if (expires == now || time_after(expires, timeo))
 547                        expires = timeo;
 548        }
 549        if (!list_empty(&queue->timer_list.list))
 550                rpc_set_queue_timer(queue, expires);
 551        spin_unlock(&queue->lock);
 552}
 553
 554static void __rpc_atrun(struct rpc_task *task)
 555{
 556        task->tk_status = 0;
 557}
 558
 559/*
 560 * Run a task at a later time
 561 */
 562void rpc_delay(struct rpc_task *task, unsigned long delay)
 563{
 564        task->tk_timeout = delay;
 565        rpc_sleep_on(&delay_queue, task, __rpc_atrun);
 566}
 567EXPORT_SYMBOL_GPL(rpc_delay);
 568
 569/*
 570 * Helper to call task->tk_ops->rpc_call_prepare
 571 */
 572static void rpc_prepare_task(struct rpc_task *task)
 573{
 574        task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 575}
 576
 577/*
 578 * Helper that calls task->tk_ops->rpc_call_done if it exists
 579 */
 580void rpc_exit_task(struct rpc_task *task)
 581{
 582        task->tk_action = NULL;
 583        if (task->tk_ops->rpc_call_done != NULL) {
 584                task->tk_ops->rpc_call_done(task, task->tk_calldata);
 585                if (task->tk_action != NULL) {
 586                        WARN_ON(RPC_ASSASSINATED(task));
 587                        /* Always release the RPC slot and buffer memory */
 588                        xprt_release(task);
 589                }
 590        }
 591}
 592EXPORT_SYMBOL_GPL(rpc_exit_task);
 593
 594void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
 595{
 596        if (ops->rpc_release != NULL)
 597                ops->rpc_release(calldata);
 598}
 599
 600/*
 601 * This is the RPC `scheduler' (or rather, the finite state machine).
 602 */
 603static void __rpc_execute(struct rpc_task *task)
 604{
 605        struct rpc_wait_queue *queue;
 606        int task_is_async = RPC_IS_ASYNC(task);
 607        int status = 0;
 608
 609        dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
 610                        task->tk_pid, task->tk_flags);
 611
 612        BUG_ON(RPC_IS_QUEUED(task));
 613
 614        for (;;) {
 615
 616                /*
 617                 * Execute any pending callback.
 618                 */
 619                if (task->tk_callback) {
 620                        void (*save_callback)(struct rpc_task *);
 621
 622                        /*
 623                         * We set tk_callback to NULL before calling it,
 624                         * in case it sets the tk_callback field itself:
 625                         */
 626                        save_callback = task->tk_callback;
 627                        task->tk_callback = NULL;
 628                        save_callback(task);
 629                }
 630
 631                /*
 632                 * Perform the next FSM step.
 633                 * tk_action may be NULL when the task has been killed
 634                 * by someone else.
 635                 */
 636                if (!RPC_IS_QUEUED(task)) {
 637                        if (task->tk_action == NULL)
 638                                break;
 639                        task->tk_action(task);
 640                }
 641
 642                /*
 643                 * Lockless check for whether task is sleeping or not.
 644                 */
 645                if (!RPC_IS_QUEUED(task))
 646                        continue;
 647                /*
 648                 * The queue->lock protects against races with
 649                 * rpc_make_runnable().
 650                 *
 651                 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
 652                 * rpc_task, rpc_make_runnable() can assign it to a
 653                 * different workqueue. We therefore cannot assume that the
 654                 * rpc_task pointer may still be dereferenced.
 655                 */
 656                queue = task->tk_waitqueue;
 657                spin_lock_bh(&queue->lock);
 658                if (!RPC_IS_QUEUED(task)) {
 659                        spin_unlock_bh(&queue->lock);
 660                        continue;
 661                }
 662                rpc_clear_running(task);
 663                spin_unlock_bh(&queue->lock);
 664                if (task_is_async)
 665                        return;
 666
 667                /* sync task: sleep here */
 668                dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
 669                status = out_of_line_wait_on_bit(&task->tk_runstate,
 670                                RPC_TASK_QUEUED, rpc_wait_bit_killable,
 671                                TASK_KILLABLE);
 672                if (status == -ERESTARTSYS) {
 673                        /*
 674                         * When a sync task receives a signal, it exits with
 675                         * -ERESTARTSYS. In order to catch any callbacks that
 676                         * clean up after sleeping on some queue, we don't
 677                         * break the loop here, but go around once more.
 678                         */
 679                        dprintk("RPC: %5u got signal\n", task->tk_pid);
 680                        task->tk_flags |= RPC_TASK_KILLED;
 681                        rpc_exit(task, -ERESTARTSYS);
 682                        rpc_wake_up_task(task);
 683                }
 684                rpc_set_running(task);
 685                dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
 686        }
 687
 688        dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
 689                        task->tk_status);
 690        /* Release all resources associated with the task */
 691        rpc_release_task(task);
 692}
 693
 694/*
 695 * User-visible entry point to the scheduler.
 696 *
 697 * This may be called recursively if e.g. an async NFS task updates
 698 * the attributes and finds that dirty pages must be flushed.
 699 * NOTE: Upon exit of this function the task is guaranteed to be
 700 *       released. In particular note that tk_release() will have
 701 *       been called, so your task memory may have been freed.
 702 */
 703void rpc_execute(struct rpc_task *task)
 704{
 705        rpc_set_active(task);
 706        rpc_set_running(task);
 707        __rpc_execute(task);
 708}
 709
 710static void rpc_async_schedule(struct work_struct *work)
 711{
 712        __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
 713}
 714
 715struct rpc_buffer {
 716        size_t  len;
 717        char    data[];
 718};
 719
 720/**
 721 * rpc_malloc - allocate an RPC buffer
 722 * @task: RPC task that will use this buffer
 723 * @size: requested byte size
 724 *
 725 * To prevent rpciod from hanging, this allocator never sleeps,
 726 * returning NULL if the request cannot be serviced immediately.
 727 * The caller can arrange to sleep in a way that is safe for rpciod.
 728 *
 729 * Most requests are 'small' (under 2KiB) and can be serviced from a
 730 * mempool, ensuring that NFS reads and writes can always proceed,
 731 * and that there is good locality of reference for these buffers.
 732 *
 733 * In order to avoid memory starvation triggering more writebacks of
 734 * NFS requests, we avoid using GFP_KERNEL.
 735 */
 736void *rpc_malloc(struct rpc_task *task, size_t size)
 737{
 738        struct rpc_buffer *buf;
 739        gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
 740
 741        size += sizeof(struct rpc_buffer);
 742        if (size <= RPC_BUFFER_MAXSIZE)
 743                buf = mempool_alloc(rpc_buffer_mempool, gfp);
 744        else
 745                buf = kmalloc(size, gfp);
 746
 747        if (!buf)
 748                return NULL;
 749
 750        buf->len = size;
 751        dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
 752                        task->tk_pid, size, buf);
 753        return &buf->data;
 754}
 755EXPORT_SYMBOL_GPL(rpc_malloc);
 756
 757/**
 758 * rpc_free - free buffer allocated via rpc_malloc
 759 * @buffer: buffer to free
 760 *
 761 */
 762void rpc_free(void *buffer)
 763{
 764        size_t size;
 765        struct rpc_buffer *buf;
 766
 767        if (!buffer)
 768                return;
 769
 770        buf = container_of(buffer, struct rpc_buffer, data);
 771        size = buf->len;
 772
 773        dprintk("RPC:       freeing buffer of size %zu at %p\n",
 774                        size, buf);
 775
 776        if (size <= RPC_BUFFER_MAXSIZE)
 777                mempool_free(buf, rpc_buffer_mempool);
 778        else
 779                kfree(buf);
 780}
 781EXPORT_SYMBOL_GPL(rpc_free);
 782
 783/*
 784 * Creation and deletion of RPC task structures
 785 */
 786static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
 787{
 788        memset(task, 0, sizeof(*task));
 789        atomic_set(&task->tk_count, 1);
 790        task->tk_flags  = task_setup_data->flags;
 791        task->tk_ops = task_setup_data->callback_ops;
 792        task->tk_calldata = task_setup_data->callback_data;
 793        INIT_LIST_HEAD(&task->tk_task);
 794
 795        /* Initialize retry counters */
 796        task->tk_garb_retry = 2;
 797        task->tk_cred_retry = 2;
 798
 799        task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
 800        task->tk_owner = current->tgid;
 801
 802        /* Initialize workqueue for async tasks */
 803        task->tk_workqueue = task_setup_data->workqueue;
 804
 805        task->tk_client = task_setup_data->rpc_client;
 806        if (task->tk_client != NULL) {
 807                kref_get(&task->tk_client->cl_kref);
 808                if (task->tk_client->cl_softrtry)
 809                        task->tk_flags |= RPC_TASK_SOFT;
 810        }
 811
 812        if (task->tk_ops->rpc_call_prepare != NULL)
 813                task->tk_action = rpc_prepare_task;
 814
 815        if (task_setup_data->rpc_message != NULL) {
 816                task->tk_msg.rpc_proc = task_setup_data->rpc_message->rpc_proc;
 817                task->tk_msg.rpc_argp = task_setup_data->rpc_message->rpc_argp;
 818                task->tk_msg.rpc_resp = task_setup_data->rpc_message->rpc_resp;
 819                /* Bind the user cred */
 820                rpcauth_bindcred(task, task_setup_data->rpc_message->rpc_cred, task_setup_data->flags);
 821                if (task->tk_action == NULL)
 822                        rpc_call_start(task);
 823        }
 824
 825        /* starting timestamp */
 826        task->tk_start = jiffies;
 827
 828        dprintk("RPC:       new task initialized, procpid %u\n",
 829                                task_pid_nr(current));
 830}
 831
 832static struct rpc_task *
 833rpc_alloc_task(void)
 834{
 835        return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 836}
 837
 838/*
 839 * Create a new task for the specified client.
 840 */
 841struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
 842{
 843        struct rpc_task *task = setup_data->task;
 844        unsigned short flags = 0;
 845
 846        if (task == NULL) {
 847                task = rpc_alloc_task();
 848                if (task == NULL)
 849                        goto out;
 850                flags = RPC_TASK_DYNAMIC;
 851        }
 852
 853        rpc_init_task(task, setup_data);
 854
 855        task->tk_flags |= flags;
 856        dprintk("RPC:       allocated task %p\n", task);
 857out:
 858        return task;
 859}
 860
 861static void rpc_free_task(struct rpc_task *task)
 862{
 863        const struct rpc_call_ops *tk_ops = task->tk_ops;
 864        void *calldata = task->tk_calldata;
 865
 866        if (task->tk_flags & RPC_TASK_DYNAMIC) {
 867                dprintk("RPC: %5u freeing task\n", task->tk_pid);
 868                mempool_free(task, rpc_task_mempool);
 869        }
 870        rpc_release_calldata(tk_ops, calldata);
 871}
 872
 873static void rpc_async_release(struct work_struct *work)
 874{
 875        rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
 876}
 877
 878void rpc_put_task(struct rpc_task *task)
 879{
 880        if (!atomic_dec_and_test(&task->tk_count))
 881                return;
 882        /* Release resources */
 883        if (task->tk_rqstp)
 884                xprt_release(task);
 885        if (task->tk_msg.rpc_cred)
 886                rpcauth_unbindcred(task);
 887        if (task->tk_client) {
 888                rpc_release_client(task->tk_client);
 889                task->tk_client = NULL;
 890        }
 891        if (task->tk_workqueue != NULL) {
 892                INIT_WORK(&task->u.tk_work, rpc_async_release);
 893                queue_work(task->tk_workqueue, &task->u.tk_work);
 894        } else
 895                rpc_free_task(task);
 896}
 897EXPORT_SYMBOL_GPL(rpc_put_task);
 898
 899static void rpc_release_task(struct rpc_task *task)
 900{
 901#ifdef RPC_DEBUG
 902        BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 903#endif
 904        dprintk("RPC: %5u release task\n", task->tk_pid);
 905
 906        if (!list_empty(&task->tk_task)) {
 907                struct rpc_clnt *clnt = task->tk_client;
 908                /* Remove from client task list */
 909                spin_lock(&clnt->cl_lock);
 910                list_del(&task->tk_task);
 911                spin_unlock(&clnt->cl_lock);
 912        }
 913        BUG_ON (RPC_IS_QUEUED(task));
 914
 915#ifdef RPC_DEBUG
 916        task->tk_magic = 0;
 917#endif
 918        /* Wake up anyone who is waiting for task completion */
 919        rpc_mark_complete_task(task);
 920
 921        rpc_put_task(task);
 922}
 923
 924/*
 925 * Kill all tasks for the given client.
 926 * XXX: kill their descendants as well?
 927 */
 928void rpc_killall_tasks(struct rpc_clnt *clnt)
 929{
 930        struct rpc_task *rovr;
 931
 932
 933        if (list_empty(&clnt->cl_tasks))
 934                return;
 935        dprintk("RPC:       killing all tasks for client %p\n", clnt);
 936        /*
 937         * Spin lock all_tasks to prevent changes...
 938         */
 939        spin_lock(&clnt->cl_lock);
 940        list_for_each_entry(rovr, &clnt->cl_tasks, tk_task) {
 941                if (! RPC_IS_ACTIVATED(rovr))
 942                        continue;
 943                if (!(rovr->tk_flags & RPC_TASK_KILLED)) {
 944                        rovr->tk_flags |= RPC_TASK_KILLED;
 945                        rpc_exit(rovr, -EIO);
 946                        rpc_wake_up_task(rovr);
 947                }
 948        }
 949        spin_unlock(&clnt->cl_lock);
 950}
 951EXPORT_SYMBOL_GPL(rpc_killall_tasks);
 952
 953int rpciod_up(void)
 954{
 955        return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
 956}
 957
 958void rpciod_down(void)
 959{
 960        module_put(THIS_MODULE);
 961}
 962
 963/*
 964 * Start up the rpciod workqueue.
 965 */
 966static int rpciod_start(void)
 967{
 968        struct workqueue_struct *wq;
 969
 970        /*
 971         * Create the rpciod thread and wait for it to start.
 972         */
 973        dprintk("RPC:       creating workqueue rpciod\n");
 974        wq = create_workqueue("rpciod");
 975        rpciod_workqueue = wq;
 976        return rpciod_workqueue != NULL;
 977}
 978
 979static void rpciod_stop(void)
 980{
 981        struct workqueue_struct *wq = NULL;
 982
 983        if (rpciod_workqueue == NULL)
 984                return;
 985        dprintk("RPC:       destroying workqueue rpciod\n");
 986
 987        wq = rpciod_workqueue;
 988        rpciod_workqueue = NULL;
 989        destroy_workqueue(wq);
 990}
 991
 992void
 993rpc_destroy_mempool(void)
 994{
 995        rpciod_stop();
 996        if (rpc_buffer_mempool)
 997                mempool_destroy(rpc_buffer_mempool);
 998        if (rpc_task_mempool)
 999                mempool_destroy(rpc_task_mempool);
1000        if (rpc_task_slabp)
1001                kmem_cache_destroy(rpc_task_slabp);
1002        if (rpc_buffer_slabp)
1003                kmem_cache_destroy(rpc_buffer_slabp);
1004        rpc_destroy_wait_queue(&delay_queue);
1005}
1006
1007int
1008rpc_init_mempool(void)
1009{
1010        /*
1011         * The following is not strictly a mempool initialisation,
1012         * but there is no harm in doing it here
1013         */
1014        rpc_init_wait_queue(&delay_queue, "delayq");
1015        if (!rpciod_start())
1016                goto err_nomem;
1017
1018        rpc_task_slabp = kmem_cache_create("rpc_tasks",
1019                                             sizeof(struct rpc_task),
1020                                             0, SLAB_HWCACHE_ALIGN,
1021                                             NULL);
1022        if (!rpc_task_slabp)
1023                goto err_nomem;
1024        rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1025                                             RPC_BUFFER_MAXSIZE,
1026                                             0, SLAB_HWCACHE_ALIGN,
1027                                             NULL);
1028        if (!rpc_buffer_slabp)
1029                goto err_nomem;
1030        rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1031                                                    rpc_task_slabp);
1032        if (!rpc_task_mempool)
1033                goto err_nomem;
1034        rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1035                                                      rpc_buffer_slabp);
1036        if (!rpc_buffer_mempool)
1037                goto err_nomem;
1038        return 0;
1039err_nomem:
1040        rpc_destroy_mempool();
1041        return -ENOMEM;
1042}
1043