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
 101static void rpc_rotate_queue_owner(struct rpc_wait_queue *queue)
 102{
 103        struct list_head *q = &queue->tasks[queue->priority];
 104        struct rpc_task *task;
 105
 106        if (!list_empty(q)) {
 107                task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
 108                if (task->tk_owner == queue->owner)
 109                        list_move_tail(&task->u.tk_wait.list, q);
 110        }
 111}
 112
 113static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 114{
 115        if (queue->priority != priority) {
 116                /* Fairness: rotate the list when changing priority */
 117                rpc_rotate_queue_owner(queue);
 118                queue->priority = priority;
 119        }
 120}
 121
 122static void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
 123{
 124        queue->owner = pid;
 125        queue->nr = RPC_BATCH_COUNT;
 126}
 127
 128static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 129{
 130        rpc_set_waitqueue_priority(queue, queue->maxpriority);
 131        rpc_set_waitqueue_owner(queue, 0);
 132}
 133
 134/*
 135 * Add new request to a priority queue.
 136 */
 137static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
 138                struct rpc_task *task,
 139                unsigned char queue_priority)
 140{
 141        struct list_head *q;
 142        struct rpc_task *t;
 143
 144        INIT_LIST_HEAD(&task->u.tk_wait.links);
 145        if (unlikely(queue_priority > queue->maxpriority))
 146                queue_priority = queue->maxpriority;
 147        if (queue_priority > queue->priority)
 148                rpc_set_waitqueue_priority(queue, queue_priority);
 149        q = &queue->tasks[queue_priority];
 150        list_for_each_entry(t, q, u.tk_wait.list) {
 151                if (t->tk_owner == task->tk_owner) {
 152                        list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
 153                        return;
 154                }
 155        }
 156        list_add_tail(&task->u.tk_wait.list, q);
 157}
 158
 159/*
 160 * Add new request to wait queue.
 161 *
 162 * Swapper tasks always get inserted at the head of the queue.
 163 * This should avoid many nasty memory deadlocks and hopefully
 164 * improve overall performance.
 165 * Everyone else gets appended to the queue to ensure proper FIFO behavior.
 166 */
 167static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
 168                struct rpc_task *task,
 169                unsigned char queue_priority)
 170{
 171        WARN_ON_ONCE(RPC_IS_QUEUED(task));
 172        if (RPC_IS_QUEUED(task))
 173                return;
 174
 175        if (RPC_IS_PRIORITY(queue))
 176                __rpc_add_wait_queue_priority(queue, task, queue_priority);
 177        else if (RPC_IS_SWAPPER(task))
 178                list_add(&task->u.tk_wait.list, &queue->tasks[0]);
 179        else
 180                list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
 181        task->tk_waitqueue = queue;
 182        queue->qlen++;
 183        rpc_set_queued(task);
 184
 185        dprintk("RPC: %5u added to queue %p \"%s\"\n",
 186                        task->tk_pid, queue, rpc_qname(queue));
 187}
 188
 189/*
 190 * Remove request from a priority queue.
 191 */
 192static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 193{
 194        struct rpc_task *t;
 195
 196        if (!list_empty(&task->u.tk_wait.links)) {
 197                t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
 198                list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
 199                list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
 200        }
 201}
 202
 203/*
 204 * Remove request from queue.
 205 * Note: must be called with spin lock held.
 206 */
 207static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
 208{
 209        __rpc_disable_timer(queue, task);
 210        if (RPC_IS_PRIORITY(queue))
 211                __rpc_remove_wait_queue_priority(task);
 212        list_del(&task->u.tk_wait.list);
 213        queue->qlen--;
 214        dprintk("RPC: %5u removed from queue %p \"%s\"\n",
 215                        task->tk_pid, queue, rpc_qname(queue));
 216}
 217
 218static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
 219{
 220        int i;
 221
 222        spin_lock_init(&queue->lock);
 223        for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 224                INIT_LIST_HEAD(&queue->tasks[i]);
 225        queue->maxpriority = nr_queues - 1;
 226        rpc_reset_waitqueue_priority(queue);
 227        queue->qlen = 0;
 228        setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
 229        INIT_LIST_HEAD(&queue->timer_list.list);
 230        rpc_assign_waitqueue_name(queue, qname);
 231}
 232
 233void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 234{
 235        __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
 236}
 237EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
 238
 239void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 240{
 241        __rpc_init_priority_wait_queue(queue, qname, 1);
 242}
 243EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
 244
 245void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
 246{
 247        del_timer_sync(&queue->timer_list.timer);
 248}
 249EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
 250
 251static int rpc_wait_bit_killable(void *word)
 252{
 253        if (fatal_signal_pending(current))
 254                return -ERESTARTSYS;
 255        freezable_schedule();
 256        return 0;
 257}
 258
 259#ifdef RPC_DEBUG
 260static void rpc_task_set_debuginfo(struct rpc_task *task)
 261{
 262        static atomic_t rpc_pid;
 263
 264        task->tk_pid = atomic_inc_return(&rpc_pid);
 265}
 266#else
 267static inline void rpc_task_set_debuginfo(struct rpc_task *task)
 268{
 269}
 270#endif
 271
 272static void rpc_set_active(struct rpc_task *task)
 273{
 274        trace_rpc_task_begin(task->tk_client, task, NULL);
 275
 276        rpc_task_set_debuginfo(task);
 277        set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 278}
 279
 280/*
 281 * Mark an RPC call as having completed by clearing the 'active' bit
 282 * and then waking up all tasks that were sleeping.
 283 */
 284static int rpc_complete_task(struct rpc_task *task)
 285{
 286        void *m = &task->tk_runstate;
 287        wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
 288        struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
 289        unsigned long flags;
 290        int ret;
 291
 292        trace_rpc_task_complete(task->tk_client, task, NULL);
 293
 294        spin_lock_irqsave(&wq->lock, flags);
 295        clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 296        ret = atomic_dec_and_test(&task->tk_count);
 297        if (waitqueue_active(wq))
 298                __wake_up_locked_key(wq, TASK_NORMAL, &k);
 299        spin_unlock_irqrestore(&wq->lock, flags);
 300        return ret;
 301}
 302
 303/*
 304 * Allow callers to wait for completion of an RPC call
 305 *
 306 * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
 307 * to enforce taking of the wq->lock and hence avoid races with
 308 * rpc_complete_task().
 309 */
 310int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
 311{
 312        if (action == NULL)
 313                action = rpc_wait_bit_killable;
 314        return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 315                        action, TASK_KILLABLE);
 316}
 317EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
 318
 319/*
 320 * Make an RPC task runnable.
 321 *
 322 * Note: If the task is ASYNC, and is being made runnable after sitting on an
 323 * rpc_wait_queue, this must be called with the queue spinlock held to protect
 324 * the wait queue operation.
 325 */
 326static void rpc_make_runnable(struct rpc_task *task)
 327{
 328        rpc_clear_queued(task);
 329        if (rpc_test_and_set_running(task))
 330                return;
 331        if (RPC_IS_ASYNC(task)) {
 332                INIT_WORK(&task->u.tk_work, rpc_async_schedule);
 333                queue_work(rpciod_workqueue, &task->u.tk_work);
 334        } else
 335                wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 336}
 337
 338/*
 339 * Prepare for sleeping on a wait queue.
 340 * By always appending tasks to the list we ensure FIFO behavior.
 341 * NB: An RPC task will only receive interrupt-driven events as long
 342 * as it's on a wait queue.
 343 */
 344static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
 345                struct rpc_task *task,
 346                rpc_action action,
 347                unsigned char queue_priority)
 348{
 349        dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
 350                        task->tk_pid, rpc_qname(q), jiffies);
 351
 352        trace_rpc_task_sleep(task->tk_client, task, q);
 353
 354        __rpc_add_wait_queue(q, task, queue_priority);
 355
 356        WARN_ON_ONCE(task->tk_callback != NULL);
 357        task->tk_callback = action;
 358        __rpc_add_timer(q, task);
 359}
 360
 361void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 362                                rpc_action action)
 363{
 364        /* We shouldn't ever put an inactive task to sleep */
 365        WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
 366        if (!RPC_IS_ACTIVATED(task)) {
 367                task->tk_status = -EIO;
 368                rpc_put_task_async(task);
 369                return;
 370        }
 371
 372        /*
 373         * Protect the queue operations.
 374         */
 375        spin_lock_bh(&q->lock);
 376        __rpc_sleep_on_priority(q, task, action, task->tk_priority);
 377        spin_unlock_bh(&q->lock);
 378}
 379EXPORT_SYMBOL_GPL(rpc_sleep_on);
 380
 381void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
 382                rpc_action action, int priority)
 383{
 384        /* We shouldn't ever put an inactive task to sleep */
 385        WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
 386        if (!RPC_IS_ACTIVATED(task)) {
 387                task->tk_status = -EIO;
 388                rpc_put_task_async(task);
 389                return;
 390        }
 391
 392        /*
 393         * Protect the queue operations.
 394         */
 395        spin_lock_bh(&q->lock);
 396        __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
 397        spin_unlock_bh(&q->lock);
 398}
 399EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
 400
 401/**
 402 * __rpc_do_wake_up_task - wake up a single rpc_task
 403 * @queue: wait queue
 404 * @task: task to be woken up
 405 *
 406 * Caller must hold queue->lock, and have cleared the task queued flag.
 407 */
 408static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 409{
 410        dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
 411                        task->tk_pid, jiffies);
 412
 413        /* Has the task been executed yet? If not, we cannot wake it up! */
 414        if (!RPC_IS_ACTIVATED(task)) {
 415                printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 416                return;
 417        }
 418
 419        trace_rpc_task_wakeup(task->tk_client, task, queue);
 420
 421        __rpc_remove_wait_queue(queue, task);
 422
 423        rpc_make_runnable(task);
 424
 425        dprintk("RPC:       __rpc_wake_up_task done\n");
 426}
 427
 428/*
 429 * Wake up a queued task while the queue lock is being held
 430 */
 431static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
 432{
 433        if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
 434                __rpc_do_wake_up_task(queue, task);
 435}
 436
 437/*
 438 * Tests whether rpc queue is empty
 439 */
 440int rpc_queue_empty(struct rpc_wait_queue *queue)
 441{
 442        int res;
 443
 444        spin_lock_bh(&queue->lock);
 445        res = queue->qlen;
 446        spin_unlock_bh(&queue->lock);
 447        return res == 0;
 448}
 449EXPORT_SYMBOL_GPL(rpc_queue_empty);
 450
 451/*
 452 * Wake up a task on a specific queue
 453 */
 454void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 455{
 456        spin_lock_bh(&queue->lock);
 457        rpc_wake_up_task_queue_locked(queue, task);
 458        spin_unlock_bh(&queue->lock);
 459}
 460EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
 461
 462/*
 463 * Wake up the next task on a priority queue.
 464 */
 465static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
 466{
 467        struct list_head *q;
 468        struct rpc_task *task;
 469
 470        /*
 471         * Service a batch of tasks from a single owner.
 472         */
 473        q = &queue->tasks[queue->priority];
 474        if (!list_empty(q)) {
 475                task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 476                if (queue->owner == task->tk_owner) {
 477                        if (--queue->nr)
 478                                goto out;
 479                        list_move_tail(&task->u.tk_wait.list, q);
 480                }
 481                /*
 482                 * Check if we need to switch queues.
 483                 */
 484                goto new_owner;
 485        }
 486
 487        /*
 488         * Service the next queue.
 489         */
 490        do {
 491                if (q == &queue->tasks[0])
 492                        q = &queue->tasks[queue->maxpriority];
 493                else
 494                        q = q - 1;
 495                if (!list_empty(q)) {
 496                        task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 497                        goto new_queue;
 498                }
 499        } while (q != &queue->tasks[queue->priority]);
 500
 501        rpc_reset_waitqueue_priority(queue);
 502        return NULL;
 503
 504new_queue:
 505        rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 506new_owner:
 507        rpc_set_waitqueue_owner(queue, task->tk_owner);
 508out:
 509        return task;
 510}
 511
 512static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
 513{
 514        if (RPC_IS_PRIORITY(queue))
 515                return __rpc_find_next_queued_priority(queue);
 516        if (!list_empty(&queue->tasks[0]))
 517                return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
 518        return NULL;
 519}
 520
 521/*
 522 * Wake up the first task on the wait queue.
 523 */
 524struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
 525                bool (*func)(struct rpc_task *, void *), void *data)
 526{
 527        struct rpc_task *task = NULL;
 528
 529        dprintk("RPC:       wake_up_first(%p \"%s\")\n",
 530                        queue, rpc_qname(queue));
 531        spin_lock_bh(&queue->lock);
 532        task = __rpc_find_next_queued(queue);
 533        if (task != NULL) {
 534                if (func(task, data))
 535                        rpc_wake_up_task_queue_locked(queue, task);
 536                else
 537                        task = NULL;
 538        }
 539        spin_unlock_bh(&queue->lock);
 540
 541        return task;
 542}
 543EXPORT_SYMBOL_GPL(rpc_wake_up_first);
 544
 545static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
 546{
 547        return true;
 548}
 549
 550/*
 551 * Wake up the next task on the wait queue.
 552*/
 553struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
 554{
 555        return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
 556}
 557EXPORT_SYMBOL_GPL(rpc_wake_up_next);
 558
 559/**
 560 * rpc_wake_up - wake up all rpc_tasks
 561 * @queue: rpc_wait_queue on which the tasks are sleeping
 562 *
 563 * Grabs queue->lock
 564 */
 565void rpc_wake_up(struct rpc_wait_queue *queue)
 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                        rpc_wake_up_task_queue_locked(queue, task);
 578                }
 579                if (head == &queue->tasks[0])
 580                        break;
 581                head--;
 582        }
 583        spin_unlock_bh(&queue->lock);
 584}
 585EXPORT_SYMBOL_GPL(rpc_wake_up);
 586
 587/**
 588 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 589 * @queue: rpc_wait_queue on which the tasks are sleeping
 590 * @status: status value to set
 591 *
 592 * Grabs queue->lock
 593 */
 594void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 595{
 596        struct list_head *head;
 597
 598        spin_lock_bh(&queue->lock);
 599        head = &queue->tasks[queue->maxpriority];
 600        for (;;) {
 601                while (!list_empty(head)) {
 602                        struct rpc_task *task;
 603                        task = list_first_entry(head,
 604                                        struct rpc_task,
 605                                        u.tk_wait.list);
 606                        task->tk_status = status;
 607                        rpc_wake_up_task_queue_locked(queue, task);
 608                }
 609                if (head == &queue->tasks[0])
 610                        break;
 611                head--;
 612        }
 613        spin_unlock_bh(&queue->lock);
 614}
 615EXPORT_SYMBOL_GPL(rpc_wake_up_status);
 616
 617static void __rpc_queue_timer_fn(unsigned long ptr)
 618{
 619        struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
 620        struct rpc_task *task, *n;
 621        unsigned long expires, now, timeo;
 622
 623        spin_lock(&queue->lock);
 624        expires = now = jiffies;
 625        list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
 626                timeo = task->u.tk_wait.expires;
 627                if (time_after_eq(now, timeo)) {
 628                        dprintk("RPC: %5u timeout\n", task->tk_pid);
 629                        task->tk_status = -ETIMEDOUT;
 630                        rpc_wake_up_task_queue_locked(queue, task);
 631                        continue;
 632                }
 633                if (expires == now || time_after(expires, timeo))
 634                        expires = timeo;
 635        }
 636        if (!list_empty(&queue->timer_list.list))
 637                rpc_set_queue_timer(queue, expires);
 638        spin_unlock(&queue->lock);
 639}
 640
 641static void __rpc_atrun(struct rpc_task *task)
 642{
 643        task->tk_status = 0;
 644}
 645
 646/*
 647 * Run a task at a later time
 648 */
 649void rpc_delay(struct rpc_task *task, unsigned long delay)
 650{
 651        task->tk_timeout = delay;
 652        rpc_sleep_on(&delay_queue, task, __rpc_atrun);
 653}
 654EXPORT_SYMBOL_GPL(rpc_delay);
 655
 656/*
 657 * Helper to call task->tk_ops->rpc_call_prepare
 658 */
 659void rpc_prepare_task(struct rpc_task *task)
 660{
 661        task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 662}
 663
 664static void
 665rpc_init_task_statistics(struct rpc_task *task)
 666{
 667        /* Initialize retry counters */
 668        task->tk_garb_retry = 2;
 669        task->tk_cred_retry = 2;
 670        task->tk_rebind_retry = 2;
 671
 672        /* starting timestamp */
 673        task->tk_start = ktime_get();
 674}
 675
 676static void
 677rpc_reset_task_statistics(struct rpc_task *task)
 678{
 679        task->tk_timeouts = 0;
 680        task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
 681
 682        rpc_init_task_statistics(task);
 683}
 684
 685/*
 686 * Helper that calls task->tk_ops->rpc_call_done if it exists
 687 */
 688void rpc_exit_task(struct rpc_task *task)
 689{
 690        task->tk_action = NULL;
 691        if (task->tk_ops->rpc_call_done != NULL) {
 692                task->tk_ops->rpc_call_done(task, task->tk_calldata);
 693                if (task->tk_action != NULL) {
 694                        WARN_ON(RPC_ASSASSINATED(task));
 695                        /* Always release the RPC slot and buffer memory */
 696                        xprt_release(task);
 697                        rpc_reset_task_statistics(task);
 698                }
 699        }
 700}
 701
 702void rpc_exit(struct rpc_task *task, int status)
 703{
 704        task->tk_status = status;
 705        task->tk_action = rpc_exit_task;
 706        if (RPC_IS_QUEUED(task))
 707                rpc_wake_up_queued_task(task->tk_waitqueue, task);
 708}
 709EXPORT_SYMBOL_GPL(rpc_exit);
 710
 711void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
 712{
 713        if (ops->rpc_release != NULL)
 714                ops->rpc_release(calldata);
 715}
 716
 717/*
 718 * This is the RPC `scheduler' (or rather, the finite state machine).
 719 */
 720static void __rpc_execute(struct rpc_task *task)
 721{
 722        struct rpc_wait_queue *queue;
 723        int task_is_async = RPC_IS_ASYNC(task);
 724        int status = 0;
 725
 726        dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
 727                        task->tk_pid, task->tk_flags);
 728
 729        WARN_ON_ONCE(RPC_IS_QUEUED(task));
 730        if (RPC_IS_QUEUED(task))
 731                return;
 732
 733        for (;;) {
 734                void (*do_action)(struct rpc_task *);
 735
 736                /*
 737                 * Execute any pending callback first.
 738                 */
 739                do_action = task->tk_callback;
 740                task->tk_callback = NULL;
 741                if (do_action == NULL) {
 742                        /*
 743                         * Perform the next FSM step.
 744                         * tk_action may be NULL if the task has been killed.
 745                         * In particular, note that rpc_killall_tasks may
 746                         * do this at any time, so beware when dereferencing.
 747                         */
 748                        do_action = task->tk_action;
 749                        if (do_action == NULL)
 750                                break;
 751                }
 752                trace_rpc_task_run_action(task->tk_client, task, task->tk_action);
 753                do_action(task);
 754
 755                /*
 756                 * Lockless check for whether task is sleeping or not.
 757                 */
 758                if (!RPC_IS_QUEUED(task))
 759                        continue;
 760                /*
 761                 * The queue->lock protects against races with
 762                 * rpc_make_runnable().
 763                 *
 764                 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
 765                 * rpc_task, rpc_make_runnable() can assign it to a
 766                 * different workqueue. We therefore cannot assume that the
 767                 * rpc_task pointer may still be dereferenced.
 768                 */
 769                queue = task->tk_waitqueue;
 770                spin_lock_bh(&queue->lock);
 771                if (!RPC_IS_QUEUED(task)) {
 772                        spin_unlock_bh(&queue->lock);
 773                        continue;
 774                }
 775                rpc_clear_running(task);
 776                spin_unlock_bh(&queue->lock);
 777                if (task_is_async)
 778                        return;
 779
 780                /* sync task: sleep here */
 781                dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
 782                status = out_of_line_wait_on_bit(&task->tk_runstate,
 783                                RPC_TASK_QUEUED, rpc_wait_bit_killable,
 784                                TASK_KILLABLE);
 785                if (status == -ERESTARTSYS) {
 786                        /*
 787                         * When a sync task receives a signal, it exits with
 788                         * -ERESTARTSYS. In order to catch any callbacks that
 789                         * clean up after sleeping on some queue, we don't
 790                         * break the loop here, but go around once more.
 791                         */
 792                        dprintk("RPC: %5u got signal\n", task->tk_pid);
 793                        task->tk_flags |= RPC_TASK_KILLED;
 794                        rpc_exit(task, -ERESTARTSYS);
 795                }
 796                rpc_set_running(task);
 797                dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
 798        }
 799
 800        dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
 801                        task->tk_status);
 802        /* Release all resources associated with the task */
 803        rpc_release_task(task);
 804}
 805
 806/*
 807 * User-visible entry point to the scheduler.
 808 *
 809 * This may be called recursively if e.g. an async NFS task updates
 810 * the attributes and finds that dirty pages must be flushed.
 811 * NOTE: Upon exit of this function the task is guaranteed to be
 812 *       released. In particular note that tk_release() will have
 813 *       been called, so your task memory may have been freed.
 814 */
 815void rpc_execute(struct rpc_task *task)
 816{
 817        rpc_set_active(task);
 818        rpc_make_runnable(task);
 819        if (!RPC_IS_ASYNC(task))
 820                __rpc_execute(task);
 821}
 822
 823static void rpc_async_schedule(struct work_struct *work)
 824{
 825        current->flags |= PF_FSTRANS;
 826        __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
 827        current->flags &= ~PF_FSTRANS;
 828}
 829
 830/**
 831 * rpc_malloc - allocate an RPC buffer
 832 * @task: RPC task that will use this buffer
 833 * @size: requested byte size
 834 *
 835 * To prevent rpciod from hanging, this allocator never sleeps,
 836 * returning NULL if the request cannot be serviced immediately.
 837 * The caller can arrange to sleep in a way that is safe for rpciod.
 838 *
 839 * Most requests are 'small' (under 2KiB) and can be serviced from a
 840 * mempool, ensuring that NFS reads and writes can always proceed,
 841 * and that there is good locality of reference for these buffers.
 842 *
 843 * In order to avoid memory starvation triggering more writebacks of
 844 * NFS requests, we avoid using GFP_KERNEL.
 845 */
 846void *rpc_malloc(struct rpc_task *task, size_t size)
 847{
 848        struct rpc_buffer *buf;
 849        gfp_t gfp = GFP_NOWAIT;
 850
 851        if (RPC_IS_SWAPPER(task))
 852                gfp |= __GFP_MEMALLOC;
 853
 854        size += sizeof(struct rpc_buffer);
 855        if (size <= RPC_BUFFER_MAXSIZE)
 856                buf = mempool_alloc(rpc_buffer_mempool, gfp);
 857        else
 858                buf = kmalloc(size, gfp);
 859
 860        if (!buf)
 861                return NULL;
 862
 863        buf->len = size;
 864        dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
 865                        task->tk_pid, size, buf);
 866        return &buf->data;
 867}
 868EXPORT_SYMBOL_GPL(rpc_malloc);
 869
 870/**
 871 * rpc_free - free buffer allocated via rpc_malloc
 872 * @buffer: buffer to free
 873 *
 874 */
 875void rpc_free(void *buffer)
 876{
 877        size_t size;
 878        struct rpc_buffer *buf;
 879
 880        if (!buffer)
 881                return;
 882
 883        buf = container_of(buffer, struct rpc_buffer, data);
 884        size = buf->len;
 885
 886        dprintk("RPC:       freeing buffer of size %zu at %p\n",
 887                        size, buf);
 888
 889        if (size <= RPC_BUFFER_MAXSIZE)
 890                mempool_free(buf, rpc_buffer_mempool);
 891        else
 892                kfree(buf);
 893}
 894EXPORT_SYMBOL_GPL(rpc_free);
 895
 896/*
 897 * Creation and deletion of RPC task structures
 898 */
 899static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
 900{
 901        memset(task, 0, sizeof(*task));
 902        atomic_set(&task->tk_count, 1);
 903        task->tk_flags  = task_setup_data->flags;
 904        task->tk_ops = task_setup_data->callback_ops;
 905        task->tk_calldata = task_setup_data->callback_data;
 906        INIT_LIST_HEAD(&task->tk_task);
 907
 908        task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
 909        task->tk_owner = current->tgid;
 910
 911        /* Initialize workqueue for async tasks */
 912        task->tk_workqueue = task_setup_data->workqueue;
 913
 914        if (task->tk_ops->rpc_call_prepare != NULL)
 915                task->tk_action = rpc_prepare_task;
 916
 917        rpc_init_task_statistics(task);
 918
 919        dprintk("RPC:       new task initialized, procpid %u\n",
 920                                task_pid_nr(current));
 921}
 922
 923static struct rpc_task *
 924rpc_alloc_task(void)
 925{
 926        return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO);
 927}
 928
 929/*
 930 * Create a new task for the specified client.
 931 */
 932struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
 933{
 934        struct rpc_task *task = setup_data->task;
 935        unsigned short flags = 0;
 936
 937        if (task == NULL) {
 938                task = rpc_alloc_task();
 939                if (task == NULL) {
 940                        rpc_release_calldata(setup_data->callback_ops,
 941                                        setup_data->callback_data);
 942                        return ERR_PTR(-ENOMEM);
 943                }
 944                flags = RPC_TASK_DYNAMIC;
 945        }
 946
 947        rpc_init_task(task, setup_data);
 948        task->tk_flags |= flags;
 949        dprintk("RPC:       allocated task %p\n", task);
 950        return task;
 951}
 952
 953/*
 954 * rpc_free_task - release rpc task and perform cleanups
 955 *
 956 * Note that we free up the rpc_task _after_ rpc_release_calldata()
 957 * in order to work around a workqueue dependency issue.
 958 *
 959 * Tejun Heo states:
 960 * "Workqueue currently considers two work items to be the same if they're
 961 * on the same address and won't execute them concurrently - ie. it
 962 * makes a work item which is queued again while being executed wait
 963 * for the previous execution to complete.
 964 *
 965 * If a work function frees the work item, and then waits for an event
 966 * which should be performed by another work item and *that* work item
 967 * recycles the freed work item, it can create a false dependency loop.
 968 * There really is no reliable way to detect this short of verifying
 969 * every memory free."
 970 *
 971 */
 972static void rpc_free_task(struct rpc_task *task)
 973{
 974        unsigned short tk_flags = task->tk_flags;
 975
 976        rpc_release_calldata(task->tk_ops, task->tk_calldata);
 977
 978        if (tk_flags & RPC_TASK_DYNAMIC) {
 979                dprintk("RPC: %5u freeing task\n", task->tk_pid);
 980                mempool_free(task, rpc_task_mempool);
 981        }
 982}
 983
 984static void rpc_async_release(struct work_struct *work)
 985{
 986        rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
 987}
 988
 989static void rpc_release_resources_task(struct rpc_task *task)
 990{
 991        xprt_release(task);
 992        if (task->tk_msg.rpc_cred) {
 993                put_rpccred(task->tk_msg.rpc_cred);
 994                task->tk_msg.rpc_cred = NULL;
 995        }
 996        rpc_task_release_client(task);
 997}
 998
 999static void rpc_final_put_task(struct rpc_task *task,
1000                struct workqueue_struct *q)
1001{
1002        if (q != NULL) {
1003                INIT_WORK(&task->u.tk_work, rpc_async_release);
1004                queue_work(q, &task->u.tk_work);
1005        } else
1006                rpc_free_task(task);
1007}
1008
1009static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1010{
1011        if (atomic_dec_and_test(&task->tk_count)) {
1012                rpc_release_resources_task(task);
1013                rpc_final_put_task(task, q);
1014        }
1015}
1016
1017void rpc_put_task(struct rpc_task *task)
1018{
1019        rpc_do_put_task(task, NULL);
1020}
1021EXPORT_SYMBOL_GPL(rpc_put_task);
1022
1023void rpc_put_task_async(struct rpc_task *task)
1024{
1025        rpc_do_put_task(task, task->tk_workqueue);
1026}
1027EXPORT_SYMBOL_GPL(rpc_put_task_async);
1028
1029static void rpc_release_task(struct rpc_task *task)
1030{
1031        dprintk("RPC: %5u release task\n", task->tk_pid);
1032
1033        WARN_ON_ONCE(RPC_IS_QUEUED(task));
1034
1035        rpc_release_resources_task(task);
1036
1037        /*
1038         * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1039         * so it should be safe to use task->tk_count as a test for whether
1040         * or not any other processes still hold references to our rpc_task.
1041         */
1042        if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1043                /* Wake up anyone who may be waiting for task completion */
1044                if (!rpc_complete_task(task))
1045                        return;
1046        } else {
1047                if (!atomic_dec_and_test(&task->tk_count))
1048                        return;
1049        }
1050        rpc_final_put_task(task, task->tk_workqueue);
1051}
1052
1053int rpciod_up(void)
1054{
1055        return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1056}
1057
1058void rpciod_down(void)
1059{
1060        module_put(THIS_MODULE);
1061}
1062
1063/*
1064 * Start up the rpciod workqueue.
1065 */
1066static int rpciod_start(void)
1067{
1068        struct workqueue_struct *wq;
1069
1070        /*
1071         * Create the rpciod thread and wait for it to start.
1072         */
1073        dprintk("RPC:       creating workqueue rpciod\n");
1074        wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 1);
1075        rpciod_workqueue = wq;
1076        return rpciod_workqueue != NULL;
1077}
1078
1079static void rpciod_stop(void)
1080{
1081        struct workqueue_struct *wq = NULL;
1082
1083        if (rpciod_workqueue == NULL)
1084                return;
1085        dprintk("RPC:       destroying workqueue rpciod\n");
1086
1087        wq = rpciod_workqueue;
1088        rpciod_workqueue = NULL;
1089        destroy_workqueue(wq);
1090}
1091
1092void
1093rpc_destroy_mempool(void)
1094{
1095        rpciod_stop();
1096        if (rpc_buffer_mempool)
1097                mempool_destroy(rpc_buffer_mempool);
1098        if (rpc_task_mempool)
1099                mempool_destroy(rpc_task_mempool);
1100        if (rpc_task_slabp)
1101                kmem_cache_destroy(rpc_task_slabp);
1102        if (rpc_buffer_slabp)
1103                kmem_cache_destroy(rpc_buffer_slabp);
1104        rpc_destroy_wait_queue(&delay_queue);
1105}
1106
1107int
1108rpc_init_mempool(void)
1109{
1110        /*
1111         * The following is not strictly a mempool initialisation,
1112         * but there is no harm in doing it here
1113         */
1114        rpc_init_wait_queue(&delay_queue, "delayq");
1115        if (!rpciod_start())
1116                goto err_nomem;
1117
1118        rpc_task_slabp = kmem_cache_create("rpc_tasks",
1119                                             sizeof(struct rpc_task),
1120                                             0, SLAB_HWCACHE_ALIGN,
1121                                             NULL);
1122        if (!rpc_task_slabp)
1123                goto err_nomem;
1124        rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1125                                             RPC_BUFFER_MAXSIZE,
1126                                             0, SLAB_HWCACHE_ALIGN,
1127                                             NULL);
1128        if (!rpc_buffer_slabp)
1129                goto err_nomem;
1130        rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1131                                                    rpc_task_slabp);
1132        if (!rpc_task_mempool)
1133                goto err_nomem;
1134        rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1135                                                      rpc_buffer_slabp);
1136        if (!rpc_buffer_mempool)
1137                goto err_nomem;
1138        return 0;
1139err_nomem:
1140        rpc_destroy_mempool();
1141        return -ENOMEM;
1142}
1143