net/sunrpc/sched.c

   1 /*
   2  * linux/net/sunrpc/sched.c
   3  *
   4  * Scheduling for synchronous and asynchronous RPC requests.
   5  *
   6  * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
   7  *
   8  * TCP NFS related read + write fixes
   9  * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
  10  */
  11
  12 #include <linux/module.h>
  13
  14 #include <linux/sched.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/slab.h>
  17 #include <linux/mempool.h>
  18 #include <linux/smp.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/mutex.h>
  21 #include <linux/freezer.h>
  22
  23 #include <linux/sunrpc/clnt.h>
  24
  25 #include "sunrpc.h"
  26
  27 #ifdef RPC_DEBUG
  28 #define RPCDBG_FACILITY         RPCDBG_SCHED
  29 #endif
  30
  31 #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)
  40 static struct kmem_cache        *rpc_task_slabp __read_mostly;
  41 static struct kmem_cache        *rpc_buffer_slabp __read_mostly;
  42 static mempool_t        *rpc_task_mempool __read_mostly;
  43 static mempool_t        *rpc_buffer_mempool __read_mostly;
  44
  45 static void                     rpc_async_schedule(struct work_struct *);
  46 static void                      rpc_release_task(struct rpc_task *task);
  47 static void __rpc_queue_timer_fn(unsigned long ptr);
  48
  49 /*
  50  * RPC tasks sit here while waiting for conditions to improve.
  51  */
  52 static struct rpc_wait_queue delay_queue;
  53
  54 /*
  55  * rpciod-related stuff
  56  */
  57 struct 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  */
  64 static 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
  76 static void
  77 rpc_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  */
  86 static void
  87 __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
  88 {
  89         if (!task->tk_timeout)
  90                 return;
  91
  92         dprintk("RPC: %5u setting alarm for %lu ms\n",
  93                         task->tk_pid, task->tk_timeout * 1000 / HZ);
  94
  95         task->u.tk_wait.expires = jiffies + task->tk_timeout;
  96         if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
  97                 rpc_set_queue_timer(queue, task->u.tk_wait.expires);
  98         list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
  99 }
 100
 101 static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 102 {
 103         queue->priority = priority;
 104 }
 105
 106 static void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
 107 {
 108         queue->owner = pid;
 109         queue->nr = RPC_BATCH_COUNT;
 110 }
 111
 112 static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 113 {
 114         rpc_set_waitqueue_priority(queue, queue->maxpriority);
 115         rpc_set_waitqueue_owner(queue, 0);
 116 }
 117
 118 /*
 119  * Add new request to a priority queue.
 120  */
 121 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
 122                 struct rpc_task *task,
 123                 unsigned char queue_priority)
 124 {
 125         struct list_head *q;
 126         struct rpc_task *t;
 127
 128         INIT_LIST_HEAD(&task->u.tk_wait.links);
 129         if (unlikely(queue_priority > queue->maxpriority))
 130                 queue_priority = queue->maxpriority;
 131         if (queue_priority > queue->priority)
 132                 rpc_set_waitqueue_priority(queue, queue_priority);
 133         q = &queue->tasks[queue_priority];
 134         list_for_each_entry(t, q, u.tk_wait.list) {
 135                 if (t->tk_owner == task->tk_owner) {
 136                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
 137                         return;
 138                 }
 139         }
 140         list_add_tail(&task->u.tk_wait.list, q);
 141 }
 142
 143 /*
 144  * Add new request to wait queue.
 145  *
 146  * Swapper tasks always get inserted at the head of the queue.
 147  * This should avoid many nasty memory deadlocks and hopefully
 148  * improve overall performance.
 149  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
 150  */
 151 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
 152                 struct rpc_task *task,
 153                 unsigned char queue_priority)
 154 {
 155         WARN_ON_ONCE(RPC_IS_QUEUED(task));
 156         if (RPC_IS_QUEUED(task))
 157                 return;
 158
 159         if (RPC_IS_PRIORITY(queue))
 160                 __rpc_add_wait_queue_priority(queue, task, queue_priority);
 161         else if (RPC_IS_SWAPPER(task))
 162                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
 163         else
 164                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
 165         task->tk_waitqueue = queue;
 166         queue->qlen++;
 167         rpc_set_queued(task);
 168
 169         dprintk("RPC: %5u added to queue %p \"%s\"\n",
 170                         task->tk_pid, queue, rpc_qname(queue));
 171 }
 172
 173 /*
 174  * Remove request from a priority queue.
 175  */
 176 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 177 {
 178         struct rpc_task *t;
 179
 180         if (!list_empty(&task->u.tk_wait.links)) {
 181                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
 182                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
 183                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
 184         }
 185 }
 186
 187 /*
 188  * Remove request from queue.
 189  * Note: must be called with spin lock held.
 190  */
 191 static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
 192 {
 193         __rpc_disable_timer(queue, task);
 194         if (RPC_IS_PRIORITY(queue))
 195                 __rpc_remove_wait_queue_priority(task);
 196         list_del(&task->u.tk_wait.list);
 197         queue->qlen--;
 198         dprintk("RPC: %5u removed from queue %p \"%s\"\n",
 199                         task->tk_pid, queue, rpc_qname(queue));
 200 }
 201
 202 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
 203 {
 204         int i;
 205
 206         spin_lock_init(&queue->lock);
 207         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 208                 INIT_LIST_HEAD(&queue->tasks[i]);
 209         queue->maxpriority = nr_queues - 1;
 210         rpc_reset_waitqueue_priority(queue);
 211         queue->qlen = 0;
 212         setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
 213         INIT_LIST_HEAD(&queue->timer_list.list);
 214         rpc_assign_waitqueue_name(queue, qname);
 215 }
 216
 217 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 218 {
 219         __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
 220 }
 221 EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
 222
 223 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 224 {
 225         __rpc_init_priority_wait_queue(queue, qname, 1);
 226 }
 227 EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
 228
 229 void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
 230 {
 231         del_timer_sync(&queue->timer_list.timer);
 232 }
 233 EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
 234
 235 static int rpc_wait_bit_killable(void *word)
 236 {
 237         if (fatal_signal_pending(current))
 238                 return -ERESTARTSYS;
 239         freezable_schedule();
 240         return 0;
 241 }
 242
 243 #ifdef RPC_DEBUG
 244 static void rpc_task_set_debuginfo(struct rpc_task *task)
 245 {
 246         static atomic_t rpc_pid;
 247
 248         task->tk_pid = atomic_inc_return(&rpc_pid);
 249 }
 250 #else
 251 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
 252 {
 253 }
 254 #endif
 255
 256 static void rpc_set_active(struct rpc_task *task)
 257 {
 258         trace_rpc_task_begin(task->tk_client, task, NULL);
 259
 260         rpc_task_set_debuginfo(task);
 261         set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 262 }
 263
 264 /*
 265  * Mark an RPC call as having completed by clearing the 'active' bit
 266  * and then waking up all tasks that were sleeping.
 267  */
 268 static int rpc_complete_task(struct rpc_task *task)
 269 {
 270         void *m = &task->tk_runstate;
 271         wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
 272         struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
 273         unsigned long flags;
 274         int ret;
 275
 276         trace_rpc_task_complete(task->tk_client, task, NULL);
 277
 278         spin_lock_irqsave(&wq->lock, flags);
 279         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 280         ret = atomic_dec_and_test(&task->tk_count);
 281         if (waitqueue_active(wq))
 282                 __wake_up_locked_key(wq, TASK_NORMAL, &k);
 283         spin_unlock_irqrestore(&wq->lock, flags);
 284         return ret;
 285 }
 286
 287 /*
 288  * Allow callers to wait for completion of an RPC call
 289  *
 290  * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
 291  * to enforce taking of the wq->lock and hence avoid races with
 292  * rpc_complete_task().
 293  */
 294 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
 295 {
 296         if (action == NULL)
 297                 action = rpc_wait_bit_killable;
 298         return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 299                         action, TASK_KILLABLE);
 300 }
 301 EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
 302
 303 /*
 304  * Make an RPC task runnable.
 305  *
 306  * Note: If the task is ASYNC, and is being made runnable after sitting on an
 307  * rpc_wait_queue, this must be called with the queue spinlock held to protect
 308  * the wait queue operation.
 309  */
 310 static void rpc_make_runnable(struct rpc_task *task)
 311 {
 312         rpc_clear_queued(task);
 313         if (rpc_test_and_set_running(task))
 314                 return;
 315         if (RPC_IS_ASYNC(task)) {
 316                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
 317                 queue_work(rpciod_workqueue, &task->u.tk_work);
 318         } else
 319                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 320 }
 321
 322 /*
 323  * Prepare for sleeping on a wait queue.
 324  * By always appending tasks to the list we ensure FIFO behavior.
 325  * NB: An RPC task will only receive interrupt-driven events as long
 326  * as it's on a wait queue.
 327  */
 328 static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
 329                 struct rpc_task *task,
 330                 rpc_action action,
 331                 unsigned char queue_priority)
 332 {
 333         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
 334                         task->tk_pid, rpc_qname(q), jiffies);
 335
 336         trace_rpc_task_sleep(task->tk_client, task, q);
 337
 338         __rpc_add_wait_queue(q, task, queue_priority);
 339
 340         WARN_ON_ONCE(task->tk_callback != NULL);
 341         task->tk_callback = action;
 342         __rpc_add_timer(q, task);
 343 }
 344
 345 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 346                                 rpc_action action)
 347 {
 348         /* We shouldn't ever put an inactive task to sleep */
 349         WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
 350         if (!RPC_IS_ACTIVATED(task)) {
 351                 task->tk_status = -EIO;
 352                 rpc_put_task_async(task);
 353                 return;
 354         }
 355
 356         /*
 357          * Protect the queue operations.
 358          */
 359         spin_lock_bh(&q->lock);
 360         __rpc_sleep_on_priority(q, task, action, task->tk_priority);
 361         spin_unlock_bh(&q->lock);
 362 }
 363 EXPORT_SYMBOL_GPL(rpc_sleep_on);
 364
 365 void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
 366                 rpc_action action, int priority)
 367 {
 368         /* We shouldn't ever put an inactive task to sleep */
 369         WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
 370         if (!RPC_IS_ACTIVATED(task)) {
 371                 task->tk_status = -EIO;
 372                 rpc_put_task_async(task);
 373                 return;
 374         }
 375
 376         /*
 377          * Protect the queue operations.
 378          */
 379         spin_lock_bh(&q->lock);
 380         __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
 381         spin_unlock_bh(&q->lock);
 382 }
 383 EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
 384
 385 /**
 386  * __rpc_do_wake_up_task - wake up a single rpc_task
 387  * @queue: wait queue
 388  * @task: task to be woken up
 389  *
 390  * Caller must hold queue->lock, and have cleared the task queued flag.
 391  */
 392 static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 393 {
 394         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
 395                         task->tk_pid, jiffies);
 396
 397         /* Has the task been executed yet? If not, we cannot wake it up! */
 398         if (!RPC_IS_ACTIVATED(task)) {
 399                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 400                 return;
 401         }
 402
 403         trace_rpc_task_wakeup(task->tk_client, task, queue);
 404
 405         __rpc_remove_wait_queue(queue, task);
 406
 407         rpc_make_runnable(task);
 408
 409         dprintk("RPC:       __rpc_wake_up_task done\n");
 410 }
 411
 412 /*
 413  * Wake up a queued task while the queue lock is being held
 414  */
 415 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
 416 {
 417         if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
 418                 __rpc_do_wake_up_task(queue, task);
 419 }
 420
 421 /*
 422  * Tests whether rpc queue is empty
 423  */
 424 int rpc_queue_empty(struct rpc_wait_queue *queue)
 425 {
 426         int res;
 427
 428         spin_lock_bh(&queue->lock);
 429         res = queue->qlen;
 430         spin_unlock_bh(&queue->lock);
 431         return res == 0;
 432 }
 433 EXPORT_SYMBOL_GPL(rpc_queue_empty);
 434
 435 /*
 436  * Wake up a task on a specific queue
 437  */
 438 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 439 {
 440         spin_lock_bh(&queue->lock);
 441         rpc_wake_up_task_queue_locked(queue, task);
 442         spin_unlock_bh(&queue->lock);
 443 }
 444 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
 445
 446 /*
 447  * Wake up the next task on a priority queue.
 448  */
 449 static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
 450 {
 451         struct list_head *q;
 452         struct rpc_task *task;
 453
 454         /*
 455          * Service a batch of tasks from a single owner.
 456          */
 457         q = &queue->tasks[queue->priority];
 458         if (!list_empty(q)) {
 459                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 460                 if (queue->owner == task->tk_owner) {
 461                         if (--queue->nr)
 462                                 goto out;
 463                         list_move_tail(&task->u.tk_wait.list, q);
 464                 }
 465                 /*
 466                  * Check if we need to switch queues.
 467                  */
 468                 goto new_owner;
 469         }
 470
 471         /*
 472          * Service the next queue.
 473          */
 474         do {
 475                 if (q == &queue->tasks[0])
 476                         q = &queue->tasks[queue->maxpriority];
 477                 else
 478                         q = q - 1;
 479                 if (!list_empty(q)) {
 480                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 481                         goto new_queue;
 482                 }
 483         } while (q != &queue->tasks[queue->priority]);
 484
 485         rpc_reset_waitqueue_priority(queue);
 486         return NULL;
 487
 488 new_queue:
 489         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 490 new_owner:
 491         rpc_set_waitqueue_owner(queue, task->tk_owner);
 492 out:
 493         return task;
 494 }
 495
 496 static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
 497 {
 498         if (RPC_IS_PRIORITY(queue))
 499                 return __rpc_find_next_queued_priority(queue);
 500         if (!list_empty(&queue->tasks[0]))
 501                 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
 502         return NULL;
 503 }
 504
 505 /*
 506  * Wake up the first task on the wait queue.
 507  */
 508 struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
 509                 bool (*func)(struct rpc_task *, void *), void *data)
 510 {
 511         struct rpc_task *task = NULL;
 512
 513         dprintk("RPC:       wake_up_first(%p \"%s\")\n",
 514                         queue, rpc_qname(queue));
 515         spin_lock_bh(&queue->lock);
 516         task = __rpc_find_next_queued(queue);
 517         if (task != NULL) {
 518                 if (func(task, data))
 519                         rpc_wake_up_task_queue_locked(queue, task);
 520                 else
 521                         task = NULL;
 522         }
 523         spin_unlock_bh(&queue->lock);
 524
 525         return task;
 526 }
 527 EXPORT_SYMBOL_GPL(rpc_wake_up_first);
 528
 529 static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
 530 {
 531         return true;
 532 }
 533
 534 /*
 535  * Wake up the next task on the wait queue.
 536 */
 537 struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
 538 {
 539         return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
 540 }
 541 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
 542
 543 /**
 544  * rpc_wake_up - wake up all rpc_tasks
 545  * @queue: rpc_wait_queue on which the tasks are sleeping
 546  *
 547  * Grabs queue->lock
 548  */
 549 void rpc_wake_up(struct rpc_wait_queue *queue)
 550 {
 551         struct list_head *head;
 552
 553         spin_lock_bh(&queue->lock);
 554         head = &queue->tasks[queue->maxpriority];
 555         for (;;) {
 556                 while (!list_empty(head)) {
 557                         struct rpc_task *task;
 558                         task = list_first_entry(head,
 559                                         struct rpc_task,
 560                                         u.tk_wait.list);
 561                         rpc_wake_up_task_queue_locked(queue, task);
 562                 }
 563                 if (head == &queue->tasks[0])
 564                         break;
 565                 head--;
 566         }
 567         spin_unlock_bh(&queue->lock);
 568 }
 569 EXPORT_SYMBOL_GPL(rpc_wake_up);
 570
 571 /**
 572  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 573  * @queue: rpc_wait_queue on which the tasks are sleeping
 574  * @status: status value to set
 575  *
 576  * Grabs queue->lock
 577  */
 578 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 579 {
 580         struct list_head *head;
 581
 582         spin_lock_bh(&queue->lock);
 583         head = &queue->tasks[queue->maxpriority];
 584         for (;;) {
 585                 while (!list_empty(head)) {
 586                         struct rpc_task *task;
 587                         task = list_first_entry(head,
 588                                         struct rpc_task,
 589                                         u.tk_wait.list);
 590                         task->tk_status = status;
 591                         rpc_wake_up_task_queue_locked(queue, task);
 592                 }
 593                 if (head == &queue->tasks[0])
 594                         break;
 595                 head--;
 596         }
 597         spin_unlock_bh(&queue->lock);
 598 }
 599 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
 600
 601 static void __rpc_queue_timer_fn(unsigned long ptr)
 602 {
 603         struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
 604         struct rpc_task *task, *n;
 605         unsigned long expires, now, timeo;
 606
 607         spin_lock(&queue->lock);
 608         expires = now = jiffies;
 609         list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
 610                 timeo = task->u.tk_wait.expires;
 611                 if (time_after_eq(now, timeo)) {
 612                         dprintk("RPC: %5u timeout\n", task->tk_pid);
 613                         task->tk_status = -ETIMEDOUT;
 614                         rpc_wake_up_task_queue_locked(queue, task);
 615                         continue;
 616                 }
 617                 if (expires == now || time_after(expires, timeo))
 618                         expires = timeo;
 619         }
 620         if (!list_empty(&queue->timer_list.list))
 621                 rpc_set_queue_timer(queue, expires);
 622         spin_unlock(&queue->lock);
 623 }
 624
 625 static void __rpc_atrun(struct rpc_task *task)
 626 {
 627         task->tk_status = 0;
 628 }
 629
 630 /*
 631  * Run a task at a later time
 632  */
 633 void rpc_delay(struct rpc_task *task, unsigned long delay)
 634 {
 635         task->tk_timeout = delay;
 636         rpc_sleep_on(&delay_queue, task, __rpc_atrun);
 637 }
 638 EXPORT_SYMBOL_GPL(rpc_delay);
 639
 640 /*
 641  * Helper to call task->tk_ops->rpc_call_prepare
 642  */
 643 void rpc_prepare_task(struct rpc_task *task)
 644 {
 645         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 646 }
 647
 648 static void
 649 rpc_init_task_statistics(struct rpc_task *task)
 650 {
 651         /* Initialize retry counters */
 652         task->tk_garb_retry = 2;
 653         task->tk_cred_retry = 2;
 654         task->tk_rebind_retry = 2;
 655
 656         /* starting timestamp */
 657         task->tk_start = ktime_get();
 658 }
 659
 660 static void
 661 rpc_reset_task_statistics(struct rpc_task *task)
 662 {
 663         task->tk_timeouts = 0;
 664         task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
 665
 666         rpc_init_task_statistics(task);
 667 }
 668
 669 /*
 670  * Helper that calls task->tk_ops->rpc_call_done if it exists
 671  */
 672 void rpc_exit_task(struct rpc_task *task)
 673 {
 674         task->tk_action = NULL;
 675         if (task->tk_ops->rpc_call_done != NULL) {
 676                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
 677                 if (task->tk_action != NULL) {
 678                         WARN_ON(RPC_ASSASSINATED(task));
 679                         /* Always release the RPC slot and buffer memory */
 680                         xprt_release(task);
 681                         rpc_reset_task_statistics(task);
 682                 }
 683         }
 684 }
 685
 686 void rpc_exit(struct rpc_task *task, int status)
 687 {
 688         task->tk_status = status;
 689         task->tk_action = rpc_exit_task;
 690         if (RPC_IS_QUEUED(task))
 691                 rpc_wake_up_queued_task(task->tk_waitqueue, task);
 692 }
 693 EXPORT_SYMBOL_GPL(rpc_exit);
 694
 695 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
 696 {
 697         if (ops->rpc_release != NULL)
 698                 ops->rpc_release(calldata);
 699 }
 700
 701 /*
 702  * This is the RPC `scheduler' (or rather, the finite state machine).
 703  */
 704 static void __rpc_execute(struct rpc_task *task)
 705 {
 706         struct rpc_wait_queue *queue;
 707         int task_is_async = RPC_IS_ASYNC(task);
 708         int status = 0;
 709
 710         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
 711                         task->tk_pid, task->tk_flags);
 712
 713         WARN_ON_ONCE(RPC_IS_QUEUED(task));
 714         if (RPC_IS_QUEUED(task))
 715                 return;
 716
 717         for (;;) {
 718                 void (*do_action)(struct rpc_task *);
 719
 720                 /*
 721                  * Execute any pending callback first.
 722                  */
 723                 do_action = task->tk_callback;
 724                 task->tk_callback = NULL;
 725                 if (do_action == NULL) {
 726                         /*
 727                          * Perform the next FSM step.
 728                          * tk_action may be NULL if the task has been killed.
 729                          * In particular, note that rpc_killall_tasks may
 730                          * do this at any time, so beware when dereferencing.
 731                          */
 732                         do_action = task->tk_action;
 733                         if (do_action == NULL)
 734                                 break;
 735                 }
 736                 trace_rpc_task_run_action(task->tk_client, task, task->tk_action);
 737                 do_action(task);
 738
 739                 /*
 740                  * Lockless check for whether task is sleeping or not.
 741                  */
 742                 if (!RPC_IS_QUEUED(task))
 743                         continue;
 744                 /*
 745                  * The queue->lock protects against races with
 746                  * rpc_make_runnable().
 747                  *
 748                  * Note that once we clear RPC_TASK_RUNNING on an asynchronous
 749                  * rpc_task, rpc_make_runnable() can assign it to a
 750                  * different workqueue. We therefore cannot assume that the
 751                  * rpc_task pointer may still be dereferenced.
 752                  */
 753                 queue = task->tk_waitqueue;
 754                 spin_lock_bh(&queue->lock);
 755                 if (!RPC_IS_QUEUED(task)) {
 756                         spin_unlock_bh(&queue->lock);
 757                         continue;
 758                 }
 759                 rpc_clear_running(task);
 760                 spin_unlock_bh(&queue->lock);
 761                 if (task_is_async)
 762                         return;
 763
 764                 /* sync task: sleep here */
 765                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
 766                 status = out_of_line_wait_on_bit(&task->tk_runstate,
 767                                 RPC_TASK_QUEUED, rpc_wait_bit_killable,
 768                                 TASK_KILLABLE);
 769                 if (status == -ERESTARTSYS) {
 770                         /*
 771                          * When a sync task receives a signal, it exits with
 772                          * -ERESTARTSYS. In order to catch any callbacks that
 773                          * clean up after sleeping on some queue, we don't
 774                          * break the loop here, but go around once more.
 775                          */
 776                         dprintk("RPC: %5u got signal\n", task->tk_pid);
 777                         task->tk_flags |= RPC_TASK_KILLED;
 778                         rpc_exit(task, -ERESTARTSYS);
 779                 }
 780                 rpc_set_running(task);
 781                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
 782         }
 783
 784         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
 785                         task->tk_status);
 786         /* Release all resources associated with the task */
 787         rpc_release_task(task);
 788 }
 789
 790 /*
 791  * User-visible entry point to the scheduler.
 792  *
 793  * This may be called recursively if e.g. an async NFS task updates
 794  * the attributes and finds that dirty pages must be flushed.
 795  * NOTE: Upon exit of this function the task is guaranteed to be
 796  *       released. In particular note that tk_release() will have
 797  *       been called, so your task memory may have been freed.
 798  */
 799 void rpc_execute(struct rpc_task *task)
 800 {
 801         rpc_set_active(task);
 802         rpc_make_runnable(task);
 803         if (!RPC_IS_ASYNC(task))
 804                 __rpc_execute(task);
 805 }
 806
 807 static void rpc_async_schedule(struct work_struct *work)
 808 {
 809         current->flags |= PF_FSTRANS;
 810         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
 811         current->flags &= ~PF_FSTRANS;
 812 }
 813
 814 /**
 815  * rpc_malloc - allocate an RPC buffer
 816  * @task: RPC task that will use this buffer
 817  * @size: requested byte size
 818  *
 819  * To prevent rpciod from hanging, this allocator never sleeps,
 820  * returning NULL if the request cannot be serviced immediately.
 821  * The caller can arrange to sleep in a way that is safe for rpciod.
 822  *
 823  * Most requests are 'small' (under 2KiB) and can be serviced from a
 824  * mempool, ensuring that NFS reads and writes can always proceed,
 825  * and that there is good locality of reference for these buffers.
 826  *
 827  * In order to avoid memory starvation triggering more writebacks of
 828  * NFS requests, we avoid using GFP_KERNEL.
 829  */
 830 void *rpc_malloc(struct rpc_task *task, size_t size)
 831 {
 832         struct rpc_buffer *buf;
 833         gfp_t gfp = GFP_NOWAIT;
 834
 835         if (RPC_IS_SWAPPER(task))
 836                 gfp |= __GFP_MEMALLOC;
 837
 838         size += sizeof(struct rpc_buffer);
 839         if (size <= RPC_BUFFER_MAXSIZE)
 840                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
 841         else
 842                 buf = kmalloc(size, gfp);
 843
 844         if (!buf)
 845                 return NULL;
 846
 847         buf->len = size;
 848         dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
 849                         task->tk_pid, size, buf);
 850         return &buf->data;
 851 }
 852 EXPORT_SYMBOL_GPL(rpc_malloc);
 853
 854 /**
 855  * rpc_free - free buffer allocated via rpc_malloc
 856  * @buffer: buffer to free
 857  *
 858  */
 859 void rpc_free(void *buffer)
 860 {
 861         size_t size;
 862         struct rpc_buffer *buf;
 863
 864         if (!buffer)
 865                 return;
 866
 867         buf = container_of(buffer, struct rpc_buffer, data);
 868         size = buf->len;
 869
 870         dprintk("RPC:       freeing buffer of size %zu at %p\n",
 871                         size, buf);
 872
 873         if (size <= RPC_BUFFER_MAXSIZE)
 874                 mempool_free(buf, rpc_buffer_mempool);
 875         else
 876                 kfree(buf);
 877 }
 878 EXPORT_SYMBOL_GPL(rpc_free);
 879
 880 /*
 881  * Creation and deletion of RPC task structures
 882  */
 883 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
 884 {
 885         memset(task, 0, sizeof(*task));
 886         atomic_set(&task->tk_count, 1);
 887         task->tk_flags  = task_setup_data->flags;
 888         task->tk_ops = task_setup_data->callback_ops;
 889         task->tk_calldata = task_setup_data->callback_data;
 890         INIT_LIST_HEAD(&task->tk_task);
 891
 892         task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
 893         task->tk_owner = current->tgid;
 894
 895         /* Initialize workqueue for async tasks */
 896         task->tk_workqueue = task_setup_data->workqueue;
 897
 898         if (task->tk_ops->rpc_call_prepare != NULL)
 899                 task->tk_action = rpc_prepare_task;
 900
 901         rpc_init_task_statistics(task);
 902
 903         dprintk("RPC:       new task initialized, procpid %u\n",
 904                                 task_pid_nr(current));
 905 }
 906
 907 static struct rpc_task *
 908 rpc_alloc_task(void)
 909 {
 910         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO);
 911 }
 912
 913 /*
 914  * Create a new task for the specified client.
 915  */
 916 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
 917 {
 918         struct rpc_task *task = setup_data->task;
 919         unsigned short flags = 0;
 920
 921         if (task == NULL) {
 922                 task = rpc_alloc_task();
 923                 if (task == NULL) {
 924                         rpc_release_calldata(setup_data->callback_ops,
 925                                         setup_data->callback_data);
 926                         return ERR_PTR(-ENOMEM);
 927                 }
 928                 flags = RPC_TASK_DYNAMIC;
 929         }
 930
 931         rpc_init_task(task, setup_data);
 932         task->tk_flags |= flags;
 933         dprintk("RPC:       allocated task %p\n", task);
 934         return task;
 935 }
 936
 937 static void rpc_free_task(struct rpc_task *task)
 938 {
 939         const struct rpc_call_ops *tk_ops = task->tk_ops;
 940         void *calldata = task->tk_calldata;
 941
 942         if (task->tk_flags & RPC_TASK_DYNAMIC) {
 943                 dprintk("RPC: %5u freeing task\n", task->tk_pid);
 944                 mempool_free(task, rpc_task_mempool);
 945         }
 946         rpc_release_calldata(tk_ops, calldata);
 947 }
 948
 949 static void rpc_async_release(struct work_struct *work)
 950 {
 951         rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
 952 }
 953
 954 static void rpc_release_resources_task(struct rpc_task *task)
 955 {
 956         if (task->tk_rqstp)
 957                 xprt_release(task);
 958         if (task->tk_msg.rpc_cred) {
 959                 put_rpccred(task->tk_msg.rpc_cred);
 960                 task->tk_msg.rpc_cred = NULL;
 961         }
 962         rpc_task_release_client(task);
 963 }
 964
 965 static void rpc_final_put_task(struct rpc_task *task,
 966                 struct workqueue_struct *q)
 967 {
 968         if (q != NULL) {
 969                 INIT_WORK(&task->u.tk_work, rpc_async_release);
 970                 queue_work(q, &task->u.tk_work);
 971         } else
 972                 rpc_free_task(task);
 973 }
 974
 975 static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
 976 {
 977         if (atomic_dec_and_test(&task->tk_count)) {
 978                 rpc_release_resources_task(task);
 979                 rpc_final_put_task(task, q);
 980         }
 981 }
 982
 983 void rpc_put_task(struct rpc_task *task)
 984 {
 985         rpc_do_put_task(task, NULL);
 986 }
 987 EXPORT_SYMBOL_GPL(rpc_put_task);
 988
 989 void rpc_put_task_async(struct rpc_task *task)
 990 {
 991         rpc_do_put_task(task, task->tk_workqueue);
 992 }
 993 EXPORT_SYMBOL_GPL(rpc_put_task_async);
 994
 995 static void rpc_release_task(struct rpc_task *task)
 996 {
 997         dprintk("RPC: %5u release task\n", task->tk_pid);
 998
 999         WARN_ON_ONCE(RPC_IS_QUEUED(task));
1000
1001         rpc_release_resources_task(task);
1002
1003         /*
1004          * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1005          * so it should be safe to use task->tk_count as a test for whether
1006          * or not any other processes still hold references to our rpc_task.
1007          */
1008         if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1009                 /* Wake up anyone who may be waiting for task completion */
1010                 if (!rpc_complete_task(task))
1011                         return;
1012         } else {
1013                 if (!atomic_dec_and_test(&task->tk_count))
1014                         return;
1015         }
1016         rpc_final_put_task(task, task->tk_workqueue);
1017 }
1018
1019 int rpciod_up(void)
1020 {
1021         return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1022 }
1023
1024 void rpciod_down(void)
1025 {
1026         module_put(THIS_MODULE);
1027 }
1028
1029 /*
1030  * Start up the rpciod workqueue.
1031  */
1032 static int rpciod_start(void)
1033 {
1034         struct workqueue_struct *wq;
1035
1036         /*
1037          * Create the rpciod thread and wait for it to start.
1038          */
1039         dprintk("RPC:       creating workqueue rpciod\n");
1040         wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 1);
1041         rpciod_workqueue = wq;
1042         return rpciod_workqueue != NULL;
1043 }
1044
1045 static void rpciod_stop(void)
1046 {
1047         struct workqueue_struct *wq = NULL;
1048
1049         if (rpciod_workqueue == NULL)
1050                 return;
1051         dprintk("RPC:       destroying workqueue rpciod\n");
1052
1053         wq = rpciod_workqueue;
1054         rpciod_workqueue = NULL;
1055         destroy_workqueue(wq);
1056 }
1057
1058 void
1059 rpc_destroy_mempool(void)
1060 {
1061         rpciod_stop();
1062         if (rpc_buffer_mempool)
1063                 mempool_destroy(rpc_buffer_mempool);
1064         if (rpc_task_mempool)
1065                 mempool_destroy(rpc_task_mempool);
1066         if (rpc_task_slabp)
1067                 kmem_cache_destroy(rpc_task_slabp);
1068         if (rpc_buffer_slabp)
1069                 kmem_cache_destroy(rpc_buffer_slabp);
1070         rpc_destroy_wait_queue(&delay_queue);
1071 }
1072
1073 int
1074 rpc_init_mempool(void)
1075 {
1076         /*
1077          * The following is not strictly a mempool initialisation,
1078          * but there is no harm in doing it here
1079          */
1080         rpc_init_wait_queue(&delay_queue, "delayq");
1081         if (!rpciod_start())
1082                 goto err_nomem;
1083
1084         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1085                                              sizeof(struct rpc_task),
1086                                              0, SLAB_HWCACHE_ALIGN,
1087                                              NULL);
1088         if (!rpc_task_slabp)
1089                 goto err_nomem;
1090         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1091                                              RPC_BUFFER_MAXSIZE,
1092                                              0, SLAB_HWCACHE_ALIGN,
1093                                              NULL);
1094         if (!rpc_buffer_slabp)
1095                 goto err_nomem;
1096         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1097                                                     rpc_task_slabp);
1098         if (!rpc_task_mempool)
1099                 goto err_nomem;
1100         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1101                                                       rpc_buffer_slabp);
1102         if (!rpc_buffer_mempool)
1103                 goto err_nomem;
1104         return 0;
1105 err_nomem:
1106         rpc_destroy_mempool();
1107         return -ENOMEM;
1108 }