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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 static int                      rpc_task_id;
  29 #endif
  30
  31 /*
  32  * RPC slabs and memory pools
  33  */
  34 #define RPC_BUFFER_MAXSIZE      (2048)
  35 #define RPC_BUFFER_POOLSIZE     (8)
  36 #define RPC_TASK_POOLSIZE       (8)
  37 static kmem_cache_t     *rpc_task_slabp __read_mostly;
  38 static kmem_cache_t     *rpc_buffer_slabp __read_mostly;
  39 static mempool_t        *rpc_task_mempool __read_mostly;
  40 static mempool_t        *rpc_buffer_mempool __read_mostly;
  41
  42 static void                     __rpc_default_timer(struct rpc_task *task);
  43 static void                     rpciod_killall(void);
  44 static void                     rpc_async_schedule(void *);
  45
  46 /*
  47  * RPC tasks sit here while waiting for conditions to improve.
  48  */
  49 static RPC_WAITQ(delay_queue, "delayq");
  50
  51 /*
  52  * All RPC tasks are linked into this list
  53  */
  54 static LIST_HEAD(all_tasks);
  55
  56 /*
  57  * rpciod-related stuff
  58  */
  59 static DEFINE_MUTEX(rpciod_mutex);
  60 static unsigned int             rpciod_users;
  61 struct workqueue_struct *rpciod_workqueue;
  62
  63 /*
  64  * Spinlock for other critical sections of code.
  65  */
  66 static DEFINE_SPINLOCK(rpc_sched_lock);
  67
  68 /*
  69  * Disable the timer for a given RPC task. Should be called with
  70  * queue->lock and bh_disabled in order to avoid races within
  71  * rpc_run_timer().
  72  */
  73 static inline void
  74 __rpc_disable_timer(struct rpc_task *task)
  75 {
  76         dprintk("RPC: %4d disabling timer\n", task->tk_pid);
  77         task->tk_timeout_fn = NULL;
  78         task->tk_timeout = 0;
  79 }
  80
  81 /*
  82  * Run a timeout function.
  83  * We use the callback in order to allow __rpc_wake_up_task()
  84  * and friends to disable the timer synchronously on SMP systems
  85  * without calling del_timer_sync(). The latter could cause a
  86  * deadlock if called while we're holding spinlocks...
  87  */
  88 static void rpc_run_timer(struct rpc_task *task)
  89 {
  90         void (*callback)(struct rpc_task *);
  91
  92         callback = task->tk_timeout_fn;
  93         task->tk_timeout_fn = NULL;
  94         if (callback && RPC_IS_QUEUED(task)) {
  95                 dprintk("RPC: %4d running timer\n", task->tk_pid);
  96                 callback(task);
  97         }
  98         smp_mb__before_clear_bit();
  99         clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
 100         smp_mb__after_clear_bit();
 101 }
 102
 103 /*
 104  * Set up a timer for the current task.
 105  */
 106 static inline void
 107 __rpc_add_timer(struct rpc_task *task, rpc_action timer)
 108 {
 109         if (!task->tk_timeout)
 110                 return;
 111
 112         dprintk("RPC: %4d setting alarm for %lu ms\n",
 113                         task->tk_pid, task->tk_timeout * 1000 / HZ);
 114
 115         if (timer)
 116                 task->tk_timeout_fn = timer;
 117         else
 118                 task->tk_timeout_fn = __rpc_default_timer;
 119         set_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
 120         mod_timer(&task->tk_timer, jiffies + task->tk_timeout);
 121 }
 122
 123 /*
 124  * Delete any timer for the current task. Because we use del_timer_sync(),
 125  * this function should never be called while holding queue->lock.
 126  */
 127 static void
 128 rpc_delete_timer(struct rpc_task *task)
 129 {
 130         if (RPC_IS_QUEUED(task))
 131                 return;
 132         if (test_and_clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate)) {
 133                 del_singleshot_timer_sync(&task->tk_timer);
 134                 dprintk("RPC: %4d deleting timer\n", task->tk_pid);
 135         }
 136 }
 137
 138 /*
 139  * Add new request to a priority queue.
 140  */
 141 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
 142 {
 143         struct list_head *q;
 144         struct rpc_task *t;
 145
 146         INIT_LIST_HEAD(&task->u.tk_wait.links);
 147         q = &queue->tasks[task->tk_priority];
 148         if (unlikely(task->tk_priority > queue->maxpriority))
 149                 q = &queue->tasks[queue->maxpriority];
 150         list_for_each_entry(t, q, u.tk_wait.list) {
 151                 if (t->tk_cookie == task->tk_cookie) {
 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  */
 167 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
 168 {
 169         BUG_ON (RPC_IS_QUEUED(task));
 170
 171         if (RPC_IS_PRIORITY(queue))
 172                 __rpc_add_wait_queue_priority(queue, task);
 173         else if (RPC_IS_SWAPPER(task))
 174                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
 175         else
 176                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
 177         task->u.tk_wait.rpc_waitq = queue;
 178         queue->qlen++;
 179         rpc_set_queued(task);
 180
 181         dprintk("RPC: %4d added to queue %p \"%s\"\n",
 182                                 task->tk_pid, queue, rpc_qname(queue));
 183 }
 184
 185 /*
 186  * Remove request from a priority queue.
 187  */
 188 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 189 {
 190         struct rpc_task *t;
 191
 192         if (!list_empty(&task->u.tk_wait.links)) {
 193                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
 194                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
 195                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
 196         }
 197         list_del(&task->u.tk_wait.list);
 198 }
 199
 200 /*
 201  * Remove request from queue.
 202  * Note: must be called with spin lock held.
 203  */
 204 static void __rpc_remove_wait_queue(struct rpc_task *task)
 205 {
 206         struct rpc_wait_queue *queue;
 207         queue = task->u.tk_wait.rpc_waitq;
 208
 209         if (RPC_IS_PRIORITY(queue))
 210                 __rpc_remove_wait_queue_priority(task);
 211         else
 212                 list_del(&task->u.tk_wait.list);
 213         queue->qlen--;
 214         dprintk("RPC: %4d removed from queue %p \"%s\"\n",
 215                                 task->tk_pid, queue, rpc_qname(queue));
 216 }
 217
 218 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 219 {
 220         queue->priority = priority;
 221         queue->count = 1 << (priority * 2);
 222 }
 223
 224 static inline void rpc_set_waitqueue_cookie(struct rpc_wait_queue *queue, unsigned long cookie)
 225 {
 226         queue->cookie = cookie;
 227         queue->nr = RPC_BATCH_COUNT;
 228 }
 229
 230 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 231 {
 232         rpc_set_waitqueue_priority(queue, queue->maxpriority);
 233         rpc_set_waitqueue_cookie(queue, 0);
 234 }
 235
 236 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, int maxprio)
 237 {
 238         int i;
 239
 240         spin_lock_init(&queue->lock);
 241         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 242                 INIT_LIST_HEAD(&queue->tasks[i]);
 243         queue->maxpriority = maxprio;
 244         rpc_reset_waitqueue_priority(queue);
 245 #ifdef RPC_DEBUG
 246         queue->name = qname;
 247 #endif
 248 }
 249
 250 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 251 {
 252         __rpc_init_priority_wait_queue(queue, qname, RPC_PRIORITY_HIGH);
 253 }
 254
 255 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 256 {
 257         __rpc_init_priority_wait_queue(queue, qname, 0);
 258 }
 259 EXPORT_SYMBOL(rpc_init_wait_queue);
 260
 261 static int rpc_wait_bit_interruptible(void *word)
 262 {
 263         if (signal_pending(current))
 264                 return -ERESTARTSYS;
 265         schedule();
 266         return 0;
 267 }
 268
 269 static void rpc_set_active(struct rpc_task *task)
 270 {
 271         if (test_and_set_bit(RPC_TASK_ACTIVE, &task->tk_runstate) != 0)
 272                 return;
 273         spin_lock(&rpc_sched_lock);
 274 #ifdef RPC_DEBUG
 275         task->tk_magic = RPC_TASK_MAGIC_ID;
 276         task->tk_pid = rpc_task_id++;
 277 #endif
 278         /* Add to global list of all tasks */
 279         list_add_tail(&task->tk_task, &all_tasks);
 280         spin_unlock(&rpc_sched_lock);
 281 }
 282
 283 /*
 284  * Mark an RPC call as having completed by clearing the 'active' bit
 285  */
 286 static void rpc_mark_complete_task(struct rpc_task *task)
 287 {
 288         smp_mb__before_clear_bit();
 289         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
 290         smp_mb__after_clear_bit();
 291         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
 292 }
 293
 294 /*
 295  * Allow callers to wait for completion of an RPC call
 296  */
 297 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
 298 {
 299         if (action == NULL)
 300                 action = rpc_wait_bit_interruptible;
 301         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 302                         action, TASK_INTERRUPTIBLE);
 303 }
 304 EXPORT_SYMBOL(__rpc_wait_for_completion_task);
 305
 306 /*
 307  * Make an RPC task runnable.
 308  *
 309  * Note: If the task is ASYNC, this must be called with
 310  * the spinlock held to protect the wait queue operation.
 311  */
 312 static void rpc_make_runnable(struct rpc_task *task)
 313 {
 314         BUG_ON(task->tk_timeout_fn);
 315         rpc_clear_queued(task);
 316         if (rpc_test_and_set_running(task))
 317                 return;
 318         /* We might have raced */
 319         if (RPC_IS_QUEUED(task)) {
 320                 rpc_clear_running(task);
 321                 return;
 322         }
 323         if (RPC_IS_ASYNC(task)) {
 324                 int status;
 325
 326                 INIT_WORK(&task->u.tk_work, rpc_async_schedule, (void *)task);
 327                 status = queue_work(task->tk_workqueue, &task->u.tk_work);
 328                 if (status < 0) {
 329                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
 330                         task->tk_status = status;
 331                         return;
 332                 }
 333         } else
 334                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 335 }
 336
 337 /*
 338  * Prepare for sleeping on a wait queue.
 339  * By always appending tasks to the list we ensure FIFO behavior.
 340  * NB: An RPC task will only receive interrupt-driven events as long
 341  * as it's on a wait queue.
 342  */
 343 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 344                         rpc_action action, rpc_action timer)
 345 {
 346         dprintk("RPC: %4d sleep_on(queue \"%s\" time %ld)\n", task->tk_pid,
 347                                 rpc_qname(q), jiffies);
 348
 349         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
 350                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
 351                 return;
 352         }
 353
 354         __rpc_add_wait_queue(q, task);
 355
 356         BUG_ON(task->tk_callback != NULL);
 357         task->tk_callback = action;
 358         __rpc_add_timer(task, timer);
 359 }
 360
 361 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 362                                 rpc_action action, rpc_action timer)
 363 {
 364         /* Mark the task as being activated if so needed */
 365         rpc_set_active(task);
 366
 367         /*
 368          * Protect the queue operations.
 369          */
 370         spin_lock_bh(&q->lock);
 371         __rpc_sleep_on(q, task, action, timer);
 372         spin_unlock_bh(&q->lock);
 373 }
 374
 375 /**
 376  * __rpc_do_wake_up_task - wake up a single rpc_task
 377  * @task: task to be woken up
 378  *
 379  * Caller must hold queue->lock, and have cleared the task queued flag.
 380  */
 381 static void __rpc_do_wake_up_task(struct rpc_task *task)
 382 {
 383         dprintk("RPC: %4d __rpc_wake_up_task (now %ld)\n", task->tk_pid, jiffies);
 384
 385 #ifdef RPC_DEBUG
 386         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 387 #endif
 388         /* Has the task been executed yet? If not, we cannot wake it up! */
 389         if (!RPC_IS_ACTIVATED(task)) {
 390                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 391                 return;
 392         }
 393
 394         __rpc_disable_timer(task);
 395         __rpc_remove_wait_queue(task);
 396
 397         rpc_make_runnable(task);
 398
 399         dprintk("RPC:      __rpc_wake_up_task done\n");
 400 }
 401
 402 /*
 403  * Wake up the specified task
 404  */
 405 static void __rpc_wake_up_task(struct rpc_task *task)
 406 {
 407         if (rpc_start_wakeup(task)) {
 408                 if (RPC_IS_QUEUED(task))
 409                         __rpc_do_wake_up_task(task);
 410                 rpc_finish_wakeup(task);
 411         }
 412 }
 413
 414 /*
 415  * Default timeout handler if none specified by user
 416  */
 417 static void
 418 __rpc_default_timer(struct rpc_task *task)
 419 {
 420         dprintk("RPC: %d timeout (default timer)\n", task->tk_pid);
 421         task->tk_status = -ETIMEDOUT;
 422         rpc_wake_up_task(task);
 423 }
 424
 425 /*
 426  * Wake up the specified task
 427  */
 428 void rpc_wake_up_task(struct rpc_task *task)
 429 {
 430         rcu_read_lock_bh();
 431         if (rpc_start_wakeup(task)) {
 432                 if (RPC_IS_QUEUED(task)) {
 433                         struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
 434
 435                         /* Note: we're already in a bh-safe context */
 436                         spin_lock(&queue->lock);
 437                         __rpc_do_wake_up_task(task);
 438                         spin_unlock(&queue->lock);
 439                 }
 440                 rpc_finish_wakeup(task);
 441         }
 442         rcu_read_unlock_bh();
 443 }
 444
 445 /*
 446  * Wake up the next task on a priority queue.
 447  */
 448 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
 449 {
 450         struct list_head *q;
 451         struct rpc_task *task;
 452
 453         /*
 454          * Service a batch of tasks from a single cookie.
 455          */
 456         q = &queue->tasks[queue->priority];
 457         if (!list_empty(q)) {
 458                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 459                 if (queue->cookie == task->tk_cookie) {
 460                         if (--queue->nr)
 461                                 goto out;
 462                         list_move_tail(&task->u.tk_wait.list, q);
 463                 }
 464                 /*
 465                  * Check if we need to switch queues.
 466                  */
 467                 if (--queue->count)
 468                         goto new_cookie;
 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_cookie:
 491         rpc_set_waitqueue_cookie(queue, task->tk_cookie);
 492 out:
 493         __rpc_wake_up_task(task);
 494         return task;
 495 }
 496
 497 /*
 498  * Wake up the next task on the wait queue.
 499  */
 500 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
 501 {
 502         struct rpc_task *task = NULL;
 503
 504         dprintk("RPC:      wake_up_next(%p \"%s\")\n", queue, rpc_qname(queue));
 505         rcu_read_lock_bh();
 506         spin_lock(&queue->lock);
 507         if (RPC_IS_PRIORITY(queue))
 508                 task = __rpc_wake_up_next_priority(queue);
 509         else {
 510                 task_for_first(task, &queue->tasks[0])
 511                         __rpc_wake_up_task(task);
 512         }
 513         spin_unlock(&queue->lock);
 514         rcu_read_unlock_bh();
 515
 516         return task;
 517 }
 518
 519 /**
 520  * rpc_wake_up - wake up all rpc_tasks
 521  * @queue: rpc_wait_queue on which the tasks are sleeping
 522  *
 523  * Grabs queue->lock
 524  */
 525 void rpc_wake_up(struct rpc_wait_queue *queue)
 526 {
 527         struct rpc_task *task, *next;
 528         struct list_head *head;
 529
 530         rcu_read_lock_bh();
 531         spin_lock(&queue->lock);
 532         head = &queue->tasks[queue->maxpriority];
 533         for (;;) {
 534                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
 535                         __rpc_wake_up_task(task);
 536                 if (head == &queue->tasks[0])
 537                         break;
 538                 head--;
 539         }
 540         spin_unlock(&queue->lock);
 541         rcu_read_unlock_bh();
 542 }
 543
 544 /**
 545  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 546  * @queue: rpc_wait_queue on which the tasks are sleeping
 547  * @status: status value to set
 548  *
 549  * Grabs queue->lock
 550  */
 551 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 552 {
 553         struct rpc_task *task, *next;
 554         struct list_head *head;
 555
 556         rcu_read_lock_bh();
 557         spin_lock(&queue->lock);
 558         head = &queue->tasks[queue->maxpriority];
 559         for (;;) {
 560                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
 561                         task->tk_status = status;
 562                         __rpc_wake_up_task(task);
 563                 }
 564                 if (head == &queue->tasks[0])
 565                         break;
 566                 head--;
 567         }
 568         spin_unlock(&queue->lock);
 569         rcu_read_unlock_bh();
 570 }
 571
 572 static void __rpc_atrun(struct rpc_task *task)
 573 {
 574         rpc_wake_up_task(task);
 575 }
 576
 577 /*
 578  * Run a task at a later time
 579  */
 580 void rpc_delay(struct rpc_task *task, unsigned long delay)
 581 {
 582         task->tk_timeout = delay;
 583         rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
 584 }
 585
 586 /*
 587  * Helper to call task->tk_ops->rpc_call_prepare
 588  */
 589 static void rpc_prepare_task(struct rpc_task *task)
 590 {
 591         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 592 }
 593
 594 /*
 595  * Helper that calls task->tk_ops->rpc_call_done if it exists
 596  */
 597 void rpc_exit_task(struct rpc_task *task)
 598 {
 599         task->tk_action = NULL;
 600         if (task->tk_ops->rpc_call_done != NULL) {
 601                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
 602                 if (task->tk_action != NULL) {
 603                         WARN_ON(RPC_ASSASSINATED(task));
 604                         /* Always release the RPC slot and buffer memory */
 605                         xprt_release(task);
 606                 }
 607         }
 608 }
 609 EXPORT_SYMBOL(rpc_exit_task);
 610
 611 /*
 612  * This is the RPC `scheduler' (or rather, the finite state machine).
 613  */
 614 static int __rpc_execute(struct rpc_task *task)
 615 {
 616         int             status = 0;
 617
 618         dprintk("RPC: %4d rpc_execute flgs %x\n",
 619                                 task->tk_pid, task->tk_flags);
 620
 621         BUG_ON(RPC_IS_QUEUED(task));
 622
 623         for (;;) {
 624                 /*
 625                  * Garbage collection of pending timers...
 626                  */
 627                 rpc_delete_timer(task);
 628
 629                 /*
 630                  * Execute any pending callback.
 631                  */
 632                 if (RPC_DO_CALLBACK(task)) {
 633                         /* Define a callback save pointer */
 634                         void (*save_callback)(struct rpc_task *);
 635
 636                         /*
 637                          * If a callback exists, save it, reset it,
 638                          * call it.
 639                          * The save is needed to stop from resetting
 640                          * another callback set within the callback handler
 641                          * - Dave
 642                          */
 643                         save_callback=task->tk_callback;
 644                         task->tk_callback=NULL;
 645                         lock_kernel();
 646                         save_callback(task);
 647                         unlock_kernel();
 648                 }
 649
 650                 /*
 651                  * Perform the next FSM step.
 652                  * tk_action may be NULL when the task has been killed
 653                  * by someone else.
 654                  */
 655                 if (!RPC_IS_QUEUED(task)) {
 656                         if (task->tk_action == NULL)
 657                                 break;
 658                         lock_kernel();
 659                         task->tk_action(task);
 660                         unlock_kernel();
 661                 }
 662
 663                 /*
 664                  * Lockless check for whether task is sleeping or not.
 665                  */
 666                 if (!RPC_IS_QUEUED(task))
 667                         continue;
 668                 rpc_clear_running(task);
 669                 if (RPC_IS_ASYNC(task)) {
 670                         /* Careful! we may have raced... */
 671                         if (RPC_IS_QUEUED(task))
 672                                 return 0;
 673                         if (rpc_test_and_set_running(task))
 674                                 return 0;
 675                         continue;
 676                 }
 677
 678                 /* sync task: sleep here */
 679                 dprintk("RPC: %4d sync task going to sleep\n", task->tk_pid);
 680                 /* Note: Caller should be using rpc_clnt_sigmask() */
 681                 status = out_of_line_wait_on_bit(&task->tk_runstate,
 682                                 RPC_TASK_QUEUED, rpc_wait_bit_interruptible,
 683                                 TASK_INTERRUPTIBLE);
 684                 if (status == -ERESTARTSYS) {
 685                         /*
 686                          * When a sync task receives a signal, it exits with
 687                          * -ERESTARTSYS. In order to catch any callbacks that
 688                          * clean up after sleeping on some queue, we don't
 689                          * break the loop here, but go around once more.
 690                          */
 691                         dprintk("RPC: %4d got signal\n", task->tk_pid);
 692                         task->tk_flags |= RPC_TASK_KILLED;
 693                         rpc_exit(task, -ERESTARTSYS);
 694                         rpc_wake_up_task(task);
 695                 }
 696                 rpc_set_running(task);
 697                 dprintk("RPC: %4d sync task resuming\n", task->tk_pid);
 698         }
 699
 700         dprintk("RPC: %4d, return %d, status %d\n", task->tk_pid, status, task->tk_status);
 701         /* Release all resources associated with the task */
 702         rpc_release_task(task);
 703         return status;
 704 }
 705
 706 /*
 707  * User-visible entry point to the scheduler.
 708  *
 709  * This may be called recursively if e.g. an async NFS task updates
 710  * the attributes and finds that dirty pages must be flushed.
 711  * NOTE: Upon exit of this function the task is guaranteed to be
 712  *       released. In particular note that tk_release() will have
 713  *       been called, so your task memory may have been freed.
 714  */
 715 int
 716 rpc_execute(struct rpc_task *task)
 717 {
 718         rpc_set_active(task);
 719         rpc_set_running(task);
 720         return __rpc_execute(task);
 721 }
 722
 723 static void rpc_async_schedule(void *arg)
 724 {
 725         __rpc_execute((struct rpc_task *)arg);
 726 }
 727
 728 /**
 729  * rpc_malloc - allocate an RPC buffer
 730  * @task: RPC task that will use this buffer
 731  * @size: requested byte size
 732  *
 733  * We try to ensure that some NFS reads and writes can always proceed
 734  * by using a mempool when allocating 'small' buffers.
 735  * In order to avoid memory starvation triggering more writebacks of
 736  * NFS requests, we use GFP_NOFS rather than GFP_KERNEL.
 737  */
 738 void * rpc_malloc(struct rpc_task *task, size_t size)
 739 {
 740         struct rpc_rqst *req = task->tk_rqstp;
 741         gfp_t   gfp;
 742
 743         if (task->tk_flags & RPC_TASK_SWAPPER)
 744                 gfp = GFP_ATOMIC;
 745         else
 746                 gfp = GFP_NOFS;
 747
 748         if (size > RPC_BUFFER_MAXSIZE) {
 749                 req->rq_buffer = kmalloc(size, gfp);
 750                 if (req->rq_buffer)
 751                         req->rq_bufsize = size;
 752         } else {
 753                 req->rq_buffer = mempool_alloc(rpc_buffer_mempool, gfp);
 754                 if (req->rq_buffer)
 755                         req->rq_bufsize = RPC_BUFFER_MAXSIZE;
 756         }
 757         return req->rq_buffer;
 758 }
 759
 760 /**
 761  * rpc_free - free buffer allocated via rpc_malloc
 762  * @task: RPC task with a buffer to be freed
 763  *
 764  */
 765 void rpc_free(struct rpc_task *task)
 766 {
 767         struct rpc_rqst *req = task->tk_rqstp;
 768
 769         if (req->rq_buffer) {
 770                 if (req->rq_bufsize == RPC_BUFFER_MAXSIZE)
 771                         mempool_free(req->rq_buffer, rpc_buffer_mempool);
 772                 else
 773                         kfree(req->rq_buffer);
 774                 req->rq_buffer = NULL;
 775                 req->rq_bufsize = 0;
 776         }
 777 }
 778
 779 /*
 780  * Creation and deletion of RPC task structures
 781  */
 782 void rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 783 {
 784         memset(task, 0, sizeof(*task));
 785         init_timer(&task->tk_timer);
 786         task->tk_timer.data     = (unsigned long) task;
 787         task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
 788         atomic_set(&task->tk_count, 1);
 789         task->tk_client = clnt;
 790         task->tk_flags  = flags;
 791         task->tk_ops = tk_ops;
 792         if (tk_ops->rpc_call_prepare != NULL)
 793                 task->tk_action = rpc_prepare_task;
 794         task->tk_calldata = calldata;
 795
 796         /* Initialize retry counters */
 797         task->tk_garb_retry = 2;
 798         task->tk_cred_retry = 2;
 799
 800         task->tk_priority = RPC_PRIORITY_NORMAL;
 801         task->tk_cookie = (unsigned long)current;
 802
 803         /* Initialize workqueue for async tasks */
 804         task->tk_workqueue = rpciod_workqueue;
 805
 806         if (clnt) {
 807                 atomic_inc(&clnt->cl_users);
 808                 if (clnt->cl_softrtry)
 809                         task->tk_flags |= RPC_TASK_SOFT;
 810                 if (!clnt->cl_intr)
 811                         task->tk_flags |= RPC_TASK_NOINTR;
 812         }
 813
 814         BUG_ON(task->tk_ops == NULL);
 815
 816         /* starting timestamp */
 817         task->tk_start = jiffies;
 818
 819         dprintk("RPC: %4d new task procpid %d\n", task->tk_pid,
 820                                 current->pid);
 821 }
 822
 823 static struct rpc_task *
 824 rpc_alloc_task(void)
 825 {
 826         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 827 }
 828
 829 static void rpc_free_task(struct rcu_head *rcu)
 830 {
 831         struct rpc_task *task = container_of(rcu, struct rpc_task, u.tk_rcu);
 832         dprintk("RPC: %4d freeing task\n", task->tk_pid);
 833         mempool_free(task, rpc_task_mempool);
 834 }
 835
 836 /*
 837  * Create a new task for the specified client.  We have to
 838  * clean up after an allocation failure, as the client may
 839  * have specified "oneshot".
 840  */
 841 struct rpc_task *rpc_new_task(struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 842 {
 843         struct rpc_task *task;
 844
 845         task = rpc_alloc_task();
 846         if (!task)
 847                 goto cleanup;
 848
 849         rpc_init_task(task, clnt, flags, tk_ops, calldata);
 850
 851         dprintk("RPC: %4d allocated task\n", task->tk_pid);
 852         task->tk_flags |= RPC_TASK_DYNAMIC;
 853 out:
 854         return task;
 855
 856 cleanup:
 857         /* Check whether to release the client */
 858         if (clnt) {
 859                 printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
 860                         atomic_read(&clnt->cl_users), clnt->cl_oneshot);
 861                 atomic_inc(&clnt->cl_users); /* pretend we were used ... */
 862                 rpc_release_client(clnt);
 863         }
 864         goto out;
 865 }
 866
 867
 868 void rpc_put_task(struct rpc_task *task)
 869 {
 870         const struct rpc_call_ops *tk_ops = task->tk_ops;
 871         void *calldata = task->tk_calldata;
 872
 873         if (!atomic_dec_and_test(&task->tk_count))
 874                 return;
 875         /* Release resources */
 876         if (task->tk_rqstp)
 877                 xprt_release(task);
 878         if (task->tk_msg.rpc_cred)
 879                 rpcauth_unbindcred(task);
 880         if (task->tk_client) {
 881                 rpc_release_client(task->tk_client);
 882                 task->tk_client = NULL;
 883         }
 884         if (task->tk_flags & RPC_TASK_DYNAMIC)
 885                 call_rcu_bh(&task->u.tk_rcu, rpc_free_task);
 886         if (tk_ops->rpc_release)
 887                 tk_ops->rpc_release(calldata);
 888 }
 889 EXPORT_SYMBOL(rpc_put_task);
 890
 891 void rpc_release_task(struct rpc_task *task)
 892 {
 893 #ifdef RPC_DEBUG
 894         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 895 #endif
 896         dprintk("RPC: %4d release task\n", task->tk_pid);
 897
 898         /* Remove from global task list */
 899         spin_lock(&rpc_sched_lock);
 900         list_del(&task->tk_task);
 901         spin_unlock(&rpc_sched_lock);
 902
 903         BUG_ON (RPC_IS_QUEUED(task));
 904
 905         /* Synchronously delete any running timer */
 906         rpc_delete_timer(task);
 907
 908 #ifdef RPC_DEBUG
 909         task->tk_magic = 0;
 910 #endif
 911         /* Wake up anyone who is waiting for task completion */
 912         rpc_mark_complete_task(task);
 913
 914         rpc_put_task(task);
 915 }
 916
 917 /**
 918  * rpc_run_task - Allocate a new RPC task, then run rpc_execute against it
 919  * @clnt: pointer to RPC client
 920  * @flags: RPC flags
 921  * @ops: RPC call ops
 922  * @data: user call data
 923  */
 924 struct rpc_task *rpc_run_task(struct rpc_clnt *clnt, int flags,
 925                                         const struct rpc_call_ops *ops,
 926                                         void *data)
 927 {
 928         struct rpc_task *task;
 929         task = rpc_new_task(clnt, flags, ops, data);
 930         if (task == NULL) {
 931                 if (ops->rpc_release != NULL)
 932                         ops->rpc_release(data);
 933                 return ERR_PTR(-ENOMEM);
 934         }
 935         atomic_inc(&task->tk_count);
 936         rpc_execute(task);
 937         return task;
 938 }
 939 EXPORT_SYMBOL(rpc_run_task);
 940
 941 /*
 942  * Kill all tasks for the given client.
 943  * XXX: kill their descendants as well?
 944  */
 945 void rpc_killall_tasks(struct rpc_clnt *clnt)
 946 {
 947         struct rpc_task *rovr;
 948         struct list_head *le;
 949
 950         dprintk("RPC:      killing all tasks for client %p\n", clnt);
 951
 952         /*
 953          * Spin lock all_tasks to prevent changes...
 954          */
 955         spin_lock(&rpc_sched_lock);
 956         alltask_for_each(rovr, le, &all_tasks) {
 957                 if (! RPC_IS_ACTIVATED(rovr))
 958                         continue;
 959                 if (!clnt || rovr->tk_client == clnt) {
 960                         rovr->tk_flags |= RPC_TASK_KILLED;
 961                         rpc_exit(rovr, -EIO);
 962                         rpc_wake_up_task(rovr);
 963                 }
 964         }
 965         spin_unlock(&rpc_sched_lock);
 966 }
 967
 968 static DECLARE_MUTEX_LOCKED(rpciod_running);
 969
 970 static void rpciod_killall(void)
 971 {
 972         unsigned long flags;
 973
 974         while (!list_empty(&all_tasks)) {
 975                 clear_thread_flag(TIF_SIGPENDING);
 976                 rpc_killall_tasks(NULL);
 977                 flush_workqueue(rpciod_workqueue);
 978                 if (!list_empty(&all_tasks)) {
 979                         dprintk("rpciod_killall: waiting for tasks to exit\n");
 980                         yield();
 981                 }
 982         }
 983
 984         spin_lock_irqsave(&current->sighand->siglock, flags);
 985         recalc_sigpending();
 986         spin_unlock_irqrestore(&current->sighand->siglock, flags);
 987 }
 988
 989 /*
 990  * Start up the rpciod process if it's not already running.
 991  */
 992 int
 993 rpciod_up(void)
 994 {
 995         struct workqueue_struct *wq;
 996         int error = 0;
 997
 998         mutex_lock(&rpciod_mutex);
 999         dprintk("rpciod_up: users %d\n", rpciod_users);
1000         rpciod_users++;
1001         if (rpciod_workqueue)
1002                 goto out;
1003         /*
1004          * If there's no pid, we should be the first user.
1005          */
1006         if (rpciod_users > 1)
1007                 printk(KERN_WARNING "rpciod_up: no workqueue, %d users??\n", rpciod_users);
1008         /*
1009          * Create the rpciod thread and wait for it to start.
1010          */
1011         error = -ENOMEM;
1012         wq = create_workqueue("rpciod");
1013         if (wq == NULL) {
1014                 printk(KERN_WARNING "rpciod_up: create workqueue failed, error=%d\n", error);
1015                 rpciod_users--;
1016                 goto out;
1017         }
1018         rpciod_workqueue = wq;
1019         error = 0;
1020 out:
1021         mutex_unlock(&rpciod_mutex);
1022         return error;
1023 }
1024
1025 void
1026 rpciod_down(void)
1027 {
1028         mutex_lock(&rpciod_mutex);
1029         dprintk("rpciod_down sema %d\n", rpciod_users);
1030         if (rpciod_users) {
1031                 if (--rpciod_users)
1032                         goto out;
1033         } else
1034                 printk(KERN_WARNING "rpciod_down: no users??\n");
1035
1036         if (!rpciod_workqueue) {
1037                 dprintk("rpciod_down: Nothing to do!\n");
1038                 goto out;
1039         }
1040         rpciod_killall();
1041
1042         destroy_workqueue(rpciod_workqueue);
1043         rpciod_workqueue = NULL;
1044  out:
1045         mutex_unlock(&rpciod_mutex);
1046 }
1047
1048 #ifdef RPC_DEBUG
1049 void rpc_show_tasks(void)
1050 {
1051         struct list_head *le;
1052         struct rpc_task *t;
1053
1054         spin_lock(&rpc_sched_lock);
1055         if (list_empty(&all_tasks)) {
1056                 spin_unlock(&rpc_sched_lock);
1057                 return;
1058         }
1059         printk("-pid- proc flgs status -client- -prog- --rqstp- -timeout "
1060                 "-rpcwait -action- ---ops--\n");
1061         alltask_for_each(t, le, &all_tasks) {
1062                 const char *rpc_waitq = "none";
1063
1064                 if (RPC_IS_QUEUED(t))
1065                         rpc_waitq = rpc_qname(t->u.tk_wait.rpc_waitq);
1066
1067                 printk("%05d %04d %04x %06d %8p %6d %8p %08ld %8s %8p %8p\n",
1068                         t->tk_pid,
1069                         (t->tk_msg.rpc_proc ? t->tk_msg.rpc_proc->p_proc : -1),
1070                         t->tk_flags, t->tk_status,
1071                         t->tk_client,
1072                         (t->tk_client ? t->tk_client->cl_prog : 0),
1073                         t->tk_rqstp, t->tk_timeout,
1074                         rpc_waitq,
1075                         t->tk_action, t->tk_ops);
1076         }
1077         spin_unlock(&rpc_sched_lock);
1078 }
1079 #endif
1080
1081 void
1082 rpc_destroy_mempool(void)
1083 {
1084         if (rpc_buffer_mempool)
1085                 mempool_destroy(rpc_buffer_mempool);
1086         if (rpc_task_mempool)
1087                 mempool_destroy(rpc_task_mempool);
1088         if (rpc_task_slabp)
1089                 kmem_cache_destroy(rpc_task_slabp);
1090         if (rpc_buffer_slabp)
1091                 kmem_cache_destroy(rpc_buffer_slabp);
1092 }
1093
1094 int
1095 rpc_init_mempool(void)
1096 {
1097         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1098                                              sizeof(struct rpc_task),
1099                                              0, SLAB_HWCACHE_ALIGN,
1100                                              NULL, NULL);
1101         if (!rpc_task_slabp)
1102                 goto err_nomem;
1103         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1104                                              RPC_BUFFER_MAXSIZE,
1105                                              0, SLAB_HWCACHE_ALIGN,
1106                                              NULL, NULL);
1107         if (!rpc_buffer_slabp)
1108                 goto err_nomem;
1109         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1110                                                     rpc_task_slabp);
1111         if (!rpc_task_mempool)
1112                 goto err_nomem;
1113         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1114                                                       rpc_buffer_slabp);
1115         if (!rpc_buffer_mempool)
1116                 goto err_nomem;
1117         return 0;
1118 err_nomem:
1119         rpc_destroy_mempool();
1120         return -ENOMEM;
1121 }