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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
  22 #include <linux/sunrpc/clnt.h>
  23 #include <linux/sunrpc/xprt.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 that create another task (e.g. for contacting the portmapper)
  48  * will wait on this queue for their child's completion
  49  */
  50 static RPC_WAITQ(childq, "childq");
  51
  52 /*
  53  * RPC tasks sit here while waiting for conditions to improve.
  54  */
  55 static RPC_WAITQ(delay_queue, "delayq");
  56
  57 /*
  58  * All RPC tasks are linked into this list
  59  */
  60 static LIST_HEAD(all_tasks);
  61
  62 /*
  63  * rpciod-related stuff
  64  */
  65 static DECLARE_MUTEX(rpciod_sema);
  66 static unsigned int             rpciod_users;
  67 static struct workqueue_struct *rpciod_workqueue;
  68
  69 /*
  70  * Spinlock for other critical sections of code.
  71  */
  72 static DEFINE_SPINLOCK(rpc_sched_lock);
  73
  74 /*
  75  * Disable the timer for a given RPC task. Should be called with
  76  * queue->lock and bh_disabled in order to avoid races within
  77  * rpc_run_timer().
  78  */
  79 static inline void
  80 __rpc_disable_timer(struct rpc_task *task)
  81 {
  82         dprintk("RPC: %4d disabling timer\n", task->tk_pid);
  83         task->tk_timeout_fn = NULL;
  84         task->tk_timeout = 0;
  85 }
  86
  87 /*
  88  * Run a timeout function.
  89  * We use the callback in order to allow __rpc_wake_up_task()
  90  * and friends to disable the timer synchronously on SMP systems
  91  * without calling del_timer_sync(). The latter could cause a
  92  * deadlock if called while we're holding spinlocks...
  93  */
  94 static void rpc_run_timer(struct rpc_task *task)
  95 {
  96         void (*callback)(struct rpc_task *);
  97
  98         callback = task->tk_timeout_fn;
  99         task->tk_timeout_fn = NULL;
 100         if (callback && RPC_IS_QUEUED(task)) {
 101                 dprintk("RPC: %4d running timer\n", task->tk_pid);
 102                 callback(task);
 103         }
 104         smp_mb__before_clear_bit();
 105         clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
 106         smp_mb__after_clear_bit();
 107 }
 108
 109 /*
 110  * Set up a timer for the current task.
 111  */
 112 static inline void
 113 __rpc_add_timer(struct rpc_task *task, rpc_action timer)
 114 {
 115         if (!task->tk_timeout)
 116                 return;
 117
 118         dprintk("RPC: %4d setting alarm for %lu ms\n",
 119                         task->tk_pid, task->tk_timeout * 1000 / HZ);
 120
 121         if (timer)
 122                 task->tk_timeout_fn = timer;
 123         else
 124                 task->tk_timeout_fn = __rpc_default_timer;
 125         set_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
 126         mod_timer(&task->tk_timer, jiffies + task->tk_timeout);
 127 }
 128
 129 /*
 130  * Delete any timer for the current task. Because we use del_timer_sync(),
 131  * this function should never be called while holding queue->lock.
 132  */
 133 static void
 134 rpc_delete_timer(struct rpc_task *task)
 135 {
 136         if (RPC_IS_QUEUED(task))
 137                 return;
 138         if (test_and_clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate)) {
 139                 del_singleshot_timer_sync(&task->tk_timer);
 140                 dprintk("RPC: %4d deleting timer\n", task->tk_pid);
 141         }
 142 }
 143
 144 /*
 145  * Add new request to a priority queue.
 146  */
 147 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
 148 {
 149         struct list_head *q;
 150         struct rpc_task *t;
 151
 152         INIT_LIST_HEAD(&task->u.tk_wait.links);
 153         q = &queue->tasks[task->tk_priority];
 154         if (unlikely(task->tk_priority > queue->maxpriority))
 155                 q = &queue->tasks[queue->maxpriority];
 156         list_for_each_entry(t, q, u.tk_wait.list) {
 157                 if (t->tk_cookie == task->tk_cookie) {
 158                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
 159                         return;
 160                 }
 161         }
 162         list_add_tail(&task->u.tk_wait.list, q);
 163 }
 164
 165 /*
 166  * Add new request to wait queue.
 167  *
 168  * Swapper tasks always get inserted at the head of the queue.
 169  * This should avoid many nasty memory deadlocks and hopefully
 170  * improve overall performance.
 171  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
 172  */
 173 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
 174 {
 175         BUG_ON (RPC_IS_QUEUED(task));
 176
 177         if (RPC_IS_PRIORITY(queue))
 178                 __rpc_add_wait_queue_priority(queue, task);
 179         else if (RPC_IS_SWAPPER(task))
 180                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
 181         else
 182                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
 183         task->u.tk_wait.rpc_waitq = queue;
 184         rpc_set_queued(task);
 185
 186         dprintk("RPC: %4d added to queue %p \"%s\"\n",
 187                                 task->tk_pid, queue, rpc_qname(queue));
 188 }
 189
 190 /*
 191  * Remove request from a priority queue.
 192  */
 193 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 194 {
 195         struct rpc_task *t;
 196
 197         if (!list_empty(&task->u.tk_wait.links)) {
 198                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
 199                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
 200                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
 201         }
 202         list_del(&task->u.tk_wait.list);
 203 }
 204
 205 /*
 206  * Remove request from queue.
 207  * Note: must be called with spin lock held.
 208  */
 209 static void __rpc_remove_wait_queue(struct rpc_task *task)
 210 {
 211         struct rpc_wait_queue *queue;
 212         queue = task->u.tk_wait.rpc_waitq;
 213
 214         if (RPC_IS_PRIORITY(queue))
 215                 __rpc_remove_wait_queue_priority(task);
 216         else
 217                 list_del(&task->u.tk_wait.list);
 218         dprintk("RPC: %4d removed from queue %p \"%s\"\n",
 219                                 task->tk_pid, queue, rpc_qname(queue));
 220 }
 221
 222 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 223 {
 224         queue->priority = priority;
 225         queue->count = 1 << (priority * 2);
 226 }
 227
 228 static inline void rpc_set_waitqueue_cookie(struct rpc_wait_queue *queue, unsigned long cookie)
 229 {
 230         queue->cookie = cookie;
 231         queue->nr = RPC_BATCH_COUNT;
 232 }
 233
 234 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 235 {
 236         rpc_set_waitqueue_priority(queue, queue->maxpriority);
 237         rpc_set_waitqueue_cookie(queue, 0);
 238 }
 239
 240 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, int maxprio)
 241 {
 242         int i;
 243
 244         spin_lock_init(&queue->lock);
 245         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 246                 INIT_LIST_HEAD(&queue->tasks[i]);
 247         queue->maxpriority = maxprio;
 248         rpc_reset_waitqueue_priority(queue);
 249 #ifdef RPC_DEBUG
 250         queue->name = qname;
 251 #endif
 252 }
 253
 254 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 255 {
 256         __rpc_init_priority_wait_queue(queue, qname, RPC_PRIORITY_HIGH);
 257 }
 258
 259 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 260 {
 261         __rpc_init_priority_wait_queue(queue, qname, 0);
 262 }
 263 EXPORT_SYMBOL(rpc_init_wait_queue);
 264
 265 static int rpc_wait_bit_interruptible(void *word)
 266 {
 267         if (signal_pending(current))
 268                 return -ERESTARTSYS;
 269         schedule();
 270         return 0;
 271 }
 272
 273 /*
 274  * Mark an RPC call as having completed by clearing the 'active' bit
 275  */
 276 static inline void rpc_mark_complete_task(struct rpc_task *task)
 277 {
 278         rpc_clear_active(task);
 279         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
 280 }
 281
 282 /*
 283  * Allow callers to wait for completion of an RPC call
 284  */
 285 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
 286 {
 287         if (action == NULL)
 288                 action = rpc_wait_bit_interruptible;
 289         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 290                         action, TASK_INTERRUPTIBLE);
 291 }
 292 EXPORT_SYMBOL(__rpc_wait_for_completion_task);
 293
 294 /*
 295  * Make an RPC task runnable.
 296  *
 297  * Note: If the task is ASYNC, this must be called with
 298  * the spinlock held to protect the wait queue operation.
 299  */
 300 static void rpc_make_runnable(struct rpc_task *task)
 301 {
 302         int do_ret;
 303
 304         BUG_ON(task->tk_timeout_fn);
 305         do_ret = rpc_test_and_set_running(task);
 306         rpc_clear_queued(task);
 307         if (do_ret)
 308                 return;
 309         if (RPC_IS_ASYNC(task)) {
 310                 int status;
 311
 312                 INIT_WORK(&task->u.tk_work, rpc_async_schedule, (void *)task);
 313                 status = queue_work(task->tk_workqueue, &task->u.tk_work);
 314                 if (status < 0) {
 315                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
 316                         task->tk_status = status;
 317                         return;
 318                 }
 319         } else
 320                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 321 }
 322
 323 /*
 324  * Place a newly initialized task on the workqueue.
 325  */
 326 static inline void
 327 rpc_schedule_run(struct rpc_task *task)
 328 {
 329         rpc_set_active(task);
 330         rpc_make_runnable(task);
 331 }
 332
 333 /*
 334  * Prepare for sleeping on a wait queue.
 335  * By always appending tasks to the list we ensure FIFO behavior.
 336  * NB: An RPC task will only receive interrupt-driven events as long
 337  * as it's on a wait queue.
 338  */
 339 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 340                         rpc_action action, rpc_action timer)
 341 {
 342         dprintk("RPC: %4d sleep_on(queue \"%s\" time %ld)\n", task->tk_pid,
 343                                 rpc_qname(q), jiffies);
 344
 345         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
 346                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
 347                 return;
 348         }
 349
 350         /* Mark the task as being activated if so needed */
 351         rpc_set_active(task);
 352
 353         __rpc_add_wait_queue(q, task);
 354
 355         BUG_ON(task->tk_callback != NULL);
 356         task->tk_callback = action;
 357         __rpc_add_timer(task, timer);
 358 }
 359
 360 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 361                                 rpc_action action, rpc_action timer)
 362 {
 363         /*
 364          * Protect the queue operations.
 365          */
 366         spin_lock_bh(&q->lock);
 367         __rpc_sleep_on(q, task, action, timer);
 368         spin_unlock_bh(&q->lock);
 369 }
 370
 371 /**
 372  * __rpc_do_wake_up_task - wake up a single rpc_task
 373  * @task: task to be woken up
 374  *
 375  * Caller must hold queue->lock, and have cleared the task queued flag.
 376  */
 377 static void __rpc_do_wake_up_task(struct rpc_task *task)
 378 {
 379         dprintk("RPC: %4d __rpc_wake_up_task (now %ld)\n", task->tk_pid, jiffies);
 380
 381 #ifdef RPC_DEBUG
 382         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 383 #endif
 384         /* Has the task been executed yet? If not, we cannot wake it up! */
 385         if (!RPC_IS_ACTIVATED(task)) {
 386                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 387                 return;
 388         }
 389
 390         __rpc_disable_timer(task);
 391         __rpc_remove_wait_queue(task);
 392
 393         rpc_make_runnable(task);
 394
 395         dprintk("RPC:      __rpc_wake_up_task done\n");
 396 }
 397
 398 /*
 399  * Wake up the specified task
 400  */
 401 static void __rpc_wake_up_task(struct rpc_task *task)
 402 {
 403         if (rpc_start_wakeup(task)) {
 404                 if (RPC_IS_QUEUED(task))
 405                         __rpc_do_wake_up_task(task);
 406                 rpc_finish_wakeup(task);
 407         }
 408 }
 409
 410 /*
 411  * Default timeout handler if none specified by user
 412  */
 413 static void
 414 __rpc_default_timer(struct rpc_task *task)
 415 {
 416         dprintk("RPC: %d timeout (default timer)\n", task->tk_pid);
 417         task->tk_status = -ETIMEDOUT;
 418         rpc_wake_up_task(task);
 419 }
 420
 421 /*
 422  * Wake up the specified task
 423  */
 424 void rpc_wake_up_task(struct rpc_task *task)
 425 {
 426         if (rpc_start_wakeup(task)) {
 427                 if (RPC_IS_QUEUED(task)) {
 428                         struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
 429
 430                         spin_lock_bh(&queue->lock);
 431                         __rpc_do_wake_up_task(task);
 432                         spin_unlock_bh(&queue->lock);
 433                 }
 434                 rpc_finish_wakeup(task);
 435         }
 436 }
 437
 438 /*
 439  * Wake up the next task on a priority queue.
 440  */
 441 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
 442 {
 443         struct list_head *q;
 444         struct rpc_task *task;
 445
 446         /*
 447          * Service a batch of tasks from a single cookie.
 448          */
 449         q = &queue->tasks[queue->priority];
 450         if (!list_empty(q)) {
 451                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 452                 if (queue->cookie == task->tk_cookie) {
 453                         if (--queue->nr)
 454                                 goto out;
 455                         list_move_tail(&task->u.tk_wait.list, q);
 456                 }
 457                 /*
 458                  * Check if we need to switch queues.
 459                  */
 460                 if (--queue->count)
 461                         goto new_cookie;
 462         }
 463
 464         /*
 465          * Service the next queue.
 466          */
 467         do {
 468                 if (q == &queue->tasks[0])
 469                         q = &queue->tasks[queue->maxpriority];
 470                 else
 471                         q = q - 1;
 472                 if (!list_empty(q)) {
 473                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 474                         goto new_queue;
 475                 }
 476         } while (q != &queue->tasks[queue->priority]);
 477
 478         rpc_reset_waitqueue_priority(queue);
 479         return NULL;
 480
 481 new_queue:
 482         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 483 new_cookie:
 484         rpc_set_waitqueue_cookie(queue, task->tk_cookie);
 485 out:
 486         __rpc_wake_up_task(task);
 487         return task;
 488 }
 489
 490 /*
 491  * Wake up the next task on the wait queue.
 492  */
 493 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
 494 {
 495         struct rpc_task *task = NULL;
 496
 497         dprintk("RPC:      wake_up_next(%p \"%s\")\n", queue, rpc_qname(queue));
 498         spin_lock_bh(&queue->lock);
 499         if (RPC_IS_PRIORITY(queue))
 500                 task = __rpc_wake_up_next_priority(queue);
 501         else {
 502                 task_for_first(task, &queue->tasks[0])
 503                         __rpc_wake_up_task(task);
 504         }
 505         spin_unlock_bh(&queue->lock);
 506
 507         return task;
 508 }
 509
 510 /**
 511  * rpc_wake_up - wake up all rpc_tasks
 512  * @queue: rpc_wait_queue on which the tasks are sleeping
 513  *
 514  * Grabs queue->lock
 515  */
 516 void rpc_wake_up(struct rpc_wait_queue *queue)
 517 {
 518         struct rpc_task *task;
 519
 520         struct list_head *head;
 521         spin_lock_bh(&queue->lock);
 522         head = &queue->tasks[queue->maxpriority];
 523         for (;;) {
 524                 while (!list_empty(head)) {
 525                         task = list_entry(head->next, struct rpc_task, u.tk_wait.list);
 526                         __rpc_wake_up_task(task);
 527                 }
 528                 if (head == &queue->tasks[0])
 529                         break;
 530                 head--;
 531         }
 532         spin_unlock_bh(&queue->lock);
 533 }
 534
 535 /**
 536  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 537  * @queue: rpc_wait_queue on which the tasks are sleeping
 538  * @status: status value to set
 539  *
 540  * Grabs queue->lock
 541  */
 542 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 543 {
 544         struct list_head *head;
 545         struct rpc_task *task;
 546
 547         spin_lock_bh(&queue->lock);
 548         head = &queue->tasks[queue->maxpriority];
 549         for (;;) {
 550                 while (!list_empty(head)) {
 551                         task = list_entry(head->next, struct rpc_task, u.tk_wait.list);
 552                         task->tk_status = status;
 553                         __rpc_wake_up_task(task);
 554                 }
 555                 if (head == &queue->tasks[0])
 556                         break;
 557                 head--;
 558         }
 559         spin_unlock_bh(&queue->lock);
 560 }
 561
 562 /*
 563  * Run a task at a later time
 564  */
 565 static void     __rpc_atrun(struct rpc_task *);
 566 void
 567 rpc_delay(struct rpc_task *task, unsigned long delay)
 568 {
 569         task->tk_timeout = delay;
 570         rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
 571 }
 572
 573 static void
 574 __rpc_atrun(struct rpc_task *task)
 575 {
 576         task->tk_status = 0;
 577         rpc_wake_up_task(task);
 578 }
 579
 580 /*
 581  * Helper to call task->tk_ops->rpc_call_prepare
 582  */
 583 static void rpc_prepare_task(struct rpc_task *task)
 584 {
 585         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 586 }
 587
 588 /*
 589  * Helper that calls task->tk_ops->rpc_call_done if it exists
 590  */
 591 void rpc_exit_task(struct rpc_task *task)
 592 {
 593         task->tk_action = NULL;
 594         if (task->tk_ops->rpc_call_done != NULL) {
 595                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
 596                 if (task->tk_action != NULL) {
 597                         WARN_ON(RPC_ASSASSINATED(task));
 598                         /* Always release the RPC slot and buffer memory */
 599                         xprt_release(task);
 600                 }
 601         }
 602 }
 603 EXPORT_SYMBOL(rpc_exit_task);
 604
 605 /*
 606  * This is the RPC `scheduler' (or rather, the finite state machine).
 607  */
 608 static int __rpc_execute(struct rpc_task *task)
 609 {
 610         int             status = 0;
 611
 612         dprintk("RPC: %4d rpc_execute flgs %x\n",
 613                                 task->tk_pid, task->tk_flags);
 614
 615         BUG_ON(RPC_IS_QUEUED(task));
 616
 617         for (;;) {
 618                 /*
 619                  * Garbage collection of pending timers...
 620                  */
 621                 rpc_delete_timer(task);
 622
 623                 /*
 624                  * Execute any pending callback.
 625                  */
 626                 if (RPC_DO_CALLBACK(task)) {
 627                         /* Define a callback save pointer */
 628                         void (*save_callback)(struct rpc_task *);
 629
 630                         /*
 631                          * If a callback exists, save it, reset it,
 632                          * call it.
 633                          * The save is needed to stop from resetting
 634                          * another callback set within the callback handler
 635                          * - Dave
 636                          */
 637                         save_callback=task->tk_callback;
 638                         task->tk_callback=NULL;
 639                         lock_kernel();
 640                         save_callback(task);
 641                         unlock_kernel();
 642                 }
 643
 644                 /*
 645                  * Perform the next FSM step.
 646                  * tk_action may be NULL when the task has been killed
 647                  * by someone else.
 648                  */
 649                 if (!RPC_IS_QUEUED(task)) {
 650                         if (task->tk_action == NULL)
 651                                 break;
 652                         lock_kernel();
 653                         task->tk_action(task);
 654                         unlock_kernel();
 655                 }
 656
 657                 /*
 658                  * Lockless check for whether task is sleeping or not.
 659                  */
 660                 if (!RPC_IS_QUEUED(task))
 661                         continue;
 662                 rpc_clear_running(task);
 663                 if (RPC_IS_ASYNC(task)) {
 664                         /* Careful! we may have raced... */
 665                         if (RPC_IS_QUEUED(task))
 666                                 return 0;
 667                         if (rpc_test_and_set_running(task))
 668                                 return 0;
 669                         continue;
 670                 }
 671
 672                 /* sync task: sleep here */
 673                 dprintk("RPC: %4d sync task going to sleep\n", task->tk_pid);
 674                 /* Note: Caller should be using rpc_clnt_sigmask() */
 675                 status = out_of_line_wait_on_bit(&task->tk_runstate,
 676                                 RPC_TASK_QUEUED, rpc_wait_bit_interruptible,
 677                                 TASK_INTERRUPTIBLE);
 678                 if (status == -ERESTARTSYS) {
 679                         /*
 680                          * When a sync task receives a signal, it exits with
 681                          * -ERESTARTSYS. In order to catch any callbacks that
 682                          * clean up after sleeping on some queue, we don't
 683                          * break the loop here, but go around once more.
 684                          */
 685                         dprintk("RPC: %4d got signal\n", task->tk_pid);
 686                         task->tk_flags |= RPC_TASK_KILLED;
 687                         rpc_exit(task, -ERESTARTSYS);
 688                         rpc_wake_up_task(task);
 689                 }
 690                 rpc_set_running(task);
 691                 dprintk("RPC: %4d sync task resuming\n", task->tk_pid);
 692         }
 693
 694         dprintk("RPC: %4d, return %d, status %d\n", task->tk_pid, status, task->tk_status);
 695         /* Wake up anyone who is waiting for task completion */
 696         rpc_mark_complete_task(task);
 697         /* Release all resources associated with the task */
 698         rpc_release_task(task);
 699         return status;
 700 }
 701
 702 /*
 703  * User-visible entry point to the scheduler.
 704  *
 705  * This may be called recursively if e.g. an async NFS task updates
 706  * the attributes and finds that dirty pages must be flushed.
 707  * NOTE: Upon exit of this function the task is guaranteed to be
 708  *       released. In particular note that tk_release() will have
 709  *       been called, so your task memory may have been freed.
 710  */
 711 int
 712 rpc_execute(struct rpc_task *task)
 713 {
 714         rpc_set_active(task);
 715         rpc_set_running(task);
 716         return __rpc_execute(task);
 717 }
 718
 719 static void rpc_async_schedule(void *arg)
 720 {
 721         __rpc_execute((struct rpc_task *)arg);
 722 }
 723
 724 /**
 725  * rpc_malloc - allocate an RPC buffer
 726  * @task: RPC task that will use this buffer
 727  * @size: requested byte size
 728  *
 729  * We try to ensure that some NFS reads and writes can always proceed
 730  * by using a mempool when allocating 'small' buffers.
 731  * In order to avoid memory starvation triggering more writebacks of
 732  * NFS requests, we use GFP_NOFS rather than GFP_KERNEL.
 733  */
 734 void * rpc_malloc(struct rpc_task *task, size_t size)
 735 {
 736         struct rpc_rqst *req = task->tk_rqstp;
 737         gfp_t   gfp;
 738
 739         if (task->tk_flags & RPC_TASK_SWAPPER)
 740                 gfp = GFP_ATOMIC;
 741         else
 742                 gfp = GFP_NOFS;
 743
 744         if (size > RPC_BUFFER_MAXSIZE) {
 745                 req->rq_buffer = kmalloc(size, gfp);
 746                 if (req->rq_buffer)
 747                         req->rq_bufsize = size;
 748         } else {
 749                 req->rq_buffer = mempool_alloc(rpc_buffer_mempool, gfp);
 750                 if (req->rq_buffer)
 751                         req->rq_bufsize = RPC_BUFFER_MAXSIZE;
 752         }
 753         return req->rq_buffer;
 754 }
 755
 756 /**
 757  * rpc_free - free buffer allocated via rpc_malloc
 758  * @task: RPC task with a buffer to be freed
 759  *
 760  */
 761 void rpc_free(struct rpc_task *task)
 762 {
 763         struct rpc_rqst *req = task->tk_rqstp;
 764
 765         if (req->rq_buffer) {
 766                 if (req->rq_bufsize == RPC_BUFFER_MAXSIZE)
 767                         mempool_free(req->rq_buffer, rpc_buffer_mempool);
 768                 else
 769                         kfree(req->rq_buffer);
 770                 req->rq_buffer = NULL;
 771                 req->rq_bufsize = 0;
 772         }
 773 }
 774
 775 /*
 776  * Creation and deletion of RPC task structures
 777  */
 778 void rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 779 {
 780         memset(task, 0, sizeof(*task));
 781         init_timer(&task->tk_timer);
 782         task->tk_timer.data     = (unsigned long) task;
 783         task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
 784         atomic_set(&task->tk_count, 1);
 785         task->tk_client = clnt;
 786         task->tk_flags  = flags;
 787         task->tk_ops = tk_ops;
 788         if (tk_ops->rpc_call_prepare != NULL)
 789                 task->tk_action = rpc_prepare_task;
 790         task->tk_calldata = calldata;
 791
 792         /* Initialize retry counters */
 793         task->tk_garb_retry = 2;
 794         task->tk_cred_retry = 2;
 795
 796         task->tk_priority = RPC_PRIORITY_NORMAL;
 797         task->tk_cookie = (unsigned long)current;
 798
 799         /* Initialize workqueue for async tasks */
 800         task->tk_workqueue = rpciod_workqueue;
 801
 802         if (clnt) {
 803                 atomic_inc(&clnt->cl_users);
 804                 if (clnt->cl_softrtry)
 805                         task->tk_flags |= RPC_TASK_SOFT;
 806                 if (!clnt->cl_intr)
 807                         task->tk_flags |= RPC_TASK_NOINTR;
 808         }
 809
 810 #ifdef RPC_DEBUG
 811         task->tk_magic = RPC_TASK_MAGIC_ID;
 812         task->tk_pid = rpc_task_id++;
 813 #endif
 814         /* Add to global list of all tasks */
 815         spin_lock(&rpc_sched_lock);
 816         list_add_tail(&task->tk_task, &all_tasks);
 817         spin_unlock(&rpc_sched_lock);
 818
 819         BUG_ON(task->tk_ops == NULL);
 820
 821         dprintk("RPC: %4d new task procpid %d\n", task->tk_pid,
 822                                 current->pid);
 823 }
 824
 825 static struct rpc_task *
 826 rpc_alloc_task(void)
 827 {
 828         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 829 }
 830
 831 static void rpc_free_task(struct rpc_task *task)
 832 {
 833         dprintk("RPC: %4d freeing task\n", task->tk_pid);
 834         mempool_free(task, rpc_task_mempool);
 835 }
 836
 837 /*
 838  * Create a new task for the specified client.  We have to
 839  * clean up after an allocation failure, as the client may
 840  * have specified "oneshot".
 841  */
 842 struct rpc_task *rpc_new_task(struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 843 {
 844         struct rpc_task *task;
 845
 846         task = rpc_alloc_task();
 847         if (!task)
 848                 goto cleanup;
 849
 850         rpc_init_task(task, clnt, flags, tk_ops, calldata);
 851
 852         dprintk("RPC: %4d allocated task\n", task->tk_pid);
 853         task->tk_flags |= RPC_TASK_DYNAMIC;
 854 out:
 855         return task;
 856
 857 cleanup:
 858         /* Check whether to release the client */
 859         if (clnt) {
 860                 printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
 861                         atomic_read(&clnt->cl_users), clnt->cl_oneshot);
 862                 atomic_inc(&clnt->cl_users); /* pretend we were used ... */
 863                 rpc_release_client(clnt);
 864         }
 865         goto out;
 866 }
 867
 868 void rpc_release_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 #ifdef RPC_DEBUG
 874         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 875 #endif
 876         if (!atomic_dec_and_test(&task->tk_count))
 877                 return;
 878         dprintk("RPC: %4d release task\n", task->tk_pid);
 879
 880         /* Remove from global task list */
 881         spin_lock(&rpc_sched_lock);
 882         list_del(&task->tk_task);
 883         spin_unlock(&rpc_sched_lock);
 884
 885         BUG_ON (RPC_IS_QUEUED(task));
 886
 887         /* Synchronously delete any running timer */
 888         rpc_delete_timer(task);
 889
 890         /* Release resources */
 891         if (task->tk_rqstp)
 892                 xprt_release(task);
 893         if (task->tk_msg.rpc_cred)
 894                 rpcauth_unbindcred(task);
 895         if (task->tk_client) {
 896                 rpc_release_client(task->tk_client);
 897                 task->tk_client = NULL;
 898         }
 899
 900 #ifdef RPC_DEBUG
 901         task->tk_magic = 0;
 902 #endif
 903         if (task->tk_flags & RPC_TASK_DYNAMIC)
 904                 rpc_free_task(task);
 905         if (tk_ops->rpc_release)
 906                 tk_ops->rpc_release(calldata);
 907 }
 908
 909 /**
 910  * rpc_run_task - Allocate a new RPC task, then run rpc_execute against it
 911  * @clnt - pointer to RPC client
 912  * @flags - RPC flags
 913  * @ops - RPC call ops
 914  * @data - user call data
 915  */
 916 struct rpc_task *rpc_run_task(struct rpc_clnt *clnt, int flags,
 917                                         const struct rpc_call_ops *ops,
 918                                         void *data)
 919 {
 920         struct rpc_task *task;
 921         task = rpc_new_task(clnt, flags, ops, data);
 922         if (task == NULL)
 923                 return ERR_PTR(-ENOMEM);
 924         atomic_inc(&task->tk_count);
 925         rpc_execute(task);
 926         return task;
 927 }
 928 EXPORT_SYMBOL(rpc_run_task);
 929
 930 /**
 931  * rpc_find_parent - find the parent of a child task.
 932  * @child: child task
 933  *
 934  * Checks that the parent task is still sleeping on the
 935  * queue 'childq'. If so returns a pointer to the parent.
 936  * Upon failure returns NULL.
 937  *
 938  * Caller must hold childq.lock
 939  */
 940 static inline struct rpc_task *rpc_find_parent(struct rpc_task *child, struct rpc_task *parent)
 941 {
 942         struct rpc_task *task;
 943         struct list_head *le;
 944
 945         task_for_each(task, le, &childq.tasks[0])
 946                 if (task == parent)
 947                         return parent;
 948
 949         return NULL;
 950 }
 951
 952 static void rpc_child_exit(struct rpc_task *child, void *calldata)
 953 {
 954         struct rpc_task *parent;
 955
 956         spin_lock_bh(&childq.lock);
 957         if ((parent = rpc_find_parent(child, calldata)) != NULL) {
 958                 parent->tk_status = child->tk_status;
 959                 __rpc_wake_up_task(parent);
 960         }
 961         spin_unlock_bh(&childq.lock);
 962 }
 963
 964 static const struct rpc_call_ops rpc_child_ops = {
 965         .rpc_call_done = rpc_child_exit,
 966 };
 967
 968 /*
 969  * Note: rpc_new_task releases the client after a failure.
 970  */
 971 struct rpc_task *
 972 rpc_new_child(struct rpc_clnt *clnt, struct rpc_task *parent)
 973 {
 974         struct rpc_task *task;
 975
 976         task = rpc_new_task(clnt, RPC_TASK_ASYNC | RPC_TASK_CHILD, &rpc_child_ops, parent);
 977         if (!task)
 978                 goto fail;
 979         return task;
 980
 981 fail:
 982         parent->tk_status = -ENOMEM;
 983         return NULL;
 984 }
 985
 986 void rpc_run_child(struct rpc_task *task, struct rpc_task *child, rpc_action func)
 987 {
 988         spin_lock_bh(&childq.lock);
 989         /* N.B. Is it possible for the child to have already finished? */
 990         __rpc_sleep_on(&childq, task, func, NULL);
 991         rpc_schedule_run(child);
 992         spin_unlock_bh(&childq.lock);
 993 }
 994
 995 /*
 996  * Kill all tasks for the given client.
 997  * XXX: kill their descendants as well?
 998  */
 999 void rpc_killall_tasks(struct rpc_clnt *clnt)
1000 {
1001         struct rpc_task *rovr;
1002         struct list_head *le;
1003
1004         dprintk("RPC:      killing all tasks for client %p\n", clnt);
1005
1006         /*
1007          * Spin lock all_tasks to prevent changes...
1008          */
1009         spin_lock(&rpc_sched_lock);
1010         alltask_for_each(rovr, le, &all_tasks) {
1011                 if (! RPC_IS_ACTIVATED(rovr))
1012                         continue;
1013                 if (!clnt || rovr->tk_client == clnt) {
1014                         rovr->tk_flags |= RPC_TASK_KILLED;
1015                         rpc_exit(rovr, -EIO);
1016                         rpc_wake_up_task(rovr);
1017                 }
1018         }
1019         spin_unlock(&rpc_sched_lock);
1020 }
1021
1022 static DECLARE_MUTEX_LOCKED(rpciod_running);
1023
1024 static void rpciod_killall(void)
1025 {
1026         unsigned long flags;
1027
1028         while (!list_empty(&all_tasks)) {
1029                 clear_thread_flag(TIF_SIGPENDING);
1030                 rpc_killall_tasks(NULL);
1031                 flush_workqueue(rpciod_workqueue);
1032                 if (!list_empty(&all_tasks)) {
1033                         dprintk("rpciod_killall: waiting for tasks to exit\n");
1034                         yield();
1035                 }
1036         }
1037
1038         spin_lock_irqsave(&current->sighand->siglock, flags);
1039         recalc_sigpending();
1040         spin_unlock_irqrestore(&current->sighand->siglock, flags);
1041 }
1042
1043 /*
1044  * Start up the rpciod process if it's not already running.
1045  */
1046 int
1047 rpciod_up(void)
1048 {
1049         struct workqueue_struct *wq;
1050         int error = 0;
1051
1052         down(&rpciod_sema);
1053         dprintk("rpciod_up: users %d\n", rpciod_users);
1054         rpciod_users++;
1055         if (rpciod_workqueue)
1056                 goto out;
1057         /*
1058          * If there's no pid, we should be the first user.
1059          */
1060         if (rpciod_users > 1)
1061                 printk(KERN_WARNING "rpciod_up: no workqueue, %d users??\n", rpciod_users);
1062         /*
1063          * Create the rpciod thread and wait for it to start.
1064          */
1065         error = -ENOMEM;
1066         wq = create_workqueue("rpciod");
1067         if (wq == NULL) {
1068                 printk(KERN_WARNING "rpciod_up: create workqueue failed, error=%d\n", error);
1069                 rpciod_users--;
1070                 goto out;
1071         }
1072         rpciod_workqueue = wq;
1073         error = 0;
1074 out:
1075         up(&rpciod_sema);
1076         return error;
1077 }
1078
1079 void
1080 rpciod_down(void)
1081 {
1082         down(&rpciod_sema);
1083         dprintk("rpciod_down sema %d\n", rpciod_users);
1084         if (rpciod_users) {
1085                 if (--rpciod_users)
1086                         goto out;
1087         } else
1088                 printk(KERN_WARNING "rpciod_down: no users??\n");
1089
1090         if (!rpciod_workqueue) {
1091                 dprintk("rpciod_down: Nothing to do!\n");
1092                 goto out;
1093         }
1094         rpciod_killall();
1095
1096         destroy_workqueue(rpciod_workqueue);
1097         rpciod_workqueue = NULL;
1098  out:
1099         up(&rpciod_sema);
1100 }
1101
1102 #ifdef RPC_DEBUG
1103 void rpc_show_tasks(void)
1104 {
1105         struct list_head *le;
1106         struct rpc_task *t;
1107
1108         spin_lock(&rpc_sched_lock);
1109         if (list_empty(&all_tasks)) {
1110                 spin_unlock(&rpc_sched_lock);
1111                 return;
1112         }
1113         printk("-pid- proc flgs status -client- -prog- --rqstp- -timeout "
1114                 "-rpcwait -action- ---ops--\n");
1115         alltask_for_each(t, le, &all_tasks) {
1116                 const char *rpc_waitq = "none";
1117
1118                 if (RPC_IS_QUEUED(t))
1119                         rpc_waitq = rpc_qname(t->u.tk_wait.rpc_waitq);
1120
1121                 printk("%05d %04d %04x %06d %8p %6d %8p %08ld %8s %8p %8p\n",
1122                         t->tk_pid,
1123                         (t->tk_msg.rpc_proc ? t->tk_msg.rpc_proc->p_proc : -1),
1124                         t->tk_flags, t->tk_status,
1125                         t->tk_client,
1126                         (t->tk_client ? t->tk_client->cl_prog : 0),
1127                         t->tk_rqstp, t->tk_timeout,
1128                         rpc_waitq,
1129                         t->tk_action, t->tk_ops);
1130         }
1131         spin_unlock(&rpc_sched_lock);
1132 }
1133 #endif
1134
1135 void
1136 rpc_destroy_mempool(void)
1137 {
1138         if (rpc_buffer_mempool)
1139                 mempool_destroy(rpc_buffer_mempool);
1140         if (rpc_task_mempool)
1141                 mempool_destroy(rpc_task_mempool);
1142         if (rpc_task_slabp && kmem_cache_destroy(rpc_task_slabp))
1143                 printk(KERN_INFO "rpc_task: not all structures were freed\n");
1144         if (rpc_buffer_slabp && kmem_cache_destroy(rpc_buffer_slabp))
1145                 printk(KERN_INFO "rpc_buffers: not all structures were freed\n");
1146 }
1147
1148 int
1149 rpc_init_mempool(void)
1150 {
1151         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1152                                              sizeof(struct rpc_task),
1153                                              0, SLAB_HWCACHE_ALIGN,
1154                                              NULL, NULL);
1155         if (!rpc_task_slabp)
1156                 goto err_nomem;
1157         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1158                                              RPC_BUFFER_MAXSIZE,
1159                                              0, SLAB_HWCACHE_ALIGN,
1160                                              NULL, NULL);
1161         if (!rpc_buffer_slabp)
1162                 goto err_nomem;
1163         rpc_task_mempool = mempool_create(RPC_TASK_POOLSIZE,
1164                                             mempool_alloc_slab,
1165                                             mempool_free_slab,
1166                                             rpc_task_slabp);
1167         if (!rpc_task_mempool)
1168                 goto err_nomem;
1169         rpc_buffer_mempool = mempool_create(RPC_BUFFER_POOLSIZE,
1170                                             mempool_alloc_slab,
1171                                             mempool_free_slab,
1172                                             rpc_buffer_slabp);
1173         if (!rpc_buffer_mempool)
1174                 goto err_nomem;
1175         return 0;
1176 err_nomem:
1177         rpc_destroy_mempool();
1178         return -ENOMEM;
1179 }