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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;
  38 static kmem_cache_t     *rpc_buffer_slabp;
  39 static mempool_t        *rpc_task_mempool;
  40 static mempool_t        *rpc_buffer_mempool;
  41
  42 static void                     __rpc_default_timer(struct rpc_task *task);
  43 static void                     rpciod_killall(void);
  44 static void                     rpc_free(struct rpc_task *task);
  45
  46 static void                     rpc_async_schedule(void *);
  47
  48 /*
  49  * RPC tasks that create another task (e.g. for contacting the portmapper)
  50  * will wait on this queue for their child's completion
  51  */
  52 static RPC_WAITQ(childq, "childq");
  53
  54 /*
  55  * RPC tasks sit here while waiting for conditions to improve.
  56  */
  57 static RPC_WAITQ(delay_queue, "delayq");
  58
  59 /*
  60  * All RPC tasks are linked into this list
  61  */
  62 static LIST_HEAD(all_tasks);
  63
  64 /*
  65  * rpciod-related stuff
  66  */
  67 static DECLARE_MUTEX(rpciod_sema);
  68 static unsigned int             rpciod_users;
  69 static struct workqueue_struct *rpciod_workqueue;
  70
  71 /*
  72  * Spinlock for other critical sections of code.
  73  */
  74 static DEFINE_SPINLOCK(rpc_sched_lock);
  75
  76 /*
  77  * Disable the timer for a given RPC task. Should be called with
  78  * queue->lock and bh_disabled in order to avoid races within
  79  * rpc_run_timer().
  80  */
  81 static inline void
  82 __rpc_disable_timer(struct rpc_task *task)
  83 {
  84         dprintk("RPC: %4d disabling timer\n", task->tk_pid);
  85         task->tk_timeout_fn = NULL;
  86         task->tk_timeout = 0;
  87 }
  88
  89 /*
  90  * Run a timeout function.
  91  * We use the callback in order to allow __rpc_wake_up_task()
  92  * and friends to disable the timer synchronously on SMP systems
  93  * without calling del_timer_sync(). The latter could cause a
  94  * deadlock if called while we're holding spinlocks...
  95  */
  96 static void rpc_run_timer(struct rpc_task *task)
  97 {
  98         void (*callback)(struct rpc_task *);
  99
 100         callback = task->tk_timeout_fn;
 101         task->tk_timeout_fn = NULL;
 102         if (callback && RPC_IS_QUEUED(task)) {
 103                 dprintk("RPC: %4d running timer\n", task->tk_pid);
 104                 callback(task);
 105         }
 106         smp_mb__before_clear_bit();
 107         clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
 108         smp_mb__after_clear_bit();
 109 }
 110
 111 /*
 112  * Set up a timer for the current task.
 113  */
 114 static inline void
 115 __rpc_add_timer(struct rpc_task *task, rpc_action timer)
 116 {
 117         if (!task->tk_timeout)
 118                 return;
 119
 120         dprintk("RPC: %4d setting alarm for %lu ms\n",
 121                         task->tk_pid, task->tk_timeout * 1000 / HZ);
 122
 123         if (timer)
 124                 task->tk_timeout_fn = timer;
 125         else
 126                 task->tk_timeout_fn = __rpc_default_timer;
 127         set_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
 128         mod_timer(&task->tk_timer, jiffies + task->tk_timeout);
 129 }
 130
 131 /*
 132  * Delete any timer for the current task. Because we use del_timer_sync(),
 133  * this function should never be called while holding queue->lock.
 134  */
 135 static void
 136 rpc_delete_timer(struct rpc_task *task)
 137 {
 138         if (RPC_IS_QUEUED(task))
 139                 return;
 140         if (test_and_clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate)) {
 141                 del_singleshot_timer_sync(&task->tk_timer);
 142                 dprintk("RPC: %4d deleting timer\n", task->tk_pid);
 143         }
 144 }
 145
 146 /*
 147  * Add new request to a priority queue.
 148  */
 149 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
 150 {
 151         struct list_head *q;
 152         struct rpc_task *t;
 153
 154         INIT_LIST_HEAD(&task->u.tk_wait.links);
 155         q = &queue->tasks[task->tk_priority];
 156         if (unlikely(task->tk_priority > queue->maxpriority))
 157                 q = &queue->tasks[queue->maxpriority];
 158         list_for_each_entry(t, q, u.tk_wait.list) {
 159                 if (t->tk_cookie == task->tk_cookie) {
 160                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
 161                         return;
 162                 }
 163         }
 164         list_add_tail(&task->u.tk_wait.list, q);
 165 }
 166
 167 /*
 168  * Add new request to wait queue.
 169  *
 170  * Swapper tasks always get inserted at the head of the queue.
 171  * This should avoid many nasty memory deadlocks and hopefully
 172  * improve overall performance.
 173  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
 174  */
 175 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
 176 {
 177         BUG_ON (RPC_IS_QUEUED(task));
 178
 179         if (RPC_IS_PRIORITY(queue))
 180                 __rpc_add_wait_queue_priority(queue, task);
 181         else if (RPC_IS_SWAPPER(task))
 182                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
 183         else
 184                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
 185         task->u.tk_wait.rpc_waitq = queue;
 186         rpc_set_queued(task);
 187
 188         dprintk("RPC: %4d added to queue %p \"%s\"\n",
 189                                 task->tk_pid, queue, rpc_qname(queue));
 190 }
 191
 192 /*
 193  * Remove request from a priority queue.
 194  */
 195 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 196 {
 197         struct rpc_task *t;
 198
 199         if (!list_empty(&task->u.tk_wait.links)) {
 200                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
 201                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
 202                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
 203         }
 204         list_del(&task->u.tk_wait.list);
 205 }
 206
 207 /*
 208  * Remove request from queue.
 209  * Note: must be called with spin lock held.
 210  */
 211 static void __rpc_remove_wait_queue(struct rpc_task *task)
 212 {
 213         struct rpc_wait_queue *queue;
 214         queue = task->u.tk_wait.rpc_waitq;
 215
 216         if (RPC_IS_PRIORITY(queue))
 217                 __rpc_remove_wait_queue_priority(task);
 218         else
 219                 list_del(&task->u.tk_wait.list);
 220         dprintk("RPC: %4d removed from queue %p \"%s\"\n",
 221                                 task->tk_pid, queue, rpc_qname(queue));
 222 }
 223
 224 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 225 {
 226         queue->priority = priority;
 227         queue->count = 1 << (priority * 2);
 228 }
 229
 230 static inline void rpc_set_waitqueue_cookie(struct rpc_wait_queue *queue, unsigned long cookie)
 231 {
 232         queue->cookie = cookie;
 233         queue->nr = RPC_BATCH_COUNT;
 234 }
 235
 236 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 237 {
 238         rpc_set_waitqueue_priority(queue, queue->maxpriority);
 239         rpc_set_waitqueue_cookie(queue, 0);
 240 }
 241
 242 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, int maxprio)
 243 {
 244         int i;
 245
 246         spin_lock_init(&queue->lock);
 247         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 248                 INIT_LIST_HEAD(&queue->tasks[i]);
 249         queue->maxpriority = maxprio;
 250         rpc_reset_waitqueue_priority(queue);
 251 #ifdef RPC_DEBUG
 252         queue->name = qname;
 253 #endif
 254 }
 255
 256 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 257 {
 258         __rpc_init_priority_wait_queue(queue, qname, RPC_PRIORITY_HIGH);
 259 }
 260
 261 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 262 {
 263         __rpc_init_priority_wait_queue(queue, qname, 0);
 264 }
 265 EXPORT_SYMBOL(rpc_init_wait_queue);
 266
 267 /*
 268  * Make an RPC task runnable.
 269  *
 270  * Note: If the task is ASYNC, this must be called with
 271  * the spinlock held to protect the wait queue operation.
 272  */
 273 static void rpc_make_runnable(struct rpc_task *task)
 274 {
 275         int do_ret;
 276
 277         BUG_ON(task->tk_timeout_fn);
 278         do_ret = rpc_test_and_set_running(task);
 279         rpc_clear_queued(task);
 280         if (do_ret)
 281                 return;
 282         if (RPC_IS_ASYNC(task)) {
 283                 int status;
 284
 285                 INIT_WORK(&task->u.tk_work, rpc_async_schedule, (void *)task);
 286                 status = queue_work(task->tk_workqueue, &task->u.tk_work);
 287                 if (status < 0) {
 288                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
 289                         task->tk_status = status;
 290                         return;
 291                 }
 292         } else
 293                 wake_up(&task->u.tk_wait.waitq);
 294 }
 295
 296 /*
 297  * Place a newly initialized task on the workqueue.
 298  */
 299 static inline void
 300 rpc_schedule_run(struct rpc_task *task)
 301 {
 302         /* Don't run a child twice! */
 303         if (RPC_IS_ACTIVATED(task))
 304                 return;
 305         task->tk_active = 1;
 306         rpc_make_runnable(task);
 307 }
 308
 309 /*
 310  * Prepare for sleeping on a wait queue.
 311  * By always appending tasks to the list we ensure FIFO behavior.
 312  * NB: An RPC task will only receive interrupt-driven events as long
 313  * as it's on a wait queue.
 314  */
 315 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 316                         rpc_action action, rpc_action timer)
 317 {
 318         dprintk("RPC: %4d sleep_on(queue \"%s\" time %ld)\n", task->tk_pid,
 319                                 rpc_qname(q), jiffies);
 320
 321         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
 322                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
 323                 return;
 324         }
 325
 326         /* Mark the task as being activated if so needed */
 327         if (!RPC_IS_ACTIVATED(task))
 328                 task->tk_active = 1;
 329
 330         __rpc_add_wait_queue(q, task);
 331
 332         BUG_ON(task->tk_callback != NULL);
 333         task->tk_callback = action;
 334         __rpc_add_timer(task, timer);
 335 }
 336
 337 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 338                                 rpc_action action, rpc_action timer)
 339 {
 340         /*
 341          * Protect the queue operations.
 342          */
 343         spin_lock_bh(&q->lock);
 344         __rpc_sleep_on(q, task, action, timer);
 345         spin_unlock_bh(&q->lock);
 346 }
 347
 348 /**
 349  * __rpc_do_wake_up_task - wake up a single rpc_task
 350  * @task: task to be woken up
 351  *
 352  * Caller must hold queue->lock, and have cleared the task queued flag.
 353  */
 354 static void __rpc_do_wake_up_task(struct rpc_task *task)
 355 {
 356         dprintk("RPC: %4d __rpc_wake_up_task (now %ld)\n", task->tk_pid, jiffies);
 357
 358 #ifdef RPC_DEBUG
 359         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 360 #endif
 361         /* Has the task been executed yet? If not, we cannot wake it up! */
 362         if (!RPC_IS_ACTIVATED(task)) {
 363                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 364                 return;
 365         }
 366
 367         __rpc_disable_timer(task);
 368         __rpc_remove_wait_queue(task);
 369
 370         rpc_make_runnable(task);
 371
 372         dprintk("RPC:      __rpc_wake_up_task done\n");
 373 }
 374
 375 /*
 376  * Wake up the specified task
 377  */
 378 static void __rpc_wake_up_task(struct rpc_task *task)
 379 {
 380         if (rpc_start_wakeup(task)) {
 381                 if (RPC_IS_QUEUED(task))
 382                         __rpc_do_wake_up_task(task);
 383                 rpc_finish_wakeup(task);
 384         }
 385 }
 386
 387 /*
 388  * Default timeout handler if none specified by user
 389  */
 390 static void
 391 __rpc_default_timer(struct rpc_task *task)
 392 {
 393         dprintk("RPC: %d timeout (default timer)\n", task->tk_pid);
 394         task->tk_status = -ETIMEDOUT;
 395         rpc_wake_up_task(task);
 396 }
 397
 398 /*
 399  * Wake up the specified task
 400  */
 401 void rpc_wake_up_task(struct rpc_task *task)
 402 {
 403         if (rpc_start_wakeup(task)) {
 404                 if (RPC_IS_QUEUED(task)) {
 405                         struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
 406
 407                         spin_lock_bh(&queue->lock);
 408                         __rpc_do_wake_up_task(task);
 409                         spin_unlock_bh(&queue->lock);
 410                 }
 411                 rpc_finish_wakeup(task);
 412         }
 413 }
 414
 415 /*
 416  * Wake up the next task on a priority queue.
 417  */
 418 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
 419 {
 420         struct list_head *q;
 421         struct rpc_task *task;
 422
 423         /*
 424          * Service a batch of tasks from a single cookie.
 425          */
 426         q = &queue->tasks[queue->priority];
 427         if (!list_empty(q)) {
 428                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 429                 if (queue->cookie == task->tk_cookie) {
 430                         if (--queue->nr)
 431                                 goto out;
 432                         list_move_tail(&task->u.tk_wait.list, q);
 433                 }
 434                 /*
 435                  * Check if we need to switch queues.
 436                  */
 437                 if (--queue->count)
 438                         goto new_cookie;
 439         }
 440
 441         /*
 442          * Service the next queue.
 443          */
 444         do {
 445                 if (q == &queue->tasks[0])
 446                         q = &queue->tasks[queue->maxpriority];
 447                 else
 448                         q = q - 1;
 449                 if (!list_empty(q)) {
 450                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 451                         goto new_queue;
 452                 }
 453         } while (q != &queue->tasks[queue->priority]);
 454
 455         rpc_reset_waitqueue_priority(queue);
 456         return NULL;
 457
 458 new_queue:
 459         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 460 new_cookie:
 461         rpc_set_waitqueue_cookie(queue, task->tk_cookie);
 462 out:
 463         __rpc_wake_up_task(task);
 464         return task;
 465 }
 466
 467 /*
 468  * Wake up the next task on the wait queue.
 469  */
 470 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
 471 {
 472         struct rpc_task *task = NULL;
 473
 474         dprintk("RPC:      wake_up_next(%p \"%s\")\n", queue, rpc_qname(queue));
 475         spin_lock_bh(&queue->lock);
 476         if (RPC_IS_PRIORITY(queue))
 477                 task = __rpc_wake_up_next_priority(queue);
 478         else {
 479                 task_for_first(task, &queue->tasks[0])
 480                         __rpc_wake_up_task(task);
 481         }
 482         spin_unlock_bh(&queue->lock);
 483
 484         return task;
 485 }
 486
 487 /**
 488  * rpc_wake_up - wake up all rpc_tasks
 489  * @queue: rpc_wait_queue on which the tasks are sleeping
 490  *
 491  * Grabs queue->lock
 492  */
 493 void rpc_wake_up(struct rpc_wait_queue *queue)
 494 {
 495         struct rpc_task *task;
 496
 497         struct list_head *head;
 498         spin_lock_bh(&queue->lock);
 499         head = &queue->tasks[queue->maxpriority];
 500         for (;;) {
 501                 while (!list_empty(head)) {
 502                         task = list_entry(head->next, struct rpc_task, u.tk_wait.list);
 503                         __rpc_wake_up_task(task);
 504                 }
 505                 if (head == &queue->tasks[0])
 506                         break;
 507                 head--;
 508         }
 509         spin_unlock_bh(&queue->lock);
 510 }
 511
 512 /**
 513  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 514  * @queue: rpc_wait_queue on which the tasks are sleeping
 515  * @status: status value to set
 516  *
 517  * Grabs queue->lock
 518  */
 519 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 520 {
 521         struct list_head *head;
 522         struct rpc_task *task;
 523
 524         spin_lock_bh(&queue->lock);
 525         head = &queue->tasks[queue->maxpriority];
 526         for (;;) {
 527                 while (!list_empty(head)) {
 528                         task = list_entry(head->next, struct rpc_task, u.tk_wait.list);
 529                         task->tk_status = status;
 530                         __rpc_wake_up_task(task);
 531                 }
 532                 if (head == &queue->tasks[0])
 533                         break;
 534                 head--;
 535         }
 536         spin_unlock_bh(&queue->lock);
 537 }
 538
 539 /*
 540  * Run a task at a later time
 541  */
 542 static void     __rpc_atrun(struct rpc_task *);
 543 void
 544 rpc_delay(struct rpc_task *task, unsigned long delay)
 545 {
 546         task->tk_timeout = delay;
 547         rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
 548 }
 549
 550 static void
 551 __rpc_atrun(struct rpc_task *task)
 552 {
 553         task->tk_status = 0;
 554         rpc_wake_up_task(task);
 555 }
 556
 557 /*
 558  * This is the RPC `scheduler' (or rather, the finite state machine).
 559  */
 560 static int __rpc_execute(struct rpc_task *task)
 561 {
 562         int             status = 0;
 563
 564         dprintk("RPC: %4d rpc_execute flgs %x\n",
 565                                 task->tk_pid, task->tk_flags);
 566
 567         BUG_ON(RPC_IS_QUEUED(task));
 568
 569  restarted:
 570         while (1) {
 571                 /*
 572                  * Garbage collection of pending timers...
 573                  */
 574                 rpc_delete_timer(task);
 575
 576                 /*
 577                  * Execute any pending callback.
 578                  */
 579                 if (RPC_DO_CALLBACK(task)) {
 580                         /* Define a callback save pointer */
 581                         void (*save_callback)(struct rpc_task *);
 582
 583                         /*
 584                          * If a callback exists, save it, reset it,
 585                          * call it.
 586                          * The save is needed to stop from resetting
 587                          * another callback set within the callback handler
 588                          * - Dave
 589                          */
 590                         save_callback=task->tk_callback;
 591                         task->tk_callback=NULL;
 592                         lock_kernel();
 593                         save_callback(task);
 594                         unlock_kernel();
 595                 }
 596
 597                 /*
 598                  * Perform the next FSM step.
 599                  * tk_action may be NULL when the task has been killed
 600                  * by someone else.
 601                  */
 602                 if (!RPC_IS_QUEUED(task)) {
 603                         if (!task->tk_action)
 604                                 break;
 605                         lock_kernel();
 606                         task->tk_action(task);
 607                         unlock_kernel();
 608                 }
 609
 610                 /*
 611                  * Lockless check for whether task is sleeping or not.
 612                  */
 613                 if (!RPC_IS_QUEUED(task))
 614                         continue;
 615                 rpc_clear_running(task);
 616                 if (RPC_IS_ASYNC(task)) {
 617                         /* Careful! we may have raced... */
 618                         if (RPC_IS_QUEUED(task))
 619                                 return 0;
 620                         if (rpc_test_and_set_running(task))
 621                                 return 0;
 622                         continue;
 623                 }
 624
 625                 /* sync task: sleep here */
 626                 dprintk("RPC: %4d sync task going to sleep\n", task->tk_pid);
 627                 if (RPC_TASK_UNINTERRUPTIBLE(task)) {
 628                         __wait_event(task->u.tk_wait.waitq, !RPC_IS_QUEUED(task));
 629                 } else {
 630                         __wait_event_interruptible(task->u.tk_wait.waitq, !RPC_IS_QUEUED(task), status);
 631                         /*
 632                          * When a sync task receives a signal, it exits with
 633                          * -ERESTARTSYS. In order to catch any callbacks that
 634                          * clean up after sleeping on some queue, we don't
 635                          * break the loop here, but go around once more.
 636                          */
 637                         if (status == -ERESTARTSYS) {
 638                                 dprintk("RPC: %4d got signal\n", task->tk_pid);
 639                                 task->tk_flags |= RPC_TASK_KILLED;
 640                                 rpc_exit(task, -ERESTARTSYS);
 641                                 rpc_wake_up_task(task);
 642                         }
 643                 }
 644                 rpc_set_running(task);
 645                 dprintk("RPC: %4d sync task resuming\n", task->tk_pid);
 646         }
 647
 648         if (task->tk_exit) {
 649                 lock_kernel();
 650                 task->tk_exit(task);
 651                 unlock_kernel();
 652                 /* If tk_action is non-null, the user wants us to restart */
 653                 if (task->tk_action) {
 654                         if (!RPC_ASSASSINATED(task)) {
 655                                 /* Release RPC slot and buffer memory */
 656                                 if (task->tk_rqstp)
 657                                         xprt_release(task);
 658                                 rpc_free(task);
 659                                 goto restarted;
 660                         }
 661                         printk(KERN_ERR "RPC: dead task tries to walk away.\n");
 662                 }
 663         }
 664
 665         dprintk("RPC: %4d exit() = %d\n", task->tk_pid, task->tk_status);
 666         status = task->tk_status;
 667
 668         /* Release all resources associated with the task */
 669         rpc_release_task(task);
 670         return status;
 671 }
 672
 673 /*
 674  * User-visible entry point to the scheduler.
 675  *
 676  * This may be called recursively if e.g. an async NFS task updates
 677  * the attributes and finds that dirty pages must be flushed.
 678  * NOTE: Upon exit of this function the task is guaranteed to be
 679  *       released. In particular note that tk_release() will have
 680  *       been called, so your task memory may have been freed.
 681  */
 682 int
 683 rpc_execute(struct rpc_task *task)
 684 {
 685         BUG_ON(task->tk_active);
 686
 687         task->tk_active = 1;
 688         rpc_set_running(task);
 689         return __rpc_execute(task);
 690 }
 691
 692 static void rpc_async_schedule(void *arg)
 693 {
 694         __rpc_execute((struct rpc_task *)arg);
 695 }
 696
 697 /*
 698  * Allocate memory for RPC purposes.
 699  *
 700  * We try to ensure that some NFS reads and writes can always proceed
 701  * by using a mempool when allocating 'small' buffers.
 702  * In order to avoid memory starvation triggering more writebacks of
 703  * NFS requests, we use GFP_NOFS rather than GFP_KERNEL.
 704  */
 705 void *
 706 rpc_malloc(struct rpc_task *task, size_t size)
 707 {
 708         int     gfp;
 709
 710         if (task->tk_flags & RPC_TASK_SWAPPER)
 711                 gfp = GFP_ATOMIC;
 712         else
 713                 gfp = GFP_NOFS;
 714
 715         if (size > RPC_BUFFER_MAXSIZE) {
 716                 task->tk_buffer =  kmalloc(size, gfp);
 717                 if (task->tk_buffer)
 718                         task->tk_bufsize = size;
 719         } else {
 720                 task->tk_buffer =  mempool_alloc(rpc_buffer_mempool, gfp);
 721                 if (task->tk_buffer)
 722                         task->tk_bufsize = RPC_BUFFER_MAXSIZE;
 723         }
 724         return task->tk_buffer;
 725 }
 726
 727 static void
 728 rpc_free(struct rpc_task *task)
 729 {
 730         if (task->tk_buffer) {
 731                 if (task->tk_bufsize == RPC_BUFFER_MAXSIZE)
 732                         mempool_free(task->tk_buffer, rpc_buffer_mempool);
 733                 else
 734                         kfree(task->tk_buffer);
 735                 task->tk_buffer = NULL;
 736                 task->tk_bufsize = 0;
 737         }
 738 }
 739
 740 /*
 741  * Creation and deletion of RPC task structures
 742  */
 743 void rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt, rpc_action callback, int flags)
 744 {
 745         memset(task, 0, sizeof(*task));
 746         init_timer(&task->tk_timer);
 747         task->tk_timer.data     = (unsigned long) task;
 748         task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
 749         task->tk_client = clnt;
 750         task->tk_flags  = flags;
 751         task->tk_exit   = callback;
 752
 753         /* Initialize retry counters */
 754         task->tk_garb_retry = 2;
 755         task->tk_cred_retry = 2;
 756
 757         task->tk_priority = RPC_PRIORITY_NORMAL;
 758         task->tk_cookie = (unsigned long)current;
 759
 760         /* Initialize workqueue for async tasks */
 761         task->tk_workqueue = rpciod_workqueue;
 762         if (!RPC_IS_ASYNC(task))
 763                 init_waitqueue_head(&task->u.tk_wait.waitq);
 764
 765         if (clnt) {
 766                 atomic_inc(&clnt->cl_users);
 767                 if (clnt->cl_softrtry)
 768                         task->tk_flags |= RPC_TASK_SOFT;
 769                 if (!clnt->cl_intr)
 770                         task->tk_flags |= RPC_TASK_NOINTR;
 771         }
 772
 773 #ifdef RPC_DEBUG
 774         task->tk_magic = RPC_TASK_MAGIC_ID;
 775         task->tk_pid = rpc_task_id++;
 776 #endif
 777         /* Add to global list of all tasks */
 778         spin_lock(&rpc_sched_lock);
 779         list_add_tail(&task->tk_task, &all_tasks);
 780         spin_unlock(&rpc_sched_lock);
 781
 782         dprintk("RPC: %4d new task procpid %d\n", task->tk_pid,
 783                                 current->pid);
 784 }
 785
 786 static struct rpc_task *
 787 rpc_alloc_task(void)
 788 {
 789         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 790 }
 791
 792 static void
 793 rpc_default_free_task(struct rpc_task *task)
 794 {
 795         dprintk("RPC: %4d freeing task\n", task->tk_pid);
 796         mempool_free(task, rpc_task_mempool);
 797 }
 798
 799 /*
 800  * Create a new task for the specified client.  We have to
 801  * clean up after an allocation failure, as the client may
 802  * have specified "oneshot".
 803  */
 804 struct rpc_task *
 805 rpc_new_task(struct rpc_clnt *clnt, rpc_action callback, int flags)
 806 {
 807         struct rpc_task *task;
 808
 809         task = rpc_alloc_task();
 810         if (!task)
 811                 goto cleanup;
 812
 813         rpc_init_task(task, clnt, callback, flags);
 814
 815         /* Replace tk_release */
 816         task->tk_release = rpc_default_free_task;
 817
 818         dprintk("RPC: %4d allocated task\n", task->tk_pid);
 819         task->tk_flags |= RPC_TASK_DYNAMIC;
 820 out:
 821         return task;
 822
 823 cleanup:
 824         /* Check whether to release the client */
 825         if (clnt) {
 826                 printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
 827                         atomic_read(&clnt->cl_users), clnt->cl_oneshot);
 828                 atomic_inc(&clnt->cl_users); /* pretend we were used ... */
 829                 rpc_release_client(clnt);
 830         }
 831         goto out;
 832 }
 833
 834 void rpc_release_task(struct rpc_task *task)
 835 {
 836         dprintk("RPC: %4d release task\n", task->tk_pid);
 837
 838 #ifdef RPC_DEBUG
 839         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 840 #endif
 841
 842         /* Remove from global task list */
 843         spin_lock(&rpc_sched_lock);
 844         list_del(&task->tk_task);
 845         spin_unlock(&rpc_sched_lock);
 846
 847         BUG_ON (RPC_IS_QUEUED(task));
 848         task->tk_active = 0;
 849
 850         /* Synchronously delete any running timer */
 851         rpc_delete_timer(task);
 852
 853         /* Release resources */
 854         if (task->tk_rqstp)
 855                 xprt_release(task);
 856         if (task->tk_msg.rpc_cred)
 857                 rpcauth_unbindcred(task);
 858         rpc_free(task);
 859         if (task->tk_client) {
 860                 rpc_release_client(task->tk_client);
 861                 task->tk_client = NULL;
 862         }
 863
 864 #ifdef RPC_DEBUG
 865         task->tk_magic = 0;
 866 #endif
 867         if (task->tk_release)
 868                 task->tk_release(task);
 869 }
 870
 871 /**
 872  * rpc_find_parent - find the parent of a child task.
 873  * @child: child task
 874  *
 875  * Checks that the parent task is still sleeping on the
 876  * queue 'childq'. If so returns a pointer to the parent.
 877  * Upon failure returns NULL.
 878  *
 879  * Caller must hold childq.lock
 880  */
 881 static inline struct rpc_task *rpc_find_parent(struct rpc_task *child)
 882 {
 883         struct rpc_task *task, *parent;
 884         struct list_head *le;
 885
 886         parent = (struct rpc_task *) child->tk_calldata;
 887         task_for_each(task, le, &childq.tasks[0])
 888                 if (task == parent)
 889                         return parent;
 890
 891         return NULL;
 892 }
 893
 894 static void rpc_child_exit(struct rpc_task *child)
 895 {
 896         struct rpc_task *parent;
 897
 898         spin_lock_bh(&childq.lock);
 899         if ((parent = rpc_find_parent(child)) != NULL) {
 900                 parent->tk_status = child->tk_status;
 901                 __rpc_wake_up_task(parent);
 902         }
 903         spin_unlock_bh(&childq.lock);
 904 }
 905
 906 /*
 907  * Note: rpc_new_task releases the client after a failure.
 908  */
 909 struct rpc_task *
 910 rpc_new_child(struct rpc_clnt *clnt, struct rpc_task *parent)
 911 {
 912         struct rpc_task *task;
 913
 914         task = rpc_new_task(clnt, NULL, RPC_TASK_ASYNC | RPC_TASK_CHILD);
 915         if (!task)
 916                 goto fail;
 917         task->tk_exit = rpc_child_exit;
 918         task->tk_calldata = parent;
 919         return task;
 920
 921 fail:
 922         parent->tk_status = -ENOMEM;
 923         return NULL;
 924 }
 925
 926 void rpc_run_child(struct rpc_task *task, struct rpc_task *child, rpc_action func)
 927 {
 928         spin_lock_bh(&childq.lock);
 929         /* N.B. Is it possible for the child to have already finished? */
 930         __rpc_sleep_on(&childq, task, func, NULL);
 931         rpc_schedule_run(child);
 932         spin_unlock_bh(&childq.lock);
 933 }
 934
 935 /*
 936  * Kill all tasks for the given client.
 937  * XXX: kill their descendants as well?
 938  */
 939 void rpc_killall_tasks(struct rpc_clnt *clnt)
 940 {
 941         struct rpc_task *rovr;
 942         struct list_head *le;
 943
 944         dprintk("RPC:      killing all tasks for client %p\n", clnt);
 945
 946         /*
 947          * Spin lock all_tasks to prevent changes...
 948          */
 949         spin_lock(&rpc_sched_lock);
 950         alltask_for_each(rovr, le, &all_tasks) {
 951                 if (! RPC_IS_ACTIVATED(rovr))
 952                         continue;
 953                 if (!clnt || rovr->tk_client == clnt) {
 954                         rovr->tk_flags |= RPC_TASK_KILLED;
 955                         rpc_exit(rovr, -EIO);
 956                         rpc_wake_up_task(rovr);
 957                 }
 958         }
 959         spin_unlock(&rpc_sched_lock);
 960 }
 961
 962 static DECLARE_MUTEX_LOCKED(rpciod_running);
 963
 964 static void rpciod_killall(void)
 965 {
 966         unsigned long flags;
 967
 968         while (!list_empty(&all_tasks)) {
 969                 clear_thread_flag(TIF_SIGPENDING);
 970                 rpc_killall_tasks(NULL);
 971                 flush_workqueue(rpciod_workqueue);
 972                 if (!list_empty(&all_tasks)) {
 973                         dprintk("rpciod_killall: waiting for tasks to exit\n");
 974                         yield();
 975                 }
 976         }
 977
 978         spin_lock_irqsave(&current->sighand->siglock, flags);
 979         recalc_sigpending();
 980         spin_unlock_irqrestore(&current->sighand->siglock, flags);
 981 }
 982
 983 /*
 984  * Start up the rpciod process if it's not already running.
 985  */
 986 int
 987 rpciod_up(void)
 988 {
 989         struct workqueue_struct *wq;
 990         int error = 0;
 991
 992         down(&rpciod_sema);
 993         dprintk("rpciod_up: users %d\n", rpciod_users);
 994         rpciod_users++;
 995         if (rpciod_workqueue)
 996                 goto out;
 997         /*
 998          * If there's no pid, we should be the first user.
 999          */
1000         if (rpciod_users > 1)
1001                 printk(KERN_WARNING "rpciod_up: no workqueue, %d users??\n", rpciod_users);
1002         /*
1003          * Create the rpciod thread and wait for it to start.
1004          */
1005         error = -ENOMEM;
1006         wq = create_workqueue("rpciod");
1007         if (wq == NULL) {
1008                 printk(KERN_WARNING "rpciod_up: create workqueue failed, error=%d\n", error);
1009                 rpciod_users--;
1010                 goto out;
1011         }
1012         rpciod_workqueue = wq;
1013         error = 0;
1014 out:
1015         up(&rpciod_sema);
1016         return error;
1017 }
1018
1019 void
1020 rpciod_down(void)
1021 {
1022         down(&rpciod_sema);
1023         dprintk("rpciod_down sema %d\n", rpciod_users);
1024         if (rpciod_users) {
1025                 if (--rpciod_users)
1026                         goto out;
1027         } else
1028                 printk(KERN_WARNING "rpciod_down: no users??\n");
1029
1030         if (!rpciod_workqueue) {
1031                 dprintk("rpciod_down: Nothing to do!\n");
1032                 goto out;
1033         }
1034         rpciod_killall();
1035
1036         destroy_workqueue(rpciod_workqueue);
1037         rpciod_workqueue = NULL;
1038  out:
1039         up(&rpciod_sema);
1040 }
1041
1042 #ifdef RPC_DEBUG
1043 void rpc_show_tasks(void)
1044 {
1045         struct list_head *le;
1046         struct rpc_task *t;
1047
1048         spin_lock(&rpc_sched_lock);
1049         if (list_empty(&all_tasks)) {
1050                 spin_unlock(&rpc_sched_lock);
1051                 return;
1052         }
1053         printk("-pid- proc flgs status -client- -prog- --rqstp- -timeout "
1054                 "-rpcwait -action- --exit--\n");
1055         alltask_for_each(t, le, &all_tasks) {
1056                 const char *rpc_waitq = "none";
1057
1058                 if (RPC_IS_QUEUED(t))
1059                         rpc_waitq = rpc_qname(t->u.tk_wait.rpc_waitq);
1060
1061                 printk("%05d %04d %04x %06d %8p %6d %8p %08ld %8s %8p %8p\n",
1062                         t->tk_pid,
1063                         (t->tk_msg.rpc_proc ? t->tk_msg.rpc_proc->p_proc : -1),
1064                         t->tk_flags, t->tk_status,
1065                         t->tk_client,
1066                         (t->tk_client ? t->tk_client->cl_prog : 0),
1067                         t->tk_rqstp, t->tk_timeout,
1068                         rpc_waitq,
1069                         t->tk_action, t->tk_exit);
1070         }
1071         spin_unlock(&rpc_sched_lock);
1072 }
1073 #endif
1074
1075 void
1076 rpc_destroy_mempool(void)
1077 {
1078         if (rpc_buffer_mempool)
1079                 mempool_destroy(rpc_buffer_mempool);
1080         if (rpc_task_mempool)
1081                 mempool_destroy(rpc_task_mempool);
1082         if (rpc_task_slabp && kmem_cache_destroy(rpc_task_slabp))
1083                 printk(KERN_INFO "rpc_task: not all structures were freed\n");
1084         if (rpc_buffer_slabp && kmem_cache_destroy(rpc_buffer_slabp))
1085                 printk(KERN_INFO "rpc_buffers: not all structures were freed\n");
1086 }
1087
1088 int
1089 rpc_init_mempool(void)
1090 {
1091         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1092                                              sizeof(struct rpc_task),
1093                                              0, SLAB_HWCACHE_ALIGN,
1094                                              NULL, NULL);
1095         if (!rpc_task_slabp)
1096                 goto err_nomem;
1097         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1098                                              RPC_BUFFER_MAXSIZE,
1099                                              0, SLAB_HWCACHE_ALIGN,
1100                                              NULL, NULL);
1101         if (!rpc_buffer_slabp)
1102                 goto err_nomem;
1103         rpc_task_mempool = mempool_create(RPC_TASK_POOLSIZE,
1104                                             mempool_alloc_slab,
1105                                             mempool_free_slab,
1106                                             rpc_task_slabp);
1107         if (!rpc_task_mempool)
1108                 goto err_nomem;
1109         rpc_buffer_mempool = mempool_create(RPC_BUFFER_POOLSIZE,
1110                                             mempool_alloc_slab,
1111                                             mempool_free_slab,
1112                                             rpc_buffer_slabp);
1113         if (!rpc_buffer_mempool)
1114                 goto err_nomem;
1115         return 0;
1116 err_nomem:
1117         rpc_destroy_mempool();
1118         return -ENOMEM;
1119 }