net/sunrpc/sched.c

   1 /*
   2  * linux/net/sunrpc/sched.c
   3  *
   4  * Scheduling for synchronous and asynchronous RPC requests.
   5  *
   6  * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
   7  *
   8  * TCP NFS related read + write fixes
   9  * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
  10  */
  11
  12 #include <linux/module.h>
  13
  14 #include <linux/sched.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/slab.h>
  17 #include <linux/mempool.h>
  18 #include <linux/smp.h>
  19 #include <linux/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 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         queue->qlen++;
 185         rpc_set_queued(task);
 186
 187         dprintk("RPC: %4d added to queue %p \"%s\"\n",
 188                                 task->tk_pid, queue, rpc_qname(queue));
 189 }
 190
 191 /*
 192  * Remove request from a priority queue.
 193  */
 194 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 195 {
 196         struct rpc_task *t;
 197
 198         if (!list_empty(&task->u.tk_wait.links)) {
 199                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
 200                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
 201                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
 202         }
 203         list_del(&task->u.tk_wait.list);
 204 }
 205
 206 /*
 207  * Remove request from queue.
 208  * Note: must be called with spin lock held.
 209  */
 210 static void __rpc_remove_wait_queue(struct rpc_task *task)
 211 {
 212         struct rpc_wait_queue *queue;
 213         queue = task->u.tk_wait.rpc_waitq;
 214
 215         if (RPC_IS_PRIORITY(queue))
 216                 __rpc_remove_wait_queue_priority(task);
 217         else
 218                 list_del(&task->u.tk_wait.list);
 219         queue->qlen--;
 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 static int rpc_wait_bit_interruptible(void *word)
 268 {
 269         if (signal_pending(current))
 270                 return -ERESTARTSYS;
 271         schedule();
 272         return 0;
 273 }
 274
 275 /*
 276  * Mark an RPC call as having completed by clearing the 'active' bit
 277  */
 278 static inline void rpc_mark_complete_task(struct rpc_task *task)
 279 {
 280         rpc_clear_active(task);
 281         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
 282 }
 283
 284 /*
 285  * Allow callers to wait for completion of an RPC call
 286  */
 287 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
 288 {
 289         if (action == NULL)
 290                 action = rpc_wait_bit_interruptible;
 291         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 292                         action, TASK_INTERRUPTIBLE);
 293 }
 294 EXPORT_SYMBOL(__rpc_wait_for_completion_task);
 295
 296 /*
 297  * Make an RPC task runnable.
 298  *
 299  * Note: If the task is ASYNC, this must be called with
 300  * the spinlock held to protect the wait queue operation.
 301  */
 302 static void rpc_make_runnable(struct rpc_task *task)
 303 {
 304         int do_ret;
 305
 306         BUG_ON(task->tk_timeout_fn);
 307         do_ret = rpc_test_and_set_running(task);
 308         rpc_clear_queued(task);
 309         if (do_ret)
 310                 return;
 311         if (RPC_IS_ASYNC(task)) {
 312                 int status;
 313
 314                 INIT_WORK(&task->u.tk_work, rpc_async_schedule, (void *)task);
 315                 status = queue_work(task->tk_workqueue, &task->u.tk_work);
 316                 if (status < 0) {
 317                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
 318                         task->tk_status = status;
 319                         return;
 320                 }
 321         } else
 322                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 323 }
 324
 325 /*
 326  * Place a newly initialized task on the workqueue.
 327  */
 328 static inline void
 329 rpc_schedule_run(struct rpc_task *task)
 330 {
 331         rpc_set_active(task);
 332         rpc_make_runnable(task);
 333 }
 334
 335 /*
 336  * Prepare for sleeping on a wait queue.
 337  * By always appending tasks to the list we ensure FIFO behavior.
 338  * NB: An RPC task will only receive interrupt-driven events as long
 339  * as it's on a wait queue.
 340  */
 341 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 342                         rpc_action action, rpc_action timer)
 343 {
 344         dprintk("RPC: %4d sleep_on(queue \"%s\" time %ld)\n", task->tk_pid,
 345                                 rpc_qname(q), jiffies);
 346
 347         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
 348                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
 349                 return;
 350         }
 351
 352         /* Mark the task as being activated if so needed */
 353         rpc_set_active(task);
 354
 355         __rpc_add_wait_queue(q, task);
 356
 357         BUG_ON(task->tk_callback != NULL);
 358         task->tk_callback = action;
 359         __rpc_add_timer(task, timer);
 360 }
 361
 362 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 363                                 rpc_action action, rpc_action timer)
 364 {
 365         /*
 366          * Protect the queue operations.
 367          */
 368         spin_lock_bh(&q->lock);
 369         __rpc_sleep_on(q, task, action, timer);
 370         spin_unlock_bh(&q->lock);
 371 }
 372
 373 /**
 374  * __rpc_do_wake_up_task - wake up a single rpc_task
 375  * @task: task to be woken up
 376  *
 377  * Caller must hold queue->lock, and have cleared the task queued flag.
 378  */
 379 static void __rpc_do_wake_up_task(struct rpc_task *task)
 380 {
 381         dprintk("RPC: %4d __rpc_wake_up_task (now %ld)\n", task->tk_pid, jiffies);
 382
 383 #ifdef RPC_DEBUG
 384         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 385 #endif
 386         /* Has the task been executed yet? If not, we cannot wake it up! */
 387         if (!RPC_IS_ACTIVATED(task)) {
 388                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 389                 return;
 390         }
 391
 392         __rpc_disable_timer(task);
 393         __rpc_remove_wait_queue(task);
 394
 395         rpc_make_runnable(task);
 396
 397         dprintk("RPC:      __rpc_wake_up_task done\n");
 398 }
 399
 400 /*
 401  * Wake up the specified task
 402  */
 403 static void __rpc_wake_up_task(struct rpc_task *task)
 404 {
 405         if (rpc_start_wakeup(task)) {
 406                 if (RPC_IS_QUEUED(task))
 407                         __rpc_do_wake_up_task(task);
 408                 rpc_finish_wakeup(task);
 409         }
 410 }
 411
 412 /*
 413  * Default timeout handler if none specified by user
 414  */
 415 static void
 416 __rpc_default_timer(struct rpc_task *task)
 417 {
 418         dprintk("RPC: %d timeout (default timer)\n", task->tk_pid);
 419         task->tk_status = -ETIMEDOUT;
 420         rpc_wake_up_task(task);
 421 }
 422
 423 /*
 424  * Wake up the specified task
 425  */
 426 void rpc_wake_up_task(struct rpc_task *task)
 427 {
 428         if (rpc_start_wakeup(task)) {
 429                 if (RPC_IS_QUEUED(task)) {
 430                         struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
 431
 432                         spin_lock_bh(&queue->lock);
 433                         __rpc_do_wake_up_task(task);
 434                         spin_unlock_bh(&queue->lock);
 435                 }
 436                 rpc_finish_wakeup(task);
 437         }
 438 }
 439
 440 /*
 441  * Wake up the next task on a priority queue.
 442  */
 443 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
 444 {
 445         struct list_head *q;
 446         struct rpc_task *task;
 447
 448         /*
 449          * Service a batch of tasks from a single cookie.
 450          */
 451         q = &queue->tasks[queue->priority];
 452         if (!list_empty(q)) {
 453                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 454                 if (queue->cookie == task->tk_cookie) {
 455                         if (--queue->nr)
 456                                 goto out;
 457                         list_move_tail(&task->u.tk_wait.list, q);
 458                 }
 459                 /*
 460                  * Check if we need to switch queues.
 461                  */
 462                 if (--queue->count)
 463                         goto new_cookie;
 464         }
 465
 466         /*
 467          * Service the next queue.
 468          */
 469         do {
 470                 if (q == &queue->tasks[0])
 471                         q = &queue->tasks[queue->maxpriority];
 472                 else
 473                         q = q - 1;
 474                 if (!list_empty(q)) {
 475                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 476                         goto new_queue;
 477                 }
 478         } while (q != &queue->tasks[queue->priority]);
 479
 480         rpc_reset_waitqueue_priority(queue);
 481         return NULL;
 482
 483 new_queue:
 484         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 485 new_cookie:
 486         rpc_set_waitqueue_cookie(queue, task->tk_cookie);
 487 out:
 488         __rpc_wake_up_task(task);
 489         return task;
 490 }
 491
 492 /*
 493  * Wake up the next task on the wait queue.
 494  */
 495 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
 496 {
 497         struct rpc_task *task = NULL;
 498
 499         dprintk("RPC:      wake_up_next(%p \"%s\")\n", queue, rpc_qname(queue));
 500         spin_lock_bh(&queue->lock);
 501         if (RPC_IS_PRIORITY(queue))
 502                 task = __rpc_wake_up_next_priority(queue);
 503         else {
 504                 task_for_first(task, &queue->tasks[0])
 505                         __rpc_wake_up_task(task);
 506         }
 507         spin_unlock_bh(&queue->lock);
 508
 509         return task;
 510 }
 511
 512 /**
 513  * rpc_wake_up - wake up all rpc_tasks
 514  * @queue: rpc_wait_queue on which the tasks are sleeping
 515  *
 516  * Grabs queue->lock
 517  */
 518 void rpc_wake_up(struct rpc_wait_queue *queue)
 519 {
 520         struct rpc_task *task, *next;
 521         struct list_head *head;
 522
 523         spin_lock_bh(&queue->lock);
 524         head = &queue->tasks[queue->maxpriority];
 525         for (;;) {
 526                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
 527                         __rpc_wake_up_task(task);
 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 rpc_task *task, *next;
 545         struct list_head *head;
 546
 547         spin_lock_bh(&queue->lock);
 548         head = &queue->tasks[queue->maxpriority];
 549         for (;;) {
 550                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
 551                         task->tk_status = status;
 552                         __rpc_wake_up_task(task);
 553                 }
 554                 if (head == &queue->tasks[0])
 555                         break;
 556                 head--;
 557         }
 558         spin_unlock_bh(&queue->lock);
 559 }
 560
 561 /*
 562  * Run a task at a later time
 563  */
 564 static void     __rpc_atrun(struct rpc_task *);
 565 void
 566 rpc_delay(struct rpc_task *task, unsigned long delay)
 567 {
 568         task->tk_timeout = delay;
 569         rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
 570 }
 571
 572 static void
 573 __rpc_atrun(struct rpc_task *task)
 574 {
 575         task->tk_status = 0;
 576         rpc_wake_up_task(task);
 577 }
 578
 579 /*
 580  * Helper to call task->tk_ops->rpc_call_prepare
 581  */
 582 static void rpc_prepare_task(struct rpc_task *task)
 583 {
 584         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 585 }
 586
 587 /*
 588  * Helper that calls task->tk_ops->rpc_call_done if it exists
 589  */
 590 void rpc_exit_task(struct rpc_task *task)
 591 {
 592         task->tk_action = NULL;
 593         if (task->tk_ops->rpc_call_done != NULL) {
 594                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
 595                 if (task->tk_action != NULL) {
 596                         WARN_ON(RPC_ASSASSINATED(task));
 597                         /* Always release the RPC slot and buffer memory */
 598                         xprt_release(task);
 599                 }
 600         }
 601 }
 602 EXPORT_SYMBOL(rpc_exit_task);
 603
 604 /*
 605  * This is the RPC `scheduler' (or rather, the finite state machine).
 606  */
 607 static int __rpc_execute(struct rpc_task *task)
 608 {
 609         int             status = 0;
 610
 611         dprintk("RPC: %4d rpc_execute flgs %x\n",
 612                                 task->tk_pid, task->tk_flags);
 613
 614         BUG_ON(RPC_IS_QUEUED(task));
 615
 616         for (;;) {
 617                 /*
 618                  * Garbage collection of pending timers...
 619                  */
 620                 rpc_delete_timer(task);
 621
 622                 /*
 623                  * Execute any pending callback.
 624                  */
 625                 if (RPC_DO_CALLBACK(task)) {
 626                         /* Define a callback save pointer */
 627                         void (*save_callback)(struct rpc_task *);
 628
 629                         /*
 630                          * If a callback exists, save it, reset it,
 631                          * call it.
 632                          * The save is needed to stop from resetting
 633                          * another callback set within the callback handler
 634                          * - Dave
 635                          */
 636                         save_callback=task->tk_callback;
 637                         task->tk_callback=NULL;
 638                         lock_kernel();
 639                         save_callback(task);
 640                         unlock_kernel();
 641                 }
 642
 643                 /*
 644                  * Perform the next FSM step.
 645                  * tk_action may be NULL when the task has been killed
 646                  * by someone else.
 647                  */
 648                 if (!RPC_IS_QUEUED(task)) {
 649                         if (task->tk_action == NULL)
 650                                 break;
 651                         lock_kernel();
 652                         task->tk_action(task);
 653                         unlock_kernel();
 654                 }
 655
 656                 /*
 657                  * Lockless check for whether task is sleeping or not.
 658                  */
 659                 if (!RPC_IS_QUEUED(task))
 660                         continue;
 661                 rpc_clear_running(task);
 662                 if (RPC_IS_ASYNC(task)) {
 663                         /* Careful! we may have raced... */
 664                         if (RPC_IS_QUEUED(task))
 665                                 return 0;
 666                         if (rpc_test_and_set_running(task))
 667                                 return 0;
 668                         continue;
 669                 }
 670
 671                 /* sync task: sleep here */
 672                 dprintk("RPC: %4d sync task going to sleep\n", task->tk_pid);
 673                 /* Note: Caller should be using rpc_clnt_sigmask() */
 674                 status = out_of_line_wait_on_bit(&task->tk_runstate,
 675                                 RPC_TASK_QUEUED, rpc_wait_bit_interruptible,
 676                                 TASK_INTERRUPTIBLE);
 677                 if (status == -ERESTARTSYS) {
 678                         /*
 679                          * When a sync task receives a signal, it exits with
 680                          * -ERESTARTSYS. In order to catch any callbacks that
 681                          * clean up after sleeping on some queue, we don't
 682                          * break the loop here, but go around once more.
 683                          */
 684                         dprintk("RPC: %4d got signal\n", task->tk_pid);
 685                         task->tk_flags |= RPC_TASK_KILLED;
 686                         rpc_exit(task, -ERESTARTSYS);
 687                         rpc_wake_up_task(task);
 688                 }
 689                 rpc_set_running(task);
 690                 dprintk("RPC: %4d sync task resuming\n", task->tk_pid);
 691         }
 692
 693         dprintk("RPC: %4d, return %d, status %d\n", task->tk_pid, status, task->tk_status);
 694         /* Wake up anyone who is waiting for task completion */
 695         rpc_mark_complete_task(task);
 696         /* Release all resources associated with the task */
 697         rpc_release_task(task);
 698         return status;
 699 }
 700
 701 /*
 702  * User-visible entry point to the scheduler.
 703  *
 704  * This may be called recursively if e.g. an async NFS task updates
 705  * the attributes and finds that dirty pages must be flushed.
 706  * NOTE: Upon exit of this function the task is guaranteed to be
 707  *       released. In particular note that tk_release() will have
 708  *       been called, so your task memory may have been freed.
 709  */
 710 int
 711 rpc_execute(struct rpc_task *task)
 712 {
 713         rpc_set_active(task);
 714         rpc_set_running(task);
 715         return __rpc_execute(task);
 716 }
 717
 718 static void rpc_async_schedule(void *arg)
 719 {
 720         __rpc_execute((struct rpc_task *)arg);
 721 }
 722
 723 /**
 724  * rpc_malloc - allocate an RPC buffer
 725  * @task: RPC task that will use this buffer
 726  * @size: requested byte size
 727  *
 728  * We try to ensure that some NFS reads and writes can always proceed
 729  * by using a mempool when allocating 'small' buffers.
 730  * In order to avoid memory starvation triggering more writebacks of
 731  * NFS requests, we use GFP_NOFS rather than GFP_KERNEL.
 732  */
 733 void * rpc_malloc(struct rpc_task *task, size_t size)
 734 {
 735         struct rpc_rqst *req = task->tk_rqstp;
 736         gfp_t   gfp;
 737
 738         if (task->tk_flags & RPC_TASK_SWAPPER)
 739                 gfp = GFP_ATOMIC;
 740         else
 741                 gfp = GFP_NOFS;
 742
 743         if (size > RPC_BUFFER_MAXSIZE) {
 744                 req->rq_buffer = kmalloc(size, gfp);
 745                 if (req->rq_buffer)
 746                         req->rq_bufsize = size;
 747         } else {
 748                 req->rq_buffer = mempool_alloc(rpc_buffer_mempool, gfp);
 749                 if (req->rq_buffer)
 750                         req->rq_bufsize = RPC_BUFFER_MAXSIZE;
 751         }
 752         return req->rq_buffer;
 753 }
 754
 755 /**
 756  * rpc_free - free buffer allocated via rpc_malloc
 757  * @task: RPC task with a buffer to be freed
 758  *
 759  */
 760 void rpc_free(struct rpc_task *task)
 761 {
 762         struct rpc_rqst *req = task->tk_rqstp;
 763
 764         if (req->rq_buffer) {
 765                 if (req->rq_bufsize == RPC_BUFFER_MAXSIZE)
 766                         mempool_free(req->rq_buffer, rpc_buffer_mempool);
 767                 else
 768                         kfree(req->rq_buffer);
 769                 req->rq_buffer = NULL;
 770                 req->rq_bufsize = 0;
 771         }
 772 }
 773
 774 /*
 775  * Creation and deletion of RPC task structures
 776  */
 777 void rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 778 {
 779         memset(task, 0, sizeof(*task));
 780         init_timer(&task->tk_timer);
 781         task->tk_timer.data     = (unsigned long) task;
 782         task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
 783         atomic_set(&task->tk_count, 1);
 784         task->tk_client = clnt;
 785         task->tk_flags  = flags;
 786         task->tk_ops = tk_ops;
 787         if (tk_ops->rpc_call_prepare != NULL)
 788                 task->tk_action = rpc_prepare_task;
 789         task->tk_calldata = calldata;
 790
 791         /* Initialize retry counters */
 792         task->tk_garb_retry = 2;
 793         task->tk_cred_retry = 2;
 794
 795         task->tk_priority = RPC_PRIORITY_NORMAL;
 796         task->tk_cookie = (unsigned long)current;
 797
 798         /* Initialize workqueue for async tasks */
 799         task->tk_workqueue = rpciod_workqueue;
 800
 801         if (clnt) {
 802                 atomic_inc(&clnt->cl_users);
 803                 if (clnt->cl_softrtry)
 804                         task->tk_flags |= RPC_TASK_SOFT;
 805                 if (!clnt->cl_intr)
 806                         task->tk_flags |= RPC_TASK_NOINTR;
 807         }
 808
 809 #ifdef RPC_DEBUG
 810         task->tk_magic = RPC_TASK_MAGIC_ID;
 811         task->tk_pid = rpc_task_id++;
 812 #endif
 813         /* Add to global list of all tasks */
 814         spin_lock(&rpc_sched_lock);
 815         list_add_tail(&task->tk_task, &all_tasks);
 816         spin_unlock(&rpc_sched_lock);
 817
 818         BUG_ON(task->tk_ops == NULL);
 819
 820         /* starting timestamp */
 821         task->tk_start = jiffies;
 822
 823         dprintk("RPC: %4d new task procpid %d\n", task->tk_pid,
 824                                 current->pid);
 825 }
 826
 827 static struct rpc_task *
 828 rpc_alloc_task(void)
 829 {
 830         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 831 }
 832
 833 static void rpc_free_task(struct rpc_task *task)
 834 {
 835         dprintk("RPC: %4d freeing task\n", task->tk_pid);
 836         mempool_free(task, rpc_task_mempool);
 837 }
 838
 839 /*
 840  * Create a new task for the specified client.  We have to
 841  * clean up after an allocation failure, as the client may
 842  * have specified "oneshot".
 843  */
 844 struct rpc_task *rpc_new_task(struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 845 {
 846         struct rpc_task *task;
 847
 848         task = rpc_alloc_task();
 849         if (!task)
 850                 goto cleanup;
 851
 852         rpc_init_task(task, clnt, flags, tk_ops, calldata);
 853
 854         dprintk("RPC: %4d allocated task\n", task->tk_pid);
 855         task->tk_flags |= RPC_TASK_DYNAMIC;
 856 out:
 857         return task;
 858
 859 cleanup:
 860         /* Check whether to release the client */
 861         if (clnt) {
 862                 printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
 863                         atomic_read(&clnt->cl_users), clnt->cl_oneshot);
 864                 atomic_inc(&clnt->cl_users); /* pretend we were used ... */
 865                 rpc_release_client(clnt);
 866         }
 867         goto out;
 868 }
 869
 870 void rpc_release_task(struct rpc_task *task)
 871 {
 872         const struct rpc_call_ops *tk_ops = task->tk_ops;
 873         void *calldata = task->tk_calldata;
 874
 875 #ifdef RPC_DEBUG
 876         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 877 #endif
 878         if (!atomic_dec_and_test(&task->tk_count))
 879                 return;
 880         dprintk("RPC: %4d release task\n", task->tk_pid);
 881
 882         /* Remove from global task list */
 883         spin_lock(&rpc_sched_lock);
 884         list_del(&task->tk_task);
 885         spin_unlock(&rpc_sched_lock);
 886
 887         BUG_ON (RPC_IS_QUEUED(task));
 888
 889         /* Synchronously delete any running timer */
 890         rpc_delete_timer(task);
 891
 892         /* Release resources */
 893         if (task->tk_rqstp)
 894                 xprt_release(task);
 895         if (task->tk_msg.rpc_cred)
 896                 rpcauth_unbindcred(task);
 897         if (task->tk_client) {
 898                 rpc_release_client(task->tk_client);
 899                 task->tk_client = NULL;
 900         }
 901
 902 #ifdef RPC_DEBUG
 903         task->tk_magic = 0;
 904 #endif
 905         if (task->tk_flags & RPC_TASK_DYNAMIC)
 906                 rpc_free_task(task);
 907         if (tk_ops->rpc_release)
 908                 tk_ops->rpc_release(calldata);
 909 }
 910
 911 /**
 912  * rpc_run_task - Allocate a new RPC task, then run rpc_execute against it
 913  * @clnt: pointer to RPC client
 914  * @flags: RPC flags
 915  * @ops: RPC call ops
 916  * @data: user call data
 917  */
 918 struct rpc_task *rpc_run_task(struct rpc_clnt *clnt, int flags,
 919                                         const struct rpc_call_ops *ops,
 920                                         void *data)
 921 {
 922         struct rpc_task *task;
 923         task = rpc_new_task(clnt, flags, ops, data);
 924         if (task == NULL) {
 925                 if (ops->rpc_release != NULL)
 926                         ops->rpc_release(data);
 927                 return ERR_PTR(-ENOMEM);
 928         }
 929         atomic_inc(&task->tk_count);
 930         rpc_execute(task);
 931         return task;
 932 }
 933 EXPORT_SYMBOL(rpc_run_task);
 934
 935 /**
 936  * rpc_find_parent - find the parent of a child task.
 937  * @child: child task
 938  * @parent: parent task
 939  *
 940  * Checks that the parent task is still sleeping on the
 941  * queue 'childq'. If so returns a pointer to the parent.
 942  * Upon failure returns NULL.
 943  *
 944  * Caller must hold childq.lock
 945  */
 946 static inline struct rpc_task *rpc_find_parent(struct rpc_task *child, struct rpc_task *parent)
 947 {
 948         struct rpc_task *task;
 949         struct list_head *le;
 950
 951         task_for_each(task, le, &childq.tasks[0])
 952                 if (task == parent)
 953                         return parent;
 954
 955         return NULL;
 956 }
 957
 958 static void rpc_child_exit(struct rpc_task *child, void *calldata)
 959 {
 960         struct rpc_task *parent;
 961
 962         spin_lock_bh(&childq.lock);
 963         if ((parent = rpc_find_parent(child, calldata)) != NULL) {
 964                 parent->tk_status = child->tk_status;
 965                 __rpc_wake_up_task(parent);
 966         }
 967         spin_unlock_bh(&childq.lock);
 968 }
 969
 970 static const struct rpc_call_ops rpc_child_ops = {
 971         .rpc_call_done = rpc_child_exit,
 972 };
 973
 974 /*
 975  * Note: rpc_new_task releases the client after a failure.
 976  */
 977 struct rpc_task *
 978 rpc_new_child(struct rpc_clnt *clnt, struct rpc_task *parent)
 979 {
 980         struct rpc_task *task;
 981
 982         task = rpc_new_task(clnt, RPC_TASK_ASYNC | RPC_TASK_CHILD, &rpc_child_ops, parent);
 983         if (!task)
 984                 goto fail;
 985         return task;
 986
 987 fail:
 988         parent->tk_status = -ENOMEM;
 989         return NULL;
 990 }
 991
 992 void rpc_run_child(struct rpc_task *task, struct rpc_task *child, rpc_action func)
 993 {
 994         spin_lock_bh(&childq.lock);
 995         /* N.B. Is it possible for the child to have already finished? */
 996         __rpc_sleep_on(&childq, task, func, NULL);
 997         rpc_schedule_run(child);
 998         spin_unlock_bh(&childq.lock);
 999 }
1000
1001 /*
1002  * Kill all tasks for the given client.
1003  * XXX: kill their descendants as well?
1004  */
1005 void rpc_killall_tasks(struct rpc_clnt *clnt)
1006 {
1007         struct rpc_task *rovr;
1008         struct list_head *le;
1009
1010         dprintk("RPC:      killing all tasks for client %p\n", clnt);
1011
1012         /*
1013          * Spin lock all_tasks to prevent changes...
1014          */
1015         spin_lock(&rpc_sched_lock);
1016         alltask_for_each(rovr, le, &all_tasks) {
1017                 if (! RPC_IS_ACTIVATED(rovr))
1018                         continue;
1019                 if (!clnt || rovr->tk_client == clnt) {
1020                         rovr->tk_flags |= RPC_TASK_KILLED;
1021                         rpc_exit(rovr, -EIO);
1022                         rpc_wake_up_task(rovr);
1023                 }
1024         }
1025         spin_unlock(&rpc_sched_lock);
1026 }
1027
1028 static DECLARE_MUTEX_LOCKED(rpciod_running);
1029
1030 static void rpciod_killall(void)
1031 {
1032         unsigned long flags;
1033
1034         while (!list_empty(&all_tasks)) {
1035                 clear_thread_flag(TIF_SIGPENDING);
1036                 rpc_killall_tasks(NULL);
1037                 flush_workqueue(rpciod_workqueue);
1038                 if (!list_empty(&all_tasks)) {
1039                         dprintk("rpciod_killall: waiting for tasks to exit\n");
1040                         yield();
1041                 }
1042         }
1043
1044         spin_lock_irqsave(&current->sighand->siglock, flags);
1045         recalc_sigpending();
1046         spin_unlock_irqrestore(&current->sighand->siglock, flags);
1047 }
1048
1049 /*
1050  * Start up the rpciod process if it's not already running.
1051  */
1052 int
1053 rpciod_up(void)
1054 {
1055         struct workqueue_struct *wq;
1056         int error = 0;
1057
1058         down(&rpciod_sema);
1059         dprintk("rpciod_up: users %d\n", rpciod_users);
1060         rpciod_users++;
1061         if (rpciod_workqueue)
1062                 goto out;
1063         /*
1064          * If there's no pid, we should be the first user.
1065          */
1066         if (rpciod_users > 1)
1067                 printk(KERN_WARNING "rpciod_up: no workqueue, %d users??\n", rpciod_users);
1068         /*
1069          * Create the rpciod thread and wait for it to start.
1070          */
1071         error = -ENOMEM;
1072         wq = create_workqueue("rpciod");
1073         if (wq == NULL) {
1074                 printk(KERN_WARNING "rpciod_up: create workqueue failed, error=%d\n", error);
1075                 rpciod_users--;
1076                 goto out;
1077         }
1078         rpciod_workqueue = wq;
1079         error = 0;
1080 out:
1081         up(&rpciod_sema);
1082         return error;
1083 }
1084
1085 void
1086 rpciod_down(void)
1087 {
1088         down(&rpciod_sema);
1089         dprintk("rpciod_down sema %d\n", rpciod_users);
1090         if (rpciod_users) {
1091                 if (--rpciod_users)
1092                         goto out;
1093         } else
1094                 printk(KERN_WARNING "rpciod_down: no users??\n");
1095
1096         if (!rpciod_workqueue) {
1097                 dprintk("rpciod_down: Nothing to do!\n");
1098                 goto out;
1099         }
1100         rpciod_killall();
1101
1102         destroy_workqueue(rpciod_workqueue);
1103         rpciod_workqueue = NULL;
1104  out:
1105         up(&rpciod_sema);
1106 }
1107
1108 #ifdef RPC_DEBUG
1109 void rpc_show_tasks(void)
1110 {
1111         struct list_head *le;
1112         struct rpc_task *t;
1113
1114         spin_lock(&rpc_sched_lock);
1115         if (list_empty(&all_tasks)) {
1116                 spin_unlock(&rpc_sched_lock);
1117                 return;
1118         }
1119         printk("-pid- proc flgs status -client- -prog- --rqstp- -timeout "
1120                 "-rpcwait -action- ---ops--\n");
1121         alltask_for_each(t, le, &all_tasks) {
1122                 const char *rpc_waitq = "none";
1123
1124                 if (RPC_IS_QUEUED(t))
1125                         rpc_waitq = rpc_qname(t->u.tk_wait.rpc_waitq);
1126
1127                 printk("%05d %04d %04x %06d %8p %6d %8p %08ld %8s %8p %8p\n",
1128                         t->tk_pid,
1129                         (t->tk_msg.rpc_proc ? t->tk_msg.rpc_proc->p_proc : -1),
1130                         t->tk_flags, t->tk_status,
1131                         t->tk_client,
1132                         (t->tk_client ? t->tk_client->cl_prog : 0),
1133                         t->tk_rqstp, t->tk_timeout,
1134                         rpc_waitq,
1135                         t->tk_action, t->tk_ops);
1136         }
1137         spin_unlock(&rpc_sched_lock);
1138 }
1139 #endif
1140
1141 void
1142 rpc_destroy_mempool(void)
1143 {
1144         if (rpc_buffer_mempool)
1145                 mempool_destroy(rpc_buffer_mempool);
1146         if (rpc_task_mempool)
1147                 mempool_destroy(rpc_task_mempool);
1148         if (rpc_task_slabp && kmem_cache_destroy(rpc_task_slabp))
1149                 printk(KERN_INFO "rpc_task: not all structures were freed\n");
1150         if (rpc_buffer_slabp && kmem_cache_destroy(rpc_buffer_slabp))
1151                 printk(KERN_INFO "rpc_buffers: not all structures were freed\n");
1152 }
1153
1154 int
1155 rpc_init_mempool(void)
1156 {
1157         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1158                                              sizeof(struct rpc_task),
1159                                              0, SLAB_HWCACHE_ALIGN,
1160                                              NULL, NULL);
1161         if (!rpc_task_slabp)
1162                 goto err_nomem;
1163         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1164                                              RPC_BUFFER_MAXSIZE,
1165                                              0, SLAB_HWCACHE_ALIGN,
1166                                              NULL, NULL);
1167         if (!rpc_buffer_slabp)
1168                 goto err_nomem;
1169         rpc_task_mempool = mempool_create(RPC_TASK_POOLSIZE,
1170                                             mempool_alloc_slab,
1171                                             mempool_free_slab,
1172                                             rpc_task_slabp);
1173         if (!rpc_task_mempool)
1174                 goto err_nomem;
1175         rpc_buffer_mempool = mempool_create(RPC_BUFFER_POOLSIZE,
1176                                             mempool_alloc_slab,
1177                                             mempool_free_slab,
1178                                             rpc_buffer_slabp);
1179         if (!rpc_buffer_mempool)
1180                 goto err_nomem;
1181         return 0;
1182 err_nomem:
1183         rpc_destroy_mempool();
1184         return -ENOMEM;
1185 }