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 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         BUG_ON(task->tk_timeout_fn);
 303         rpc_clear_queued(task);
 304         if (rpc_test_and_set_running(task))
 305                 return;
 306         /* We might have raced */
 307         if (RPC_IS_QUEUED(task)) {
 308                 rpc_clear_running(task);
 309                 return;
 310         }
 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         dprintk("RPC: %4d new task procpid %d\n", task->tk_pid,
 821                                 current->pid);
 822 }
 823
 824 static struct rpc_task *
 825 rpc_alloc_task(void)
 826 {
 827         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 828 }
 829
 830 static void rpc_free_task(struct rpc_task *task)
 831 {
 832         dprintk("RPC: %4d freeing task\n", task->tk_pid);
 833         mempool_free(task, rpc_task_mempool);
 834 }
 835
 836 /*
 837  * Create a new task for the specified client.  We have to
 838  * clean up after an allocation failure, as the client may
 839  * have specified "oneshot".
 840  */
 841 struct rpc_task *rpc_new_task(struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 842 {
 843         struct rpc_task *task;
 844
 845         task = rpc_alloc_task();
 846         if (!task)
 847                 goto cleanup;
 848
 849         rpc_init_task(task, clnt, flags, tk_ops, calldata);
 850
 851         dprintk("RPC: %4d allocated task\n", task->tk_pid);
 852         task->tk_flags |= RPC_TASK_DYNAMIC;
 853 out:
 854         return task;
 855
 856 cleanup:
 857         /* Check whether to release the client */
 858         if (clnt) {
 859                 printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
 860                         atomic_read(&clnt->cl_users), clnt->cl_oneshot);
 861                 atomic_inc(&clnt->cl_users); /* pretend we were used ... */
 862                 rpc_release_client(clnt);
 863         }
 864         goto out;
 865 }
 866
 867 void rpc_release_task(struct rpc_task *task)
 868 {
 869         const struct rpc_call_ops *tk_ops = task->tk_ops;
 870         void *calldata = task->tk_calldata;
 871
 872 #ifdef RPC_DEBUG
 873         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 874 #endif
 875         if (!atomic_dec_and_test(&task->tk_count))
 876                 return;
 877         dprintk("RPC: %4d release task\n", task->tk_pid);
 878
 879         /* Remove from global task list */
 880         spin_lock(&rpc_sched_lock);
 881         list_del(&task->tk_task);
 882         spin_unlock(&rpc_sched_lock);
 883
 884         BUG_ON (RPC_IS_QUEUED(task));
 885
 886         /* Synchronously delete any running timer */
 887         rpc_delete_timer(task);
 888
 889         /* Release resources */
 890         if (task->tk_rqstp)
 891                 xprt_release(task);
 892         if (task->tk_msg.rpc_cred)
 893                 rpcauth_unbindcred(task);
 894         if (task->tk_client) {
 895                 rpc_release_client(task->tk_client);
 896                 task->tk_client = NULL;
 897         }
 898
 899 #ifdef RPC_DEBUG
 900         task->tk_magic = 0;
 901 #endif
 902         if (task->tk_flags & RPC_TASK_DYNAMIC)
 903                 rpc_free_task(task);
 904         if (tk_ops->rpc_release)
 905                 tk_ops->rpc_release(calldata);
 906 }
 907
 908 /**
 909  * rpc_run_task - Allocate a new RPC task, then run rpc_execute against it
 910  * @clnt: pointer to RPC client
 911  * @flags: RPC flags
 912  * @ops: RPC call ops
 913  * @data: user call data
 914  */
 915 struct rpc_task *rpc_run_task(struct rpc_clnt *clnt, int flags,
 916                                         const struct rpc_call_ops *ops,
 917                                         void *data)
 918 {
 919         struct rpc_task *task;
 920         task = rpc_new_task(clnt, flags, ops, data);
 921         if (task == NULL)
 922                 return ERR_PTR(-ENOMEM);
 923         atomic_inc(&task->tk_count);
 924         rpc_execute(task);
 925         return task;
 926 }
 927 EXPORT_SYMBOL(rpc_run_task);
 928
 929 /**
 930  * rpc_find_parent - find the parent of a child task.
 931  * @child: child task
 932  * @parent: parent 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 }