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   1 /*
   2  * linux/net/sunrpc/sched.c
   3  *
   4  * Scheduling for synchronous and asynchronous RPC requests.
   5  *
   6  * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
   7  *
   8  * TCP NFS related read + write fixes
   9  * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
  10  */
  11
  12 #include <linux/module.h>
  13
  14 #include <linux/sched.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/slab.h>
  17 #include <linux/mempool.h>
  18 #include <linux/smp.h>
  19 #include <linux/smp_lock.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/mutex.h>
  22
  23 #include <linux/sunrpc/clnt.h>
  24 #include <linux/sunrpc/xprt.h>
  25
  26 #ifdef RPC_DEBUG
  27 #define RPCDBG_FACILITY         RPCDBG_SCHED
  28 #define RPC_TASK_MAGIC_ID       0xf00baa
  29 static int                      rpc_task_id;
  30 #endif
  31
  32 /*
  33  * RPC slabs and memory pools
  34  */
  35 #define RPC_BUFFER_MAXSIZE      (2048)
  36 #define RPC_BUFFER_POOLSIZE     (8)
  37 #define RPC_TASK_POOLSIZE       (8)
  38 static kmem_cache_t     *rpc_task_slabp __read_mostly;
  39 static kmem_cache_t     *rpc_buffer_slabp __read_mostly;
  40 static mempool_t        *rpc_task_mempool __read_mostly;
  41 static mempool_t        *rpc_buffer_mempool __read_mostly;
  42
  43 static void                     __rpc_default_timer(struct rpc_task *task);
  44 static void                     rpciod_killall(void);
  45 static void                     rpc_async_schedule(void *);
  46
  47 /*
  48  * RPC tasks that create another task (e.g. for contacting the portmapper)
  49  * will wait on this queue for their child's completion
  50  */
  51 static RPC_WAITQ(childq, "childq");
  52
  53 /*
  54  * RPC tasks sit here while waiting for conditions to improve.
  55  */
  56 static RPC_WAITQ(delay_queue, "delayq");
  57
  58 /*
  59  * All RPC tasks are linked into this list
  60  */
  61 static LIST_HEAD(all_tasks);
  62
  63 /*
  64  * rpciod-related stuff
  65  */
  66 static DEFINE_MUTEX(rpciod_mutex);
  67 static unsigned int             rpciod_users;
  68 static struct workqueue_struct *rpciod_workqueue;
  69
  70 /*
  71  * Spinlock for other critical sections of code.
  72  */
  73 static DEFINE_SPINLOCK(rpc_sched_lock);
  74
  75 /*
  76  * Disable the timer for a given RPC task. Should be called with
  77  * queue->lock and bh_disabled in order to avoid races within
  78  * rpc_run_timer().
  79  */
  80 static inline void
  81 __rpc_disable_timer(struct rpc_task *task)
  82 {
  83         dprintk("RPC: %4d disabling timer\n", task->tk_pid);
  84         task->tk_timeout_fn = NULL;
  85         task->tk_timeout = 0;
  86 }
  87
  88 /*
  89  * Run a timeout function.
  90  * We use the callback in order to allow __rpc_wake_up_task()
  91  * and friends to disable the timer synchronously on SMP systems
  92  * without calling del_timer_sync(). The latter could cause a
  93  * deadlock if called while we're holding spinlocks...
  94  */
  95 static void rpc_run_timer(struct rpc_task *task)
  96 {
  97         void (*callback)(struct rpc_task *);
  98
  99         callback = task->tk_timeout_fn;
 100         task->tk_timeout_fn = NULL;
 101         if (callback && RPC_IS_QUEUED(task)) {
 102                 dprintk("RPC: %4d running timer\n", task->tk_pid);
 103                 callback(task);
 104         }
 105         smp_mb__before_clear_bit();
 106         clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
 107         smp_mb__after_clear_bit();
 108 }
 109
 110 /*
 111  * Set up a timer for the current task.
 112  */
 113 static inline void
 114 __rpc_add_timer(struct rpc_task *task, rpc_action timer)
 115 {
 116         if (!task->tk_timeout)
 117                 return;
 118
 119         dprintk("RPC: %4d setting alarm for %lu ms\n",
 120                         task->tk_pid, task->tk_timeout * 1000 / HZ);
 121
 122         if (timer)
 123                 task->tk_timeout_fn = timer;
 124         else
 125                 task->tk_timeout_fn = __rpc_default_timer;
 126         set_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
 127         mod_timer(&task->tk_timer, jiffies + task->tk_timeout);
 128 }
 129
 130 /*
 131  * Delete any timer for the current task. Because we use del_timer_sync(),
 132  * this function should never be called while holding queue->lock.
 133  */
 134 static void
 135 rpc_delete_timer(struct rpc_task *task)
 136 {
 137         if (RPC_IS_QUEUED(task))
 138                 return;
 139         if (test_and_clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate)) {
 140                 del_singleshot_timer_sync(&task->tk_timer);
 141                 dprintk("RPC: %4d deleting timer\n", task->tk_pid);
 142         }
 143 }
 144
 145 /*
 146  * Add new request to a priority queue.
 147  */
 148 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
 149 {
 150         struct list_head *q;
 151         struct rpc_task *t;
 152
 153         INIT_LIST_HEAD(&task->u.tk_wait.links);
 154         q = &queue->tasks[task->tk_priority];
 155         if (unlikely(task->tk_priority > queue->maxpriority))
 156                 q = &queue->tasks[queue->maxpriority];
 157         list_for_each_entry(t, q, u.tk_wait.list) {
 158                 if (t->tk_cookie == task->tk_cookie) {
 159                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
 160                         return;
 161                 }
 162         }
 163         list_add_tail(&task->u.tk_wait.list, q);
 164 }
 165
 166 /*
 167  * Add new request to wait queue.
 168  *
 169  * Swapper tasks always get inserted at the head of the queue.
 170  * This should avoid many nasty memory deadlocks and hopefully
 171  * improve overall performance.
 172  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
 173  */
 174 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
 175 {
 176         BUG_ON (RPC_IS_QUEUED(task));
 177
 178         if (RPC_IS_PRIORITY(queue))
 179                 __rpc_add_wait_queue_priority(queue, task);
 180         else if (RPC_IS_SWAPPER(task))
 181                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
 182         else
 183                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
 184         task->u.tk_wait.rpc_waitq = queue;
 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         dprintk("RPC: %4d removed from queue %p \"%s\"\n",
 220                                 task->tk_pid, queue, rpc_qname(queue));
 221 }
 222
 223 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 224 {
 225         queue->priority = priority;
 226         queue->count = 1 << (priority * 2);
 227 }
 228
 229 static inline void rpc_set_waitqueue_cookie(struct rpc_wait_queue *queue, unsigned long cookie)
 230 {
 231         queue->cookie = cookie;
 232         queue->nr = RPC_BATCH_COUNT;
 233 }
 234
 235 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 236 {
 237         rpc_set_waitqueue_priority(queue, queue->maxpriority);
 238         rpc_set_waitqueue_cookie(queue, 0);
 239 }
 240
 241 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, int maxprio)
 242 {
 243         int i;
 244
 245         spin_lock_init(&queue->lock);
 246         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 247                 INIT_LIST_HEAD(&queue->tasks[i]);
 248         queue->maxpriority = maxprio;
 249         rpc_reset_waitqueue_priority(queue);
 250 #ifdef RPC_DEBUG
 251         queue->name = qname;
 252 #endif
 253 }
 254
 255 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 256 {
 257         __rpc_init_priority_wait_queue(queue, qname, RPC_PRIORITY_HIGH);
 258 }
 259
 260 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 261 {
 262         __rpc_init_priority_wait_queue(queue, qname, 0);
 263 }
 264 EXPORT_SYMBOL(rpc_init_wait_queue);
 265
 266 static int rpc_wait_bit_interruptible(void *word)
 267 {
 268         if (signal_pending(current))
 269                 return -ERESTARTSYS;
 270         schedule();
 271         return 0;
 272 }
 273
 274 /*
 275  * Mark an RPC call as having completed by clearing the 'active' bit
 276  */
 277 static inline void rpc_mark_complete_task(struct rpc_task *task)
 278 {
 279         rpc_clear_active(task);
 280         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
 281 }
 282
 283 /*
 284  * Allow callers to wait for completion of an RPC call
 285  */
 286 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
 287 {
 288         if (action == NULL)
 289                 action = rpc_wait_bit_interruptible;
 290         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 291                         action, TASK_INTERRUPTIBLE);
 292 }
 293 EXPORT_SYMBOL(__rpc_wait_for_completion_task);
 294
 295 /*
 296  * Make an RPC task runnable.
 297  *
 298  * Note: If the task is ASYNC, this must be called with
 299  * the spinlock held to protect the wait queue operation.
 300  */
 301 static void rpc_make_runnable(struct rpc_task *task)
 302 {
 303         int do_ret;
 304
 305         BUG_ON(task->tk_timeout_fn);
 306         do_ret = rpc_test_and_set_running(task);
 307         rpc_clear_queued(task);
 308         if (do_ret)
 309                 return;
 310         if (RPC_IS_ASYNC(task)) {
 311                 int status;
 312
 313                 INIT_WORK(&task->u.tk_work, rpc_async_schedule, (void *)task);
 314                 status = queue_work(task->tk_workqueue, &task->u.tk_work);
 315                 if (status < 0) {
 316                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
 317                         task->tk_status = status;
 318                         return;
 319                 }
 320         } else
 321                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 322 }
 323
 324 /*
 325  * Place a newly initialized task on the workqueue.
 326  */
 327 static inline void
 328 rpc_schedule_run(struct rpc_task *task)
 329 {
 330         rpc_set_active(task);
 331         rpc_make_runnable(task);
 332 }
 333
 334 /*
 335  * Prepare for sleeping on a wait queue.
 336  * By always appending tasks to the list we ensure FIFO behavior.
 337  * NB: An RPC task will only receive interrupt-driven events as long
 338  * as it's on a wait queue.
 339  */
 340 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 341                         rpc_action action, rpc_action timer)
 342 {
 343         dprintk("RPC: %4d sleep_on(queue \"%s\" time %ld)\n", task->tk_pid,
 344                                 rpc_qname(q), jiffies);
 345
 346         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
 347                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
 348                 return;
 349         }
 350
 351         /* Mark the task as being activated if so needed */
 352         rpc_set_active(task);
 353
 354         __rpc_add_wait_queue(q, task);
 355
 356         BUG_ON(task->tk_callback != NULL);
 357         task->tk_callback = action;
 358         __rpc_add_timer(task, timer);
 359 }
 360
 361 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 362                                 rpc_action action, rpc_action timer)
 363 {
 364         /*
 365          * Protect the queue operations.
 366          */
 367         spin_lock_bh(&q->lock);
 368         __rpc_sleep_on(q, task, action, timer);
 369         spin_unlock_bh(&q->lock);
 370 }
 371
 372 /**
 373  * __rpc_do_wake_up_task - wake up a single rpc_task
 374  * @task: task to be woken up
 375  *
 376  * Caller must hold queue->lock, and have cleared the task queued flag.
 377  */
 378 static void __rpc_do_wake_up_task(struct rpc_task *task)
 379 {
 380         dprintk("RPC: %4d __rpc_wake_up_task (now %ld)\n", task->tk_pid, jiffies);
 381
 382 #ifdef RPC_DEBUG
 383         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 384 #endif
 385         /* Has the task been executed yet? If not, we cannot wake it up! */
 386         if (!RPC_IS_ACTIVATED(task)) {
 387                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 388                 return;
 389         }
 390
 391         __rpc_disable_timer(task);
 392         __rpc_remove_wait_queue(task);
 393
 394         rpc_make_runnable(task);
 395
 396         dprintk("RPC:      __rpc_wake_up_task done\n");
 397 }
 398
 399 /*
 400  * Wake up the specified task
 401  */
 402 static void __rpc_wake_up_task(struct rpc_task *task)
 403 {
 404         if (rpc_start_wakeup(task)) {
 405                 if (RPC_IS_QUEUED(task))
 406                         __rpc_do_wake_up_task(task);
 407                 rpc_finish_wakeup(task);
 408         }
 409 }
 410
 411 /*
 412  * Default timeout handler if none specified by user
 413  */
 414 static void
 415 __rpc_default_timer(struct rpc_task *task)
 416 {
 417         dprintk("RPC: %d timeout (default timer)\n", task->tk_pid);
 418         task->tk_status = -ETIMEDOUT;
 419         rpc_wake_up_task(task);
 420 }
 421
 422 /*
 423  * Wake up the specified task
 424  */
 425 void rpc_wake_up_task(struct rpc_task *task)
 426 {
 427         if (rpc_start_wakeup(task)) {
 428                 if (RPC_IS_QUEUED(task)) {
 429                         struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
 430
 431                         spin_lock_bh(&queue->lock);
 432                         __rpc_do_wake_up_task(task);
 433                         spin_unlock_bh(&queue->lock);
 434                 }
 435                 rpc_finish_wakeup(task);
 436         }
 437 }
 438
 439 /*
 440  * Wake up the next task on a priority queue.
 441  */
 442 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
 443 {
 444         struct list_head *q;
 445         struct rpc_task *task;
 446
 447         /*
 448          * Service a batch of tasks from a single cookie.
 449          */
 450         q = &queue->tasks[queue->priority];
 451         if (!list_empty(q)) {
 452                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 453                 if (queue->cookie == task->tk_cookie) {
 454                         if (--queue->nr)
 455                                 goto out;
 456                         list_move_tail(&task->u.tk_wait.list, q);
 457                 }
 458                 /*
 459                  * Check if we need to switch queues.
 460                  */
 461                 if (--queue->count)
 462                         goto new_cookie;
 463         }
 464
 465         /*
 466          * Service the next queue.
 467          */
 468         do {
 469                 if (q == &queue->tasks[0])
 470                         q = &queue->tasks[queue->maxpriority];
 471                 else
 472                         q = q - 1;
 473                 if (!list_empty(q)) {
 474                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 475                         goto new_queue;
 476                 }
 477         } while (q != &queue->tasks[queue->priority]);
 478
 479         rpc_reset_waitqueue_priority(queue);
 480         return NULL;
 481
 482 new_queue:
 483         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 484 new_cookie:
 485         rpc_set_waitqueue_cookie(queue, task->tk_cookie);
 486 out:
 487         __rpc_wake_up_task(task);
 488         return task;
 489 }
 490
 491 /*
 492  * Wake up the next task on the wait queue.
 493  */
 494 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
 495 {
 496         struct rpc_task *task = NULL;
 497
 498         dprintk("RPC:      wake_up_next(%p \"%s\")\n", queue, rpc_qname(queue));
 499         spin_lock_bh(&queue->lock);
 500         if (RPC_IS_PRIORITY(queue))
 501                 task = __rpc_wake_up_next_priority(queue);
 502         else {
 503                 task_for_first(task, &queue->tasks[0])
 504                         __rpc_wake_up_task(task);
 505         }
 506         spin_unlock_bh(&queue->lock);
 507
 508         return task;
 509 }
 510
 511 /**
 512  * rpc_wake_up - wake up all rpc_tasks
 513  * @queue: rpc_wait_queue on which the tasks are sleeping
 514  *
 515  * Grabs queue->lock
 516  */
 517 void rpc_wake_up(struct rpc_wait_queue *queue)
 518 {
 519         struct rpc_task *task, *next;
 520         struct list_head *head;
 521
 522         spin_lock_bh(&queue->lock);
 523         head = &queue->tasks[queue->maxpriority];
 524         for (;;) {
 525                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
 526                         __rpc_wake_up_task(task);
 527                 if (head == &queue->tasks[0])
 528                         break;
 529                 head--;
 530         }
 531         spin_unlock_bh(&queue->lock);
 532 }
 533
 534 /**
 535  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 536  * @queue: rpc_wait_queue on which the tasks are sleeping
 537  * @status: status value to set
 538  *
 539  * Grabs queue->lock
 540  */
 541 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 542 {
 543         struct rpc_task *task, *next;
 544         struct list_head *head;
 545
 546         spin_lock_bh(&queue->lock);
 547         head = &queue->tasks[queue->maxpriority];
 548         for (;;) {
 549                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
 550                         task->tk_status = status;
 551                         __rpc_wake_up_task(task);
 552                 }
 553                 if (head == &queue->tasks[0])
 554                         break;
 555                 head--;
 556         }
 557         spin_unlock_bh(&queue->lock);
 558 }
 559
 560 /*
 561  * Run a task at a later time
 562  */
 563 static void     __rpc_atrun(struct rpc_task *);
 564 void
 565 rpc_delay(struct rpc_task *task, unsigned long delay)
 566 {
 567         task->tk_timeout = delay;
 568         rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
 569 }
 570
 571 static void
 572 __rpc_atrun(struct rpc_task *task)
 573 {
 574         task->tk_status = 0;
 575         rpc_wake_up_task(task);
 576 }
 577
 578 /*
 579  * Helper to call task->tk_ops->rpc_call_prepare
 580  */
 581 static void rpc_prepare_task(struct rpc_task *task)
 582 {
 583         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 584 }
 585
 586 /*
 587  * Helper that calls task->tk_ops->rpc_call_done if it exists
 588  */
 589 void rpc_exit_task(struct rpc_task *task)
 590 {
 591         task->tk_action = NULL;
 592         if (task->tk_ops->rpc_call_done != NULL) {
 593                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
 594                 if (task->tk_action != NULL) {
 595                         WARN_ON(RPC_ASSASSINATED(task));
 596                         /* Always release the RPC slot and buffer memory */
 597                         xprt_release(task);
 598                 }
 599         }
 600 }
 601 EXPORT_SYMBOL(rpc_exit_task);
 602
 603 /*
 604  * This is the RPC `scheduler' (or rather, the finite state machine).
 605  */
 606 static int __rpc_execute(struct rpc_task *task)
 607 {
 608         int             status = 0;
 609
 610         dprintk("RPC: %4d rpc_execute flgs %x\n",
 611                                 task->tk_pid, task->tk_flags);
 612
 613         BUG_ON(RPC_IS_QUEUED(task));
 614
 615         for (;;) {
 616                 /*
 617                  * Garbage collection of pending timers...
 618                  */
 619                 rpc_delete_timer(task);
 620
 621                 /*
 622                  * Execute any pending callback.
 623                  */
 624                 if (RPC_DO_CALLBACK(task)) {
 625                         /* Define a callback save pointer */
 626                         void (*save_callback)(struct rpc_task *);
 627
 628                         /*
 629                          * If a callback exists, save it, reset it,
 630                          * call it.
 631                          * The save is needed to stop from resetting
 632                          * another callback set within the callback handler
 633                          * - Dave
 634                          */
 635                         save_callback=task->tk_callback;
 636                         task->tk_callback=NULL;
 637                         lock_kernel();
 638                         save_callback(task);
 639                         unlock_kernel();
 640                 }
 641
 642                 /*
 643                  * Perform the next FSM step.
 644                  * tk_action may be NULL when the task has been killed
 645                  * by someone else.
 646                  */
 647                 if (!RPC_IS_QUEUED(task)) {
 648                         if (task->tk_action == NULL)
 649                                 break;
 650                         lock_kernel();
 651                         task->tk_action(task);
 652                         unlock_kernel();
 653                 }
 654
 655                 /*
 656                  * Lockless check for whether task is sleeping or not.
 657                  */
 658                 if (!RPC_IS_QUEUED(task))
 659                         continue;
 660                 rpc_clear_running(task);
 661                 if (RPC_IS_ASYNC(task)) {
 662                         /* Careful! we may have raced... */
 663                         if (RPC_IS_QUEUED(task))
 664                                 return 0;
 665                         if (rpc_test_and_set_running(task))
 666                                 return 0;
 667                         continue;
 668                 }
 669
 670                 /* sync task: sleep here */
 671                 dprintk("RPC: %4d sync task going to sleep\n", task->tk_pid);
 672                 /* Note: Caller should be using rpc_clnt_sigmask() */
 673                 status = out_of_line_wait_on_bit(&task->tk_runstate,
 674                                 RPC_TASK_QUEUED, rpc_wait_bit_interruptible,
 675                                 TASK_INTERRUPTIBLE);
 676                 if (status == -ERESTARTSYS) {
 677                         /*
 678                          * When a sync task receives a signal, it exits with
 679                          * -ERESTARTSYS. In order to catch any callbacks that
 680                          * clean up after sleeping on some queue, we don't
 681                          * break the loop here, but go around once more.
 682                          */
 683                         dprintk("RPC: %4d got signal\n", task->tk_pid);
 684                         task->tk_flags |= RPC_TASK_KILLED;
 685                         rpc_exit(task, -ERESTARTSYS);
 686                         rpc_wake_up_task(task);
 687                 }
 688                 rpc_set_running(task);
 689                 dprintk("RPC: %4d sync task resuming\n", task->tk_pid);
 690         }
 691
 692         dprintk("RPC: %4d, return %d, status %d\n", task->tk_pid, status, task->tk_status);
 693         /* Wake up anyone who is waiting for task completion */
 694         rpc_mark_complete_task(task);
 695         /* Release all resources associated with the task */
 696         rpc_release_task(task);
 697         return status;
 698 }
 699
 700 /*
 701  * User-visible entry point to the scheduler.
 702  *
 703  * This may be called recursively if e.g. an async NFS task updates
 704  * the attributes and finds that dirty pages must be flushed.
 705  * NOTE: Upon exit of this function the task is guaranteed to be
 706  *       released. In particular note that tk_release() will have
 707  *       been called, so your task memory may have been freed.
 708  */
 709 int
 710 rpc_execute(struct rpc_task *task)
 711 {
 712         rpc_set_active(task);
 713         rpc_set_running(task);
 714         return __rpc_execute(task);
 715 }
 716
 717 static void rpc_async_schedule(void *arg)
 718 {
 719         __rpc_execute((struct rpc_task *)arg);
 720 }
 721
 722 /**
 723  * rpc_malloc - allocate an RPC buffer
 724  * @task: RPC task that will use this buffer
 725  * @size: requested byte size
 726  *
 727  * We try to ensure that some NFS reads and writes can always proceed
 728  * by using a mempool when allocating 'small' buffers.
 729  * In order to avoid memory starvation triggering more writebacks of
 730  * NFS requests, we use GFP_NOFS rather than GFP_KERNEL.
 731  */
 732 void * rpc_malloc(struct rpc_task *task, size_t size)
 733 {
 734         struct rpc_rqst *req = task->tk_rqstp;
 735         gfp_t   gfp;
 736
 737         if (task->tk_flags & RPC_TASK_SWAPPER)
 738                 gfp = GFP_ATOMIC;
 739         else
 740                 gfp = GFP_NOFS;
 741
 742         if (size > RPC_BUFFER_MAXSIZE) {
 743                 req->rq_buffer = kmalloc(size, gfp);
 744                 if (req->rq_buffer)
 745                         req->rq_bufsize = size;
 746         } else {
 747                 req->rq_buffer = mempool_alloc(rpc_buffer_mempool, gfp);
 748                 if (req->rq_buffer)
 749                         req->rq_bufsize = RPC_BUFFER_MAXSIZE;
 750         }
 751         return req->rq_buffer;
 752 }
 753
 754 /**
 755  * rpc_free - free buffer allocated via rpc_malloc
 756  * @task: RPC task with a buffer to be freed
 757  *
 758  */
 759 void rpc_free(struct rpc_task *task)
 760 {
 761         struct rpc_rqst *req = task->tk_rqstp;
 762
 763         if (req->rq_buffer) {
 764                 if (req->rq_bufsize == RPC_BUFFER_MAXSIZE)
 765                         mempool_free(req->rq_buffer, rpc_buffer_mempool);
 766                 else
 767                         kfree(req->rq_buffer);
 768                 req->rq_buffer = NULL;
 769                 req->rq_bufsize = 0;
 770         }
 771 }
 772
 773 /*
 774  * Creation and deletion of RPC task structures
 775  */
 776 void rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 777 {
 778         memset(task, 0, sizeof(*task));
 779         init_timer(&task->tk_timer);
 780         task->tk_timer.data     = (unsigned long) task;
 781         task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
 782         atomic_set(&task->tk_count, 1);
 783         task->tk_client = clnt;
 784         task->tk_flags  = flags;
 785         task->tk_ops = tk_ops;
 786         if (tk_ops->rpc_call_prepare != NULL)
 787                 task->tk_action = rpc_prepare_task;
 788         task->tk_calldata = calldata;
 789
 790         /* Initialize retry counters */
 791         task->tk_garb_retry = 2;
 792         task->tk_cred_retry = 2;
 793
 794         task->tk_priority = RPC_PRIORITY_NORMAL;
 795         task->tk_cookie = (unsigned long)current;
 796
 797         /* Initialize workqueue for async tasks */
 798         task->tk_workqueue = rpciod_workqueue;
 799
 800         if (clnt) {
 801                 atomic_inc(&clnt->cl_users);
 802                 if (clnt->cl_softrtry)
 803                         task->tk_flags |= RPC_TASK_SOFT;
 804                 if (!clnt->cl_intr)
 805                         task->tk_flags |= RPC_TASK_NOINTR;
 806         }
 807
 808 #ifdef RPC_DEBUG
 809         task->tk_magic = RPC_TASK_MAGIC_ID;
 810         task->tk_pid = rpc_task_id++;
 811 #endif
 812         /* Add to global list of all tasks */
 813         spin_lock(&rpc_sched_lock);
 814         list_add_tail(&task->tk_task, &all_tasks);
 815         spin_unlock(&rpc_sched_lock);
 816
 817         BUG_ON(task->tk_ops == NULL);
 818
 819         dprintk("RPC: %4d new task procpid %d\n", task->tk_pid,
 820                                 current->pid);
 821 }
 822
 823 static struct rpc_task *
 824 rpc_alloc_task(void)
 825 {
 826         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 827 }
 828
 829 static void rpc_free_task(struct rpc_task *task)
 830 {
 831         dprintk("RPC: %4d freeing task\n", task->tk_pid);
 832         mempool_free(task, rpc_task_mempool);
 833 }
 834
 835 /*
 836  * Create a new task for the specified client.  We have to
 837  * clean up after an allocation failure, as the client may
 838  * have specified "oneshot".
 839  */
 840 struct rpc_task *rpc_new_task(struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 841 {
 842         struct rpc_task *task;
 843
 844         task = rpc_alloc_task();
 845         if (!task)
 846                 goto cleanup;
 847
 848         rpc_init_task(task, clnt, flags, tk_ops, calldata);
 849
 850         dprintk("RPC: %4d allocated task\n", task->tk_pid);
 851         task->tk_flags |= RPC_TASK_DYNAMIC;
 852 out:
 853         return task;
 854
 855 cleanup:
 856         /* Check whether to release the client */
 857         if (clnt) {
 858                 printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
 859                         atomic_read(&clnt->cl_users), clnt->cl_oneshot);
 860                 atomic_inc(&clnt->cl_users); /* pretend we were used ... */
 861                 rpc_release_client(clnt);
 862         }
 863         goto out;
 864 }
 865
 866 void rpc_release_task(struct rpc_task *task)
 867 {
 868         const struct rpc_call_ops *tk_ops = task->tk_ops;
 869         void *calldata = task->tk_calldata;
 870
 871 #ifdef RPC_DEBUG
 872         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 873 #endif
 874         if (!atomic_dec_and_test(&task->tk_count))
 875                 return;
 876         dprintk("RPC: %4d release task\n", task->tk_pid);
 877
 878         /* Remove from global task list */
 879         spin_lock(&rpc_sched_lock);
 880         list_del(&task->tk_task);
 881         spin_unlock(&rpc_sched_lock);
 882
 883         BUG_ON (RPC_IS_QUEUED(task));
 884
 885         /* Synchronously delete any running timer */
 886         rpc_delete_timer(task);
 887
 888         /* Release resources */
 889         if (task->tk_rqstp)
 890                 xprt_release(task);
 891         if (task->tk_msg.rpc_cred)
 892                 rpcauth_unbindcred(task);
 893         if (task->tk_client) {
 894                 rpc_release_client(task->tk_client);
 895                 task->tk_client = NULL;
 896         }
 897
 898 #ifdef RPC_DEBUG
 899         task->tk_magic = 0;
 900 #endif
 901         if (task->tk_flags & RPC_TASK_DYNAMIC)
 902                 rpc_free_task(task);
 903         if (tk_ops->rpc_release)
 904                 tk_ops->rpc_release(calldata);
 905 }
 906
 907 /**
 908  * rpc_run_task - Allocate a new RPC task, then run rpc_execute against it
 909  * @clnt: pointer to RPC client
 910  * @flags: RPC flags
 911  * @ops: RPC call ops
 912  * @data: user call data
 913  */
 914 struct rpc_task *rpc_run_task(struct rpc_clnt *clnt, int flags,
 915                                         const struct rpc_call_ops *ops,
 916                                         void *data)
 917 {
 918         struct rpc_task *task;
 919         task = rpc_new_task(clnt, flags, ops, data);
 920         if (task == NULL)
 921                 return ERR_PTR(-ENOMEM);
 922         atomic_inc(&task->tk_count);
 923         rpc_execute(task);
 924         return task;
 925 }
 926 EXPORT_SYMBOL(rpc_run_task);
 927
 928 /**
 929  * rpc_find_parent - find the parent of a child task.
 930  * @child: child task
 931  * @parent: parent task
 932  *
 933  * Checks that the parent task is still sleeping on the
 934  * queue 'childq'. If so returns a pointer to the parent.
 935  * Upon failure returns NULL.
 936  *
 937  * Caller must hold childq.lock
 938  */
 939 static inline struct rpc_task *rpc_find_parent(struct rpc_task *child, struct rpc_task *parent)
 940 {
 941         struct rpc_task *task;
 942         struct list_head *le;
 943
 944         task_for_each(task, le, &childq.tasks[0])
 945                 if (task == parent)
 946                         return parent;
 947
 948         return NULL;
 949 }
 950
 951 static void rpc_child_exit(struct rpc_task *child, void *calldata)
 952 {
 953         struct rpc_task *parent;
 954
 955         spin_lock_bh(&childq.lock);
 956         if ((parent = rpc_find_parent(child, calldata)) != NULL) {
 957                 parent->tk_status = child->tk_status;
 958                 __rpc_wake_up_task(parent);
 959         }
 960         spin_unlock_bh(&childq.lock);
 961 }
 962
 963 static const struct rpc_call_ops rpc_child_ops = {
 964         .rpc_call_done = rpc_child_exit,
 965 };
 966
 967 /*
 968  * Note: rpc_new_task releases the client after a failure.
 969  */
 970 struct rpc_task *
 971 rpc_new_child(struct rpc_clnt *clnt, struct rpc_task *parent)
 972 {
 973         struct rpc_task *task;
 974
 975         task = rpc_new_task(clnt, RPC_TASK_ASYNC | RPC_TASK_CHILD, &rpc_child_ops, parent);
 976         if (!task)
 977                 goto fail;
 978         return task;
 979
 980 fail:
 981         parent->tk_status = -ENOMEM;
 982         return NULL;
 983 }
 984
 985 void rpc_run_child(struct rpc_task *task, struct rpc_task *child, rpc_action func)
 986 {
 987         spin_lock_bh(&childq.lock);
 988         /* N.B. Is it possible for the child to have already finished? */
 989         __rpc_sleep_on(&childq, task, func, NULL);
 990         rpc_schedule_run(child);
 991         spin_unlock_bh(&childq.lock);
 992 }
 993
 994 /*
 995  * Kill all tasks for the given client.
 996  * XXX: kill their descendants as well?
 997  */
 998 void rpc_killall_tasks(struct rpc_clnt *clnt)
 999 {
1000         struct rpc_task *rovr;
1001         struct list_head *le;
1002
1003         dprintk("RPC:      killing all tasks for client %p\n", clnt);
1004
1005         /*
1006          * Spin lock all_tasks to prevent changes...
1007          */
1008         spin_lock(&rpc_sched_lock);
1009         alltask_for_each(rovr, le, &all_tasks) {
1010                 if (! RPC_IS_ACTIVATED(rovr))
1011                         continue;
1012                 if (!clnt || rovr->tk_client == clnt) {
1013                         rovr->tk_flags |= RPC_TASK_KILLED;
1014                         rpc_exit(rovr, -EIO);
1015                         rpc_wake_up_task(rovr);
1016                 }
1017         }
1018         spin_unlock(&rpc_sched_lock);
1019 }
1020
1021 static DECLARE_MUTEX_LOCKED(rpciod_running);
1022
1023 static void rpciod_killall(void)
1024 {
1025         unsigned long flags;
1026
1027         while (!list_empty(&all_tasks)) {
1028                 clear_thread_flag(TIF_SIGPENDING);
1029                 rpc_killall_tasks(NULL);
1030                 flush_workqueue(rpciod_workqueue);
1031                 if (!list_empty(&all_tasks)) {
1032                         dprintk("rpciod_killall: waiting for tasks to exit\n");
1033                         yield();
1034                 }
1035         }
1036
1037         spin_lock_irqsave(&current->sighand->siglock, flags);
1038         recalc_sigpending();
1039         spin_unlock_irqrestore(&current->sighand->siglock, flags);
1040 }
1041
1042 /*
1043  * Start up the rpciod process if it's not already running.
1044  */
1045 int
1046 rpciod_up(void)
1047 {
1048         struct workqueue_struct *wq;
1049         int error = 0;
1050
1051         mutex_lock(&rpciod_mutex);
1052         dprintk("rpciod_up: users %d\n", rpciod_users);
1053         rpciod_users++;
1054         if (rpciod_workqueue)
1055                 goto out;
1056         /*
1057          * If there's no pid, we should be the first user.
1058          */
1059         if (rpciod_users > 1)
1060                 printk(KERN_WARNING "rpciod_up: no workqueue, %d users??\n", rpciod_users);
1061         /*
1062          * Create the rpciod thread and wait for it to start.
1063          */
1064         error = -ENOMEM;
1065         wq = create_workqueue("rpciod");
1066         if (wq == NULL) {
1067                 printk(KERN_WARNING "rpciod_up: create workqueue failed, error=%d\n", error);
1068                 rpciod_users--;
1069                 goto out;
1070         }
1071         rpciod_workqueue = wq;
1072         error = 0;
1073 out:
1074         mutex_unlock(&rpciod_mutex);
1075         return error;
1076 }
1077
1078 void
1079 rpciod_down(void)
1080 {
1081         mutex_lock(&rpciod_mutex);
1082         dprintk("rpciod_down sema %d\n", rpciod_users);
1083         if (rpciod_users) {
1084                 if (--rpciod_users)
1085                         goto out;
1086         } else
1087                 printk(KERN_WARNING "rpciod_down: no users??\n");
1088
1089         if (!rpciod_workqueue) {
1090                 dprintk("rpciod_down: Nothing to do!\n");
1091                 goto out;
1092         }
1093         rpciod_killall();
1094
1095         destroy_workqueue(rpciod_workqueue);
1096         rpciod_workqueue = NULL;
1097  out:
1098         mutex_unlock(&rpciod_mutex);
1099 }
1100
1101 #ifdef RPC_DEBUG
1102 void rpc_show_tasks(void)
1103 {
1104         struct list_head *le;
1105         struct rpc_task *t;
1106
1107         spin_lock(&rpc_sched_lock);
1108         if (list_empty(&all_tasks)) {
1109                 spin_unlock(&rpc_sched_lock);
1110                 return;
1111         }
1112         printk("-pid- proc flgs status -client- -prog- --rqstp- -timeout "
1113                 "-rpcwait -action- ---ops--\n");
1114         alltask_for_each(t, le, &all_tasks) {
1115                 const char *rpc_waitq = "none";
1116
1117                 if (RPC_IS_QUEUED(t))
1118                         rpc_waitq = rpc_qname(t->u.tk_wait.rpc_waitq);
1119
1120                 printk("%05d %04d %04x %06d %8p %6d %8p %08ld %8s %8p %8p\n",
1121                         t->tk_pid,
1122                         (t->tk_msg.rpc_proc ? t->tk_msg.rpc_proc->p_proc : -1),
1123                         t->tk_flags, t->tk_status,
1124                         t->tk_client,
1125                         (t->tk_client ? t->tk_client->cl_prog : 0),
1126                         t->tk_rqstp, t->tk_timeout,
1127                         rpc_waitq,
1128                         t->tk_action, t->tk_ops);
1129         }
1130         spin_unlock(&rpc_sched_lock);
1131 }
1132 #endif
1133
1134 void
1135 rpc_destroy_mempool(void)
1136 {
1137         if (rpc_buffer_mempool)
1138                 mempool_destroy(rpc_buffer_mempool);
1139         if (rpc_task_mempool)
1140                 mempool_destroy(rpc_task_mempool);
1141         if (rpc_task_slabp && kmem_cache_destroy(rpc_task_slabp))
1142                 printk(KERN_INFO "rpc_task: not all structures were freed\n");
1143         if (rpc_buffer_slabp && kmem_cache_destroy(rpc_buffer_slabp))
1144                 printk(KERN_INFO "rpc_buffers: not all structures were freed\n");
1145 }
1146
1147 int
1148 rpc_init_mempool(void)
1149 {
1150         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1151                                              sizeof(struct rpc_task),
1152                                              0, SLAB_HWCACHE_ALIGN,
1153                                              NULL, NULL);
1154         if (!rpc_task_slabp)
1155                 goto err_nomem;
1156         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1157                                              RPC_BUFFER_MAXSIZE,
1158                                              0, SLAB_HWCACHE_ALIGN,
1159                                              NULL, NULL);
1160         if (!rpc_buffer_slabp)
1161                 goto err_nomem;
1162         rpc_task_mempool = mempool_create(RPC_TASK_POOLSIZE,
1163                                             mempool_alloc_slab,
1164                                             mempool_free_slab,
1165                                             rpc_task_slabp);
1166         if (!rpc_task_mempool)
1167                 goto err_nomem;
1168         rpc_buffer_mempool = mempool_create(RPC_BUFFER_POOLSIZE,
1169                                             mempool_alloc_slab,
1170                                             mempool_free_slab,
1171                                             rpc_buffer_slabp);
1172         if (!rpc_buffer_mempool)
1173                 goto err_nomem;
1174         return 0;
1175 err_nomem:
1176         rpc_destroy_mempool();
1177         return -ENOMEM;
1178 }