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 #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 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         queue->qlen++;
 186         rpc_set_queued(task);
 187
 188         dprintk("RPC: %4d added to queue %p \"%s\"\n",
 189                                 task->tk_pid, queue, rpc_qname(queue));
 190 }
 191
 192 /*
 193  * Remove request from a priority queue.
 194  */
 195 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
 196 {
 197         struct rpc_task *t;
 198
 199         if (!list_empty(&task->u.tk_wait.links)) {
 200                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
 201                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
 202                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
 203         }
 204         list_del(&task->u.tk_wait.list);
 205 }
 206
 207 /*
 208  * Remove request from queue.
 209  * Note: must be called with spin lock held.
 210  */
 211 static void __rpc_remove_wait_queue(struct rpc_task *task)
 212 {
 213         struct rpc_wait_queue *queue;
 214         queue = task->u.tk_wait.rpc_waitq;
 215
 216         if (RPC_IS_PRIORITY(queue))
 217                 __rpc_remove_wait_queue_priority(task);
 218         else
 219                 list_del(&task->u.tk_wait.list);
 220         queue->qlen--;
 221         dprintk("RPC: %4d removed from queue %p \"%s\"\n",
 222                                 task->tk_pid, queue, rpc_qname(queue));
 223 }
 224
 225 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
 226 {
 227         queue->priority = priority;
 228         queue->count = 1 << (priority * 2);
 229 }
 230
 231 static inline void rpc_set_waitqueue_cookie(struct rpc_wait_queue *queue, unsigned long cookie)
 232 {
 233         queue->cookie = cookie;
 234         queue->nr = RPC_BATCH_COUNT;
 235 }
 236
 237 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
 238 {
 239         rpc_set_waitqueue_priority(queue, queue->maxpriority);
 240         rpc_set_waitqueue_cookie(queue, 0);
 241 }
 242
 243 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, int maxprio)
 244 {
 245         int i;
 246
 247         spin_lock_init(&queue->lock);
 248         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
 249                 INIT_LIST_HEAD(&queue->tasks[i]);
 250         queue->maxpriority = maxprio;
 251         rpc_reset_waitqueue_priority(queue);
 252 #ifdef RPC_DEBUG
 253         queue->name = qname;
 254 #endif
 255 }
 256
 257 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 258 {
 259         __rpc_init_priority_wait_queue(queue, qname, RPC_PRIORITY_HIGH);
 260 }
 261
 262 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
 263 {
 264         __rpc_init_priority_wait_queue(queue, qname, 0);
 265 }
 266 EXPORT_SYMBOL(rpc_init_wait_queue);
 267
 268 static int rpc_wait_bit_interruptible(void *word)
 269 {
 270         if (signal_pending(current))
 271                 return -ERESTARTSYS;
 272         schedule();
 273         return 0;
 274 }
 275
 276 /*
 277  * Mark an RPC call as having completed by clearing the 'active' bit
 278  */
 279 static inline void rpc_mark_complete_task(struct rpc_task *task)
 280 {
 281         rpc_clear_active(task);
 282         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
 283 }
 284
 285 /*
 286  * Allow callers to wait for completion of an RPC call
 287  */
 288 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
 289 {
 290         if (action == NULL)
 291                 action = rpc_wait_bit_interruptible;
 292         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
 293                         action, TASK_INTERRUPTIBLE);
 294 }
 295 EXPORT_SYMBOL(__rpc_wait_for_completion_task);
 296
 297 /*
 298  * Make an RPC task runnable.
 299  *
 300  * Note: If the task is ASYNC, this must be called with
 301  * the spinlock held to protect the wait queue operation.
 302  */
 303 static void rpc_make_runnable(struct rpc_task *task)
 304 {
 305         int do_ret;
 306
 307         BUG_ON(task->tk_timeout_fn);
 308         do_ret = rpc_test_and_set_running(task);
 309         rpc_clear_queued(task);
 310         if (do_ret)
 311                 return;
 312         if (RPC_IS_ASYNC(task)) {
 313                 int status;
 314
 315                 INIT_WORK(&task->u.tk_work, rpc_async_schedule, (void *)task);
 316                 status = queue_work(task->tk_workqueue, &task->u.tk_work);
 317                 if (status < 0) {
 318                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
 319                         task->tk_status = status;
 320                         return;
 321                 }
 322         } else
 323                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 324 }
 325
 326 /*
 327  * Place a newly initialized task on the workqueue.
 328  */
 329 static inline void
 330 rpc_schedule_run(struct rpc_task *task)
 331 {
 332         rpc_set_active(task);
 333         rpc_make_runnable(task);
 334 }
 335
 336 /*
 337  * Prepare for sleeping on a wait queue.
 338  * By always appending tasks to the list we ensure FIFO behavior.
 339  * NB: An RPC task will only receive interrupt-driven events as long
 340  * as it's on a wait queue.
 341  */
 342 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 343                         rpc_action action, rpc_action timer)
 344 {
 345         dprintk("RPC: %4d sleep_on(queue \"%s\" time %ld)\n", task->tk_pid,
 346                                 rpc_qname(q), jiffies);
 347
 348         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
 349                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
 350                 return;
 351         }
 352
 353         /* Mark the task as being activated if so needed */
 354         rpc_set_active(task);
 355
 356         __rpc_add_wait_queue(q, task);
 357
 358         BUG_ON(task->tk_callback != NULL);
 359         task->tk_callback = action;
 360         __rpc_add_timer(task, timer);
 361 }
 362
 363 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 364                                 rpc_action action, rpc_action timer)
 365 {
 366         /*
 367          * Protect the queue operations.
 368          */
 369         spin_lock_bh(&q->lock);
 370         __rpc_sleep_on(q, task, action, timer);
 371         spin_unlock_bh(&q->lock);
 372 }
 373
 374 /**
 375  * __rpc_do_wake_up_task - wake up a single rpc_task
 376  * @task: task to be woken up
 377  *
 378  * Caller must hold queue->lock, and have cleared the task queued flag.
 379  */
 380 static void __rpc_do_wake_up_task(struct rpc_task *task)
 381 {
 382         dprintk("RPC: %4d __rpc_wake_up_task (now %ld)\n", task->tk_pid, jiffies);
 383
 384 #ifdef RPC_DEBUG
 385         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 386 #endif
 387         /* Has the task been executed yet? If not, we cannot wake it up! */
 388         if (!RPC_IS_ACTIVATED(task)) {
 389                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 390                 return;
 391         }
 392
 393         __rpc_disable_timer(task);
 394         __rpc_remove_wait_queue(task);
 395
 396         rpc_make_runnable(task);
 397
 398         dprintk("RPC:      __rpc_wake_up_task done\n");
 399 }
 400
 401 /*
 402  * Wake up the specified task
 403  */
 404 static void __rpc_wake_up_task(struct rpc_task *task)
 405 {
 406         if (rpc_start_wakeup(task)) {
 407                 if (RPC_IS_QUEUED(task))
 408                         __rpc_do_wake_up_task(task);
 409                 rpc_finish_wakeup(task);
 410         }
 411 }
 412
 413 /*
 414  * Default timeout handler if none specified by user
 415  */
 416 static void
 417 __rpc_default_timer(struct rpc_task *task)
 418 {
 419         dprintk("RPC: %d timeout (default timer)\n", task->tk_pid);
 420         task->tk_status = -ETIMEDOUT;
 421         rpc_wake_up_task(task);
 422 }
 423
 424 /*
 425  * Wake up the specified task
 426  */
 427 void rpc_wake_up_task(struct rpc_task *task)
 428 {
 429         if (rpc_start_wakeup(task)) {
 430                 if (RPC_IS_QUEUED(task)) {
 431                         struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
 432
 433                         spin_lock_bh(&queue->lock);
 434                         __rpc_do_wake_up_task(task);
 435                         spin_unlock_bh(&queue->lock);
 436                 }
 437                 rpc_finish_wakeup(task);
 438         }
 439 }
 440
 441 /*
 442  * Wake up the next task on a priority queue.
 443  */
 444 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
 445 {
 446         struct list_head *q;
 447         struct rpc_task *task;
 448
 449         /*
 450          * Service a batch of tasks from a single cookie.
 451          */
 452         q = &queue->tasks[queue->priority];
 453         if (!list_empty(q)) {
 454                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 455                 if (queue->cookie == task->tk_cookie) {
 456                         if (--queue->nr)
 457                                 goto out;
 458                         list_move_tail(&task->u.tk_wait.list, q);
 459                 }
 460                 /*
 461                  * Check if we need to switch queues.
 462                  */
 463                 if (--queue->count)
 464                         goto new_cookie;
 465         }
 466
 467         /*
 468          * Service the next queue.
 469          */
 470         do {
 471                 if (q == &queue->tasks[0])
 472                         q = &queue->tasks[queue->maxpriority];
 473                 else
 474                         q = q - 1;
 475                 if (!list_empty(q)) {
 476                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
 477                         goto new_queue;
 478                 }
 479         } while (q != &queue->tasks[queue->priority]);
 480
 481         rpc_reset_waitqueue_priority(queue);
 482         return NULL;
 483
 484 new_queue:
 485         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 486 new_cookie:
 487         rpc_set_waitqueue_cookie(queue, task->tk_cookie);
 488 out:
 489         __rpc_wake_up_task(task);
 490         return task;
 491 }
 492
 493 /*
 494  * Wake up the next task on the wait queue.
 495  */
 496 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
 497 {
 498         struct rpc_task *task = NULL;
 499
 500         dprintk("RPC:      wake_up_next(%p \"%s\")\n", queue, rpc_qname(queue));
 501         spin_lock_bh(&queue->lock);
 502         if (RPC_IS_PRIORITY(queue))
 503                 task = __rpc_wake_up_next_priority(queue);
 504         else {
 505                 task_for_first(task, &queue->tasks[0])
 506                         __rpc_wake_up_task(task);
 507         }
 508         spin_unlock_bh(&queue->lock);
 509
 510         return task;
 511 }
 512
 513 /**
 514  * rpc_wake_up - wake up all rpc_tasks
 515  * @queue: rpc_wait_queue on which the tasks are sleeping
 516  *
 517  * Grabs queue->lock
 518  */
 519 void rpc_wake_up(struct rpc_wait_queue *queue)
 520 {
 521         struct rpc_task *task, *next;
 522         struct list_head *head;
 523
 524         spin_lock_bh(&queue->lock);
 525         head = &queue->tasks[queue->maxpriority];
 526         for (;;) {
 527                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
 528                         __rpc_wake_up_task(task);
 529                 if (head == &queue->tasks[0])
 530                         break;
 531                 head--;
 532         }
 533         spin_unlock_bh(&queue->lock);
 534 }
 535
 536 /**
 537  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 538  * @queue: rpc_wait_queue on which the tasks are sleeping
 539  * @status: status value to set
 540  *
 541  * Grabs queue->lock
 542  */
 543 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 544 {
 545         struct rpc_task *task, *next;
 546         struct list_head *head;
 547
 548         spin_lock_bh(&queue->lock);
 549         head = &queue->tasks[queue->maxpriority];
 550         for (;;) {
 551                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
 552                         task->tk_status = status;
 553                         __rpc_wake_up_task(task);
 554                 }
 555                 if (head == &queue->tasks[0])
 556                         break;
 557                 head--;
 558         }
 559         spin_unlock_bh(&queue->lock);
 560 }
 561
 562 /*
 563  * Run a task at a later time
 564  */
 565 static void     __rpc_atrun(struct rpc_task *);
 566 void
 567 rpc_delay(struct rpc_task *task, unsigned long delay)
 568 {
 569         task->tk_timeout = delay;
 570         rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
 571 }
 572
 573 static void
 574 __rpc_atrun(struct rpc_task *task)
 575 {
 576         task->tk_status = 0;
 577         rpc_wake_up_task(task);
 578 }
 579
 580 /*
 581  * Helper to call task->tk_ops->rpc_call_prepare
 582  */
 583 static void rpc_prepare_task(struct rpc_task *task)
 584 {
 585         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 586 }
 587
 588 /*
 589  * Helper that calls task->tk_ops->rpc_call_done if it exists
 590  */
 591 void rpc_exit_task(struct rpc_task *task)
 592 {
 593         task->tk_action = NULL;
 594         if (task->tk_ops->rpc_call_done != NULL) {
 595                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
 596                 if (task->tk_action != NULL) {
 597                         WARN_ON(RPC_ASSASSINATED(task));
 598                         /* Always release the RPC slot and buffer memory */
 599                         xprt_release(task);
 600                 }
 601         }
 602 }
 603 EXPORT_SYMBOL(rpc_exit_task);
 604
 605 /*
 606  * This is the RPC `scheduler' (or rather, the finite state machine).
 607  */
 608 static int __rpc_execute(struct rpc_task *task)
 609 {
 610         int             status = 0;
 611
 612         dprintk("RPC: %4d rpc_execute flgs %x\n",
 613                                 task->tk_pid, task->tk_flags);
 614
 615         BUG_ON(RPC_IS_QUEUED(task));
 616
 617         for (;;) {
 618                 /*
 619                  * Garbage collection of pending timers...
 620                  */
 621                 rpc_delete_timer(task);
 622
 623                 /*
 624                  * Execute any pending callback.
 625                  */
 626                 if (RPC_DO_CALLBACK(task)) {
 627                         /* Define a callback save pointer */
 628                         void (*save_callback)(struct rpc_task *);
 629
 630                         /*
 631                          * If a callback exists, save it, reset it,
 632                          * call it.
 633                          * The save is needed to stop from resetting
 634                          * another callback set within the callback handler
 635                          * - Dave
 636                          */
 637                         save_callback=task->tk_callback;
 638                         task->tk_callback=NULL;
 639                         lock_kernel();
 640                         save_callback(task);
 641                         unlock_kernel();
 642                 }
 643
 644                 /*
 645                  * Perform the next FSM step.
 646                  * tk_action may be NULL when the task has been killed
 647                  * by someone else.
 648                  */
 649                 if (!RPC_IS_QUEUED(task)) {
 650                         if (task->tk_action == NULL)
 651                                 break;
 652                         lock_kernel();
 653                         task->tk_action(task);
 654                         unlock_kernel();
 655                 }
 656
 657                 /*
 658                  * Lockless check for whether task is sleeping or not.
 659                  */
 660                 if (!RPC_IS_QUEUED(task))
 661                         continue;
 662                 rpc_clear_running(task);
 663                 if (RPC_IS_ASYNC(task)) {
 664                         /* Careful! we may have raced... */
 665                         if (RPC_IS_QUEUED(task))
 666                                 return 0;
 667                         if (rpc_test_and_set_running(task))
 668                                 return 0;
 669                         continue;
 670                 }
 671
 672                 /* sync task: sleep here */
 673                 dprintk("RPC: %4d sync task going to sleep\n", task->tk_pid);
 674                 /* Note: Caller should be using rpc_clnt_sigmask() */
 675                 status = out_of_line_wait_on_bit(&task->tk_runstate,
 676                                 RPC_TASK_QUEUED, rpc_wait_bit_interruptible,
 677                                 TASK_INTERRUPTIBLE);
 678                 if (status == -ERESTARTSYS) {
 679                         /*
 680                          * When a sync task receives a signal, it exits with
 681                          * -ERESTARTSYS. In order to catch any callbacks that
 682                          * clean up after sleeping on some queue, we don't
 683                          * break the loop here, but go around once more.
 684                          */
 685                         dprintk("RPC: %4d got signal\n", task->tk_pid);
 686                         task->tk_flags |= RPC_TASK_KILLED;
 687                         rpc_exit(task, -ERESTARTSYS);
 688                         rpc_wake_up_task(task);
 689                 }
 690                 rpc_set_running(task);
 691                 dprintk("RPC: %4d sync task resuming\n", task->tk_pid);
 692         }
 693
 694         dprintk("RPC: %4d, return %d, status %d\n", task->tk_pid, status, task->tk_status);
 695         /* Wake up anyone who is waiting for task completion */
 696         rpc_mark_complete_task(task);
 697         /* Release all resources associated with the task */
 698         rpc_release_task(task);
 699         return status;
 700 }
 701
 702 /*
 703  * User-visible entry point to the scheduler.
 704  *
 705  * This may be called recursively if e.g. an async NFS task updates
 706  * the attributes and finds that dirty pages must be flushed.
 707  * NOTE: Upon exit of this function the task is guaranteed to be
 708  *       released. In particular note that tk_release() will have
 709  *       been called, so your task memory may have been freed.
 710  */
 711 int
 712 rpc_execute(struct rpc_task *task)
 713 {
 714         rpc_set_active(task);
 715         rpc_set_running(task);
 716         return __rpc_execute(task);
 717 }
 718
 719 static void rpc_async_schedule(void *arg)
 720 {
 721         __rpc_execute((struct rpc_task *)arg);
 722 }
 723
 724 /**
 725  * rpc_malloc - allocate an RPC buffer
 726  * @task: RPC task that will use this buffer
 727  * @size: requested byte size
 728  *
 729  * We try to ensure that some NFS reads and writes can always proceed
 730  * by using a mempool when allocating 'small' buffers.
 731  * In order to avoid memory starvation triggering more writebacks of
 732  * NFS requests, we use GFP_NOFS rather than GFP_KERNEL.
 733  */
 734 void * rpc_malloc(struct rpc_task *task, size_t size)
 735 {
 736         struct rpc_rqst *req = task->tk_rqstp;
 737         gfp_t   gfp;
 738
 739         if (task->tk_flags & RPC_TASK_SWAPPER)
 740                 gfp = GFP_ATOMIC;
 741         else
 742                 gfp = GFP_NOFS;
 743
 744         if (size > RPC_BUFFER_MAXSIZE) {
 745                 req->rq_buffer = kmalloc(size, gfp);
 746                 if (req->rq_buffer)
 747                         req->rq_bufsize = size;
 748         } else {
 749                 req->rq_buffer = mempool_alloc(rpc_buffer_mempool, gfp);
 750                 if (req->rq_buffer)
 751                         req->rq_bufsize = RPC_BUFFER_MAXSIZE;
 752         }
 753         return req->rq_buffer;
 754 }
 755
 756 /**
 757  * rpc_free - free buffer allocated via rpc_malloc
 758  * @task: RPC task with a buffer to be freed
 759  *
 760  */
 761 void rpc_free(struct rpc_task *task)
 762 {
 763         struct rpc_rqst *req = task->tk_rqstp;
 764
 765         if (req->rq_buffer) {
 766                 if (req->rq_bufsize == RPC_BUFFER_MAXSIZE)
 767                         mempool_free(req->rq_buffer, rpc_buffer_mempool);
 768                 else
 769                         kfree(req->rq_buffer);
 770                 req->rq_buffer = NULL;
 771                 req->rq_bufsize = 0;
 772         }
 773 }
 774
 775 /*
 776  * Creation and deletion of RPC task structures
 777  */
 778 void rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 779 {
 780         memset(task, 0, sizeof(*task));
 781         init_timer(&task->tk_timer);
 782         task->tk_timer.data     = (unsigned long) task;
 783         task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
 784         atomic_set(&task->tk_count, 1);
 785         task->tk_client = clnt;
 786         task->tk_flags  = flags;
 787         task->tk_ops = tk_ops;
 788         if (tk_ops->rpc_call_prepare != NULL)
 789                 task->tk_action = rpc_prepare_task;
 790         task->tk_calldata = calldata;
 791
 792         /* Initialize retry counters */
 793         task->tk_garb_retry = 2;
 794         task->tk_cred_retry = 2;
 795
 796         task->tk_priority = RPC_PRIORITY_NORMAL;
 797         task->tk_cookie = (unsigned long)current;
 798
 799         /* Initialize workqueue for async tasks */
 800         task->tk_workqueue = rpciod_workqueue;
 801
 802         if (clnt) {
 803                 atomic_inc(&clnt->cl_users);
 804                 if (clnt->cl_softrtry)
 805                         task->tk_flags |= RPC_TASK_SOFT;
 806                 if (!clnt->cl_intr)
 807                         task->tk_flags |= RPC_TASK_NOINTR;
 808         }
 809
 810 #ifdef RPC_DEBUG
 811         task->tk_magic = RPC_TASK_MAGIC_ID;
 812         task->tk_pid = rpc_task_id++;
 813 #endif
 814         /* Add to global list of all tasks */
 815         spin_lock(&rpc_sched_lock);
 816         list_add_tail(&task->tk_task, &all_tasks);
 817         spin_unlock(&rpc_sched_lock);
 818
 819         BUG_ON(task->tk_ops == NULL);
 820
 821         /* starting timestamp */
 822         task->tk_start = jiffies;
 823
 824         dprintk("RPC: %4d new task procpid %d\n", task->tk_pid,
 825                                 current->pid);
 826 }
 827
 828 static struct rpc_task *
 829 rpc_alloc_task(void)
 830 {
 831         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 832 }
 833
 834 static void rpc_free_task(struct rpc_task *task)
 835 {
 836         dprintk("RPC: %4d freeing task\n", task->tk_pid);
 837         mempool_free(task, rpc_task_mempool);
 838 }
 839
 840 /*
 841  * Create a new task for the specified client.  We have to
 842  * clean up after an allocation failure, as the client may
 843  * have specified "oneshot".
 844  */
 845 struct rpc_task *rpc_new_task(struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
 846 {
 847         struct rpc_task *task;
 848
 849         task = rpc_alloc_task();
 850         if (!task)
 851                 goto cleanup;
 852
 853         rpc_init_task(task, clnt, flags, tk_ops, calldata);
 854
 855         dprintk("RPC: %4d allocated task\n", task->tk_pid);
 856         task->tk_flags |= RPC_TASK_DYNAMIC;
 857 out:
 858         return task;
 859
 860 cleanup:
 861         /* Check whether to release the client */
 862         if (clnt) {
 863                 printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
 864                         atomic_read(&clnt->cl_users), clnt->cl_oneshot);
 865                 atomic_inc(&clnt->cl_users); /* pretend we were used ... */
 866                 rpc_release_client(clnt);
 867         }
 868         goto out;
 869 }
 870
 871 void rpc_release_task(struct rpc_task *task)
 872 {
 873         const struct rpc_call_ops *tk_ops = task->tk_ops;
 874         void *calldata = task->tk_calldata;
 875
 876 #ifdef RPC_DEBUG
 877         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
 878 #endif
 879         if (!atomic_dec_and_test(&task->tk_count))
 880                 return;
 881         dprintk("RPC: %4d release task\n", task->tk_pid);
 882
 883         /* Remove from global task list */
 884         spin_lock(&rpc_sched_lock);
 885         list_del(&task->tk_task);
 886         spin_unlock(&rpc_sched_lock);
 887
 888         BUG_ON (RPC_IS_QUEUED(task));
 889
 890         /* Synchronously delete any running timer */
 891         rpc_delete_timer(task);
 892
 893         /* Release resources */
 894         if (task->tk_rqstp)
 895                 xprt_release(task);
 896         if (task->tk_msg.rpc_cred)
 897                 rpcauth_unbindcred(task);
 898         if (task->tk_client) {
 899                 rpc_release_client(task->tk_client);
 900                 task->tk_client = NULL;
 901         }
 902
 903 #ifdef RPC_DEBUG
 904         task->tk_magic = 0;
 905 #endif
 906         if (task->tk_flags & RPC_TASK_DYNAMIC)
 907                 rpc_free_task(task);
 908         if (tk_ops->rpc_release)
 909                 tk_ops->rpc_release(calldata);
 910 }
 911
 912 /**
 913  * rpc_run_task - Allocate a new RPC task, then run rpc_execute against it
 914  * @clnt: pointer to RPC client
 915  * @flags: RPC flags
 916  * @ops: RPC call ops
 917  * @data: user call data
 918  */
 919 struct rpc_task *rpc_run_task(struct rpc_clnt *clnt, int flags,
 920                                         const struct rpc_call_ops *ops,
 921                                         void *data)
 922 {
 923         struct rpc_task *task;
 924         task = rpc_new_task(clnt, flags, ops, data);
 925         if (task == NULL) {
 926                 if (ops->rpc_release != NULL)
 927                         ops->rpc_release(data);
 928                 return ERR_PTR(-ENOMEM);
 929         }
 930         atomic_inc(&task->tk_count);
 931         rpc_execute(task);
 932         return task;
 933 }
 934 EXPORT_SYMBOL(rpc_run_task);
 935
 936 /**
 937  * rpc_find_parent - find the parent of a child task.
 938  * @child: child task
 939  * @parent: parent task
 940  *
 941  * Checks that the parent task is still sleeping on the
 942  * queue 'childq'. If so returns a pointer to the parent.
 943  * Upon failure returns NULL.
 944  *
 945  * Caller must hold childq.lock
 946  */
 947 static inline struct rpc_task *rpc_find_parent(struct rpc_task *child, struct rpc_task *parent)
 948 {
 949         struct rpc_task *task;
 950         struct list_head *le;
 951
 952         task_for_each(task, le, &childq.tasks[0])
 953                 if (task == parent)
 954                         return parent;
 955
 956         return NULL;
 957 }
 958
 959 static void rpc_child_exit(struct rpc_task *child, void *calldata)
 960 {
 961         struct rpc_task *parent;
 962
 963         spin_lock_bh(&childq.lock);
 964         if ((parent = rpc_find_parent(child, calldata)) != NULL) {
 965                 parent->tk_status = child->tk_status;
 966                 __rpc_wake_up_task(parent);
 967         }
 968         spin_unlock_bh(&childq.lock);
 969 }
 970
 971 static const struct rpc_call_ops rpc_child_ops = {
 972         .rpc_call_done = rpc_child_exit,
 973 };
 974
 975 /*
 976  * Note: rpc_new_task releases the client after a failure.
 977  */
 978 struct rpc_task *
 979 rpc_new_child(struct rpc_clnt *clnt, struct rpc_task *parent)
 980 {
 981         struct rpc_task *task;
 982
 983         task = rpc_new_task(clnt, RPC_TASK_ASYNC | RPC_TASK_CHILD, &rpc_child_ops, parent);
 984         if (!task)
 985                 goto fail;
 986         return task;
 987
 988 fail:
 989         parent->tk_status = -ENOMEM;
 990         return NULL;
 991 }
 992
 993 void rpc_run_child(struct rpc_task *task, struct rpc_task *child, rpc_action func)
 994 {
 995         spin_lock_bh(&childq.lock);
 996         /* N.B. Is it possible for the child to have already finished? */
 997         __rpc_sleep_on(&childq, task, func, NULL);
 998         rpc_schedule_run(child);
 999         spin_unlock_bh(&childq.lock);
1000 }
1001
1002 /*
1003  * Kill all tasks for the given client.
1004  * XXX: kill their descendants as well?
1005  */
1006 void rpc_killall_tasks(struct rpc_clnt *clnt)
1007 {
1008         struct rpc_task *rovr;
1009         struct list_head *le;
1010
1011         dprintk("RPC:      killing all tasks for client %p\n", clnt);
1012
1013         /*
1014          * Spin lock all_tasks to prevent changes...
1015          */
1016         spin_lock(&rpc_sched_lock);
1017         alltask_for_each(rovr, le, &all_tasks) {
1018                 if (! RPC_IS_ACTIVATED(rovr))
1019                         continue;
1020                 if (!clnt || rovr->tk_client == clnt) {
1021                         rovr->tk_flags |= RPC_TASK_KILLED;
1022                         rpc_exit(rovr, -EIO);
1023                         rpc_wake_up_task(rovr);
1024                 }
1025         }
1026         spin_unlock(&rpc_sched_lock);
1027 }
1028
1029 static DECLARE_MUTEX_LOCKED(rpciod_running);
1030
1031 static void rpciod_killall(void)
1032 {
1033         unsigned long flags;
1034
1035         while (!list_empty(&all_tasks)) {
1036                 clear_thread_flag(TIF_SIGPENDING);
1037                 rpc_killall_tasks(NULL);
1038                 flush_workqueue(rpciod_workqueue);
1039                 if (!list_empty(&all_tasks)) {
1040                         dprintk("rpciod_killall: waiting for tasks to exit\n");
1041                         yield();
1042                 }
1043         }
1044
1045         spin_lock_irqsave(&current->sighand->siglock, flags);
1046         recalc_sigpending();
1047         spin_unlock_irqrestore(&current->sighand->siglock, flags);
1048 }
1049
1050 /*
1051  * Start up the rpciod process if it's not already running.
1052  */
1053 int
1054 rpciod_up(void)
1055 {
1056         struct workqueue_struct *wq;
1057         int error = 0;
1058
1059         mutex_lock(&rpciod_mutex);
1060         dprintk("rpciod_up: users %d\n", rpciod_users);
1061         rpciod_users++;
1062         if (rpciod_workqueue)
1063                 goto out;
1064         /*
1065          * If there's no pid, we should be the first user.
1066          */
1067         if (rpciod_users > 1)
1068                 printk(KERN_WARNING "rpciod_up: no workqueue, %d users??\n", rpciod_users);
1069         /*
1070          * Create the rpciod thread and wait for it to start.
1071          */
1072         error = -ENOMEM;
1073         wq = create_workqueue("rpciod");
1074         if (wq == NULL) {
1075                 printk(KERN_WARNING "rpciod_up: create workqueue failed, error=%d\n", error);
1076                 rpciod_users--;
1077                 goto out;
1078         }
1079         rpciod_workqueue = wq;
1080         error = 0;
1081 out:
1082         mutex_unlock(&rpciod_mutex);
1083         return error;
1084 }
1085
1086 void
1087 rpciod_down(void)
1088 {
1089         mutex_lock(&rpciod_mutex);
1090         dprintk("rpciod_down sema %d\n", rpciod_users);
1091         if (rpciod_users) {
1092                 if (--rpciod_users)
1093                         goto out;
1094         } else
1095                 printk(KERN_WARNING "rpciod_down: no users??\n");
1096
1097         if (!rpciod_workqueue) {
1098                 dprintk("rpciod_down: Nothing to do!\n");
1099                 goto out;
1100         }
1101         rpciod_killall();
1102
1103         destroy_workqueue(rpciod_workqueue);
1104         rpciod_workqueue = NULL;
1105  out:
1106         mutex_unlock(&rpciod_mutex);
1107 }
1108
1109 #ifdef RPC_DEBUG
1110 void rpc_show_tasks(void)
1111 {
1112         struct list_head *le;
1113         struct rpc_task *t;
1114
1115         spin_lock(&rpc_sched_lock);
1116         if (list_empty(&all_tasks)) {
1117                 spin_unlock(&rpc_sched_lock);
1118                 return;
1119         }
1120         printk("-pid- proc flgs status -client- -prog- --rqstp- -timeout "
1121                 "-rpcwait -action- ---ops--\n");
1122         alltask_for_each(t, le, &all_tasks) {
1123                 const char *rpc_waitq = "none";
1124
1125                 if (RPC_IS_QUEUED(t))
1126                         rpc_waitq = rpc_qname(t->u.tk_wait.rpc_waitq);
1127
1128                 printk("%05d %04d %04x %06d %8p %6d %8p %08ld %8s %8p %8p\n",
1129                         t->tk_pid,
1130                         (t->tk_msg.rpc_proc ? t->tk_msg.rpc_proc->p_proc : -1),
1131                         t->tk_flags, t->tk_status,
1132                         t->tk_client,
1133                         (t->tk_client ? t->tk_client->cl_prog : 0),
1134                         t->tk_rqstp, t->tk_timeout,
1135                         rpc_waitq,
1136                         t->tk_action, t->tk_ops);
1137         }
1138         spin_unlock(&rpc_sched_lock);
1139 }
1140 #endif
1141
1142 void
1143 rpc_destroy_mempool(void)
1144 {
1145         if (rpc_buffer_mempool)
1146                 mempool_destroy(rpc_buffer_mempool);
1147         if (rpc_task_mempool)
1148                 mempool_destroy(rpc_task_mempool);
1149         if (rpc_task_slabp && kmem_cache_destroy(rpc_task_slabp))
1150                 printk(KERN_INFO "rpc_task: not all structures were freed\n");
1151         if (rpc_buffer_slabp && kmem_cache_destroy(rpc_buffer_slabp))
1152                 printk(KERN_INFO "rpc_buffers: not all structures were freed\n");
1153 }
1154
1155 int
1156 rpc_init_mempool(void)
1157 {
1158         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1159                                              sizeof(struct rpc_task),
1160                                              0, SLAB_HWCACHE_ALIGN,
1161                                              NULL, NULL);
1162         if (!rpc_task_slabp)
1163                 goto err_nomem;
1164         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1165                                              RPC_BUFFER_MAXSIZE,
1166                                              0, SLAB_HWCACHE_ALIGN,
1167                                              NULL, NULL);
1168         if (!rpc_buffer_slabp)
1169                 goto err_nomem;
1170         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1171                                                     rpc_task_slabp);
1172         if (!rpc_task_mempool)
1173                 goto err_nomem;
1174         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1175                                                       rpc_buffer_slabp);
1176         if (!rpc_buffer_mempool)
1177                 goto err_nomem;
1178         return 0;
1179 err_nomem:
1180         rpc_destroy_mempool();
1181         return -ENOMEM;
1182 }