headers: utsname.h redux
[linux-2.6.git] / 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/spinlock.h>
20 #include <linux/mutex.h>
21
22 #include <linux/sunrpc/clnt.h>
23
24 #include "sunrpc.h"
25
26 #ifdef RPC_DEBUG
27 #define RPCDBG_FACILITY         RPCDBG_SCHED
28 #define RPC_TASK_MAGIC_ID       0xf00baa
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 struct kmem_cache        *rpc_task_slabp __read_mostly;
38 static struct kmem_cache        *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_async_schedule(struct work_struct *);
43 static void                      rpc_release_task(struct rpc_task *task);
44 static void __rpc_queue_timer_fn(unsigned long ptr);
45
46 /*
47  * RPC tasks sit here while waiting for conditions to improve.
48  */
49 static struct rpc_wait_queue delay_queue;
50
51 /*
52  * rpciod-related stuff
53  */
54 struct workqueue_struct *rpciod_workqueue;
55
56 /*
57  * Disable the timer for a given RPC task. Should be called with
58  * queue->lock and bh_disabled in order to avoid races within
59  * rpc_run_timer().
60  */
61 static void
62 __rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
63 {
64         if (task->tk_timeout == 0)
65                 return;
66         dprintk("RPC: %5u disabling timer\n", task->tk_pid);
67         task->tk_timeout = 0;
68         list_del(&task->u.tk_wait.timer_list);
69         if (list_empty(&queue->timer_list.list))
70                 del_timer(&queue->timer_list.timer);
71 }
72
73 static void
74 rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
75 {
76         queue->timer_list.expires = expires;
77         mod_timer(&queue->timer_list.timer, expires);
78 }
79
80 /*
81  * Set up a timer for the current task.
82  */
83 static void
84 __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
85 {
86         if (!task->tk_timeout)
87                 return;
88
89         dprintk("RPC: %5u setting alarm for %lu ms\n",
90                         task->tk_pid, task->tk_timeout * 1000 / HZ);
91
92         task->u.tk_wait.expires = jiffies + task->tk_timeout;
93         if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
94                 rpc_set_queue_timer(queue, task->u.tk_wait.expires);
95         list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
96 }
97
98 /*
99  * Add new request to a priority queue.
100  */
101 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
102 {
103         struct list_head *q;
104         struct rpc_task *t;
105
106         INIT_LIST_HEAD(&task->u.tk_wait.links);
107         q = &queue->tasks[task->tk_priority];
108         if (unlikely(task->tk_priority > queue->maxpriority))
109                 q = &queue->tasks[queue->maxpriority];
110         list_for_each_entry(t, q, u.tk_wait.list) {
111                 if (t->tk_owner == task->tk_owner) {
112                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
113                         return;
114                 }
115         }
116         list_add_tail(&task->u.tk_wait.list, q);
117 }
118
119 /*
120  * Add new request to wait queue.
121  *
122  * Swapper tasks always get inserted at the head of the queue.
123  * This should avoid many nasty memory deadlocks and hopefully
124  * improve overall performance.
125  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
126  */
127 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
128 {
129         BUG_ON (RPC_IS_QUEUED(task));
130
131         if (RPC_IS_PRIORITY(queue))
132                 __rpc_add_wait_queue_priority(queue, task);
133         else if (RPC_IS_SWAPPER(task))
134                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
135         else
136                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
137         task->tk_waitqueue = queue;
138         queue->qlen++;
139         rpc_set_queued(task);
140
141         dprintk("RPC: %5u added to queue %p \"%s\"\n",
142                         task->tk_pid, queue, rpc_qname(queue));
143 }
144
145 /*
146  * Remove request from a priority queue.
147  */
148 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
149 {
150         struct rpc_task *t;
151
152         if (!list_empty(&task->u.tk_wait.links)) {
153                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
154                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
155                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
156         }
157 }
158
159 /*
160  * Remove request from queue.
161  * Note: must be called with spin lock held.
162  */
163 static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
164 {
165         __rpc_disable_timer(queue, task);
166         if (RPC_IS_PRIORITY(queue))
167                 __rpc_remove_wait_queue_priority(task);
168         list_del(&task->u.tk_wait.list);
169         queue->qlen--;
170         dprintk("RPC: %5u removed from queue %p \"%s\"\n",
171                         task->tk_pid, queue, rpc_qname(queue));
172 }
173
174 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
175 {
176         queue->priority = priority;
177         queue->count = 1 << (priority * 2);
178 }
179
180 static inline void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
181 {
182         queue->owner = pid;
183         queue->nr = RPC_BATCH_COUNT;
184 }
185
186 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
187 {
188         rpc_set_waitqueue_priority(queue, queue->maxpriority);
189         rpc_set_waitqueue_owner(queue, 0);
190 }
191
192 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
193 {
194         int i;
195
196         spin_lock_init(&queue->lock);
197         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
198                 INIT_LIST_HEAD(&queue->tasks[i]);
199         queue->maxpriority = nr_queues - 1;
200         rpc_reset_waitqueue_priority(queue);
201         queue->qlen = 0;
202         setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
203         INIT_LIST_HEAD(&queue->timer_list.list);
204 #ifdef RPC_DEBUG
205         queue->name = qname;
206 #endif
207 }
208
209 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
210 {
211         __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
212 }
213
214 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
215 {
216         __rpc_init_priority_wait_queue(queue, qname, 1);
217 }
218 EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
219
220 void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
221 {
222         del_timer_sync(&queue->timer_list.timer);
223 }
224 EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
225
226 static int rpc_wait_bit_killable(void *word)
227 {
228         if (fatal_signal_pending(current))
229                 return -ERESTARTSYS;
230         schedule();
231         return 0;
232 }
233
234 #ifdef RPC_DEBUG
235 static void rpc_task_set_debuginfo(struct rpc_task *task)
236 {
237         static atomic_t rpc_pid;
238
239         task->tk_magic = RPC_TASK_MAGIC_ID;
240         task->tk_pid = atomic_inc_return(&rpc_pid);
241 }
242 #else
243 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
244 {
245 }
246 #endif
247
248 static void rpc_set_active(struct rpc_task *task)
249 {
250         struct rpc_clnt *clnt;
251         if (test_and_set_bit(RPC_TASK_ACTIVE, &task->tk_runstate) != 0)
252                 return;
253         rpc_task_set_debuginfo(task);
254         /* Add to global list of all tasks */
255         clnt = task->tk_client;
256         if (clnt != NULL) {
257                 spin_lock(&clnt->cl_lock);
258                 list_add_tail(&task->tk_task, &clnt->cl_tasks);
259                 spin_unlock(&clnt->cl_lock);
260         }
261 }
262
263 /*
264  * Mark an RPC call as having completed by clearing the 'active' bit
265  */
266 static void rpc_mark_complete_task(struct rpc_task *task)
267 {
268         smp_mb__before_clear_bit();
269         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
270         smp_mb__after_clear_bit();
271         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
272 }
273
274 /*
275  * Allow callers to wait for completion of an RPC call
276  */
277 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
278 {
279         if (action == NULL)
280                 action = rpc_wait_bit_killable;
281         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
282                         action, TASK_KILLABLE);
283 }
284 EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
285
286 /*
287  * Make an RPC task runnable.
288  *
289  * Note: If the task is ASYNC, this must be called with
290  * the spinlock held to protect the wait queue operation.
291  */
292 static void rpc_make_runnable(struct rpc_task *task)
293 {
294         rpc_clear_queued(task);
295         if (rpc_test_and_set_running(task))
296                 return;
297         if (RPC_IS_ASYNC(task)) {
298                 int status;
299
300                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
301                 status = queue_work(rpciod_workqueue, &task->u.tk_work);
302                 if (status < 0) {
303                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
304                         task->tk_status = status;
305                         return;
306                 }
307         } else
308                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
309 }
310
311 /*
312  * Prepare for sleeping on a wait queue.
313  * By always appending tasks to the list we ensure FIFO behavior.
314  * NB: An RPC task will only receive interrupt-driven events as long
315  * as it's on a wait queue.
316  */
317 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
318                         rpc_action action)
319 {
320         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
321                         task->tk_pid, rpc_qname(q), jiffies);
322
323         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
324                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
325                 return;
326         }
327
328         __rpc_add_wait_queue(q, task);
329
330         BUG_ON(task->tk_callback != NULL);
331         task->tk_callback = action;
332         __rpc_add_timer(q, task);
333 }
334
335 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
336                                 rpc_action action)
337 {
338         /* Mark the task as being activated if so needed */
339         rpc_set_active(task);
340
341         /*
342          * Protect the queue operations.
343          */
344         spin_lock_bh(&q->lock);
345         __rpc_sleep_on(q, task, action);
346         spin_unlock_bh(&q->lock);
347 }
348 EXPORT_SYMBOL_GPL(rpc_sleep_on);
349
350 /**
351  * __rpc_do_wake_up_task - wake up a single rpc_task
352  * @queue: wait queue
353  * @task: task to be woken up
354  *
355  * Caller must hold queue->lock, and have cleared the task queued flag.
356  */
357 static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
358 {
359         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
360                         task->tk_pid, jiffies);
361
362 #ifdef RPC_DEBUG
363         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
364 #endif
365         /* Has the task been executed yet? If not, we cannot wake it up! */
366         if (!RPC_IS_ACTIVATED(task)) {
367                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
368                 return;
369         }
370
371         __rpc_remove_wait_queue(queue, task);
372
373         rpc_make_runnable(task);
374
375         dprintk("RPC:       __rpc_wake_up_task done\n");
376 }
377
378 /*
379  * Wake up a queued task while the queue lock is being held
380  */
381 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
382 {
383         if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
384                 __rpc_do_wake_up_task(queue, task);
385 }
386
387 /*
388  * Wake up a task on a specific queue
389  */
390 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
391 {
392         spin_lock_bh(&queue->lock);
393         rpc_wake_up_task_queue_locked(queue, task);
394         spin_unlock_bh(&queue->lock);
395 }
396 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
397
398 /*
399  * Wake up the specified task
400  */
401 static void rpc_wake_up_task(struct rpc_task *task)
402 {
403         rpc_wake_up_queued_task(task->tk_waitqueue, task);
404 }
405
406 /*
407  * Wake up the next task on a priority queue.
408  */
409 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
410 {
411         struct list_head *q;
412         struct rpc_task *task;
413
414         /*
415          * Service a batch of tasks from a single owner.
416          */
417         q = &queue->tasks[queue->priority];
418         if (!list_empty(q)) {
419                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
420                 if (queue->owner == task->tk_owner) {
421                         if (--queue->nr)
422                                 goto out;
423                         list_move_tail(&task->u.tk_wait.list, q);
424                 }
425                 /*
426                  * Check if we need to switch queues.
427                  */
428                 if (--queue->count)
429                         goto new_owner;
430         }
431
432         /*
433          * Service the next queue.
434          */
435         do {
436                 if (q == &queue->tasks[0])
437                         q = &queue->tasks[queue->maxpriority];
438                 else
439                         q = q - 1;
440                 if (!list_empty(q)) {
441                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
442                         goto new_queue;
443                 }
444         } while (q != &queue->tasks[queue->priority]);
445
446         rpc_reset_waitqueue_priority(queue);
447         return NULL;
448
449 new_queue:
450         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
451 new_owner:
452         rpc_set_waitqueue_owner(queue, task->tk_owner);
453 out:
454         rpc_wake_up_task_queue_locked(queue, task);
455         return task;
456 }
457
458 /*
459  * Wake up the next task on the wait queue.
460  */
461 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
462 {
463         struct rpc_task *task = NULL;
464
465         dprintk("RPC:       wake_up_next(%p \"%s\")\n",
466                         queue, rpc_qname(queue));
467         spin_lock_bh(&queue->lock);
468         if (RPC_IS_PRIORITY(queue))
469                 task = __rpc_wake_up_next_priority(queue);
470         else {
471                 task_for_first(task, &queue->tasks[0])
472                         rpc_wake_up_task_queue_locked(queue, task);
473         }
474         spin_unlock_bh(&queue->lock);
475
476         return task;
477 }
478 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
479
480 /**
481  * rpc_wake_up - wake up all rpc_tasks
482  * @queue: rpc_wait_queue on which the tasks are sleeping
483  *
484  * Grabs queue->lock
485  */
486 void rpc_wake_up(struct rpc_wait_queue *queue)
487 {
488         struct rpc_task *task, *next;
489         struct list_head *head;
490
491         spin_lock_bh(&queue->lock);
492         head = &queue->tasks[queue->maxpriority];
493         for (;;) {
494                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
495                         rpc_wake_up_task_queue_locked(queue, task);
496                 if (head == &queue->tasks[0])
497                         break;
498                 head--;
499         }
500         spin_unlock_bh(&queue->lock);
501 }
502 EXPORT_SYMBOL_GPL(rpc_wake_up);
503
504 /**
505  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
506  * @queue: rpc_wait_queue on which the tasks are sleeping
507  * @status: status value to set
508  *
509  * Grabs queue->lock
510  */
511 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
512 {
513         struct rpc_task *task, *next;
514         struct list_head *head;
515
516         spin_lock_bh(&queue->lock);
517         head = &queue->tasks[queue->maxpriority];
518         for (;;) {
519                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
520                         task->tk_status = status;
521                         rpc_wake_up_task_queue_locked(queue, task);
522                 }
523                 if (head == &queue->tasks[0])
524                         break;
525                 head--;
526         }
527         spin_unlock_bh(&queue->lock);
528 }
529 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
530
531 static void __rpc_queue_timer_fn(unsigned long ptr)
532 {
533         struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
534         struct rpc_task *task, *n;
535         unsigned long expires, now, timeo;
536
537         spin_lock(&queue->lock);
538         expires = now = jiffies;
539         list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
540                 timeo = task->u.tk_wait.expires;
541                 if (time_after_eq(now, timeo)) {
542                         dprintk("RPC: %5u timeout\n", task->tk_pid);
543                         task->tk_status = -ETIMEDOUT;
544                         rpc_wake_up_task_queue_locked(queue, task);
545                         continue;
546                 }
547                 if (expires == now || time_after(expires, timeo))
548                         expires = timeo;
549         }
550         if (!list_empty(&queue->timer_list.list))
551                 rpc_set_queue_timer(queue, expires);
552         spin_unlock(&queue->lock);
553 }
554
555 static void __rpc_atrun(struct rpc_task *task)
556 {
557         task->tk_status = 0;
558 }
559
560 /*
561  * Run a task at a later time
562  */
563 void rpc_delay(struct rpc_task *task, unsigned long delay)
564 {
565         task->tk_timeout = delay;
566         rpc_sleep_on(&delay_queue, task, __rpc_atrun);
567 }
568 EXPORT_SYMBOL_GPL(rpc_delay);
569
570 /*
571  * Helper to call task->tk_ops->rpc_call_prepare
572  */
573 void rpc_prepare_task(struct rpc_task *task)
574 {
575         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
576 }
577
578 /*
579  * Helper that calls task->tk_ops->rpc_call_done if it exists
580  */
581 void rpc_exit_task(struct rpc_task *task)
582 {
583         task->tk_action = NULL;
584         if (task->tk_ops->rpc_call_done != NULL) {
585                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
586                 if (task->tk_action != NULL) {
587                         WARN_ON(RPC_ASSASSINATED(task));
588                         /* Always release the RPC slot and buffer memory */
589                         xprt_release(task);
590                 }
591         }
592 }
593 EXPORT_SYMBOL_GPL(rpc_exit_task);
594
595 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
596 {
597         if (ops->rpc_release != NULL)
598                 ops->rpc_release(calldata);
599 }
600
601 /*
602  * This is the RPC `scheduler' (or rather, the finite state machine).
603  */
604 static void __rpc_execute(struct rpc_task *task)
605 {
606         struct rpc_wait_queue *queue;
607         int task_is_async = RPC_IS_ASYNC(task);
608         int status = 0;
609
610         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
611                         task->tk_pid, task->tk_flags);
612
613         BUG_ON(RPC_IS_QUEUED(task));
614
615         for (;;) {
616
617                 /*
618                  * Execute any pending callback.
619                  */
620                 if (task->tk_callback) {
621                         void (*save_callback)(struct rpc_task *);
622
623                         /*
624                          * We set tk_callback to NULL before calling it,
625                          * in case it sets the tk_callback field itself:
626                          */
627                         save_callback = task->tk_callback;
628                         task->tk_callback = NULL;
629                         save_callback(task);
630                 }
631
632                 /*
633                  * Perform the next FSM step.
634                  * tk_action may be NULL when the task has been killed
635                  * by someone else.
636                  */
637                 if (!RPC_IS_QUEUED(task)) {
638                         if (task->tk_action == NULL)
639                                 break;
640                         task->tk_action(task);
641                 }
642
643                 /*
644                  * Lockless check for whether task is sleeping or not.
645                  */
646                 if (!RPC_IS_QUEUED(task))
647                         continue;
648                 /*
649                  * The queue->lock protects against races with
650                  * rpc_make_runnable().
651                  *
652                  * Note that once we clear RPC_TASK_RUNNING on an asynchronous
653                  * rpc_task, rpc_make_runnable() can assign it to a
654                  * different workqueue. We therefore cannot assume that the
655                  * rpc_task pointer may still be dereferenced.
656                  */
657                 queue = task->tk_waitqueue;
658                 spin_lock_bh(&queue->lock);
659                 if (!RPC_IS_QUEUED(task)) {
660                         spin_unlock_bh(&queue->lock);
661                         continue;
662                 }
663                 rpc_clear_running(task);
664                 spin_unlock_bh(&queue->lock);
665                 if (task_is_async)
666                         return;
667
668                 /* sync task: sleep here */
669                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
670                 status = out_of_line_wait_on_bit(&task->tk_runstate,
671                                 RPC_TASK_QUEUED, rpc_wait_bit_killable,
672                                 TASK_KILLABLE);
673                 if (status == -ERESTARTSYS) {
674                         /*
675                          * When a sync task receives a signal, it exits with
676                          * -ERESTARTSYS. In order to catch any callbacks that
677                          * clean up after sleeping on some queue, we don't
678                          * break the loop here, but go around once more.
679                          */
680                         dprintk("RPC: %5u got signal\n", task->tk_pid);
681                         task->tk_flags |= RPC_TASK_KILLED;
682                         rpc_exit(task, -ERESTARTSYS);
683                         rpc_wake_up_task(task);
684                 }
685                 rpc_set_running(task);
686                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
687         }
688
689         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
690                         task->tk_status);
691         /* Release all resources associated with the task */
692         rpc_release_task(task);
693 }
694
695 /*
696  * User-visible entry point to the scheduler.
697  *
698  * This may be called recursively if e.g. an async NFS task updates
699  * the attributes and finds that dirty pages must be flushed.
700  * NOTE: Upon exit of this function the task is guaranteed to be
701  *       released. In particular note that tk_release() will have
702  *       been called, so your task memory may have been freed.
703  */
704 void rpc_execute(struct rpc_task *task)
705 {
706         rpc_set_active(task);
707         rpc_set_running(task);
708         __rpc_execute(task);
709 }
710
711 static void rpc_async_schedule(struct work_struct *work)
712 {
713         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
714 }
715
716 /**
717  * rpc_malloc - allocate an RPC buffer
718  * @task: RPC task that will use this buffer
719  * @size: requested byte size
720  *
721  * To prevent rpciod from hanging, this allocator never sleeps,
722  * returning NULL if the request cannot be serviced immediately.
723  * The caller can arrange to sleep in a way that is safe for rpciod.
724  *
725  * Most requests are 'small' (under 2KiB) and can be serviced from a
726  * mempool, ensuring that NFS reads and writes can always proceed,
727  * and that there is good locality of reference for these buffers.
728  *
729  * In order to avoid memory starvation triggering more writebacks of
730  * NFS requests, we avoid using GFP_KERNEL.
731  */
732 void *rpc_malloc(struct rpc_task *task, size_t size)
733 {
734         struct rpc_buffer *buf;
735         gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
736
737         size += sizeof(struct rpc_buffer);
738         if (size <= RPC_BUFFER_MAXSIZE)
739                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
740         else
741                 buf = kmalloc(size, gfp);
742
743         if (!buf)
744                 return NULL;
745
746         buf->len = size;
747         dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
748                         task->tk_pid, size, buf);
749         return &buf->data;
750 }
751 EXPORT_SYMBOL_GPL(rpc_malloc);
752
753 /**
754  * rpc_free - free buffer allocated via rpc_malloc
755  * @buffer: buffer to free
756  *
757  */
758 void rpc_free(void *buffer)
759 {
760         size_t size;
761         struct rpc_buffer *buf;
762
763         if (!buffer)
764                 return;
765
766         buf = container_of(buffer, struct rpc_buffer, data);
767         size = buf->len;
768
769         dprintk("RPC:       freeing buffer of size %zu at %p\n",
770                         size, buf);
771
772         if (size <= RPC_BUFFER_MAXSIZE)
773                 mempool_free(buf, rpc_buffer_mempool);
774         else
775                 kfree(buf);
776 }
777 EXPORT_SYMBOL_GPL(rpc_free);
778
779 /*
780  * Creation and deletion of RPC task structures
781  */
782 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
783 {
784         memset(task, 0, sizeof(*task));
785         atomic_set(&task->tk_count, 1);
786         task->tk_flags  = task_setup_data->flags;
787         task->tk_ops = task_setup_data->callback_ops;
788         task->tk_calldata = task_setup_data->callback_data;
789         INIT_LIST_HEAD(&task->tk_task);
790
791         /* Initialize retry counters */
792         task->tk_garb_retry = 2;
793         task->tk_cred_retry = 2;
794
795         task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
796         task->tk_owner = current->tgid;
797
798         /* Initialize workqueue for async tasks */
799         task->tk_workqueue = task_setup_data->workqueue;
800
801         task->tk_client = task_setup_data->rpc_client;
802         if (task->tk_client != NULL) {
803                 kref_get(&task->tk_client->cl_kref);
804                 if (task->tk_client->cl_softrtry)
805                         task->tk_flags |= RPC_TASK_SOFT;
806         }
807
808         if (task->tk_ops->rpc_call_prepare != NULL)
809                 task->tk_action = rpc_prepare_task;
810
811         if (task_setup_data->rpc_message != NULL) {
812                 task->tk_msg.rpc_proc = task_setup_data->rpc_message->rpc_proc;
813                 task->tk_msg.rpc_argp = task_setup_data->rpc_message->rpc_argp;
814                 task->tk_msg.rpc_resp = task_setup_data->rpc_message->rpc_resp;
815                 /* Bind the user cred */
816                 rpcauth_bindcred(task, task_setup_data->rpc_message->rpc_cred, task_setup_data->flags);
817                 if (task->tk_action == NULL)
818                         rpc_call_start(task);
819         }
820
821         /* starting timestamp */
822         task->tk_start = jiffies;
823
824         dprintk("RPC:       new task initialized, procpid %u\n",
825                                 task_pid_nr(current));
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 /*
835  * Create a new task for the specified client.
836  */
837 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
838 {
839         struct rpc_task *task = setup_data->task;
840         unsigned short flags = 0;
841
842         if (task == NULL) {
843                 task = rpc_alloc_task();
844                 if (task == NULL)
845                         goto out;
846                 flags = RPC_TASK_DYNAMIC;
847         }
848
849         rpc_init_task(task, setup_data);
850
851         task->tk_flags |= flags;
852         dprintk("RPC:       allocated task %p\n", task);
853 out:
854         return task;
855 }
856
857 static void rpc_free_task(struct rpc_task *task)
858 {
859         const struct rpc_call_ops *tk_ops = task->tk_ops;
860         void *calldata = task->tk_calldata;
861
862         if (task->tk_flags & RPC_TASK_DYNAMIC) {
863                 dprintk("RPC: %5u freeing task\n", task->tk_pid);
864                 mempool_free(task, rpc_task_mempool);
865         }
866         rpc_release_calldata(tk_ops, calldata);
867 }
868
869 static void rpc_async_release(struct work_struct *work)
870 {
871         rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
872 }
873
874 void rpc_put_task(struct rpc_task *task)
875 {
876         if (!atomic_dec_and_test(&task->tk_count))
877                 return;
878         /* Release resources */
879         if (task->tk_rqstp)
880                 xprt_release(task);
881         if (task->tk_msg.rpc_cred)
882                 rpcauth_unbindcred(task);
883         if (task->tk_client) {
884                 rpc_release_client(task->tk_client);
885                 task->tk_client = NULL;
886         }
887         if (task->tk_workqueue != NULL) {
888                 INIT_WORK(&task->u.tk_work, rpc_async_release);
889                 queue_work(task->tk_workqueue, &task->u.tk_work);
890         } else
891                 rpc_free_task(task);
892 }
893 EXPORT_SYMBOL_GPL(rpc_put_task);
894
895 static void rpc_release_task(struct rpc_task *task)
896 {
897 #ifdef RPC_DEBUG
898         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
899 #endif
900         dprintk("RPC: %5u release task\n", task->tk_pid);
901
902         if (!list_empty(&task->tk_task)) {
903                 struct rpc_clnt *clnt = task->tk_client;
904                 /* Remove from client task list */
905                 spin_lock(&clnt->cl_lock);
906                 list_del(&task->tk_task);
907                 spin_unlock(&clnt->cl_lock);
908         }
909         BUG_ON (RPC_IS_QUEUED(task));
910
911 #ifdef RPC_DEBUG
912         task->tk_magic = 0;
913 #endif
914         /* Wake up anyone who is waiting for task completion */
915         rpc_mark_complete_task(task);
916
917         rpc_put_task(task);
918 }
919
920 /*
921  * Kill all tasks for the given client.
922  * XXX: kill their descendants as well?
923  */
924 void rpc_killall_tasks(struct rpc_clnt *clnt)
925 {
926         struct rpc_task *rovr;
927
928
929         if (list_empty(&clnt->cl_tasks))
930                 return;
931         dprintk("RPC:       killing all tasks for client %p\n", clnt);
932         /*
933          * Spin lock all_tasks to prevent changes...
934          */
935         spin_lock(&clnt->cl_lock);
936         list_for_each_entry(rovr, &clnt->cl_tasks, tk_task) {
937                 if (! RPC_IS_ACTIVATED(rovr))
938                         continue;
939                 if (!(rovr->tk_flags & RPC_TASK_KILLED)) {
940                         rovr->tk_flags |= RPC_TASK_KILLED;
941                         rpc_exit(rovr, -EIO);
942                         rpc_wake_up_task(rovr);
943                 }
944         }
945         spin_unlock(&clnt->cl_lock);
946 }
947 EXPORT_SYMBOL_GPL(rpc_killall_tasks);
948
949 int rpciod_up(void)
950 {
951         return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
952 }
953
954 void rpciod_down(void)
955 {
956         module_put(THIS_MODULE);
957 }
958
959 /*
960  * Start up the rpciod workqueue.
961  */
962 static int rpciod_start(void)
963 {
964         struct workqueue_struct *wq;
965
966         /*
967          * Create the rpciod thread and wait for it to start.
968          */
969         dprintk("RPC:       creating workqueue rpciod\n");
970         wq = create_workqueue("rpciod");
971         rpciod_workqueue = wq;
972         return rpciod_workqueue != NULL;
973 }
974
975 static void rpciod_stop(void)
976 {
977         struct workqueue_struct *wq = NULL;
978
979         if (rpciod_workqueue == NULL)
980                 return;
981         dprintk("RPC:       destroying workqueue rpciod\n");
982
983         wq = rpciod_workqueue;
984         rpciod_workqueue = NULL;
985         destroy_workqueue(wq);
986 }
987
988 void
989 rpc_destroy_mempool(void)
990 {
991         rpciod_stop();
992         if (rpc_buffer_mempool)
993                 mempool_destroy(rpc_buffer_mempool);
994         if (rpc_task_mempool)
995                 mempool_destroy(rpc_task_mempool);
996         if (rpc_task_slabp)
997                 kmem_cache_destroy(rpc_task_slabp);
998         if (rpc_buffer_slabp)
999                 kmem_cache_destroy(rpc_buffer_slabp);
1000         rpc_destroy_wait_queue(&delay_queue);
1001 }
1002
1003 int
1004 rpc_init_mempool(void)
1005 {
1006         /*
1007          * The following is not strictly a mempool initialisation,
1008          * but there is no harm in doing it here
1009          */
1010         rpc_init_wait_queue(&delay_queue, "delayq");
1011         if (!rpciod_start())
1012                 goto err_nomem;
1013
1014         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1015                                              sizeof(struct rpc_task),
1016                                              0, SLAB_HWCACHE_ALIGN,
1017                                              NULL);
1018         if (!rpc_task_slabp)
1019                 goto err_nomem;
1020         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1021                                              RPC_BUFFER_MAXSIZE,
1022                                              0, SLAB_HWCACHE_ALIGN,
1023                                              NULL);
1024         if (!rpc_buffer_slabp)
1025                 goto err_nomem;
1026         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1027                                                     rpc_task_slabp);
1028         if (!rpc_task_mempool)
1029                 goto err_nomem;
1030         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1031                                                       rpc_buffer_slabp);
1032         if (!rpc_buffer_mempool)
1033                 goto err_nomem;
1034         return 0;
1035 err_nomem:
1036         rpc_destroy_mempool();
1037         return -ENOMEM;
1038 }