Remove commented-out code copied from NFS
[linux-3.10.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/smp_lock.h>
20 #include <linux/spinlock.h>
21 #include <linux/mutex.h>
22
23 #include <linux/sunrpc/clnt.h>
24
25 #ifdef RPC_DEBUG
26 #define RPCDBG_FACILITY         RPCDBG_SCHED
27 #define RPC_TASK_MAGIC_ID       0xf00baa
28 #endif
29
30 /*
31  * RPC slabs and memory pools
32  */
33 #define RPC_BUFFER_MAXSIZE      (2048)
34 #define RPC_BUFFER_POOLSIZE     (8)
35 #define RPC_TASK_POOLSIZE       (8)
36 static struct kmem_cache        *rpc_task_slabp __read_mostly;
37 static struct kmem_cache        *rpc_buffer_slabp __read_mostly;
38 static mempool_t        *rpc_task_mempool __read_mostly;
39 static mempool_t        *rpc_buffer_mempool __read_mostly;
40
41 static void                     __rpc_default_timer(struct rpc_task *task);
42 static void                     rpc_async_schedule(struct work_struct *);
43 static void                      rpc_release_task(struct rpc_task *task);
44
45 /*
46  * RPC tasks sit here while waiting for conditions to improve.
47  */
48 static RPC_WAITQ(delay_queue, "delayq");
49
50 /*
51  * rpciod-related stuff
52  */
53 struct workqueue_struct *rpciod_workqueue;
54
55 /*
56  * Disable the timer for a given RPC task. Should be called with
57  * queue->lock and bh_disabled in order to avoid races within
58  * rpc_run_timer().
59  */
60 static inline void
61 __rpc_disable_timer(struct rpc_task *task)
62 {
63         dprintk("RPC: %5u disabling timer\n", task->tk_pid);
64         task->tk_timeout_fn = NULL;
65         task->tk_timeout = 0;
66 }
67
68 /*
69  * Run a timeout function.
70  * We use the callback in order to allow __rpc_wake_up_task()
71  * and friends to disable the timer synchronously on SMP systems
72  * without calling del_timer_sync(). The latter could cause a
73  * deadlock if called while we're holding spinlocks...
74  */
75 static void rpc_run_timer(struct rpc_task *task)
76 {
77         void (*callback)(struct rpc_task *);
78
79         callback = task->tk_timeout_fn;
80         task->tk_timeout_fn = NULL;
81         if (callback && RPC_IS_QUEUED(task)) {
82                 dprintk("RPC: %5u running timer\n", task->tk_pid);
83                 callback(task);
84         }
85         smp_mb__before_clear_bit();
86         clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
87         smp_mb__after_clear_bit();
88 }
89
90 /*
91  * Set up a timer for the current task.
92  */
93 static inline void
94 __rpc_add_timer(struct rpc_task *task, rpc_action timer)
95 {
96         if (!task->tk_timeout)
97                 return;
98
99         dprintk("RPC: %5u setting alarm for %lu ms\n",
100                         task->tk_pid, task->tk_timeout * 1000 / HZ);
101
102         if (timer)
103                 task->tk_timeout_fn = timer;
104         else
105                 task->tk_timeout_fn = __rpc_default_timer;
106         set_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
107         mod_timer(&task->tk_timer, jiffies + task->tk_timeout);
108 }
109
110 /*
111  * Delete any timer for the current task. Because we use del_timer_sync(),
112  * this function should never be called while holding queue->lock.
113  */
114 static void
115 rpc_delete_timer(struct rpc_task *task)
116 {
117         if (RPC_IS_QUEUED(task))
118                 return;
119         if (test_and_clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate)) {
120                 del_singleshot_timer_sync(&task->tk_timer);
121                 dprintk("RPC: %5u deleting timer\n", task->tk_pid);
122         }
123 }
124
125 /*
126  * Add new request to a priority queue.
127  */
128 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
129 {
130         struct list_head *q;
131         struct rpc_task *t;
132
133         INIT_LIST_HEAD(&task->u.tk_wait.links);
134         q = &queue->tasks[task->tk_priority];
135         if (unlikely(task->tk_priority > queue->maxpriority))
136                 q = &queue->tasks[queue->maxpriority];
137         list_for_each_entry(t, q, u.tk_wait.list) {
138                 if (t->tk_cookie == task->tk_cookie) {
139                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
140                         return;
141                 }
142         }
143         list_add_tail(&task->u.tk_wait.list, q);
144 }
145
146 /*
147  * Add new request to wait queue.
148  *
149  * Swapper tasks always get inserted at the head of the queue.
150  * This should avoid many nasty memory deadlocks and hopefully
151  * improve overall performance.
152  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
153  */
154 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
155 {
156         BUG_ON (RPC_IS_QUEUED(task));
157
158         if (RPC_IS_PRIORITY(queue))
159                 __rpc_add_wait_queue_priority(queue, task);
160         else if (RPC_IS_SWAPPER(task))
161                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
162         else
163                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
164         task->u.tk_wait.rpc_waitq = queue;
165         queue->qlen++;
166         rpc_set_queued(task);
167
168         dprintk("RPC: %5u added to queue %p \"%s\"\n",
169                         task->tk_pid, queue, rpc_qname(queue));
170 }
171
172 /*
173  * Remove request from a priority queue.
174  */
175 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
176 {
177         struct rpc_task *t;
178
179         if (!list_empty(&task->u.tk_wait.links)) {
180                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
181                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
182                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
183         }
184         list_del(&task->u.tk_wait.list);
185 }
186
187 /*
188  * Remove request from queue.
189  * Note: must be called with spin lock held.
190  */
191 static void __rpc_remove_wait_queue(struct rpc_task *task)
192 {
193         struct rpc_wait_queue *queue;
194         queue = task->u.tk_wait.rpc_waitq;
195
196         if (RPC_IS_PRIORITY(queue))
197                 __rpc_remove_wait_queue_priority(task);
198         else
199                 list_del(&task->u.tk_wait.list);
200         queue->qlen--;
201         dprintk("RPC: %5u removed from queue %p \"%s\"\n",
202                         task->tk_pid, queue, rpc_qname(queue));
203 }
204
205 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
206 {
207         queue->priority = priority;
208         queue->count = 1 << (priority * 2);
209 }
210
211 static inline void rpc_set_waitqueue_cookie(struct rpc_wait_queue *queue, unsigned long cookie)
212 {
213         queue->cookie = cookie;
214         queue->nr = RPC_BATCH_COUNT;
215 }
216
217 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
218 {
219         rpc_set_waitqueue_priority(queue, queue->maxpriority);
220         rpc_set_waitqueue_cookie(queue, 0);
221 }
222
223 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, int maxprio)
224 {
225         int i;
226
227         spin_lock_init(&queue->lock);
228         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
229                 INIT_LIST_HEAD(&queue->tasks[i]);
230         queue->maxpriority = maxprio;
231         rpc_reset_waitqueue_priority(queue);
232 #ifdef RPC_DEBUG
233         queue->name = qname;
234 #endif
235 }
236
237 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
238 {
239         __rpc_init_priority_wait_queue(queue, qname, RPC_PRIORITY_HIGH);
240 }
241
242 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
243 {
244         __rpc_init_priority_wait_queue(queue, qname, 0);
245 }
246 EXPORT_SYMBOL(rpc_init_wait_queue);
247
248 static int rpc_wait_bit_killable(void *word)
249 {
250         if (fatal_signal_pending(current))
251                 return -ERESTARTSYS;
252         schedule();
253         return 0;
254 }
255
256 #ifdef RPC_DEBUG
257 static void rpc_task_set_debuginfo(struct rpc_task *task)
258 {
259         static atomic_t rpc_pid;
260
261         task->tk_magic = RPC_TASK_MAGIC_ID;
262         task->tk_pid = atomic_inc_return(&rpc_pid);
263 }
264 #else
265 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
266 {
267 }
268 #endif
269
270 static void rpc_set_active(struct rpc_task *task)
271 {
272         struct rpc_clnt *clnt;
273         if (test_and_set_bit(RPC_TASK_ACTIVE, &task->tk_runstate) != 0)
274                 return;
275         rpc_task_set_debuginfo(task);
276         /* Add to global list of all tasks */
277         clnt = task->tk_client;
278         if (clnt != NULL) {
279                 spin_lock(&clnt->cl_lock);
280                 list_add_tail(&task->tk_task, &clnt->cl_tasks);
281                 spin_unlock(&clnt->cl_lock);
282         }
283 }
284
285 /*
286  * Mark an RPC call as having completed by clearing the 'active' bit
287  */
288 static void rpc_mark_complete_task(struct rpc_task *task)
289 {
290         smp_mb__before_clear_bit();
291         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
292         smp_mb__after_clear_bit();
293         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
294 }
295
296 /*
297  * Allow callers to wait for completion of an RPC call
298  */
299 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
300 {
301         if (action == NULL)
302                 action = rpc_wait_bit_killable;
303         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
304                         action, TASK_KILLABLE);
305 }
306 EXPORT_SYMBOL(__rpc_wait_for_completion_task);
307
308 /*
309  * Make an RPC task runnable.
310  *
311  * Note: If the task is ASYNC, this must be called with
312  * the spinlock held to protect the wait queue operation.
313  */
314 static void rpc_make_runnable(struct rpc_task *task)
315 {
316         BUG_ON(task->tk_timeout_fn);
317         rpc_clear_queued(task);
318         if (rpc_test_and_set_running(task))
319                 return;
320         /* We might have raced */
321         if (RPC_IS_QUEUED(task)) {
322                 rpc_clear_running(task);
323                 return;
324         }
325         if (RPC_IS_ASYNC(task)) {
326                 int status;
327
328                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
329                 status = queue_work(task->tk_workqueue, &task->u.tk_work);
330                 if (status < 0) {
331                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
332                         task->tk_status = status;
333                         return;
334                 }
335         } else
336                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
337 }
338
339 /*
340  * Prepare for sleeping on a wait queue.
341  * By always appending tasks to the list we ensure FIFO behavior.
342  * NB: An RPC task will only receive interrupt-driven events as long
343  * as it's on a wait queue.
344  */
345 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
346                         rpc_action action, rpc_action timer)
347 {
348         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
349                         task->tk_pid, rpc_qname(q), jiffies);
350
351         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
352                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
353                 return;
354         }
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         /* Mark the task as being activated if so needed */
367         rpc_set_active(task);
368
369         /*
370          * Protect the queue operations.
371          */
372         spin_lock_bh(&q->lock);
373         __rpc_sleep_on(q, task, action, timer);
374         spin_unlock_bh(&q->lock);
375 }
376
377 /**
378  * __rpc_do_wake_up_task - wake up a single rpc_task
379  * @task: task to be woken up
380  *
381  * Caller must hold queue->lock, and have cleared the task queued flag.
382  */
383 static void __rpc_do_wake_up_task(struct rpc_task *task)
384 {
385         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
386                         task->tk_pid, jiffies);
387
388 #ifdef RPC_DEBUG
389         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
390 #endif
391         /* Has the task been executed yet? If not, we cannot wake it up! */
392         if (!RPC_IS_ACTIVATED(task)) {
393                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
394                 return;
395         }
396
397         __rpc_disable_timer(task);
398         __rpc_remove_wait_queue(task);
399
400         rpc_make_runnable(task);
401
402         dprintk("RPC:       __rpc_wake_up_task done\n");
403 }
404
405 /*
406  * Wake up the specified task
407  */
408 static void __rpc_wake_up_task(struct rpc_task *task)
409 {
410         if (rpc_start_wakeup(task)) {
411                 if (RPC_IS_QUEUED(task))
412                         __rpc_do_wake_up_task(task);
413                 rpc_finish_wakeup(task);
414         }
415 }
416
417 /*
418  * Default timeout handler if none specified by user
419  */
420 static void
421 __rpc_default_timer(struct rpc_task *task)
422 {
423         dprintk("RPC: %5u timeout (default timer)\n", task->tk_pid);
424         task->tk_status = -ETIMEDOUT;
425         rpc_wake_up_task(task);
426 }
427
428 /*
429  * Wake up the specified task
430  */
431 void rpc_wake_up_task(struct rpc_task *task)
432 {
433         rcu_read_lock_bh();
434         if (rpc_start_wakeup(task)) {
435                 if (RPC_IS_QUEUED(task)) {
436                         struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
437
438                         /* Note: we're already in a bh-safe context */
439                         spin_lock(&queue->lock);
440                         __rpc_do_wake_up_task(task);
441                         spin_unlock(&queue->lock);
442                 }
443                 rpc_finish_wakeup(task);
444         }
445         rcu_read_unlock_bh();
446 }
447
448 /*
449  * Wake up the next task on a priority queue.
450  */
451 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
452 {
453         struct list_head *q;
454         struct rpc_task *task;
455
456         /*
457          * Service a batch of tasks from a single cookie.
458          */
459         q = &queue->tasks[queue->priority];
460         if (!list_empty(q)) {
461                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
462                 if (queue->cookie == task->tk_cookie) {
463                         if (--queue->nr)
464                                 goto out;
465                         list_move_tail(&task->u.tk_wait.list, q);
466                 }
467                 /*
468                  * Check if we need to switch queues.
469                  */
470                 if (--queue->count)
471                         goto new_cookie;
472         }
473
474         /*
475          * Service the next queue.
476          */
477         do {
478                 if (q == &queue->tasks[0])
479                         q = &queue->tasks[queue->maxpriority];
480                 else
481                         q = q - 1;
482                 if (!list_empty(q)) {
483                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
484                         goto new_queue;
485                 }
486         } while (q != &queue->tasks[queue->priority]);
487
488         rpc_reset_waitqueue_priority(queue);
489         return NULL;
490
491 new_queue:
492         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
493 new_cookie:
494         rpc_set_waitqueue_cookie(queue, task->tk_cookie);
495 out:
496         __rpc_wake_up_task(task);
497         return task;
498 }
499
500 /*
501  * Wake up the next task on the wait queue.
502  */
503 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
504 {
505         struct rpc_task *task = NULL;
506
507         dprintk("RPC:       wake_up_next(%p \"%s\")\n",
508                         queue, rpc_qname(queue));
509         rcu_read_lock_bh();
510         spin_lock(&queue->lock);
511         if (RPC_IS_PRIORITY(queue))
512                 task = __rpc_wake_up_next_priority(queue);
513         else {
514                 task_for_first(task, &queue->tasks[0])
515                         __rpc_wake_up_task(task);
516         }
517         spin_unlock(&queue->lock);
518         rcu_read_unlock_bh();
519
520         return task;
521 }
522
523 /**
524  * rpc_wake_up - wake up all rpc_tasks
525  * @queue: rpc_wait_queue on which the tasks are sleeping
526  *
527  * Grabs queue->lock
528  */
529 void rpc_wake_up(struct rpc_wait_queue *queue)
530 {
531         struct rpc_task *task, *next;
532         struct list_head *head;
533
534         rcu_read_lock_bh();
535         spin_lock(&queue->lock);
536         head = &queue->tasks[queue->maxpriority];
537         for (;;) {
538                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
539                         __rpc_wake_up_task(task);
540                 if (head == &queue->tasks[0])
541                         break;
542                 head--;
543         }
544         spin_unlock(&queue->lock);
545         rcu_read_unlock_bh();
546 }
547
548 /**
549  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
550  * @queue: rpc_wait_queue on which the tasks are sleeping
551  * @status: status value to set
552  *
553  * Grabs queue->lock
554  */
555 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
556 {
557         struct rpc_task *task, *next;
558         struct list_head *head;
559
560         rcu_read_lock_bh();
561         spin_lock(&queue->lock);
562         head = &queue->tasks[queue->maxpriority];
563         for (;;) {
564                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
565                         task->tk_status = status;
566                         __rpc_wake_up_task(task);
567                 }
568                 if (head == &queue->tasks[0])
569                         break;
570                 head--;
571         }
572         spin_unlock(&queue->lock);
573         rcu_read_unlock_bh();
574 }
575
576 static void __rpc_atrun(struct rpc_task *task)
577 {
578         rpc_wake_up_task(task);
579 }
580
581 /*
582  * Run a task at a later time
583  */
584 void rpc_delay(struct rpc_task *task, unsigned long delay)
585 {
586         task->tk_timeout = delay;
587         rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
588 }
589
590 /*
591  * Helper to call task->tk_ops->rpc_call_prepare
592  */
593 static void rpc_prepare_task(struct rpc_task *task)
594 {
595         lock_kernel();
596         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
597         unlock_kernel();
598 }
599
600 /*
601  * Helper that calls task->tk_ops->rpc_call_done if it exists
602  */
603 void rpc_exit_task(struct rpc_task *task)
604 {
605         task->tk_action = NULL;
606         if (task->tk_ops->rpc_call_done != NULL) {
607                 lock_kernel();
608                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
609                 unlock_kernel();
610                 if (task->tk_action != NULL) {
611                         WARN_ON(RPC_ASSASSINATED(task));
612                         /* Always release the RPC slot and buffer memory */
613                         xprt_release(task);
614                 }
615         }
616 }
617 EXPORT_SYMBOL(rpc_exit_task);
618
619 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
620 {
621         if (ops->rpc_release != NULL) {
622                 lock_kernel();
623                 ops->rpc_release(calldata);
624                 unlock_kernel();
625         }
626 }
627
628 /*
629  * This is the RPC `scheduler' (or rather, the finite state machine).
630  */
631 static void __rpc_execute(struct rpc_task *task)
632 {
633         int             status = 0;
634
635         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
636                         task->tk_pid, task->tk_flags);
637
638         BUG_ON(RPC_IS_QUEUED(task));
639
640         for (;;) {
641                 /*
642                  * Garbage collection of pending timers...
643                  */
644                 rpc_delete_timer(task);
645
646                 /*
647                  * Execute any pending callback.
648                  */
649                 if (RPC_DO_CALLBACK(task)) {
650                         /* Define a callback save pointer */
651                         void (*save_callback)(struct rpc_task *);
652
653                         /*
654                          * If a callback exists, save it, reset it,
655                          * call it.
656                          * The save is needed to stop from resetting
657                          * another callback set within the callback handler
658                          * - Dave
659                          */
660                         save_callback=task->tk_callback;
661                         task->tk_callback=NULL;
662                         save_callback(task);
663                 }
664
665                 /*
666                  * Perform the next FSM step.
667                  * tk_action may be NULL when the task has been killed
668                  * by someone else.
669                  */
670                 if (!RPC_IS_QUEUED(task)) {
671                         if (task->tk_action == NULL)
672                                 break;
673                         task->tk_action(task);
674                 }
675
676                 /*
677                  * Lockless check for whether task is sleeping or not.
678                  */
679                 if (!RPC_IS_QUEUED(task))
680                         continue;
681                 rpc_clear_running(task);
682                 if (RPC_IS_ASYNC(task)) {
683                         /* Careful! we may have raced... */
684                         if (RPC_IS_QUEUED(task))
685                                 return;
686                         if (rpc_test_and_set_running(task))
687                                 return;
688                         continue;
689                 }
690
691                 /* sync task: sleep here */
692                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
693                 status = out_of_line_wait_on_bit(&task->tk_runstate,
694                                 RPC_TASK_QUEUED, rpc_wait_bit_killable,
695                                 TASK_KILLABLE);
696                 if (status == -ERESTARTSYS) {
697                         /*
698                          * When a sync task receives a signal, it exits with
699                          * -ERESTARTSYS. In order to catch any callbacks that
700                          * clean up after sleeping on some queue, we don't
701                          * break the loop here, but go around once more.
702                          */
703                         dprintk("RPC: %5u got signal\n", task->tk_pid);
704                         task->tk_flags |= RPC_TASK_KILLED;
705                         rpc_exit(task, -ERESTARTSYS);
706                         rpc_wake_up_task(task);
707                 }
708                 rpc_set_running(task);
709                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
710         }
711
712         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
713                         task->tk_status);
714         /* Release all resources associated with the task */
715         rpc_release_task(task);
716 }
717
718 /*
719  * User-visible entry point to the scheduler.
720  *
721  * This may be called recursively if e.g. an async NFS task updates
722  * the attributes and finds that dirty pages must be flushed.
723  * NOTE: Upon exit of this function the task is guaranteed to be
724  *       released. In particular note that tk_release() will have
725  *       been called, so your task memory may have been freed.
726  */
727 void rpc_execute(struct rpc_task *task)
728 {
729         rpc_set_active(task);
730         rpc_set_running(task);
731         __rpc_execute(task);
732 }
733
734 static void rpc_async_schedule(struct work_struct *work)
735 {
736         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
737 }
738
739 struct rpc_buffer {
740         size_t  len;
741         char    data[];
742 };
743
744 /**
745  * rpc_malloc - allocate an RPC buffer
746  * @task: RPC task that will use this buffer
747  * @size: requested byte size
748  *
749  * To prevent rpciod from hanging, this allocator never sleeps,
750  * returning NULL if the request cannot be serviced immediately.
751  * The caller can arrange to sleep in a way that is safe for rpciod.
752  *
753  * Most requests are 'small' (under 2KiB) and can be serviced from a
754  * mempool, ensuring that NFS reads and writes can always proceed,
755  * and that there is good locality of reference for these buffers.
756  *
757  * In order to avoid memory starvation triggering more writebacks of
758  * NFS requests, we avoid using GFP_KERNEL.
759  */
760 void *rpc_malloc(struct rpc_task *task, size_t size)
761 {
762         struct rpc_buffer *buf;
763         gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
764
765         size += sizeof(struct rpc_buffer);
766         if (size <= RPC_BUFFER_MAXSIZE)
767                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
768         else
769                 buf = kmalloc(size, gfp);
770
771         if (!buf)
772                 return NULL;
773
774         buf->len = size;
775         dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
776                         task->tk_pid, size, buf);
777         return &buf->data;
778 }
779 EXPORT_SYMBOL_GPL(rpc_malloc);
780
781 /**
782  * rpc_free - free buffer allocated via rpc_malloc
783  * @buffer: buffer to free
784  *
785  */
786 void rpc_free(void *buffer)
787 {
788         size_t size;
789         struct rpc_buffer *buf;
790
791         if (!buffer)
792                 return;
793
794         buf = container_of(buffer, struct rpc_buffer, data);
795         size = buf->len;
796
797         dprintk("RPC:       freeing buffer of size %zu at %p\n",
798                         size, buf);
799
800         if (size <= RPC_BUFFER_MAXSIZE)
801                 mempool_free(buf, rpc_buffer_mempool);
802         else
803                 kfree(buf);
804 }
805 EXPORT_SYMBOL_GPL(rpc_free);
806
807 /*
808  * Creation and deletion of RPC task structures
809  */
810 void rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
811 {
812         memset(task, 0, sizeof(*task));
813         init_timer(&task->tk_timer);
814         task->tk_timer.data     = (unsigned long) task;
815         task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
816         atomic_set(&task->tk_count, 1);
817         task->tk_client = clnt;
818         task->tk_flags  = flags;
819         task->tk_ops = tk_ops;
820         if (tk_ops->rpc_call_prepare != NULL)
821                 task->tk_action = rpc_prepare_task;
822         task->tk_calldata = calldata;
823         INIT_LIST_HEAD(&task->tk_task);
824
825         /* Initialize retry counters */
826         task->tk_garb_retry = 2;
827         task->tk_cred_retry = 2;
828
829         task->tk_priority = RPC_PRIORITY_NORMAL;
830         task->tk_cookie = (unsigned long)current;
831
832         /* Initialize workqueue for async tasks */
833         task->tk_workqueue = rpciod_workqueue;
834
835         if (clnt) {
836                 kref_get(&clnt->cl_kref);
837                 if (clnt->cl_softrtry)
838                         task->tk_flags |= RPC_TASK_SOFT;
839         }
840
841         BUG_ON(task->tk_ops == NULL);
842
843         /* starting timestamp */
844         task->tk_start = jiffies;
845
846         dprintk("RPC:       new task initialized, procpid %u\n",
847                                 task_pid_nr(current));
848 }
849
850 static struct rpc_task *
851 rpc_alloc_task(void)
852 {
853         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
854 }
855
856 static void rpc_free_task(struct rcu_head *rcu)
857 {
858         struct rpc_task *task = container_of(rcu, struct rpc_task, u.tk_rcu);
859         dprintk("RPC: %5u freeing task\n", task->tk_pid);
860         mempool_free(task, rpc_task_mempool);
861 }
862
863 /*
864  * Create a new task for the specified client.
865  */
866 struct rpc_task *rpc_new_task(struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
867 {
868         struct rpc_task *task;
869
870         task = rpc_alloc_task();
871         if (!task)
872                 goto out;
873
874         rpc_init_task(task, clnt, flags, tk_ops, calldata);
875
876         dprintk("RPC:       allocated task %p\n", task);
877         task->tk_flags |= RPC_TASK_DYNAMIC;
878 out:
879         return task;
880 }
881
882
883 void rpc_put_task(struct rpc_task *task)
884 {
885         const struct rpc_call_ops *tk_ops = task->tk_ops;
886         void *calldata = task->tk_calldata;
887
888         if (!atomic_dec_and_test(&task->tk_count))
889                 return;
890         /* Release resources */
891         if (task->tk_rqstp)
892                 xprt_release(task);
893         if (task->tk_msg.rpc_cred)
894                 rpcauth_unbindcred(task);
895         if (task->tk_client) {
896                 rpc_release_client(task->tk_client);
897                 task->tk_client = NULL;
898         }
899         if (task->tk_flags & RPC_TASK_DYNAMIC)
900                 call_rcu_bh(&task->u.tk_rcu, rpc_free_task);
901         rpc_release_calldata(tk_ops, calldata);
902 }
903 EXPORT_SYMBOL(rpc_put_task);
904
905 static void rpc_release_task(struct rpc_task *task)
906 {
907 #ifdef RPC_DEBUG
908         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
909 #endif
910         dprintk("RPC: %5u release task\n", task->tk_pid);
911
912         if (!list_empty(&task->tk_task)) {
913                 struct rpc_clnt *clnt = task->tk_client;
914                 /* Remove from client task list */
915                 spin_lock(&clnt->cl_lock);
916                 list_del(&task->tk_task);
917                 spin_unlock(&clnt->cl_lock);
918         }
919         BUG_ON (RPC_IS_QUEUED(task));
920
921         /* Synchronously delete any running timer */
922         rpc_delete_timer(task);
923
924 #ifdef RPC_DEBUG
925         task->tk_magic = 0;
926 #endif
927         /* Wake up anyone who is waiting for task completion */
928         rpc_mark_complete_task(task);
929
930         rpc_put_task(task);
931 }
932
933 /*
934  * Kill all tasks for the given client.
935  * XXX: kill their descendants as well?
936  */
937 void rpc_killall_tasks(struct rpc_clnt *clnt)
938 {
939         struct rpc_task *rovr;
940
941
942         if (list_empty(&clnt->cl_tasks))
943                 return;
944         dprintk("RPC:       killing all tasks for client %p\n", clnt);
945         /*
946          * Spin lock all_tasks to prevent changes...
947          */
948         spin_lock(&clnt->cl_lock);
949         list_for_each_entry(rovr, &clnt->cl_tasks, tk_task) {
950                 if (! RPC_IS_ACTIVATED(rovr))
951                         continue;
952                 if (!(rovr->tk_flags & RPC_TASK_KILLED)) {
953                         rovr->tk_flags |= RPC_TASK_KILLED;
954                         rpc_exit(rovr, -EIO);
955                         rpc_wake_up_task(rovr);
956                 }
957         }
958         spin_unlock(&clnt->cl_lock);
959 }
960
961 int rpciod_up(void)
962 {
963         return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
964 }
965
966 void rpciod_down(void)
967 {
968         module_put(THIS_MODULE);
969 }
970
971 /*
972  * Start up the rpciod workqueue.
973  */
974 static int rpciod_start(void)
975 {
976         struct workqueue_struct *wq;
977
978         /*
979          * Create the rpciod thread and wait for it to start.
980          */
981         dprintk("RPC:       creating workqueue rpciod\n");
982         wq = create_workqueue("rpciod");
983         rpciod_workqueue = wq;
984         return rpciod_workqueue != NULL;
985 }
986
987 static void rpciod_stop(void)
988 {
989         struct workqueue_struct *wq = NULL;
990
991         if (rpciod_workqueue == NULL)
992                 return;
993         dprintk("RPC:       destroying workqueue rpciod\n");
994
995         wq = rpciod_workqueue;
996         rpciod_workqueue = NULL;
997         destroy_workqueue(wq);
998 }
999
1000 void
1001 rpc_destroy_mempool(void)
1002 {
1003         rpciod_stop();
1004         if (rpc_buffer_mempool)
1005                 mempool_destroy(rpc_buffer_mempool);
1006         if (rpc_task_mempool)
1007                 mempool_destroy(rpc_task_mempool);
1008         if (rpc_task_slabp)
1009                 kmem_cache_destroy(rpc_task_slabp);
1010         if (rpc_buffer_slabp)
1011                 kmem_cache_destroy(rpc_buffer_slabp);
1012 }
1013
1014 int
1015 rpc_init_mempool(void)
1016 {
1017         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1018                                              sizeof(struct rpc_task),
1019                                              0, SLAB_HWCACHE_ALIGN,
1020                                              NULL);
1021         if (!rpc_task_slabp)
1022                 goto err_nomem;
1023         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1024                                              RPC_BUFFER_MAXSIZE,
1025                                              0, SLAB_HWCACHE_ALIGN,
1026                                              NULL);
1027         if (!rpc_buffer_slabp)
1028                 goto err_nomem;
1029         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1030                                                     rpc_task_slabp);
1031         if (!rpc_task_mempool)
1032                 goto err_nomem;
1033         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1034                                                       rpc_buffer_slabp);
1035         if (!rpc_buffer_mempool)
1036                 goto err_nomem;
1037         if (!rpciod_start())
1038                 goto err_nomem;
1039         return 0;
1040 err_nomem:
1041         rpc_destroy_mempool();
1042         return -ENOMEM;
1043 }