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1 #ifndef _LINUX_CLOSURE_H
2 #define _LINUX_CLOSURE_H
3 
4 #include <linux/llist.h>
5 #include <linux/sched.h>
6 #include <linux/workqueue.h>
7 
8 /*
9  * Closure is perhaps the most overused and abused term in computer science, but
10  * since I've been unable to come up with anything better you're stuck with it
11  * again.
12  *
13  * What are closures?
14  *
15  * They embed a refcount. The basic idea is they count "things that are in
16  * progress" - in flight bios, some other thread that's doing something else -
17  * anything you might want to wait on.
18  *
19  * The refcount may be manipulated with closure_get() and closure_put().
20  * closure_put() is where many of the interesting things happen, when it causes
21  * the refcount to go to 0.
22  *
23  * Closures can be used to wait on things both synchronously and asynchronously,
24  * and synchronous and asynchronous use can be mixed without restriction. To
25  * wait synchronously, use closure_sync() - you will sleep until your closure's
26  * refcount hits 1.
27  *
28  * To wait asynchronously, use
29  *   continue_at(cl, next_function, workqueue);
30  *
31  * passing it, as you might expect, the function to run when nothing is pending
32  * and the workqueue to run that function out of.
33  *
34  * continue_at() also, critically, is a macro that returns the calling function.
35  * There's good reason for this.
36  *
37  * To use safely closures asynchronously, they must always have a refcount while
38  * they are running owned by the thread that is running them. Otherwise, suppose
39  * you submit some bios and wish to have a function run when they all complete:
40  *
41  * foo_endio(struct bio *bio, int error)
42  * {
43  *	closure_put(cl);
44  * }
45  *
46  * closure_init(cl);
47  *
48  * do_stuff();
49  * closure_get(cl);
50  * bio1->bi_endio = foo_endio;
51  * bio_submit(bio1);
52  *
53  * do_more_stuff();
54  * closure_get(cl);
55  * bio2->bi_endio = foo_endio;
56  * bio_submit(bio2);
57  *
58  * continue_at(cl, complete_some_read, system_wq);
59  *
60  * If closure's refcount started at 0, complete_some_read() could run before the
61  * second bio was submitted - which is almost always not what you want! More
62  * importantly, it wouldn't be possible to say whether the original thread or
63  * complete_some_read()'s thread owned the closure - and whatever state it was
64  * associated with!
65  *
66  * So, closure_init() initializes a closure's refcount to 1 - and when a
67  * closure_fn is run, the refcount will be reset to 1 first.
68  *
69  * Then, the rule is - if you got the refcount with closure_get(), release it
70  * with closure_put() (i.e, in a bio->bi_endio function). If you have a refcount
71  * on a closure because you called closure_init() or you were run out of a
72  * closure - _always_ use continue_at(). Doing so consistently will help
73  * eliminate an entire class of particularly pernicious races.
74  *
75  * For a closure to wait on an arbitrary event, we need to introduce waitlists:
76  *
77  * struct closure_waitlist list;
78  * closure_wait_event(list, cl, condition);
79  * closure_wake_up(wait_list);
80  *
81  * These work analagously to wait_event() and wake_up() - except that instead of
82  * operating on the current thread (for wait_event()) and lists of threads, they
83  * operate on an explicit closure and lists of closures.
84  *
85  * Because it's a closure we can now wait either synchronously or
86  * asynchronously. closure_wait_event() returns the current value of the
87  * condition, and if it returned false continue_at() or closure_sync() can be
88  * used to wait for it to become true.
89  *
90  * It's useful for waiting on things when you can't sleep in the context in
91  * which you must check the condition (perhaps a spinlock held, or you might be
92  * beneath generic_make_request() - in which case you can't sleep on IO).
93  *
94  * closure_wait_event() will wait either synchronously or asynchronously,
95  * depending on whether the closure is in blocking mode or not. You can pick a
96  * mode explicitly with closure_wait_event_sync() and
97  * closure_wait_event_async(), which do just what you might expect.
98  *
99  * Lastly, you might have a wait list dedicated to a specific event, and have no
100  * need for specifying the condition - you just want to wait until someone runs
101  * closure_wake_up() on the appropriate wait list. In that case, just use
102  * closure_wait(). It will return either true or false, depending on whether the
103  * closure was already on a wait list or not - a closure can only be on one wait
104  * list at a time.
105  *
106  * Parents:
107  *
108  * closure_init() takes two arguments - it takes the closure to initialize, and
109  * a (possibly null) parent.
110  *
111  * If parent is non null, the new closure will have a refcount for its lifetime;
112  * a closure is considered to be "finished" when its refcount hits 0 and the
113  * function to run is null. Hence
114  *
115  * continue_at(cl, NULL, NULL);
116  *
117  * returns up the (spaghetti) stack of closures, precisely like normal return
118  * returns up the C stack. continue_at() with non null fn is better thought of
119  * as doing a tail call.
120  *
121  * All this implies that a closure should typically be embedded in a particular
122  * struct (which its refcount will normally control the lifetime of), and that
123  * struct can very much be thought of as a stack frame.
124  *
125  * Locking:
126  *
127  * Closures are based on work items but they can be thought of as more like
128  * threads - in that like threads and unlike work items they have a well
129  * defined lifetime; they are created (with closure_init()) and eventually
130  * complete after a continue_at(cl, NULL, NULL).
131  *
132  * Suppose you've got some larger structure with a closure embedded in it that's
133  * used for periodically doing garbage collection. You only want one garbage
134  * collection happening at a time, so the natural thing to do is protect it with
135  * a lock. However, it's difficult to use a lock protecting a closure correctly
136  * because the unlock should come after the last continue_to() (additionally, if
137  * you're using the closure asynchronously a mutex won't work since a mutex has
138  * to be unlocked by the same process that locked it).
139  *
140  * So to make it less error prone and more efficient, we also have the ability
141  * to use closures as locks:
142  *
143  * closure_init_unlocked();
144  * closure_trylock();
145  *
146  * That's all we need for trylock() - the last closure_put() implicitly unlocks
147  * it for you.  But for closure_lock(), we also need a wait list:
148  *
149  * struct closure_with_waitlist frobnicator_cl;
150  *
151  * closure_init_unlocked(&frobnicator_cl);
152  * closure_lock(&frobnicator_cl);
153  *
154  * A closure_with_waitlist embeds a closure and a wait list - much like struct
155  * delayed_work embeds a work item and a timer_list. The important thing is, use
156  * it exactly like you would a regular closure and closure_put() will magically
157  * handle everything for you.
158  *
159  * We've got closures that embed timers, too. They're called, appropriately
160  * enough:
161  * struct closure_with_timer;
162  *
163  * This gives you access to closure_delay(). It takes a refcount for a specified
164  * number of jiffies - you could then call closure_sync() (for a slightly
165  * convoluted version of msleep()) or continue_at() - which gives you the same
166  * effect as using a delayed work item, except you can reuse the work_struct
167  * already embedded in struct closure.
168  *
169  * Lastly, there's struct closure_with_waitlist_and_timer. It does what you
170  * probably expect, if you happen to need the features of both. (You don't
171  * really want to know how all this is implemented, but if I've done my job
172  * right you shouldn't have to care).
173  */
174 
175 struct closure;
176 typedef void (closure_fn) (struct closure *);
177 
178 struct closure_waitlist {
179 	struct llist_head	list;
180 };
181 
182 enum closure_type {
183 	TYPE_closure				= 0,
184 	TYPE_closure_with_waitlist		= 1,
185 	TYPE_closure_with_timer			= 2,
186 	TYPE_closure_with_waitlist_and_timer	= 3,
187 	MAX_CLOSURE_TYPE			= 3,
188 };
189 
190 enum closure_state {
191 	/*
192 	 * CLOSURE_BLOCKING: Causes closure_wait_event() to block, instead of
193 	 * waiting asynchronously
194 	 *
195 	 * CLOSURE_WAITING: Set iff the closure is on a waitlist. Must be set by
196 	 * the thread that owns the closure, and cleared by the thread that's
197 	 * waking up the closure.
198 	 *
199 	 * CLOSURE_SLEEPING: Must be set before a thread uses a closure to sleep
200 	 * - indicates that cl->task is valid and closure_put() may wake it up.
201 	 * Only set or cleared by the thread that owns the closure.
202 	 *
203 	 * CLOSURE_TIMER: Analagous to CLOSURE_WAITING, indicates that a closure
204 	 * has an outstanding timer. Must be set by the thread that owns the
205 	 * closure, and cleared by the timer function when the timer goes off.
206 	 *
207 	 * The rest are for debugging and don't affect behaviour:
208 	 *
209 	 * CLOSURE_RUNNING: Set when a closure is running (i.e. by
210 	 * closure_init() and when closure_put() runs then next function), and
211 	 * must be cleared before remaining hits 0. Primarily to help guard
212 	 * against incorrect usage and accidentally transferring references.
213 	 * continue_at() and closure_return() clear it for you, if you're doing
214 	 * something unusual you can use closure_set_dead() which also helps
215 	 * annotate where references are being transferred.
216 	 *
217 	 * CLOSURE_STACK: Sanity check - remaining should never hit 0 on a
218 	 * closure with this flag set
219 	 */
220 
221 	CLOSURE_BITS_START	= (1 << 19),
222 	CLOSURE_DESTRUCTOR	= (1 << 19),
223 	CLOSURE_BLOCKING	= (1 << 21),
224 	CLOSURE_WAITING		= (1 << 23),
225 	CLOSURE_SLEEPING	= (1 << 25),
226 	CLOSURE_TIMER		= (1 << 27),
227 	CLOSURE_RUNNING		= (1 << 29),
228 	CLOSURE_STACK		= (1 << 31),
229 };
230 
231 #define CLOSURE_GUARD_MASK					\
232 	((CLOSURE_DESTRUCTOR|CLOSURE_BLOCKING|CLOSURE_WAITING|	\
233 	  CLOSURE_SLEEPING|CLOSURE_TIMER|CLOSURE_RUNNING|CLOSURE_STACK) << 1)
234 
235 #define CLOSURE_REMAINING_MASK		(CLOSURE_BITS_START - 1)
236 #define CLOSURE_REMAINING_INITIALIZER	(1|CLOSURE_RUNNING)
237 
238 struct closure {
239 	union {
240 		struct {
241 			struct workqueue_struct *wq;
242 			struct task_struct	*task;
243 			struct llist_node	list;
244 			closure_fn		*fn;
245 		};
246 		struct work_struct	work;
247 	};
248 
249 	struct closure		*parent;
250 
251 	atomic_t		remaining;
252 
253 	enum closure_type	type;
254 
255 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
256 #define CLOSURE_MAGIC_DEAD	0xc054dead
257 #define CLOSURE_MAGIC_ALIVE	0xc054a11e
258 
259 	unsigned		magic;
260 	struct list_head	all;
261 	unsigned long		ip;
262 	unsigned long		waiting_on;
263 #endif
264 };
265 
266 struct closure_with_waitlist {
267 	struct closure		cl;
268 	struct closure_waitlist	wait;
269 };
270 
271 struct closure_with_timer {
272 	struct closure		cl;
273 	struct timer_list	timer;
274 };
275 
276 struct closure_with_waitlist_and_timer {
277 	struct closure		cl;
278 	struct closure_waitlist	wait;
279 	struct timer_list	timer;
280 };
281 
282 extern unsigned invalid_closure_type(void);
283 
284 #define __CLOSURE_TYPE(cl, _t)						\
285 	  __builtin_types_compatible_p(typeof(cl), struct _t)		\
286 		? TYPE_ ## _t :						\
287 
288 #define __closure_type(cl)						\
289 (									\
290 	__CLOSURE_TYPE(cl, closure)					\
291 	__CLOSURE_TYPE(cl, closure_with_waitlist)			\
292 	__CLOSURE_TYPE(cl, closure_with_timer)				\
293 	__CLOSURE_TYPE(cl, closure_with_waitlist_and_timer)		\
294 	invalid_closure_type()						\
295 )
296 
297 void closure_sub(struct closure *cl, int v);
298 void closure_put(struct closure *cl);
299 void closure_queue(struct closure *cl);
300 void __closure_wake_up(struct closure_waitlist *list);
301 bool closure_wait(struct closure_waitlist *list, struct closure *cl);
302 void closure_sync(struct closure *cl);
303 
304 bool closure_trylock(struct closure *cl, struct closure *parent);
305 void __closure_lock(struct closure *cl, struct closure *parent,
306 		    struct closure_waitlist *wait_list);
307 
308 void do_closure_timer_init(struct closure *cl);
309 bool __closure_delay(struct closure *cl, unsigned long delay,
310 		     struct timer_list *timer);
311 void __closure_flush(struct closure *cl, struct timer_list *timer);
312 void __closure_flush_sync(struct closure *cl, struct timer_list *timer);
313 
314 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
315 
316 void closure_debug_init(void);
317 void closure_debug_create(struct closure *cl);
318 void closure_debug_destroy(struct closure *cl);
319 
320 #else
321 
closure_debug_init(void)322 static inline void closure_debug_init(void) {}
closure_debug_create(struct closure * cl)323 static inline void closure_debug_create(struct closure *cl) {}
closure_debug_destroy(struct closure * cl)324 static inline void closure_debug_destroy(struct closure *cl) {}
325 
326 #endif
327 
closure_set_ip(struct closure * cl)328 static inline void closure_set_ip(struct closure *cl)
329 {
330 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
331 	cl->ip = _THIS_IP_;
332 #endif
333 }
334 
closure_set_ret_ip(struct closure * cl)335 static inline void closure_set_ret_ip(struct closure *cl)
336 {
337 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
338 	cl->ip = _RET_IP_;
339 #endif
340 }
341 
closure_get(struct closure * cl)342 static inline void closure_get(struct closure *cl)
343 {
344 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
345 	BUG_ON((atomic_inc_return(&cl->remaining) &
346 		CLOSURE_REMAINING_MASK) <= 1);
347 #else
348 	atomic_inc(&cl->remaining);
349 #endif
350 }
351 
closure_set_stopped(struct closure * cl)352 static inline void closure_set_stopped(struct closure *cl)
353 {
354 	atomic_sub(CLOSURE_RUNNING, &cl->remaining);
355 }
356 
closure_is_stopped(struct closure * cl)357 static inline bool closure_is_stopped(struct closure *cl)
358 {
359 	return !(atomic_read(&cl->remaining) & CLOSURE_RUNNING);
360 }
361 
closure_is_unlocked(struct closure * cl)362 static inline bool closure_is_unlocked(struct closure *cl)
363 {
364 	return atomic_read(&cl->remaining) == -1;
365 }
366 
do_closure_init(struct closure * cl,struct closure * parent,bool running)367 static inline void do_closure_init(struct closure *cl, struct closure *parent,
368 				   bool running)
369 {
370 	switch (cl->type) {
371 	case TYPE_closure_with_timer:
372 	case TYPE_closure_with_waitlist_and_timer:
373 		do_closure_timer_init(cl);
374 	default:
375 		break;
376 	}
377 
378 	cl->parent = parent;
379 	if (parent)
380 		closure_get(parent);
381 
382 	if (running) {
383 		closure_debug_create(cl);
384 		atomic_set(&cl->remaining, CLOSURE_REMAINING_INITIALIZER);
385 	} else
386 		atomic_set(&cl->remaining, -1);
387 
388 	closure_set_ip(cl);
389 }
390 
391 /*
392  * Hack to get at the embedded closure if there is one, by doing an unsafe cast:
393  * the result of __closure_type() is thrown away, it's used merely for type
394  * checking.
395  */
396 #define __to_internal_closure(cl)				\
397 ({								\
398 	BUILD_BUG_ON(__closure_type(*cl) > MAX_CLOSURE_TYPE);	\
399 	(struct closure *) cl;					\
400 })
401 
402 #define closure_init_type(cl, parent, running)			\
403 do {								\
404 	struct closure *_cl = __to_internal_closure(cl);	\
405 	_cl->type = __closure_type(*(cl));			\
406 	do_closure_init(_cl, parent, running);			\
407 } while (0)
408 
409 /**
410  * __closure_init() - Initialize a closure, skipping the memset()
411  *
412  * May be used instead of closure_init() when memory has already been zeroed.
413  */
414 #define __closure_init(cl, parent)				\
415 	closure_init_type(cl, parent, true)
416 
417 /**
418  * closure_init() - Initialize a closure, setting the refcount to 1
419  * @cl:		closure to initialize
420  * @parent:	parent of the new closure. cl will take a refcount on it for its
421  *		lifetime; may be NULL.
422  */
423 #define closure_init(cl, parent)				\
424 do {								\
425 	memset((cl), 0, sizeof(*(cl)));				\
426 	__closure_init(cl, parent);				\
427 } while (0)
428 
closure_init_stack(struct closure * cl)429 static inline void closure_init_stack(struct closure *cl)
430 {
431 	memset(cl, 0, sizeof(struct closure));
432 	atomic_set(&cl->remaining, CLOSURE_REMAINING_INITIALIZER|
433 		   CLOSURE_BLOCKING|CLOSURE_STACK);
434 }
435 
436 /**
437  * closure_init_unlocked() - Initialize a closure but leave it unlocked.
438  * @cl:		closure to initialize
439  *
440  * For when the closure will be used as a lock. The closure may not be used
441  * until after a closure_lock() or closure_trylock().
442  */
443 #define closure_init_unlocked(cl)				\
444 do {								\
445 	memset((cl), 0, sizeof(*(cl)));				\
446 	closure_init_type(cl, NULL, false);			\
447 } while (0)
448 
449 /**
450  * closure_lock() - lock and initialize a closure.
451  * @cl:		the closure to lock
452  * @parent:	the new parent for this closure
453  *
454  * The closure must be of one of the types that has a waitlist (otherwise we
455  * wouldn't be able to sleep on contention).
456  *
457  * @parent has exactly the same meaning as in closure_init(); if non null, the
458  * closure will take a reference on @parent which will be released when it is
459  * unlocked.
460  */
461 #define closure_lock(cl, parent)				\
462 	__closure_lock(__to_internal_closure(cl), parent, &(cl)->wait)
463 
464 /**
465  * closure_delay() - delay some number of jiffies
466  * @cl:		the closure that will sleep
467  * @delay:	the delay in jiffies
468  *
469  * Takes a refcount on @cl which will be released after @delay jiffies; this may
470  * be used to have a function run after a delay with continue_at(), or
471  * closure_sync() may be used for a convoluted version of msleep().
472  */
473 #define closure_delay(cl, delay)			\
474 	__closure_delay(__to_internal_closure(cl), delay, &(cl)->timer)
475 
476 #define closure_flush(cl)				\
477 	__closure_flush(__to_internal_closure(cl), &(cl)->timer)
478 
479 #define closure_flush_sync(cl)				\
480 	__closure_flush_sync(__to_internal_closure(cl), &(cl)->timer)
481 
__closure_end_sleep(struct closure * cl)482 static inline void __closure_end_sleep(struct closure *cl)
483 {
484 	__set_current_state(TASK_RUNNING);
485 
486 	if (atomic_read(&cl->remaining) & CLOSURE_SLEEPING)
487 		atomic_sub(CLOSURE_SLEEPING, &cl->remaining);
488 }
489 
__closure_start_sleep(struct closure * cl)490 static inline void __closure_start_sleep(struct closure *cl)
491 {
492 	closure_set_ip(cl);
493 	cl->task = current;
494 	set_current_state(TASK_UNINTERRUPTIBLE);
495 
496 	if (!(atomic_read(&cl->remaining) & CLOSURE_SLEEPING))
497 		atomic_add(CLOSURE_SLEEPING, &cl->remaining);
498 }
499 
500 /**
501  * closure_blocking() - returns true if the closure is in blocking mode.
502  *
503  * If a closure is in blocking mode, closure_wait_event() will sleep until the
504  * condition is true instead of waiting asynchronously.
505  */
closure_blocking(struct closure * cl)506 static inline bool closure_blocking(struct closure *cl)
507 {
508 	return atomic_read(&cl->remaining) & CLOSURE_BLOCKING;
509 }
510 
511 /**
512  * set_closure_blocking() - put a closure in blocking mode.
513  *
514  * If a closure is in blocking mode, closure_wait_event() will sleep until the
515  * condition is true instead of waiting asynchronously.
516  *
517  * Not thread safe - can only be called by the thread running the closure.
518  */
set_closure_blocking(struct closure * cl)519 static inline void set_closure_blocking(struct closure *cl)
520 {
521 	if (!closure_blocking(cl))
522 		atomic_add(CLOSURE_BLOCKING, &cl->remaining);
523 }
524 
525 /*
526  * Not thread safe - can only be called by the thread running the closure.
527  */
clear_closure_blocking(struct closure * cl)528 static inline void clear_closure_blocking(struct closure *cl)
529 {
530 	if (closure_blocking(cl))
531 		atomic_sub(CLOSURE_BLOCKING, &cl->remaining);
532 }
533 
534 /**
535  * closure_wake_up() - wake up all closures on a wait list.
536  */
closure_wake_up(struct closure_waitlist * list)537 static inline void closure_wake_up(struct closure_waitlist *list)
538 {
539 	smp_mb();
540 	__closure_wake_up(list);
541 }
542 
543 /*
544  * Wait on an event, synchronously or asynchronously - analogous to wait_event()
545  * but for closures.
546  *
547  * The loop is oddly structured so as to avoid a race; we must check the
548  * condition again after we've added ourself to the waitlist. We know if we were
549  * already on the waitlist because closure_wait() returns false; thus, we only
550  * schedule or break if closure_wait() returns false. If it returns true, we
551  * just loop again - rechecking the condition.
552  *
553  * The __closure_wake_up() is necessary because we may race with the event
554  * becoming true; i.e. we see event false -> wait -> recheck condition, but the
555  * thread that made the event true may have called closure_wake_up() before we
556  * added ourself to the wait list.
557  *
558  * We have to call closure_sync() at the end instead of just
559  * __closure_end_sleep() because a different thread might've called
560  * closure_wake_up() before us and gotten preempted before they dropped the
561  * refcount on our closure. If this was a stack allocated closure, that would be
562  * bad.
563  */
564 #define __closure_wait_event(list, cl, condition, _block)		\
565 ({									\
566 	bool block = _block;						\
567 	typeof(condition) ret;						\
568 									\
569 	while (1) {							\
570 		ret = (condition);					\
571 		if (ret) {						\
572 			__closure_wake_up(list);			\
573 			if (block)					\
574 				closure_sync(cl);			\
575 									\
576 			break;						\
577 		}							\
578 									\
579 		if (block)						\
580 			__closure_start_sleep(cl);			\
581 									\
582 		if (!closure_wait(list, cl)) {				\
583 			if (!block)					\
584 				break;					\
585 									\
586 			schedule();					\
587 		}							\
588 	}								\
589 									\
590 	ret;								\
591 })
592 
593 /**
594  * closure_wait_event() - wait on a condition, synchronously or asynchronously.
595  * @list:	the wait list to wait on
596  * @cl:		the closure that is doing the waiting
597  * @condition:	a C expression for the event to wait for
598  *
599  * If the closure is in blocking mode, sleeps until the @condition evaluates to
600  * true - exactly like wait_event().
601  *
602  * If the closure is not in blocking mode, waits asynchronously; if the
603  * condition is currently false the @cl is put onto @list and returns. @list
604  * owns a refcount on @cl; closure_sync() or continue_at() may be used later to
605  * wait for another thread to wake up @list, which drops the refcount on @cl.
606  *
607  * Returns the value of @condition; @cl will be on @list iff @condition was
608  * false.
609  *
610  * closure_wake_up(@list) must be called after changing any variable that could
611  * cause @condition to become true.
612  */
613 #define closure_wait_event(list, cl, condition)				\
614 	__closure_wait_event(list, cl, condition, closure_blocking(cl))
615 
616 #define closure_wait_event_async(list, cl, condition)			\
617 	__closure_wait_event(list, cl, condition, false)
618 
619 #define closure_wait_event_sync(list, cl, condition)			\
620 	__closure_wait_event(list, cl, condition, true)
621 
set_closure_fn(struct closure * cl,closure_fn * fn,struct workqueue_struct * wq)622 static inline void set_closure_fn(struct closure *cl, closure_fn *fn,
623 				  struct workqueue_struct *wq)
624 {
625 	BUG_ON(object_is_on_stack(cl));
626 	closure_set_ip(cl);
627 	cl->fn = fn;
628 	cl->wq = wq;
629 	/* between atomic_dec() in closure_put() */
630 	smp_mb__before_atomic_dec();
631 }
632 
633 #define continue_at(_cl, _fn, _wq)					\
634 do {									\
635 	set_closure_fn(_cl, _fn, _wq);					\
636 	closure_sub(_cl, CLOSURE_RUNNING + 1);				\
637 	return;								\
638 } while (0)
639 
640 #define closure_return(_cl)	continue_at((_cl), NULL, NULL)
641 
642 #define continue_at_nobarrier(_cl, _fn, _wq)				\
643 do {									\
644 	set_closure_fn(_cl, _fn, _wq);					\
645 	closure_queue(cl);						\
646 	return;								\
647 } while (0)
648 
649 #define closure_return_with_destructor(_cl, _destructor)		\
650 do {									\
651 	set_closure_fn(_cl, _destructor, NULL);				\
652 	closure_sub(_cl, CLOSURE_RUNNING - CLOSURE_DESTRUCTOR + 1);	\
653 	return;								\
654 } while (0)
655 
closure_call(struct closure * cl,closure_fn fn,struct workqueue_struct * wq,struct closure * parent)656 static inline void closure_call(struct closure *cl, closure_fn fn,
657 				struct workqueue_struct *wq,
658 				struct closure *parent)
659 {
660 	closure_init(cl, parent);
661 	continue_at_nobarrier(cl, fn, wq);
662 }
663 
closure_trylock_call(struct closure * cl,closure_fn fn,struct workqueue_struct * wq,struct closure * parent)664 static inline void closure_trylock_call(struct closure *cl, closure_fn fn,
665 					struct workqueue_struct *wq,
666 					struct closure *parent)
667 {
668 	if (closure_trylock(cl, parent))
669 		continue_at_nobarrier(cl, fn, wq);
670 }
671 
672 #endif /* _LINUX_CLOSURE_H */
673