1 /*
2  * workqueue.h --- work queue handling for Linux.
3  */
4 
5 #ifndef _LINUX_WORKQUEUE_H
6 #define _LINUX_WORKQUEUE_H
7 
8 #include <linux/timer.h>
9 #include <linux/linkage.h>
10 #include <linux/bitops.h>
11 #include <linux/lockdep.h>
12 #include <linux/threads.h>
13 #include <linux/atomic.h>
14 
15 struct workqueue_struct;
16 
17 struct work_struct;
18 typedef void (*work_func_t)(struct work_struct *work);
19 
20 /*
21  * The first word is the work queue pointer and the flags rolled into
22  * one
23  */
24 #define work_data_bits(work) ((unsigned long *)(&(work)->data))
25 
26 enum {
27 	WORK_STRUCT_PENDING_BIT	= 0,	/* work item is pending execution */
28 	WORK_STRUCT_DELAYED_BIT	= 1,	/* work item is delayed */
29 	WORK_STRUCT_CWQ_BIT	= 2,	/* data points to cwq */
30 	WORK_STRUCT_LINKED_BIT	= 3,	/* next work is linked to this one */
31 #ifdef CONFIG_DEBUG_OBJECTS_WORK
32 	WORK_STRUCT_STATIC_BIT	= 4,	/* static initializer (debugobjects) */
33 	WORK_STRUCT_COLOR_SHIFT	= 5,	/* color for workqueue flushing */
34 #else
35 	WORK_STRUCT_COLOR_SHIFT	= 4,	/* color for workqueue flushing */
36 #endif
37 
38 	WORK_STRUCT_COLOR_BITS	= 4,
39 
40 	WORK_STRUCT_PENDING	= 1 << WORK_STRUCT_PENDING_BIT,
41 	WORK_STRUCT_DELAYED	= 1 << WORK_STRUCT_DELAYED_BIT,
42 	WORK_STRUCT_CWQ		= 1 << WORK_STRUCT_CWQ_BIT,
43 	WORK_STRUCT_LINKED	= 1 << WORK_STRUCT_LINKED_BIT,
44 #ifdef CONFIG_DEBUG_OBJECTS_WORK
45 	WORK_STRUCT_STATIC	= 1 << WORK_STRUCT_STATIC_BIT,
46 #else
47 	WORK_STRUCT_STATIC	= 0,
48 #endif
49 
50 	/*
51 	 * The last color is no color used for works which don't
52 	 * participate in workqueue flushing.
53 	 */
54 	WORK_NR_COLORS		= (1 << WORK_STRUCT_COLOR_BITS) - 1,
55 	WORK_NO_COLOR		= WORK_NR_COLORS,
56 
57 	/* special cpu IDs */
58 	WORK_CPU_UNBOUND	= NR_CPUS,
59 	WORK_CPU_NONE		= NR_CPUS + 1,
60 	WORK_CPU_LAST		= WORK_CPU_NONE,
61 
62 	/*
63 	 * Reserve 7 bits off of cwq pointer w/ debugobjects turned
64 	 * off.  This makes cwqs aligned to 256 bytes and allows 15
65 	 * workqueue flush colors.
66 	 */
67 	WORK_STRUCT_FLAG_BITS	= WORK_STRUCT_COLOR_SHIFT +
68 				  WORK_STRUCT_COLOR_BITS,
69 
70 	WORK_STRUCT_FLAG_MASK	= (1UL << WORK_STRUCT_FLAG_BITS) - 1,
71 	WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
72 	WORK_STRUCT_NO_CPU	= WORK_CPU_NONE << WORK_STRUCT_FLAG_BITS,
73 
74 	/* bit mask for work_busy() return values */
75 	WORK_BUSY_PENDING	= 1 << 0,
76 	WORK_BUSY_RUNNING	= 1 << 1,
77 };
78 
79 struct work_struct {
80 	atomic_long_t data;
81 	struct list_head entry;
82 	work_func_t func;
83 #ifdef CONFIG_LOCKDEP
84 	struct lockdep_map lockdep_map;
85 #endif
86 };
87 
88 #define WORK_DATA_INIT()	ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU)
89 #define WORK_DATA_STATIC_INIT()	\
90 	ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU | WORK_STRUCT_STATIC)
91 
92 struct delayed_work {
93 	struct work_struct work;
94 	struct timer_list timer;
95 };
96 
to_delayed_work(struct work_struct * work)97 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
98 {
99 	return container_of(work, struct delayed_work, work);
100 }
101 
102 struct execute_work {
103 	struct work_struct work;
104 };
105 
106 #ifdef CONFIG_LOCKDEP
107 /*
108  * NB: because we have to copy the lockdep_map, setting _key
109  * here is required, otherwise it could get initialised to the
110  * copy of the lockdep_map!
111  */
112 #define __WORK_INIT_LOCKDEP_MAP(n, k) \
113 	.lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
114 #else
115 #define __WORK_INIT_LOCKDEP_MAP(n, k)
116 #endif
117 
118 #define __WORK_INITIALIZER(n, f) {				\
119 	.data = WORK_DATA_STATIC_INIT(),			\
120 	.entry	= { &(n).entry, &(n).entry },			\
121 	.func = (f),						\
122 	__WORK_INIT_LOCKDEP_MAP(#n, &(n))			\
123 	}
124 
125 #define __DELAYED_WORK_INITIALIZER(n, f) {			\
126 	.work = __WORK_INITIALIZER((n).work, (f)),		\
127 	.timer = TIMER_INITIALIZER(NULL, 0, 0),			\
128 	}
129 
130 #define __DEFERRED_WORK_INITIALIZER(n, f) {			\
131 	.work = __WORK_INITIALIZER((n).work, (f)),		\
132 	.timer = TIMER_DEFERRED_INITIALIZER(NULL, 0, 0),	\
133 	}
134 
135 #define DECLARE_WORK(n, f)					\
136 	struct work_struct n = __WORK_INITIALIZER(n, f)
137 
138 #define DECLARE_DELAYED_WORK(n, f)				\
139 	struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f)
140 
141 #define DECLARE_DEFERRED_WORK(n, f)				\
142 	struct delayed_work n = __DEFERRED_WORK_INITIALIZER(n, f)
143 
144 /*
145  * initialize a work item's function pointer
146  */
147 #define PREPARE_WORK(_work, _func)				\
148 	do {							\
149 		(_work)->func = (_func);			\
150 	} while (0)
151 
152 #define PREPARE_DELAYED_WORK(_work, _func)			\
153 	PREPARE_WORK(&(_work)->work, (_func))
154 
155 #ifdef CONFIG_DEBUG_OBJECTS_WORK
156 extern void __init_work(struct work_struct *work, int onstack);
157 extern void destroy_work_on_stack(struct work_struct *work);
work_static(struct work_struct * work)158 static inline unsigned int work_static(struct work_struct *work)
159 {
160 	return *work_data_bits(work) & WORK_STRUCT_STATIC;
161 }
162 #else
__init_work(struct work_struct * work,int onstack)163 static inline void __init_work(struct work_struct *work, int onstack) { }
destroy_work_on_stack(struct work_struct * work)164 static inline void destroy_work_on_stack(struct work_struct *work) { }
work_static(struct work_struct * work)165 static inline unsigned int work_static(struct work_struct *work) { return 0; }
166 #endif
167 
168 /*
169  * initialize all of a work item in one go
170  *
171  * NOTE! No point in using "atomic_long_set()": using a direct
172  * assignment of the work data initializer allows the compiler
173  * to generate better code.
174  */
175 #ifdef CONFIG_LOCKDEP
176 #define __INIT_WORK(_work, _func, _onstack)				\
177 	do {								\
178 		static struct lock_class_key __key;			\
179 									\
180 		__init_work((_work), _onstack);				\
181 		(_work)->data = (atomic_long_t) WORK_DATA_INIT();	\
182 		lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0);\
183 		INIT_LIST_HEAD(&(_work)->entry);			\
184 		PREPARE_WORK((_work), (_func));				\
185 	} while (0)
186 #else
187 #define __INIT_WORK(_work, _func, _onstack)				\
188 	do {								\
189 		__init_work((_work), _onstack);				\
190 		(_work)->data = (atomic_long_t) WORK_DATA_INIT();	\
191 		INIT_LIST_HEAD(&(_work)->entry);			\
192 		PREPARE_WORK((_work), (_func));				\
193 	} while (0)
194 #endif
195 
196 #define INIT_WORK(_work, _func)					\
197 	do {							\
198 		__INIT_WORK((_work), (_func), 0);		\
199 	} while (0)
200 
201 #define INIT_WORK_ONSTACK(_work, _func)				\
202 	do {							\
203 		__INIT_WORK((_work), (_func), 1);		\
204 	} while (0)
205 
206 #define INIT_DELAYED_WORK(_work, _func)				\
207 	do {							\
208 		INIT_WORK(&(_work)->work, (_func));		\
209 		init_timer(&(_work)->timer);			\
210 	} while (0)
211 
212 #define INIT_DELAYED_WORK_ONSTACK(_work, _func)			\
213 	do {							\
214 		INIT_WORK_ONSTACK(&(_work)->work, (_func));	\
215 		init_timer_on_stack(&(_work)->timer);		\
216 	} while (0)
217 
218 #define INIT_DELAYED_WORK_DEFERRABLE(_work, _func)		\
219 	do {							\
220 		INIT_WORK(&(_work)->work, (_func));		\
221 		init_timer_deferrable(&(_work)->timer);		\
222 	} while (0)
223 
224 /**
225  * work_pending - Find out whether a work item is currently pending
226  * @work: The work item in question
227  */
228 #define work_pending(work) \
229 	test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
230 
231 /**
232  * delayed_work_pending - Find out whether a delayable work item is currently
233  * pending
234  * @work: The work item in question
235  */
236 #define delayed_work_pending(w) \
237 	work_pending(&(w)->work)
238 
239 /**
240  * work_clear_pending - for internal use only, mark a work item as not pending
241  * @work: The work item in question
242  */
243 #define work_clear_pending(work) \
244 	clear_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
245 
246 /*
247  * Workqueue flags and constants.  For details, please refer to
248  * Documentation/workqueue.txt.
249  */
250 enum {
251 	WQ_NON_REENTRANT	= 1 << 0, /* guarantee non-reentrance */
252 	WQ_UNBOUND		= 1 << 1, /* not bound to any cpu */
253 	WQ_FREEZABLE		= 1 << 2, /* freeze during suspend */
254 	WQ_MEM_RECLAIM		= 1 << 3, /* may be used for memory reclaim */
255 	WQ_HIGHPRI		= 1 << 4, /* high priority */
256 	WQ_CPU_INTENSIVE	= 1 << 5, /* cpu instensive workqueue */
257 
258 	WQ_DRAINING		= 1 << 6, /* internal: workqueue is draining */
259 	WQ_RESCUER		= 1 << 7, /* internal: workqueue has rescuer */
260 
261 	WQ_MAX_ACTIVE		= 512,	  /* I like 512, better ideas? */
262 	WQ_MAX_UNBOUND_PER_CPU	= 4,	  /* 4 * #cpus for unbound wq */
263 	WQ_DFL_ACTIVE		= WQ_MAX_ACTIVE / 2,
264 };
265 
266 /* unbound wq's aren't per-cpu, scale max_active according to #cpus */
267 #define WQ_UNBOUND_MAX_ACTIVE	\
268 	max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
269 
270 /*
271  * System-wide workqueues which are always present.
272  *
273  * system_wq is the one used by schedule[_delayed]_work[_on]().
274  * Multi-CPU multi-threaded.  There are users which expect relatively
275  * short queue flush time.  Don't queue works which can run for too
276  * long.
277  *
278  * system_long_wq is similar to system_wq but may host long running
279  * works.  Queue flushing might take relatively long.
280  *
281  * system_nrt_wq is non-reentrant and guarantees that any given work
282  * item is never executed in parallel by multiple CPUs.  Queue
283  * flushing might take relatively long.
284  *
285  * system_unbound_wq is unbound workqueue.  Workers are not bound to
286  * any specific CPU, not concurrency managed, and all queued works are
287  * executed immediately as long as max_active limit is not reached and
288  * resources are available.
289  *
290  * system_freezable_wq is equivalent to system_wq except that it's
291  * freezable.
292  *
293  * system_nrt_freezable_wq is equivalent to system_nrt_wq except that
294  * it's freezable.
295  */
296 extern struct workqueue_struct *system_wq;
297 extern struct workqueue_struct *system_long_wq;
298 extern struct workqueue_struct *system_nrt_wq;
299 extern struct workqueue_struct *system_unbound_wq;
300 extern struct workqueue_struct *system_freezable_wq;
301 extern struct workqueue_struct *system_nrt_freezable_wq;
302 
303 extern struct workqueue_struct *
304 __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
305 	struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
306 
307 /**
308  * alloc_workqueue - allocate a workqueue
309  * @fmt: printf format for the name of the workqueue
310  * @flags: WQ_* flags
311  * @max_active: max in-flight work items, 0 for default
312  * @args: args for @fmt
313  *
314  * Allocate a workqueue with the specified parameters.  For detailed
315  * information on WQ_* flags, please refer to Documentation/workqueue.txt.
316  *
317  * The __lock_name macro dance is to guarantee that single lock_class_key
318  * doesn't end up with different namesm, which isn't allowed by lockdep.
319  *
320  * RETURNS:
321  * Pointer to the allocated workqueue on success, %NULL on failure.
322  */
323 #ifdef CONFIG_LOCKDEP
324 #define alloc_workqueue(fmt, flags, max_active, args...)	\
325 ({								\
326 	static struct lock_class_key __key;			\
327 	const char *__lock_name;				\
328 								\
329 	if (__builtin_constant_p(fmt))				\
330 		__lock_name = (fmt);				\
331 	else							\
332 		__lock_name = #fmt;				\
333 								\
334 	__alloc_workqueue_key((fmt), (flags), (max_active),	\
335 			      &__key, __lock_name, ##args);	\
336 })
337 #else
338 #define alloc_workqueue(fmt, flags, max_active, args...)	\
339 	__alloc_workqueue_key((fmt), (flags), (max_active),	\
340 			      NULL, NULL, ##args)
341 #endif
342 
343 /**
344  * alloc_ordered_workqueue - allocate an ordered workqueue
345  * @fmt: printf format for the name of the workqueue
346  * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
347  * @args: args for @fmt
348  *
349  * Allocate an ordered workqueue.  An ordered workqueue executes at
350  * most one work item at any given time in the queued order.  They are
351  * implemented as unbound workqueues with @max_active of one.
352  *
353  * RETURNS:
354  * Pointer to the allocated workqueue on success, %NULL on failure.
355  */
356 #define alloc_ordered_workqueue(fmt, flags, args...)		\
357 	alloc_workqueue(fmt, WQ_UNBOUND | (flags), 1, ##args)
358 
359 #define create_workqueue(name)					\
360 	alloc_workqueue((name), WQ_MEM_RECLAIM, 1)
361 #define create_freezable_workqueue(name)			\
362 	alloc_workqueue((name), WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
363 #define create_singlethread_workqueue(name)			\
364 	alloc_workqueue((name), WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
365 
366 extern void destroy_workqueue(struct workqueue_struct *wq);
367 
368 extern int queue_work(struct workqueue_struct *wq, struct work_struct *work);
369 extern int queue_work_on(int cpu, struct workqueue_struct *wq,
370 			struct work_struct *work);
371 extern int queue_delayed_work(struct workqueue_struct *wq,
372 			struct delayed_work *work, unsigned long delay);
373 extern int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
374 			struct delayed_work *work, unsigned long delay);
375 
376 extern void flush_workqueue(struct workqueue_struct *wq);
377 extern void drain_workqueue(struct workqueue_struct *wq);
378 extern void flush_scheduled_work(void);
379 
380 extern int schedule_work(struct work_struct *work);
381 extern int schedule_work_on(int cpu, struct work_struct *work);
382 extern int schedule_delayed_work(struct delayed_work *work, unsigned long delay);
383 extern int schedule_delayed_work_on(int cpu, struct delayed_work *work,
384 					unsigned long delay);
385 extern int schedule_on_each_cpu(work_func_t func);
386 extern int keventd_up(void);
387 
388 int execute_in_process_context(work_func_t fn, struct execute_work *);
389 
390 extern bool flush_work(struct work_struct *work);
391 extern bool flush_work_sync(struct work_struct *work);
392 extern bool cancel_work_sync(struct work_struct *work);
393 
394 extern bool flush_delayed_work(struct delayed_work *dwork);
395 extern bool flush_delayed_work_sync(struct delayed_work *work);
396 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
397 
398 extern void workqueue_set_max_active(struct workqueue_struct *wq,
399 				     int max_active);
400 extern bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq);
401 extern unsigned int work_cpu(struct work_struct *work);
402 extern unsigned int work_busy(struct work_struct *work);
403 
404 /*
405  * Kill off a pending schedule_delayed_work().  Note that the work callback
406  * function may still be running on return from cancel_delayed_work(), unless
407  * it returns 1 and the work doesn't re-arm itself. Run flush_workqueue() or
408  * cancel_work_sync() to wait on it.
409  */
cancel_delayed_work(struct delayed_work * work)410 static inline bool cancel_delayed_work(struct delayed_work *work)
411 {
412 	bool ret;
413 
414 	ret = del_timer_sync(&work->timer);
415 	if (ret)
416 		work_clear_pending(&work->work);
417 	return ret;
418 }
419 
420 /*
421  * Like above, but uses del_timer() instead of del_timer_sync(). This means,
422  * if it returns 0 the timer function may be running and the queueing is in
423  * progress.
424  */
__cancel_delayed_work(struct delayed_work * work)425 static inline bool __cancel_delayed_work(struct delayed_work *work)
426 {
427 	bool ret;
428 
429 	ret = del_timer(&work->timer);
430 	if (ret)
431 		work_clear_pending(&work->work);
432 	return ret;
433 }
434 
435 #ifndef CONFIG_SMP
work_on_cpu(unsigned int cpu,long (* fn)(void *),void * arg)436 static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
437 {
438 	return fn(arg);
439 }
440 #else
441 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg);
442 #endif /* CONFIG_SMP */
443 
444 #ifdef CONFIG_FREEZER
445 extern void freeze_workqueues_begin(void);
446 extern bool freeze_workqueues_busy(void);
447 extern void thaw_workqueues(void);
448 #endif /* CONFIG_FREEZER */
449 
450 #endif
451