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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 #include <linux/cpumask.h>
15
16 struct workqueue_struct;
17
18 struct work_struct;
19 typedef void (*work_func_t)(struct work_struct *work);
20 void delayed_work_timer_fn(unsigned long __data);
21
22 /*
23 * The first word is the work queue pointer and the flags rolled into
24 * one
25 */
26 #define work_data_bits(work) ((unsigned long *)(&(work)->data))
27
28 enum {
29 WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */
30 WORK_STRUCT_DELAYED_BIT = 1, /* work item is delayed */
31 WORK_STRUCT_PWQ_BIT = 2, /* data points to pwq */
32 WORK_STRUCT_LINKED_BIT = 3, /* next work is linked to this one */
33 #ifdef CONFIG_DEBUG_OBJECTS_WORK
34 WORK_STRUCT_STATIC_BIT = 4, /* static initializer (debugobjects) */
35 WORK_STRUCT_COLOR_SHIFT = 5, /* color for workqueue flushing */
36 #else
37 WORK_STRUCT_COLOR_SHIFT = 4, /* color for workqueue flushing */
38 #endif
39
40 WORK_STRUCT_COLOR_BITS = 4,
41
42 WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
43 WORK_STRUCT_DELAYED = 1 << WORK_STRUCT_DELAYED_BIT,
44 WORK_STRUCT_PWQ = 1 << WORK_STRUCT_PWQ_BIT,
45 WORK_STRUCT_LINKED = 1 << WORK_STRUCT_LINKED_BIT,
46 #ifdef CONFIG_DEBUG_OBJECTS_WORK
47 WORK_STRUCT_STATIC = 1 << WORK_STRUCT_STATIC_BIT,
48 #else
49 WORK_STRUCT_STATIC = 0,
50 #endif
51
52 /*
53 * The last color is no color used for works which don't
54 * participate in workqueue flushing.
55 */
56 WORK_NR_COLORS = (1 << WORK_STRUCT_COLOR_BITS) - 1,
57 WORK_NO_COLOR = WORK_NR_COLORS,
58
59 /* not bound to any CPU, prefer the local CPU */
60 WORK_CPU_UNBOUND = NR_CPUS,
61
62 /*
63 * Reserve 7 bits off of pwq pointer w/ debugobjects turned off.
64 * This makes pwqs aligned to 256 bytes and allows 15 workqueue
65 * flush colors.
66 */
67 WORK_STRUCT_FLAG_BITS = WORK_STRUCT_COLOR_SHIFT +
68 WORK_STRUCT_COLOR_BITS,
69
70 /* data contains off-queue information when !WORK_STRUCT_PWQ */
71 WORK_OFFQ_FLAG_BASE = WORK_STRUCT_COLOR_SHIFT,
72
73 WORK_OFFQ_CANCELING = (1 << WORK_OFFQ_FLAG_BASE),
74
75 /*
76 * When a work item is off queue, its high bits point to the last
77 * pool it was on. Cap at 31 bits and use the highest number to
78 * indicate that no pool is associated.
79 */
80 WORK_OFFQ_FLAG_BITS = 1,
81 WORK_OFFQ_POOL_SHIFT = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
82 WORK_OFFQ_LEFT = BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
83 WORK_OFFQ_POOL_BITS = WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
84 WORK_OFFQ_POOL_NONE = (1LU << WORK_OFFQ_POOL_BITS) - 1,
85
86 /* convenience constants */
87 WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
88 WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
89 WORK_STRUCT_NO_POOL = (unsigned long)WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT,
90
91 /* bit mask for work_busy() return values */
92 WORK_BUSY_PENDING = 1 << 0,
93 WORK_BUSY_RUNNING = 1 << 1,
94
95 /* maximum string length for set_worker_desc() */
96 WORKER_DESC_LEN = 24,
97 };
98
99 struct work_struct {
100 atomic_long_t data;
101 struct list_head entry;
102 work_func_t func;
103 #ifdef CONFIG_LOCKDEP
104 struct lockdep_map lockdep_map;
105 #endif
106 };
107
108 #define WORK_DATA_INIT() ATOMIC_LONG_INIT(WORK_STRUCT_NO_POOL)
109 #define WORK_DATA_STATIC_INIT() \
110 ATOMIC_LONG_INIT(WORK_STRUCT_NO_POOL | WORK_STRUCT_STATIC)
111
112 struct delayed_work {
113 struct work_struct work;
114 struct timer_list timer;
115
116 /* target workqueue and CPU ->timer uses to queue ->work */
117 struct workqueue_struct *wq;
118 int cpu;
119 };
120
121 /*
122 * A struct for workqueue attributes. This can be used to change
123 * attributes of an unbound workqueue.
124 *
125 * Unlike other fields, ->no_numa isn't a property of a worker_pool. It
126 * only modifies how apply_workqueue_attrs() select pools and thus doesn't
127 * participate in pool hash calculations or equality comparisons.
128 */
129 struct workqueue_attrs {
130 int nice; /* nice level */
131 cpumask_var_t cpumask; /* allowed CPUs */
132 bool no_numa; /* disable NUMA affinity */
133 };
134
135 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
136 {
137 return container_of(work, struct delayed_work, work);
138 }
139
140 struct execute_work {
141 struct work_struct work;
142 };
143
144 #ifdef CONFIG_LOCKDEP
145 /*
146 * NB: because we have to copy the lockdep_map, setting _key
147 * here is required, otherwise it could get initialised to the
148 * copy of the lockdep_map!
149 */
150 #define __WORK_INIT_LOCKDEP_MAP(n, k) \
151 .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
152 #else
153 #define __WORK_INIT_LOCKDEP_MAP(n, k)
154 #endif
155
156 #define __WORK_INITIALIZER(n, f) { \
157 .data = WORK_DATA_STATIC_INIT(), \
158 .entry = { &(n).entry, &(n).entry }, \
159 .func = (f), \
160 __WORK_INIT_LOCKDEP_MAP(#n, &(n)) \
161 }
162
163 #define __DELAYED_WORK_INITIALIZER(n, f, tflags) { \
164 .work = __WORK_INITIALIZER((n).work, (f)), \
165 .timer = __TIMER_INITIALIZER(delayed_work_timer_fn, \
166 0, (unsigned long)&(n), \
167 (tflags) | TIMER_IRQSAFE), \
168 }
169
170 #define DECLARE_WORK(n, f) \
171 struct work_struct n = __WORK_INITIALIZER(n, f)
172
173 #define DECLARE_DELAYED_WORK(n, f) \
174 struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
175
176 #define DECLARE_DEFERRABLE_WORK(n, f) \
177 struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
178
179 #ifdef CONFIG_DEBUG_OBJECTS_WORK
180 extern void __init_work(struct work_struct *work, int onstack);
181 extern void destroy_work_on_stack(struct work_struct *work);
182 extern void destroy_delayed_work_on_stack(struct delayed_work *work);
183 static inline unsigned int work_static(struct work_struct *work)
184 {
185 return *work_data_bits(work) & WORK_STRUCT_STATIC;
186 }
187 #else
188 static inline void __init_work(struct work_struct *work, int onstack) { }
189 static inline void destroy_work_on_stack(struct work_struct *work) { }
190 static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
191 static inline unsigned int work_static(struct work_struct *work) { return 0; }
192 #endif
193
194 /*
195 * initialize all of a work item in one go
196 *
197 * NOTE! No point in using "atomic_long_set()": using a direct
198 * assignment of the work data initializer allows the compiler
199 * to generate better code.
200 */
201 #ifdef CONFIG_LOCKDEP
202 #define __INIT_WORK(_work, _func, _onstack) \
203 do { \
204 static struct lock_class_key __key; \
205 \
206 __init_work((_work), _onstack); \
207 (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
208 lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0); \
209 INIT_LIST_HEAD(&(_work)->entry); \
210 (_work)->func = (_func); \
211 } while (0)
212 #else
213 #define __INIT_WORK(_work, _func, _onstack) \
214 do { \
215 __init_work((_work), _onstack); \
216 (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
217 INIT_LIST_HEAD(&(_work)->entry); \
218 (_work)->func = (_func); \
219 } while (0)
220 #endif
221
222 #define INIT_WORK(_work, _func) \
223 __INIT_WORK((_work), (_func), 0)
224
225 #define INIT_WORK_ONSTACK(_work, _func) \
226 __INIT_WORK((_work), (_func), 1)
227
228 #define __INIT_DELAYED_WORK(_work, _func, _tflags) \
229 do { \
230 INIT_WORK(&(_work)->work, (_func)); \
231 __setup_timer(&(_work)->timer, delayed_work_timer_fn, \
232 (unsigned long)(_work), \
233 (_tflags) | TIMER_IRQSAFE); \
234 } while (0)
235
236 #define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags) \
237 do { \
238 INIT_WORK_ONSTACK(&(_work)->work, (_func)); \
239 __setup_timer_on_stack(&(_work)->timer, \
240 delayed_work_timer_fn, \
241 (unsigned long)(_work), \
242 (_tflags) | TIMER_IRQSAFE); \
243 } while (0)
244
245 #define INIT_DELAYED_WORK(_work, _func) \
246 __INIT_DELAYED_WORK(_work, _func, 0)
247
248 #define INIT_DELAYED_WORK_ONSTACK(_work, _func) \
249 __INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
250
251 #define INIT_DEFERRABLE_WORK(_work, _func) \
252 __INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
253
254 #define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func) \
255 __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
256
257 /**
258 * work_pending - Find out whether a work item is currently pending
259 * @work: The work item in question
260 */
261 #define work_pending(work) \
262 test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
263
264 /**
265 * delayed_work_pending - Find out whether a delayable work item is currently
266 * pending
267 * @work: The work item in question
268 */
269 #define delayed_work_pending(w) \
270 work_pending(&(w)->work)
271
272 /*
273 * Workqueue flags and constants. For details, please refer to
274 * Documentation/workqueue.txt.
275 */
276 enum {
277 WQ_UNBOUND = 1 << 1, /* not bound to any cpu */
278 WQ_FREEZABLE = 1 << 2, /* freeze during suspend */
279 WQ_MEM_RECLAIM = 1 << 3, /* may be used for memory reclaim */
280 WQ_HIGHPRI = 1 << 4, /* high priority */
281 WQ_CPU_INTENSIVE = 1 << 5, /* cpu intensive workqueue */
282 WQ_SYSFS = 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
283
284 /*
285 * Per-cpu workqueues are generally preferred because they tend to
286 * show better performance thanks to cache locality. Per-cpu
287 * workqueues exclude the scheduler from choosing the CPU to
288 * execute the worker threads, which has an unfortunate side effect
289 * of increasing power consumption.
290 *
291 * The scheduler considers a CPU idle if it doesn't have any task
292 * to execute and tries to keep idle cores idle to conserve power;
293 * however, for example, a per-cpu work item scheduled from an
294 * interrupt handler on an idle CPU will force the scheduler to
295 * excute the work item on that CPU breaking the idleness, which in
296 * turn may lead to more scheduling choices which are sub-optimal
297 * in terms of power consumption.
298 *
299 * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
300 * but become unbound if workqueue.power_efficient kernel param is
301 * specified. Per-cpu workqueues which are identified to
302 * contribute significantly to power-consumption are identified and
303 * marked with this flag and enabling the power_efficient mode
304 * leads to noticeable power saving at the cost of small
305 * performance disadvantage.
306 *
307 * http://thread.gmane.org/gmane.linux.kernel/1480396
308 */
309 WQ_POWER_EFFICIENT = 1 << 7,
310
311 __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */
312 __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */
313
314 WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */
315 WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
316 WQ_DFL_ACTIVE = WQ_MAX_ACTIVE / 2,
317 };
318
319 /* unbound wq's aren't per-cpu, scale max_active according to #cpus */
320 #define WQ_UNBOUND_MAX_ACTIVE \
321 max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
322
323 /*
324 * System-wide workqueues which are always present.
325 *
326 * system_wq is the one used by schedule[_delayed]_work[_on]().
327 * Multi-CPU multi-threaded. There are users which expect relatively
328 * short queue flush time. Don't queue works which can run for too
329 * long.
330 *
331 * system_highpri_wq is similar to system_wq but for work items which
332 * require WQ_HIGHPRI.
333 *
334 * system_long_wq is similar to system_wq but may host long running
335 * works. Queue flushing might take relatively long.
336 *
337 * system_unbound_wq is unbound workqueue. Workers are not bound to
338 * any specific CPU, not concurrency managed, and all queued works are
339 * executed immediately as long as max_active limit is not reached and
340 * resources are available.
341 *
342 * system_freezable_wq is equivalent to system_wq except that it's
343 * freezable.
344 *
345 * *_power_efficient_wq are inclined towards saving power and converted
346 * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
347 * they are same as their non-power-efficient counterparts - e.g.
348 * system_power_efficient_wq is identical to system_wq if
349 * 'wq_power_efficient' is disabled. See WQ_POWER_EFFICIENT for more info.
350 */
351 extern struct workqueue_struct *system_wq;
352 extern struct workqueue_struct *system_highpri_wq;
353 extern struct workqueue_struct *system_long_wq;
354 extern struct workqueue_struct *system_unbound_wq;
355 extern struct workqueue_struct *system_freezable_wq;
356 extern struct workqueue_struct *system_power_efficient_wq;
357 extern struct workqueue_struct *system_freezable_power_efficient_wq;
358
359 extern struct workqueue_struct *
360 __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
361 struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
362
363 /**
364 * alloc_workqueue - allocate a workqueue
365 * @fmt: printf format for the name of the workqueue
366 * @flags: WQ_* flags
367 * @max_active: max in-flight work items, 0 for default
368 * @args: args for @fmt
369 *
370 * Allocate a workqueue with the specified parameters. For detailed
371 * information on WQ_* flags, please refer to Documentation/workqueue.txt.
372 *
373 * The __lock_name macro dance is to guarantee that single lock_class_key
374 * doesn't end up with different namesm, which isn't allowed by lockdep.
375 *
376 * RETURNS:
377 * Pointer to the allocated workqueue on success, %NULL on failure.
378 */
379 #ifdef CONFIG_LOCKDEP
380 #define alloc_workqueue(fmt, flags, max_active, args...) \
381 ({ \
382 static struct lock_class_key __key; \
383 const char *__lock_name; \
384 \
385 __lock_name = #fmt#args; \
386 \
387 __alloc_workqueue_key((fmt), (flags), (max_active), \
388 &__key, __lock_name, ##args); \
389 })
390 #else
391 #define alloc_workqueue(fmt, flags, max_active, args...) \
392 __alloc_workqueue_key((fmt), (flags), (max_active), \
393 NULL, NULL, ##args)
394 #endif
395
396 /**
397 * alloc_ordered_workqueue - allocate an ordered workqueue
398 * @fmt: printf format for the name of the workqueue
399 * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
400 * @args: args for @fmt
401 *
402 * Allocate an ordered workqueue. An ordered workqueue executes at
403 * most one work item at any given time in the queued order. They are
404 * implemented as unbound workqueues with @max_active of one.
405 *
406 * RETURNS:
407 * Pointer to the allocated workqueue on success, %NULL on failure.
408 */
409 #define alloc_ordered_workqueue(fmt, flags, args...) \
410 alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args)
411
412 #define create_workqueue(name) \
413 alloc_workqueue("%s", WQ_MEM_RECLAIM, 1, (name))
414 #define create_freezable_workqueue(name) \
415 alloc_workqueue("%s", WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, \
416 1, (name))
417 #define create_singlethread_workqueue(name) \
418 alloc_ordered_workqueue("%s", WQ_MEM_RECLAIM, name)
419
420 extern void destroy_workqueue(struct workqueue_struct *wq);
421
422 struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
423 void free_workqueue_attrs(struct workqueue_attrs *attrs);
424 int apply_workqueue_attrs(struct workqueue_struct *wq,
425 const struct workqueue_attrs *attrs);
426
427 extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
428 struct work_struct *work);
429 extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
430 struct delayed_work *work, unsigned long delay);
431 extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
432 struct delayed_work *dwork, unsigned long delay);
433
434 extern void flush_workqueue(struct workqueue_struct *wq);
435 extern void drain_workqueue(struct workqueue_struct *wq);
436 extern void flush_scheduled_work(void);
437
438 extern int schedule_on_each_cpu(work_func_t func);
439
440 int execute_in_process_context(work_func_t fn, struct execute_work *);
441
442 extern bool flush_work(struct work_struct *work);
443 extern bool cancel_work_sync(struct work_struct *work);
444
445 extern bool flush_delayed_work(struct delayed_work *dwork);
446 extern bool cancel_delayed_work(struct delayed_work *dwork);
447 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
448
449 extern void workqueue_set_max_active(struct workqueue_struct *wq,
450 int max_active);
451 extern bool current_is_workqueue_rescuer(void);
452 extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
453 extern unsigned int work_busy(struct work_struct *work);
454 extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
455 extern void print_worker_info(const char *log_lvl, struct task_struct *task);
456
457 /**
458 * queue_work - queue work on a workqueue
459 * @wq: workqueue to use
460 * @work: work to queue
461 *
462 * Returns %false if @work was already on a queue, %true otherwise.
463 *
464 * We queue the work to the CPU on which it was submitted, but if the CPU dies
465 * it can be processed by another CPU.
466 */
467 static inline bool queue_work(struct workqueue_struct *wq,
468 struct work_struct *work)
469 {
470 return queue_work_on(WORK_CPU_UNBOUND, wq, work);
471 }
472
473 /**
474 * queue_delayed_work - queue work on a workqueue after delay
475 * @wq: workqueue to use
476 * @dwork: delayable work to queue
477 * @delay: number of jiffies to wait before queueing
478 *
479 * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
480 */
481 static inline bool queue_delayed_work(struct workqueue_struct *wq,
482 struct delayed_work *dwork,
483 unsigned long delay)
484 {
485 return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
486 }
487
488 /**
489 * mod_delayed_work - modify delay of or queue a delayed work
490 * @wq: workqueue to use
491 * @dwork: work to queue
492 * @delay: number of jiffies to wait before queueing
493 *
494 * mod_delayed_work_on() on local CPU.
495 */
496 static inline bool mod_delayed_work(struct workqueue_struct *wq,
497 struct delayed_work *dwork,
498 unsigned long delay)
499 {
500 return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
501 }
502
503 /**
504 * schedule_work_on - put work task on a specific cpu
505 * @cpu: cpu to put the work task on
506 * @work: job to be done
507 *
508 * This puts a job on a specific cpu
509 */
510 static inline bool schedule_work_on(int cpu, struct work_struct *work)
511 {
512 return queue_work_on(cpu, system_wq, work);
513 }
514
515 /**
516 * schedule_work - put work task in global workqueue
517 * @work: job to be done
518 *
519 * Returns %false if @work was already on the kernel-global workqueue and
520 * %true otherwise.
521 *
522 * This puts a job in the kernel-global workqueue if it was not already
523 * queued and leaves it in the same position on the kernel-global
524 * workqueue otherwise.
525 */
526 static inline bool schedule_work(struct work_struct *work)
527 {
528 return queue_work(system_wq, work);
529 }
530
531 /**
532 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
533 * @cpu: cpu to use
534 * @dwork: job to be done
535 * @delay: number of jiffies to wait
536 *
537 * After waiting for a given time this puts a job in the kernel-global
538 * workqueue on the specified CPU.
539 */
540 static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
541 unsigned long delay)
542 {
543 return queue_delayed_work_on(cpu, system_wq, dwork, delay);
544 }
545
546 /**
547 * schedule_delayed_work - put work task in global workqueue after delay
548 * @dwork: job to be done
549 * @delay: number of jiffies to wait or 0 for immediate execution
550 *
551 * After waiting for a given time this puts a job in the kernel-global
552 * workqueue.
553 */
554 static inline bool schedule_delayed_work(struct delayed_work *dwork,
555 unsigned long delay)
556 {
557 return queue_delayed_work(system_wq, dwork, delay);
558 }
559
560 /**
561 * keventd_up - is workqueue initialized yet?
562 */
563 static inline bool keventd_up(void)
564 {
565 return system_wq != NULL;
566 }
567
568 #ifndef CONFIG_SMP
569 static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
570 {
571 return fn(arg);
572 }
573 #else
574 long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
575 #endif /* CONFIG_SMP */
576
577 #ifdef CONFIG_FREEZER
578 extern void freeze_workqueues_begin(void);
579 extern bool freeze_workqueues_busy(void);
580 extern void thaw_workqueues(void);
581 #endif /* CONFIG_FREEZER */
582
583 #ifdef CONFIG_SYSFS
584 int workqueue_sysfs_register(struct workqueue_struct *wq);
585 #else /* CONFIG_SYSFS */
586 static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
587 { return 0; }
588 #endif /* CONFIG_SYSFS */
589
590 #endif