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Release 4.12 include/linux/swait.h

Directory: include/linux
#ifndef _LINUX_SWAIT_H

#define _LINUX_SWAIT_H

#include <linux/list.h>
#include <linux/stddef.h>
#include <linux/spinlock.h>
#include <asm/current.h>

/*
 * Simple wait queues
 *
 * While these are very similar to the other/complex wait queues (wait.h) the
 * most important difference is that the simple waitqueue allows for
 * deterministic behaviour -- IOW it has strictly bounded IRQ and lock hold
 * times.
 *
 * In order to make this so, we had to drop a fair number of features of the
 * other waitqueue code; notably:
 *
 *  - mixing INTERRUPTIBLE and UNINTERRUPTIBLE sleeps on the same waitqueue;
 *    all wakeups are TASK_NORMAL in order to avoid O(n) lookups for the right
 *    sleeper state.
 *
 *  - the exclusive mode; because this requires preserving the list order
 *    and this is hard.
 *
 *  - custom wake functions; because you cannot give any guarantees about
 *    random code.
 *
 * As a side effect of this; the data structures are slimmer.
 *
 * One would recommend using this wait queue where possible.
 */

struct task_struct;


struct swait_queue_head {
	
raw_spinlock_t		lock;
	
struct list_head	task_list;
};


struct swait_queue {
	
struct task_struct	*task;
	
struct list_head	task_list;
};


#define __SWAITQUEUE_INITIALIZER(name) {                               \
        .task           = current,                                      \
        .task_list      = LIST_HEAD_INIT((name).task_list),             \
}


#define DECLARE_SWAITQUEUE(name)					\
	struct swait_queue name = __SWAITQUEUE_INITIALIZER(name)


#define __SWAIT_QUEUE_HEAD_INITIALIZER(name) {                               \
        .lock           = __RAW_SPIN_LOCK_UNLOCKED(name.lock),          \
        .task_list      = LIST_HEAD_INIT((name).task_list),             \
}


#define DECLARE_SWAIT_QUEUE_HEAD(name)					\
	struct swait_queue_head name = __SWAIT_QUEUE_HEAD_INITIALIZER(name)

extern void __init_swait_queue_head(struct swait_queue_head *q, const char *name,
				    struct lock_class_key *key);


#define init_swait_queue_head(q)				\
	do {                                                    \
                static struct lock_class_key __key;             \
                __init_swait_queue_head((q), #q, &__key);       \
        } while (0)

#ifdef CONFIG_LOCKDEP

# define __SWAIT_QUEUE_HEAD_INIT_ONSTACK(name)			\
	({ init_swait_queue_head(&name); name; })

# define DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(name)			\
	struct swait_queue_head name = __SWAIT_QUEUE_HEAD_INIT_ONSTACK(name)
#else

# define DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(name)			\
	DECLARE_SWAIT_QUEUE_HEAD(name)
#endif


static inline int swait_active(struct swait_queue_head *q) { return !list_empty(&q->task_list); }

Contributors

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Peter Zijlstra22100.00%1100.00%
Total22100.00%1100.00%

extern void swake_up(struct swait_queue_head *q); extern void swake_up_all(struct swait_queue_head *q); extern void swake_up_locked(struct swait_queue_head *q); extern void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait); extern void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int state); extern long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state); extern void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait); extern void finish_swait(struct swait_queue_head *q, struct swait_queue *wait); /* as per ___wait_event() but for swait, therefore "exclusive == 0" */ #define ___swait_event(wq, condition, state, ret, cmd) \ ({ \ struct swait_queue __wait; \ long __ret = ret; \ \ INIT_LIST_HEAD(&__wait.task_list); \ for (;;) { \ long __int = prepare_to_swait_event(&wq, &__wait, state);\ \ if (condition) \ break; \ \ if (___wait_is_interruptible(state) && __int) { \ __ret = __int; \ break; \ } \ \ cmd; \ } \ finish_swait(&wq, &__wait); \ __ret; \ }) #define __swait_event(wq, condition) \ (void)___swait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, \ schedule()) #define swait_event(wq, condition) \ do { \ if (condition) \ break; \ __swait_event(wq, condition); \ } while (0) #define __swait_event_timeout(wq, condition, timeout) \ ___swait_event(wq, ___wait_cond_timeout(condition), \ TASK_UNINTERRUPTIBLE, timeout, \ __ret = schedule_timeout(__ret)) #define swait_event_timeout(wq, condition, timeout) \ ({ \ long __ret = timeout; \ if (!___wait_cond_timeout(condition)) \ __ret = __swait_event_timeout(wq, condition, timeout); \ __ret; \ }) #define __swait_event_interruptible(wq, condition) \ ___swait_event(wq, condition, TASK_INTERRUPTIBLE, 0, \ schedule()) #define swait_event_interruptible(wq, condition) \ ({ \ int __ret = 0; \ if (!(condition)) \ __ret = __swait_event_interruptible(wq, condition); \ __ret; \ }) #define __swait_event_interruptible_timeout(wq, condition, timeout) \ ___swait_event(wq, ___wait_cond_timeout(condition), \ TASK_INTERRUPTIBLE, timeout, \ __ret = schedule_timeout(__ret)) #define swait_event_interruptible_timeout(wq, condition, timeout) \ ({ \ long __ret = timeout; \ if (!___wait_cond_timeout(condition)) \ __ret = __swait_event_interruptible_timeout(wq, \ condition, timeout); \ __ret; \ }) #endif /* _LINUX_SWAIT_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra378100.00%1100.00%
Total378100.00%1100.00%
Directory: include/linux
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