[linux-2.6-block.git] / include / linux / preempt.h

#ifndef __LINUX_PREEMPT_H
#define __LINUX_PREEMPT_H

/*
 * include/linux/preempt.h - macros for accessing and manipulating
 * preempt_count (used for kernel preemption, interrupt count, etc.)
 */

#include <linux/thread_info.h>
#include <linux/linkage.h>
#include <linux/list.h>

#ifdef CONFIG_DEBUG_PREEMPT
  extern void fastcall add_preempt_count(int val);
  extern void fastcall sub_preempt_count(int val);
#else
# define add_preempt_count(val)	do { preempt_count() += (val); } while (0)
# define sub_preempt_count(val)	do { preempt_count() -= (val); } while (0)
#endif

#define inc_preempt_count() add_preempt_count(1)
#define dec_preempt_count() sub_preempt_count(1)

#define preempt_count()	(current_thread_info()->preempt_count)

#ifdef CONFIG_PREEMPT

asmlinkage void preempt_schedule(void);

#define preempt_disable() \
do { \
	inc_preempt_count(); \
	barrier(); \
} while (0)

#define preempt_enable_no_resched() \
do { \
	barrier(); \
	dec_preempt_count(); \
} while (0)

#define preempt_check_resched() \
do { \
	if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
		preempt_schedule(); \
} while (0)

#define preempt_enable() \
do { \
	preempt_enable_no_resched(); \
	barrier(); \
	preempt_check_resched(); \
} while (0)

#else

#define preempt_disable()		do { } while (0)
#define preempt_enable_no_resched()	do { } while (0)
#define preempt_enable()		do { } while (0)
#define preempt_check_resched()		do { } while (0)

#endif

#ifdef CONFIG_PREEMPT_NOTIFIERS

struct preempt_notifier;

/**
 * preempt_ops - notifiers called when a task is preempted and rescheduled
 * @sched_in: we're about to be rescheduled:
 *    notifier: struct preempt_notifier for the task being scheduled
 *    cpu:  cpu we're scheduled on
 * @sched_out: we've just been preempted
 *    notifier: struct preempt_notifier for the task being preempted
 *    next: the task that's kicking us out
 */
struct preempt_ops {
	void (*sched_in)(struct preempt_notifier *notifier, int cpu);
	void (*sched_out)(struct preempt_notifier *notifier,
			  struct task_struct *next);
};

/**
 * preempt_notifier - key for installing preemption notifiers
 * @link: internal use
 * @ops: defines the notifier functions to be called
 *
 * Usually used in conjunction with container_of().
 */
struct preempt_notifier {
	struct hlist_node link;
	struct preempt_ops *ops;
};

void preempt_notifier_register(struct preempt_notifier *notifier);
void preempt_notifier_unregister(struct preempt_notifier *notifier);

static inline void preempt_notifier_init(struct preempt_notifier *notifier,
				     struct preempt_ops *ops)
{
	INIT_HLIST_NODE(&notifier->link);
	notifier->ops = ops;
}

#endif

#endif /* __LINUX_PREEMPT_H */
Commit	Line	Data
1da177e4 LT	1	#ifndef __LINUX_PREEMPT_H
	2	#define __LINUX_PREEMPT_H
	3
	4	/*
	5	* include/linux/preempt.h - macros for accessing and manipulating
	6	* preempt_count (used for kernel preemption, interrupt count, etc.)
	7	*/
	8
f037360f	9	#include <linux/thread_info.h>
1da177e4	10	#include <linux/linkage.h>
e107be36	11	#include <linux/list.h>
1da177e4 LT	12
	13	#ifdef CONFIG_DEBUG_PREEMPT
	14	extern void fastcall add_preempt_count(int val);
	15	extern void fastcall sub_preempt_count(int val);
	16	#else
	17	# define add_preempt_count(val) do { preempt_count() += (val); } while (0)
	18	# define sub_preempt_count(val) do { preempt_count() -= (val); } while (0)
	19	#endif
	20
	21	#define inc_preempt_count() add_preempt_count(1)
	22	#define dec_preempt_count() sub_preempt_count(1)
	23
	24	#define preempt_count() (current_thread_info()->preempt_count)
	25
	26	#ifdef CONFIG_PREEMPT
	27
	28	asmlinkage void preempt_schedule(void);
	29
	30	#define preempt_disable() \
	31	do { \
	32	inc_preempt_count(); \
	33	barrier(); \
	34	} while (0)
	35
	36	#define preempt_enable_no_resched() \
	37	do { \
	38	barrier(); \
	39	dec_preempt_count(); \
	40	} while (0)
	41
	42	#define preempt_check_resched() \
	43	do { \
	44	if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
	45	preempt_schedule(); \
	46	} while (0)
	47
	48	#define preempt_enable() \
	49	do { \
	50	preempt_enable_no_resched(); \
d6f02913	51	barrier(); \
1da177e4 LT	52	preempt_check_resched(); \
	53	} while (0)
	54
	55	#else
	56
	57	#define preempt_disable() do { } while (0)
	58	#define preempt_enable_no_resched() do { } while (0)
	59	#define preempt_enable() do { } while (0)
	60	#define preempt_check_resched() do { } while (0)
	61
	62	#endif
	63
e107be36 AK	64	#ifdef CONFIG_PREEMPT_NOTIFIERS
	65
	66	struct preempt_notifier;
	67
	68	/**
	69	* preempt_ops - notifiers called when a task is preempted and rescheduled
	70	* @sched_in: we're about to be rescheduled:
	71	* notifier: struct preempt_notifier for the task being scheduled
	72	* cpu: cpu we're scheduled on
	73	* @sched_out: we've just been preempted
	74	* notifier: struct preempt_notifier for the task being preempted
	75	* next: the task that's kicking us out
	76	*/
	77	struct preempt_ops {
	78	void (sched_in)(struct preempt_notifier notifier, int cpu);
	79	void (sched_out)(struct preempt_notifier notifier,
	80	struct task_struct *next);
	81	};
	82
	83	/**
	84	* preempt_notifier - key for installing preemption notifiers
	85	* @link: internal use
	86	* @ops: defines the notifier functions to be called
	87	*
	88	* Usually used in conjunction with container_of().
	89	*/
	90	struct preempt_notifier {
	91	struct hlist_node link;
	92	struct preempt_ops *ops;
	93	};
	94
	95	void preempt_notifier_register(struct preempt_notifier *notifier);
	96	void preempt_notifier_unregister(struct preempt_notifier *notifier);
	97
	98	static inline void preempt_notifier_init(struct preempt_notifier *notifier,
	99	struct preempt_ops *ops)
	100	{
	101	INIT_HLIST_NODE(&notifier->link);
	102	notifier->ops = ops;
	103	}
	104
	105	#endif
	106
1da177e4	107	#endif /* __LINUX_PREEMPT_H */