Current File : //usr/src/kernels/3.10.0-1160.88.1.el7.centos.plus.x86_64/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>
#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
extern void add_preempt_count(int val);
extern void 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_check_resched() \
do { \
if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
preempt_schedule(); \
} while (0)
#ifdef CONFIG_CONTEXT_TRACKING
void preempt_schedule_context(void);
#define preempt_check_resched_context() \
do { \
if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
preempt_schedule_context(); \
} while (0)
#else
#define preempt_check_resched_context() preempt_check_resched()
#endif /* CONFIG_CONTEXT_TRACKING */
#else /* !CONFIG_PREEMPT */
#define preempt_check_resched() do { } while (0)
#define preempt_check_resched_context() do { } while (0)
#endif /* CONFIG_PREEMPT */
#ifdef CONFIG_PREEMPT_COUNT
#define preempt_disable() \
do { \
inc_preempt_count(); \
barrier(); \
} while (0)
#define sched_preempt_enable_no_resched() \
do { \
barrier(); \
dec_preempt_count(); \
} while (0)
#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
#define preempt_enable() \
do { \
preempt_enable_no_resched(); \
barrier(); \
preempt_check_resched(); \
} while (0)
/* For debugging and tracer internals only! */
#define add_preempt_count_notrace(val) \
do { preempt_count() += (val); } while (0)
#define sub_preempt_count_notrace(val) \
do { preempt_count() -= (val); } while (0)
#define inc_preempt_count_notrace() add_preempt_count_notrace(1)
#define dec_preempt_count_notrace() sub_preempt_count_notrace(1)
#define preempt_disable_notrace() \
do { \
inc_preempt_count_notrace(); \
barrier(); \
} while (0)
#define preempt_enable_no_resched_notrace() \
do { \
barrier(); \
dec_preempt_count_notrace(); \
} while (0)
/* preempt_check_resched is OK to trace */
#define preempt_enable_notrace() \
do { \
preempt_enable_no_resched_notrace(); \
barrier(); \
preempt_check_resched_context(); \
} while (0)
#else /* !CONFIG_PREEMPT_COUNT */
/*
* Even if we don't have any preemption, we need preempt disable/enable
* to be barriers, so that we don't have things like get_user/put_user
* that can cause faults and scheduling migrate into our preempt-protected
* region.
*/
#define preempt_disable() barrier()
#define sched_preempt_enable_no_resched() barrier()
#define preempt_enable_no_resched() barrier()
#define preempt_enable() barrier()
#define preempt_disable_notrace() barrier()
#define preempt_enable_no_resched_notrace() barrier()
#define preempt_enable_notrace() barrier()
#endif /* CONFIG_PREEMPT_COUNT */
#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
*
* Please note that sched_in and out are called under different
* contexts. sched_out is called with rq lock held and irq disabled
* while sched_in is called without rq lock and irq enabled. This
* difference is intentional and depended upon by its users.
*/
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(¬ifier->link);
notifier->ops = ops;
}
#endif
#endif /* __LINUX_PREEMPT_H */
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