include/asm-generic/preempt.h

Source file repositories/reference/linux-study-clean/include/asm-generic/preempt.h

File Facts

System
Linux kernel
Corpus path
include/asm-generic/preempt.h
Extension
.h
Size
2432 bytes
Lines
101
Domain
Repository Root And Misc
Bucket
include
Inferred role
Repository Root And Misc: implementation source
Status
source implementation candidate

Why This File Exists

Top-level or miscellaneous repository surface. Use this as map coverage unless a later manual pass promotes the file into a deeper subsystem dossier.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __ASM_PREEMPT_H
#define __ASM_PREEMPT_H

#include <linux/thread_info.h>

#define PREEMPT_ENABLED	(0)

static __always_inline int preempt_count(void)
{
	return READ_ONCE(current_thread_info()->preempt_count);
}

static __always_inline volatile int *preempt_count_ptr(void)
{
	return &current_thread_info()->preempt_count;
}

static __always_inline void preempt_count_set(int pc)
{
	*preempt_count_ptr() = pc;
}

/*
 * must be macros to avoid header recursion hell
 */
#define init_task_preempt_count(p) do { \
	task_thread_info(p)->preempt_count = FORK_PREEMPT_COUNT; \
} while (0)

#define init_idle_preempt_count(p, cpu) do { \
	task_thread_info(p)->preempt_count = PREEMPT_DISABLED; \
} while (0)

static __always_inline void set_preempt_need_resched(void)
{
}

static __always_inline void clear_preempt_need_resched(void)
{
}

static __always_inline bool test_preempt_need_resched(void)
{
	return false;
}

/*
 * The various preempt_count add/sub methods
 */

static __always_inline void __preempt_count_add(int val)
{
	*preempt_count_ptr() += val;
}

static __always_inline void __preempt_count_sub(int val)
{
	*preempt_count_ptr() -= val;
}

static __always_inline bool __preempt_count_dec_and_test(void)
{
	/*
	 * Because of load-store architectures cannot do per-cpu atomic
	 * operations; we cannot use PREEMPT_NEED_RESCHED because it might get
	 * lost.
	 */
	return !--*preempt_count_ptr() && tif_need_resched();
}

/*
 * Returns true when we need to resched and can (barring IRQ state).
 */
static __always_inline bool should_resched(int preempt_offset)
{
	return unlikely(preempt_count() == preempt_offset &&
			tif_need_resched());
}

#ifdef CONFIG_PREEMPTION
extern asmlinkage void preempt_schedule(void);
extern asmlinkage void preempt_schedule_notrace(void);

#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)

void dynamic_preempt_schedule(void);
void dynamic_preempt_schedule_notrace(void);
#define __preempt_schedule()		dynamic_preempt_schedule()
#define __preempt_schedule_notrace()	dynamic_preempt_schedule_notrace()

Annotation

Implementation Notes