arch/alpha/include/asm/spinlock.h

Source file repositories/reference/linux-study-clean/arch/alpha/include/asm/spinlock.h

File Facts

System
Linux kernel
Corpus path
arch/alpha/include/asm/spinlock.h
Extension
.h
Size
2915 bytes
Lines
164
Domain
Architecture Layer
Bucket
arch/alpha
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _ALPHA_SPINLOCK_H
#define _ALPHA_SPINLOCK_H

#include <linux/kernel.h>
#include <asm/current.h>
#include <asm/barrier.h>
#include <asm/processor.h>

/*
 * Simple spin lock operations.  There are two variants, one clears IRQ's
 * on the local processor, one does not.
 *
 * We make no fairness assumptions. They have a cost.
 */

#define arch_spin_is_locked(x)	((x)->lock != 0)

static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
{
        return lock.lock == 0;
}

static inline void arch_spin_unlock(arch_spinlock_t * lock)
{
	mb();
	lock->lock = 0;
}

static inline void arch_spin_lock(arch_spinlock_t * lock)
{
	long tmp;

	__asm__ __volatile__(
	"1:	ldl_l	%0,%1\n"
	"	bne	%0,2f\n"
	"	lda	%0,1\n"
	"	stl_c	%0,%1\n"
	"	beq	%0,2f\n"
	"	mb\n"
	".subsection 2\n"
	"2:	ldl	%0,%1\n"
	"	bne	%0,2b\n"
	"	br	1b\n"
	".previous"
	: "=&r" (tmp), "=m" (lock->lock)
	: "m"(lock->lock) : "memory");
}

static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
	return !test_and_set_bit(0, &lock->lock);
}

/***********************************************************/

static inline void arch_read_lock(arch_rwlock_t *lock)
{
	long regx;

	__asm__ __volatile__(
	"1:	ldl_l	%1,%0\n"
	"	blbs	%1,6f\n"
	"	subl	%1,2,%1\n"
	"	stl_c	%1,%0\n"
	"	beq	%1,6f\n"
	"	mb\n"
	".subsection 2\n"
	"6:	ldl	%1,%0\n"
	"	blbs	%1,6b\n"
	"	br	1b\n"
	".previous"
	: "=m" (*lock), "=&r" (regx)
	: "m" (*lock) : "memory");
}

static inline void arch_write_lock(arch_rwlock_t *lock)
{
	long regx;

	__asm__ __volatile__(
	"1:	ldl_l	%1,%0\n"
	"	bne	%1,6f\n"
	"	lda	%1,1\n"
	"	stl_c	%1,%0\n"
	"	beq	%1,6f\n"
	"	mb\n"
	".subsection 2\n"
	"6:	ldl	%1,%0\n"
	"	bne	%1,6b\n"
	"	br	1b\n"

Annotation

Implementation Notes