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Code Issues Releases Wiki Activity

增加锁的持有计数

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This commit is contained in:
fslongjin
2022-04-13 11:14:49 +08:00
parent ac28a3c806
commit 7295565e5e
4 changed files with 100 additions and 38 deletions
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44
kernel/process/spinlock.h
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@ -9,7 +9,8 @@
*
*/
#pragma once
#include "../common/glib.h"
#include <common/glib.h>
#include <process/preempt.h>
/**
* @brief 定义自旋锁结构体
@ -22,8 +23,8 @@ typedef struct
/**
* @brief 初始化自旋锁
*
* @param lock
*
* @param lock
*/
void spin_init(spinlock_t *lock)
{
@ -37,21 +38,42 @@ void spin_init(spinlock_t *lock)
*/
void spin_lock(spinlock_t *lock)
{
preempt_disable();
__asm__ __volatile__("1: \n\t"
"lock decq %0 \n\t" // 尝试-1
"jns 3f \n\t" // 加锁成功，跳转到步骤3
"2: \n\t" // 加锁失败，稍后再试
"lock decq %0 \n\t" // 尝试-1
"jns 3f \n\t" // 加锁成功，跳转到步骤3
"2: \n\t" // 加锁失败，稍后再试
"pause \n\t"
"cmpq $0, %0 \n\t"
"jle 2b \n\t" // 若锁被占用，则继续重试
"jmp 1b \n\t" // 尝试加锁
"jle 2b \n\t" // 若锁被占用，则继续重试
"jmp 1b \n\t" // 尝试加锁
"3:"
: "=m"(lock->lock)::"memory");
}
void spin_unlock(spinlock_t * lock)
void spin_unlock(spinlock_t *lock)
{
__asm__ __volatile__("movq $1, %0 \n\t"
:"=m"(lock->lock)::"memory");
: "=m"(lock->lock)::"memory");
preempt_enable();
}
/**
* @brief 尝试加锁
*
* @param lock
* @return long 锁变量的值（1为成功加锁，0为加锁失败）
*/
long spin_trylock(spinlock_t *lock)
{
uint64_t tmp_val = 0;
preempt_disable();
// 交换tmp_val和lock的值，若tmp_val==1则证明加锁成功
asm volatile("lock xchgq %0, %1 \n\t" // 确保只有1个进程能得到锁
: "=q"(tmp_val), "=m"(lock->lock)
: "0"(0)
: "memory");
if (!tmp_val)
preempt_enable();
return tmp_val;
}