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如下代码红色部分,为什么我加锁两次,从来没有释放过锁,程序没有被挂起????????????????
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
#include <asm/semaphore.h>
MODULE_LICENSE("GPL");
#define MAJOR_NUM 254
static int globalvar_open(struct inode *inode, struct file *filp);
struct file_operations globalvar_fops =
{
open: globalvar_open, release:
};
static spinlock_t spin = SPIN_LOCK_UNLOCKED;
static int __init globalvar_init(void)
{
int ret;
ret = register_chrdev(MAJOR_NUM, "globalvar", &globalvar_fops);
if (ret)
{
printk("globalvar register failure");
}
else
{
printk("globalvar register success");
init_MUTEX(&sem);
}
return ret;
}
static void __exit globalvar_exit(void)
{
int ret;
ret = unregister_chrdev(MAJOR_NUM, "globalvar");
if (ret)
{
printk("globalvar unregister failure");
}
else
{
printk("globalvar unregister success");
}
}
static int globalvar_open(struct inode *inode, struct file *filp)
{
//获得自选锁
spin_lock_irq(&spin);
spin_lock_irq(&spin);
/*我觉得下面这句话不应该打印出来才对啊*/
printk("<0>11111111111111\n"); return 0;
} |
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