linux 等待队列
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#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#define GLOBALFIFO_SIZE 0X1000 //全局内存大小
#define MEM_CLEAR 0x1 //清零全局内存
#define GLOBALFIFO_MAJOR 251 //主设备号
static int globalfifo_major = GLOBALFIFO_MAJOR;
//设备结构体
struct globalfifo_dev{
struct cdev cdev; //cdev 结构体
unsigned int current_len; //fifo 有效数据长度
unsigned char mem[GLOBALFIFO_SIZE];
struct semaphore sem; //并发控制用的信号量,由于要调用copy_from_user这些函数,可能导致阻塞的函数,不能用自旋锁,用信号量
wait_queue_head_t r_wait; //阻塞读用的等待队列头
wait_queue_head_t w_wait; //阻塞写用的等待队列头
};
struct globalfifo_dev *globalfifo_devp; //设备结构体指针
//文件打开
int globalfifo_open(struct inode *inode, struct file *filp)
{
struct globalfifo_dev *dev;
dev = container_of(inode->i_cdev, struct globalfifo_dev, cdev);
filp->private_data = globalfifo_devp; //设备结构体指针赋值给文件私有数据指针
return 0;
}
//文件释放
int globalfifo_release(struct inode *inode, struct file *filp)
{
return 0;
}
//ioctl 设备控制
static int globalfifo_ioctl(struct inode *inodep, struct file *filp, unsigned int cmd, unsigned long arg)
{
struct globalfifo_dev *dev = filp->private_data; //获得设备结构体指针
switch (cmd){
case MEM_CLEAR:
//if(down_interruptible(&dev->sem))//获得信号量 进入睡眠的进程可被信号打断
// return -ERESTARTSYS;
memset(dev->mem, 0, GLOBALFIFO_SIZE);
printk(KERN_INFO "globalfifo is set to zero\n");
//up(&dev->sem);//释放信号量
break;
default:
return -EINVAL;
}
return 0;
}
//read
static ssize_t globalfifo_read(struct file *filp, char __user *buf, size_t size, loff_t *ppos)
{
unsigned long p = *ppos;
unsigned int count = size;
int ret = 0;
struct globalfifo_dev *dev = filp->private_data; //获得设备结构体指针
DECLARE_WAITQUEUE(wait, current);//定义等待队列
down(&dev->sem);// 获得信号量 进入睡眠的进程不可被信号打断
add_wait_queue(&dev->r_wait, &wait);//进入读等待队列头
//等待FIFO非空
while(dev->current_len ==0){
if(filp->f_flags & O_NONBLOCK){
ret = -EAGAIN;
goto out;
}
__set_current_state(TASK_INTERRUPTIBLE); //改变进程状态为睡眠
up(&dev->sem);
schedule();//调度其它进程执行
if(signal_pending(current)){// 如果是因为信号唤醒
ret = -ERESTARTSYS;
goto out2;
}
down(&dev->sem);
}
//内核空间->用户空间
if(count > dev->current_len){
count = dev->current_len;
}
if(copy_to_user(buf, (void*)(dev->mem + p), count)){
ret = -EFAULT;
goto out;
}else{
memcpy(dev->mem, dev->mem + count, dev->current_len - count); //fifo 数据前移
dev->current_len -= count; //有效数据长度减少
printk(KERN_INFO "read %d bytes(s), current_len:%d \n", count, dev->current_len);
wake_up_interruptible(&dev->w_wait);// 唤醒写等待队列
ret = count;
}
out: up(&dev->sem);//释放信号量
out2: remove_wait_queue(&dev->w_wait,&wait); //移除等待队列
set_current_state(TASK_RUNNING);
return ret;
}
//写函数
static ssize_t globalfifo_write(struct file *filp, const char __user *buf, size_t size, loff_t *ppos)
{
unsigned int count = size;
int ret = 0;
struct globalfifo_dev *dev = filp->private_data; //获得设备结构体指针
DECLARE_WAITQUEUE(wait, current);//定义等待队列
down(&dev->sem);// 获得信号量 进入睡眠的进程不可被信号打断
add_wait_queue(&dev->w_wait, &wait);//进入读等待队列头
//等待FIFO非空
while(dev->current_len == GLOBALFIFO_SIZE){
if(filp->f_flags & O_NONBLOCK){
ret = -EAGAIN;
goto out;
}
__set_current_state(TASK_INTERRUPTIBLE); //改变进程状态为睡眠
up(&dev->sem);
schedule();//调度其它进程执行
if(signal_pending(current)){// 如果是因为信号唤醒
ret = -ERESTARTSYS;
goto out2;
}
down(&dev->sem);
}
//分析和获取有效写长度
//if( p >= globalfifo_SIZE)
// return 0;
//if(count > globalfifo_SIZE - p)
// count = globalfifo_SIZE - p;
//if(down_interruptible(&dev->sem))//获得信号量 进入睡眠的进程可被信号打断
// return -ERESTARTSYS;
//用户空间 -> 内核空间
if(count > GLOBALFIFO_SIZE - dev->current_len){
count = GLOBALFIFO_SIZE - dev->current_len;
}
if(copy_from_user(dev->mem + dev->current_len, buf, count)){
ret = -EFAULT;
goto out;
}else{
dev->current_len += count;
printk(KERN_INFO "read %d bytes(s), current_len:%d \n", count, dev->current_len);
wake_up_interruptible(&dev->r_wait); //唤醒读等待队列
ret = count;
}
out: up(&dev->sem);//释放信号量
out2: remove_wait_queue(&dev->r_wait, &wait);
set_current_state(TASK_RUNNING);
return ret;
}
//seek 文件定位
static loff_t globalfifo_llseek(struct file *filp, loff_t offset, int orig)
{
loff_t ret = 0;
switch(orig){
case 0://相对文件开始位置偏移
if(offset < 0){
ret = -EINVAL;
break;
}
if((unsigned int)offset > GLOBALFIFO_MAJOR){
ret = -EINVAL;
break;
}
case 1://相对文件当前位置偏移
if((filp->f_pos + offset) > GLOBALFIFO_MAJOR){
ret = -EINVAL;
break;
}
if((filp->f_pos + offset) < 0){
ret = -EINVAL;
break;
}
filp->f_pos += offset;
ret = filp->f_pos;
break;
default:
ret = -EINVAL;
break;
}
return ret;
}
//文件操作结构体
static const struct file_operations globalfifo_fops = {
.owner = THIS_MODULE,
.llseek = globalfifo_llseek,
.read = globalfifo_read,
.write = globalfifo_write,
.ioctl = globalfifo_ioctl,
.open = globalfifo_open,
.release = globalfifo_release,
};
// 初始化并注册cdev
static void globalfifo_setup_cdev(struct globalfifo_dev *dev, int index)
{
int err, devno = MKDEV(globalfifo_major, index);
cdev_init(&dev->cdev, &globalfifo_fops);
dev->cdev.owner = THIS_MODULE;
err = cdev_add(&dev->cdev, devno, 1);
if(err)
printk(KERN_NOTICE "error %d adding globalfifo %d", err , index);
}
//设备加载
int globalfifo_init()
{
int result ;
dev_t devno = MKDEV(globalfifo_major, 0);
//申请设备号
if(globalfifo_major)
result = register_chrdev_region(devno, 1, "globalfifo");
else{ // 动态分配
result = alloc_chrdev_region(&devno, 0, 1, "globalfifo");
globalfifo_major = MAJOR(devno);
}
if(result <0)
return result;
//动态申请设备结构体的内体
globalfifo_devp = kmalloc(sizeof(struct globalfifo_dev), GFP_KERNEL);
if(!globalfifo_devp){//申请失败
result = -ENOMEM;
goto fail_malloc;
}
memset(globalfifo_devp, 0, sizeof(struct globalfifo_dev));
globalfifo_setup_cdev(globalfifo_devp, 0);
//globalfifo_setup_cdev(&globalfifo_devp[1], 1);
init_MUTEX(&globalfifo_devp->sem); //初始化信号量,
init_waitqueue_head(&globalfifo_devp->r_wait);//初始化读等待队列头
init_waitqueue_head(&globalfifo_devp->w_wait);//初始化写等待队列头
return 0;
fail_malloc:
unregister_chrdev_region(devno, 1);
return result;
}
//模块卸载函数
void globalfifo_exit()
{
cdev_del(&globalfifo_devp->cdev); // 注销cdev
//cdev_del(&(globalfifo_devp[1]->cdev)); // 注销cdev
kfree(globalfifo_devp); // 释放设备结构体内存
unregister_chrdev_region(MKDEV(globalfifo_major, 0), 1); //释放设备号
}
MODULE_AUTHOR("lunge");
MODULE_LICENSE("Dual BSD/GPL");
module_param(globalfifo_major, int, S_IRUGO);//模块参数 insmod xxx.ko globalfifo_major= 1000
module_init(globalfifo_init);
module_exit(globalfifo_exit);
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#define GLOBALFIFO_SIZE 0X1000 //全局内存大小
#define MEM_CLEAR 0x1 //清零全局内存
#define GLOBALFIFO_MAJOR 251 //主设备号
static int globalfifo_major = GLOBALFIFO_MAJOR;
//设备结构体
struct globalfifo_dev{
struct cdev cdev; //cdev 结构体
unsigned int current_len; //fifo 有效数据长度
unsigned char mem[GLOBALFIFO_SIZE];
struct semaphore sem; //并发控制用的信号量,由于要调用copy_from_user这些函数,可能导致阻塞的函数,不能用自旋锁,用信号量
wait_queue_head_t r_wait; //阻塞读用的等待队列头
wait_queue_head_t w_wait; //阻塞写用的等待队列头
};
struct globalfifo_dev *globalfifo_devp; //设备结构体指针
//文件打开
int globalfifo_open(struct inode *inode, struct file *filp)
{
struct globalfifo_dev *dev;
dev = container_of(inode->i_cdev, struct globalfifo_dev, cdev);
filp->private_data = globalfifo_devp; //设备结构体指针赋值给文件私有数据指针
return 0;
}
//文件释放
int globalfifo_release(struct inode *inode, struct file *filp)
{
return 0;
}
//ioctl 设备控制
static int globalfifo_ioctl(struct inode *inodep, struct file *filp, unsigned int cmd, unsigned long arg)
{
struct globalfifo_dev *dev = filp->private_data; //获得设备结构体指针
switch (cmd){
case MEM_CLEAR:
//if(down_interruptible(&dev->sem))//获得信号量 进入睡眠的进程可被信号打断
// return -ERESTARTSYS;
memset(dev->mem, 0, GLOBALFIFO_SIZE);
printk(KERN_INFO "globalfifo is set to zero\n");
//up(&dev->sem);//释放信号量
break;
default:
return -EINVAL;
}
return 0;
}
//read
static ssize_t globalfifo_read(struct file *filp, char __user *buf, size_t size, loff_t *ppos)
{
unsigned long p = *ppos;
unsigned int count = size;
int ret = 0;
struct globalfifo_dev *dev = filp->private_data; //获得设备结构体指针
DECLARE_WAITQUEUE(wait, current);//定义等待队列
down(&dev->sem);// 获得信号量 进入睡眠的进程不可被信号打断
add_wait_queue(&dev->r_wait, &wait);//进入读等待队列头
//等待FIFO非空
while(dev->current_len ==0){
if(filp->f_flags & O_NONBLOCK){
ret = -EAGAIN;
goto out;
}
__set_current_state(TASK_INTERRUPTIBLE); //改变进程状态为睡眠
up(&dev->sem);
schedule();//调度其它进程执行
if(signal_pending(current)){// 如果是因为信号唤醒
ret = -ERESTARTSYS;
goto out2;
}
down(&dev->sem);
}
//内核空间->用户空间
if(count > dev->current_len){
count = dev->current_len;
}
if(copy_to_user(buf, (void*)(dev->mem + p), count)){
ret = -EFAULT;
goto out;
}else{
memcpy(dev->mem, dev->mem + count, dev->current_len - count); //fifo 数据前移
dev->current_len -= count; //有效数据长度减少
printk(KERN_INFO "read %d bytes(s), current_len:%d \n", count, dev->current_len);
wake_up_interruptible(&dev->w_wait);// 唤醒写等待队列
ret = count;
}
out: up(&dev->sem);//释放信号量
out2: remove_wait_queue(&dev->w_wait,&wait); //移除等待队列
set_current_state(TASK_RUNNING);
return ret;
}
//写函数
static ssize_t globalfifo_write(struct file *filp, const char __user *buf, size_t size, loff_t *ppos)
{
unsigned int count = size;
int ret = 0;
struct globalfifo_dev *dev = filp->private_data; //获得设备结构体指针
DECLARE_WAITQUEUE(wait, current);//定义等待队列
down(&dev->sem);// 获得信号量 进入睡眠的进程不可被信号打断
add_wait_queue(&dev->w_wait, &wait);//进入读等待队列头
//等待FIFO非空
while(dev->current_len == GLOBALFIFO_SIZE){
if(filp->f_flags & O_NONBLOCK){
ret = -EAGAIN;
goto out;
}
__set_current_state(TASK_INTERRUPTIBLE); //改变进程状态为睡眠
up(&dev->sem);
schedule();//调度其它进程执行
if(signal_pending(current)){// 如果是因为信号唤醒
ret = -ERESTARTSYS;
goto out2;
}
down(&dev->sem);
}
//分析和获取有效写长度
//if( p >= globalfifo_SIZE)
// return 0;
//if(count > globalfifo_SIZE - p)
// count = globalfifo_SIZE - p;
//if(down_interruptible(&dev->sem))//获得信号量 进入睡眠的进程可被信号打断
// return -ERESTARTSYS;
//用户空间 -> 内核空间
if(count > GLOBALFIFO_SIZE - dev->current_len){
count = GLOBALFIFO_SIZE - dev->current_len;
}
if(copy_from_user(dev->mem + dev->current_len, buf, count)){
ret = -EFAULT;
goto out;
}else{
dev->current_len += count;
printk(KERN_INFO "read %d bytes(s), current_len:%d \n", count, dev->current_len);
wake_up_interruptible(&dev->r_wait); //唤醒读等待队列
ret = count;
}
out: up(&dev->sem);//释放信号量
out2: remove_wait_queue(&dev->r_wait, &wait);
set_current_state(TASK_RUNNING);
return ret;
}
//seek 文件定位
static loff_t globalfifo_llseek(struct file *filp, loff_t offset, int orig)
{
loff_t ret = 0;
switch(orig){
case 0://相对文件开始位置偏移
if(offset < 0){
ret = -EINVAL;
break;
}
if((unsigned int)offset > GLOBALFIFO_MAJOR){
ret = -EINVAL;
break;
}
case 1://相对文件当前位置偏移
if((filp->f_pos + offset) > GLOBALFIFO_MAJOR){
ret = -EINVAL;
break;
}
if((filp->f_pos + offset) < 0){
ret = -EINVAL;
break;
}
filp->f_pos += offset;
ret = filp->f_pos;
break;
default:
ret = -EINVAL;
break;
}
return ret;
}
//文件操作结构体
static const struct file_operations globalfifo_fops = {
.owner = THIS_MODULE,
.llseek = globalfifo_llseek,
.read = globalfifo_read,
.write = globalfifo_write,
.ioctl = globalfifo_ioctl,
.open = globalfifo_open,
.release = globalfifo_release,
};
// 初始化并注册cdev
static void globalfifo_setup_cdev(struct globalfifo_dev *dev, int index)
{
int err, devno = MKDEV(globalfifo_major, index);
cdev_init(&dev->cdev, &globalfifo_fops);
dev->cdev.owner = THIS_MODULE;
err = cdev_add(&dev->cdev, devno, 1);
if(err)
printk(KERN_NOTICE "error %d adding globalfifo %d", err , index);
}
//设备加载
int globalfifo_init()
{
int result ;
dev_t devno = MKDEV(globalfifo_major, 0);
//申请设备号
if(globalfifo_major)
result = register_chrdev_region(devno, 1, "globalfifo");
else{ // 动态分配
result = alloc_chrdev_region(&devno, 0, 1, "globalfifo");
globalfifo_major = MAJOR(devno);
}
if(result <0)
return result;
//动态申请设备结构体的内体
globalfifo_devp = kmalloc(sizeof(struct globalfifo_dev), GFP_KERNEL);
if(!globalfifo_devp){//申请失败
result = -ENOMEM;
goto fail_malloc;
}
memset(globalfifo_devp, 0, sizeof(struct globalfifo_dev));
globalfifo_setup_cdev(globalfifo_devp, 0);
//globalfifo_setup_cdev(&globalfifo_devp[1], 1);
init_MUTEX(&globalfifo_devp->sem); //初始化信号量,
init_waitqueue_head(&globalfifo_devp->r_wait);//初始化读等待队列头
init_waitqueue_head(&globalfifo_devp->w_wait);//初始化写等待队列头
return 0;
fail_malloc:
unregister_chrdev_region(devno, 1);
return result;
}
//模块卸载函数
void globalfifo_exit()
{
cdev_del(&globalfifo_devp->cdev); // 注销cdev
//cdev_del(&(globalfifo_devp[1]->cdev)); // 注销cdev
kfree(globalfifo_devp); // 释放设备结构体内存
unregister_chrdev_region(MKDEV(globalfifo_major, 0), 1); //释放设备号
}
MODULE_AUTHOR("lunge");
MODULE_LICENSE("Dual BSD/GPL");
module_param(globalfifo_major, int, S_IRUGO);//模块参数 insmod xxx.ko globalfifo_major= 1000
module_init(globalfifo_init);
module_exit(globalfifo_exit);
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