linux kfifo demo
时间: 2023-09-27 18:08:18 浏览: 69
您可以参考以下代码实现一个简单的Linux kfifo demo:
```
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/kfifo.h>
#define FIFO_SIZE 1024
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A Linux kfifo demo");
static char *fifo_buffer;
static struct kfifo my_fifo;
static int my_open(struct inode *inode, struct file *file)
{
printk(KERN_INFO "my device opened\n");
return 0;
}
static int my_close(struct inode *inode, struct file *file)
{
printk(KERN_INFO "my device closed\n");
return 0;
}
static ssize_t my_read(struct file *file, char __user *user_buf, size_t count, loff_t *ppos)
{
ssize_t ret;
if (kfifo_is_empty(&my_fifo)) {
return -EAGAIN;
}
ret = kfifo_to_user(&my_fifo, user_buf, count, ppos);
if (ret) {
printk(KERN_INFO "Read %ld bytes\n", (long)ret);
} else {
printk(KERN_ERR "Failed to read\n");
}
return ret;
}
static ssize_t my_write(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos)
{
ssize_t ret;
if (kfifo_avail(&my_fifo) < count) {
return -ENOMEM;
}
ret = kfifo_from_user(&my_fifo, user_buf, count, ppos);
if (ret) {
printk(KERN_INFO "Wrote %ld bytes\n", (long)ret);
} else {
printk(KERN_ERR "Failed to write\n");
}
return ret;
}
static struct file_operations my_fops = {
.owner = THIS_MODULE,
.open = my_open,
.release = my_close,
.read = my_read,
.write = my_write,
};
static int __init my_init(void)
{
int ret;
fifo_buffer = kmalloc(FIFO_SIZE, GFP_KERNEL);
if (!fifo_buffer) {
return -ENOMEM;
}
ret = kfifo_init(&my_fifo, fifo_buffer, FIFO_SIZE);
if (ret) {
kfree(fifo_buffer);
return ret;
}
ret = register_chrdev(0, "my_device", &my_fops);
if (ret < 0) {
kfifo_free(&my_fifo);
kfree(fifo_buffer);
return ret;
}
printk(KERN_INFO "my device registered with major number %d\n", ret);
return 0;
}
static void __exit my_exit(void)
{
unregister_chrdev(0, "my_device");
kfifo_free(&my_fifo);
kfree(fifo_buffer);
printk(KERN_INFO "my device unregistered\n");
}
module_init(my_init);
module_exit(my_exit);
```
该代码实现了一个简单的字符设备,它使用了Linux内核中提供的kfifo数据结构来实现队列的功能,用户可以通过该设备的文件描述符进行读写操作,读取数据会将队列中的数据写入用户缓冲区,写入数据会将用户缓冲区中的数据写入队列中。