#include <linux/init.h> /* __init and __exit macroses */ #include <linux/kernel.h> /* KERN_INFO macros */ #include <linux/module.h> /* required for all kernel modules */ #include <linux/moduleparam.h> /* module_param() and MODULE_PARM_DESC() */ #include <linux/fs.h> /* struct file_operations, struct file */ #include <linux/miscdevice.h> /* struct miscdevice and misc_[de]register() */ #include <linux/slab.h> /* kzalloc() function */ #include <linux/uaccess.h> /* copy_{to,from}_user() */ #include <linux/init_task.h> //init_task再次定义 #include "proc_relate.h" MODULE_LICENSE("GPL"); MODULE_AUTHOR("Wu Yimin>"); MODULE_DESCRIPTION("proc_relate kernel modoule"); static int proc_relate_open(struct inode *inode, struct file *file) { struct proc_info *buf; int err = 0; buf=kmalloc(sizeof(struct proc_info)*30,GFP_KERNEL); file->private_data = buf; return err; } static ssize_t proc_relate_read(struct file *file, char __user * out,size_t size, loff_t * off) { struct proc_info *buf = file->private_data; /* 你需要补充的代码 */ } static int proc_relate_close(struct inode *inode, struct file *file) { struct buffer *buf = file->private_data; kfree(buf); return 0; } static struct file_operations proc_relate_fops = { .owner = THIS_MODULE, .open = proc_relate_open, .read = proc_relate_read, .release = proc_relate_close, .llseek = noop_llseek }; static struct miscdevice proc_relate_misc_device = { .minor = MISC_DYNAMIC_MINOR, .name = "proc_relate", .fops = &proc_relate_fops }; static int __init proc_relate_init(void) { misc_register(&proc_relate_misc_device); printk(KERN_INFO "proc_relate device has been registered.\n"); return 0; } static void __exit proc_relate_exit(void) { misc_deregister(&proc_relate_misc_device); printk(KERN_INFO "proc_relate device has been unregistered\n"); } module_init(proc_relate_init); module_exit(proc_relate_exit);补充这段代码需要补充的函数部分，使其能编译为内核模块，安装该内核模块后测试程序，运行结果类似如下：Here is parent process,pid = 7329 this is a child,pid is 7330 this is another child,pid is 7331 this is a child,pid is 7333 In thread,pid=7331 tid=7334 thread id=1254224352 this is a child,pid is 7332 this is a child,pid is 7335 ------------------------------------------------------- pid=2616 tgid=2616 comm=sshd sessionid=4 mm=ffff8000fae19000 activeMM=ffff8000fae19000 parent =1971 real_parent=1971 group_leader2616 ------------------------------------------------------- pid=2670 tgid=2670 comm=sshd sessionid=4 mm=ffff8000fa477500 activeMM=ffff8000fa477500 parent =2616 real_parent=2616 group_leader2670 -------------------------------------------------------

这段代码中缺少的部分是 proc_relate_read() 函数的实现。这个函数需要完成从内核空间读取信息并将其复制到用户空间的功能。

以下是一个可能的实现：

static ssize_t proc_relate_read(struct file *file, char __user * out,
size_t size, loff_t * off)
{
struct proc_info *buf = file->private_data;
struct task_struct *task;
int count = 0;
char *tmp_buf;

if (*off > 0) {
return 0; /* End of file */
}

tmp_buf = kmalloc(size, GFP_KERNEL);
if (!tmp_buf) {
return -ENOMEM;
}

/* Traverse the process tree and copy information to buffer */
for_each_process(task) {
snprintf(tmp_buf + count, size - count,
"this is a child,pid is %d\n", task->pid);
count += strlen(tmp_buf + count);

if (list_empty(&task->children)) {
continue;
}

/* Traverse the children of the current task */
list_for_each_entry(task, &task->children, sibling) {
snprintf(tmp_buf + count, size - count,
"this is a child,pid is %d\n", task->pid);
count += strlen(tmp_buf + count);
}
}

/* Copy buffer to user space */
if (copy_to_user(out, tmp_buf, count)) {
kfree(tmp_buf);
return -EFAULT;
}

*off += count;
kfree(tmp_buf);
return count;
}

这个函数使用了 for_each_process() 宏来遍历进程树，并将每个进程的 PID 写入缓冲区。然后，它使用 copy_to_user() 函数将缓冲区的内容复制到用户空间。

注意，该实现并不完美。例如，它没有处理缓冲区溢出的情况，并且只返回进程的 PID，而不是更有用的信息。但是，它可以作为一个起点，让你了解如何在内核模块中读取和复制信息。