example.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/uaccess.h>

#define STRINGLEN 1024

char global_buffer[STRINGLEN];
struct proc_dir_entry *example_dir, *hello_file, *current_file, *symlink;

int proc_read_current (char *page, char **start, off_t off, int count, int *eof, void *data)
{
	int len;
	//MOD_INC_USE_COUNT;
	try_module_get(THIS_MODULE);
	len=sprintf(page, "cunt process usages: \nname: %s \npid: %d\n", current->comm, current->pid);
	//MOD_DEC_USE_COUNT;
	module_put(THIS_MODULE);
	return len;
}

int proc_read_hello(char *page, char **start, off_t off, int count, int *eof, void *data)
{
	int len;
	try_module_get(THIS_MODULE);
	len=sprintf(page, "hello message:\n %s write: %s\n", current->comm, global_buffer);
	module_put(THIS_MODULE);
	return len;
}

int proc_write_hello(struct file *fiel, const char *buffer, unsigned long count, void *data)
{
	int len;
	try_module_get(THIS_MODULE);
	if(count>=STRINGLEN)
		len=STRINGLEN-1;
	else
		len=count;
	copy_from_user(global_buffer, buffer, len);
	global_buffer[len]='\0';
	module_put(THIS_MODULE);
	return len;
}

int init_module()
{
	example_dir=proc_mkdir("proc_test", NULL);
	current_file=create_proc_read_entry("current", 0644, example_dir, proc_read_current, NULL);

	hello_file=create_proc_entry("hello", 0666, example_dir);
	strcpy(global_buffer, "hello");
	hello_file->read_proc=proc_read_hello;
	hello_file->write_proc=proc_write_hello;
	return 0;
}

void cleanup_module()
{
	remove_proc_entry("current_too", example_dir);
	remove_proc_entry("hello", example_dir);
	remove_proc_entry("current", example_dir);
	remove_proc_entry("proc_test", NULL);
}