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

#define PROCFS_MAX_SIZE         1024
#define PROCFS_NAME             "test1"

static struct proc_dir_entry *Our_Proc_File;
static char procfs_buffer[PROCFS_MAX_SIZE];
static unsigned long procfs_buffer_size = 0;

static int Device_Open = 0;
// Обработчик чтения из файла в /proc.
ssize_t procfile_read(struct file *filePointer,char *buffer, size_t buffer_len$
{
        if (*offset >= sizeof(procfs_buffer)) return 0;
        copy_to_user(buffer, procfs_buffer, sizeof(procfs_buffer));
        *offset += buffer_length;

    printk(KERN_INFO "leaving /proc/test : procfile_read, wrote %d Bytes\n",(i$

    return buffer_length;
}
static ssize_t procfile_write(struct file *file, const char *buff,
                              size_t length, loff_t *offset)
{
        procfs_buffer_size = length;
        if (procfs_buffer_size > PROCFS_MAX_SIZE)
                procfs_buffer_size = PROCFS_MAX_SIZE;

        memset(procfs_buffer, 0, sizeof(procfs_buffer));
        if (copy_from_user(procfs_buffer, buff, procfs_buffer_size))
                return -EFAULT;
        procfs_buffer[procfs_buffer_size] = '\0';
        printk(KERN_INFO "leaving /proc/test : procfile_write,  %s \n", procfs$
        return procfs_buffer_size;
}
static int procfile_open(struct inode *inode, struct file *file)
{
  static int counter = 1;
  if (Device_Open) return -EBUSY;
  Device_Open++;
  printk(KERN_INFO "procfile_was_opened\n");
  return 0;
}

static int procfile_release(struct inode *inode, struct file *file)
{
  printk("Released.\n");
  Device_Open--;                /* Теперь мы готовы обслужить другой процесс */
// Уменьшить счетчик обращений, иначе, после первой же удачной попытки открыть$

  return 0;
}
static const struct file_operations proc_fops = {
   .owner = THIS_MODULE,
   .read = procfile_read,
   .write = procfile_write,
   .open = procfile_open,
   .release = procfile_release,
};

int init_module()
{
  int rv = 0;
  printk(KERN_INFO "Trying to create /proc/test:\n");

  Our_Proc_File = proc_create(PROCFS_NAME, 0644, NULL, &proc_fops);
  if (Our_Proc_File == NULL) {
    rv = -ENOMEM;
    proc_remove(Our_Proc_File);
    printk(KERN_INFO "Error: Could not initialize /proc/test\n");
  }
  else {
    printk(KERN_INFO "Success!\n");
  }

  return rv;
}


void cleanup_module()
{
  proc_remove(Our_Proc_File);
  printk(KERN_INFO "/proc/test removed\n");
}