cant open device
- by yoavstr
I have a little problem. I install this module into my kernel and its written under /proc
When I try to open() it from user mode I get the following message:
"Can't open device file: my_dev"
static int module_permission(struct inode *inode, int op, struct nameidata *foo)
{
//if its write
if ((op == 2)&&(writer == DOESNT_EXIST)){
writer = EXIST ;
return 0;
}
//if its read
if (op == 4 ){
numOfReaders++;
return 0;
}
return -EACCES;
}
int procfs_open(struct inode *inode, struct file *file)
{
try_module_get(THIS_MODULE);
return 0;
}
static struct file_operations File_Ops_4_Our_Proc_File = {
.read = procfs_read,
.write = procfs_write,
.open = procfs_open,
.release = procfs_close,
};
static struct inode_operations Inode_Ops_4_Our_Proc_File = {
.permission = module_permission, /* check for permissions */
};
int init_module()
{
/* create the /proc file */
Our_Proc_File = create_proc_entry(PROC_ENTRY_FILENAME, 0644, NULL);
/* check if the /proc file was created successfuly */
if (Our_Proc_File == NULL){
printk(KERN_ALERT "Error: Could not initialize /proc/%s\n",
PROC_ENTRY_FILENAME);
return -ENOMEM;
}
Our_Proc_File->owner = THIS_MODULE;
Our_Proc_File->proc_iops = &Inode_Ops_4_Our_Proc_File;
Our_Proc_File->proc_fops = &File_Ops_4_Our_Proc_File;
Our_Proc_File->mode = S_IFREG | S_IRUGO | S_IWUSR;
Our_Proc_File->uid = 0;
Our_Proc_File->gid = 0;
Our_Proc_File->size = 80;
//i added init the writewr status
writer = DOESNT_EXIST;
numOfReaders = 0 ;
printk(KERN_INFO "/proc/%s created\n", PROC_ENTRY_FILENAME);
return 0;
}
