create_proc_entry "path" help?

FrankRizzo · 07-31-2011, 10:21 PM

Guys, my code:

Code:

int init_module(void)
{
    proc_entry = create_proc_entry( "bus/usb/005/004", 0666, NULL );

    if (proc_entry == NULL)
    {
      printk(KERN_INFO "Couldn't create proc entry\n");
    } 
    else 
    {
      proc_entry->proc_fops = &fops;
      printk(KERN_INFO "Module loaded.\n");
    }

    // This is intentionally forced.  Ignore it.  :-)
    return -EINVAL;
}

Always fails to create the proc entry requested. It was my understanding from a LOT of Google searching that this is permissible. As you might imagine, "/proc/bus/usb/005" already exists, as do items 001-003.

Anyone have any idea what's going on here?

Thanks!

bsat · 08-01-2011, 12:19 AM

The arguments to the create proc entries are
name : The name of the entry you want to create, not the path
mode: Permissions for read and write
parent dir: This is where you give the full path to the parent directory under which you want the entry.

So in your case, if you want entry named 004 under bus/usb/005, pass 004 as the first argument and bus/usb/005/ as the third.

FrankRizzo · 08-01-2011, 09:14 AM

The prototype for create_proc_entry is this:

Code:

struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,  struct proc_dir_entry *parent)

So, in order to be able to pass the dir as the 3rd parameter, I'll need to be able to get the "proc_dir_entry" for it.

How do I do that without calling proc_mkdir?

FrankRizzo · 08-01-2011, 01:52 PM

Hopefully this might help someone in the future if they're having the same problem.

Code:

    struct file *filp = filp_open("/proc/bus/usb/005", O_RDONLY, 0);
    struct proc_dir_entry *parent = PDE(filp->f_dentry->d_inode);
    filp_close(filp, NULL);

    proc_entry = create_proc_entry( "004", 0666, parent );