Re: create_proc_entry and !CONFIG_PROC_FS

[Andrew Morton <akpm@osdl.org>]

Adrian Bunk <bunk@fs.tum.de> wrote:
>
> Hi,
> 
> I've observed a possible problem with create_proc_entry and 
> !CONFIG_PROC_FS.
> 
> If !CONFIG_PROC_FS include/linux/proc_fs.h includes a dummy 
> create_proc_entry that simply returns NULL.
> 
> Unfortunately, many callers of this function do things like e.g.
> 
> static int __init br2684_init(void)
> {
>         struct proc_dir_entry *p;
>         if ((p = create_proc_entry("br2684", 0, atm_proc_root)) == NULL)
>                 return -ENOMEM;
>         p->proc_fops = &br2684_proc_operations;
>         br2684_ioctl_set(br2684_ioctl);
>         return 0;
> }
> 
> 
> IOW, the dummy create_proc_entry fixes the compilation but the init 
> function always returns -ENOMEM if !CONFIG_PROC_FS.
> 
> Is there any better solution than removing the dummy create_proc_entry 
> and #ifdef'ing all places where it's used?

The normal fix would be to sprinkle ifdefs throughout the driver itself.

You need to lok at the driver and ask yourself "is anyone ever going to want
to use this in a no-procfs system".  Probably, the answer is always "no". 
In which case appropriate fixes would be to ignore the problem, or disable
the driver in config if !CONFIG_PROC_FS.