Re: [PATCH] kill empty chardev open/release methods

[corbet@lwn.net (Jonathan Corbet)]

Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

> Actually it turns out you can introduce bugs doing this when the BKL is
> pushed down.
> 
> The problem is the methods are not NULL, they (with the lock pushed down
> are)
> 
> {
> 	lock_kernel();
> 	unlock_kernel();
> }
> 
> And we have drivers with setup code that does things in the wrong order
> but under the BKL. eg one I just fixed did
> 
> 	misc_register()
> 	init locks
> 	allocate memory
> 	do stuff
> 	return 0;

Hmph.

As it turns out, a misc driver will still be OK because the BKL has not
(yet) been pushed past misc_open().  What this does mean, though, is
that all of those empty and trivial open functions need to be
revisited.  I thought this looked too easy the first time through...

jon