Re: [PATCH 1/2] Introduce tty_unregister_ldisc()

[Alexey Dobriyan <adobriyan@gmail.com>]

On Wednesday 01 June 2005 09:42, Christoph Hellwig wrote:
> On Tue, May 31, 2005 at 05:28:11PM -0500, Paul Fulghum wrote:
> > An unmodified ldisc driver (externally maintained) will continue to call
> > tty_register_ldisc with NULL, but the new behavior will be to set the
> > ldisc pointer to NULL but have LDISC_FLAG_DEFINED set.
> > 
> > If you feel it is absolutely necessary to add this new function
> > for cosmetic reasons, then leave the old behavior in place
> > and make tty_unregister_ldisc a wrapper to tty_register_ldisc
> > that uses a NULL pointer.
> 
> Nah, we don't want to allow staying out of tree folks out of sync.  Adding
> a BUG_ON for ldisk beeing NULL is much more reasoable.

Why add BUG_ON?

	tty_register_ldisc(N_FOO, NULL);
			...
	tty_ldiscs[disc] = *new_ldisc;	<= NULL