Re: How to lock current->signal->tty

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

Ar Maw, 2006-08-08 am 13:11 -0400, ysgrifennodd Stephen Smalley:
> Does this look sane?  Or do we need a common helper factored from
> disassociate_ctty()?  Why is the locking different for TIOCNOTTY in the
> non-leader case?

The non-leader case for TIOCNOTTY in the base kernel is different
because it is wrong and I've fixed that one.

If you can factor disassociate_ctty out to do what you need I'd prefer
that path so the tty locking actually ends up in the tty layer.

> +	mutex_lock(&tty_mutex);
> +	tty = current->signal->tty;
>  	if (tty) {
>  		file_list_lock();

Looks sane and the lock ordering matches vhangup() which may actually
also do what you want - I'm not 100% sure I follow what SELinux tries to
do here.