Re: devfs: BKL *not* taken while opening devices

Dave Hansen
2002-04-30T16:42:54Z

Russell King wrote:
> On Mon, Apr 29, 2002 at 06:21:34PM +0100, Arjan van de Ven wrote:
>
>>I'm not convinced of that. It's not nearly a critical path and it's
>>better to get even the "dumb" drivers safe than to risk having big
>>security holes in there for years to come.
>
> Would it be worth dropping a BUG_ON(!kernel_locked()) in tty_open() to
> catch this type of error? The tty code heavily relies on the BKL.
>
> This way, such locking problems would get caught early, since everyone
> uses the tty code during boot, right?

I like the idea. But, while we're at it, does anyone have a good enough
grasp of locking the the TTY layer that we can start peeling some of the
BKL out of there? Somebody was doing tests over a serial console here
and the lockmeter data showed horrible BKL contention and hold times.

--
Dave Hansen
haveblue@us.ibm.com