Re: [Ksummit-2010-discuss] [v2] Remaining BKL users, what to do

From: Steven Rostedt
Date: Tue Oct 19 2010 - 09:44:00 EST


On Tue, 2010-10-19 at 15:36 +0200, Arnd Bergmann wrote:
> [trimming Cc list]
>
> On Tuesday 19 October 2010, Steven Rostedt wrote:
> > I think we also need to cover the PREEMPT case too. But that could be a
> > compile time check, since you can't boot a preempt kernel and make it
> > non preempt.
>
> Right. Can we turn the lock_kernel() into preempt_disable() in these
> drivers when we know we never run on SMP?

I'm not sure that will work. A holder of the BKL can call schedule or
even a mutex. The schedule code will drop the BKL and re-enable
preemption. Unless the code is known not to schedule while holding BKL,
we would need to open code the preempt_enable() around the locations
that the code may schedule.

-- Steve


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