Re: [PATCH] lockdep: change scheduler annotation

[David Miller <davem@davemloft.net>]

From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 30 Jul 2008 13:26:57 +0200

> While thinking about David's patch it _finally_ dawned on me that there
> is no reason we have a lock class per cpu..
> 
> Sorry for being dense :-/
> 
> The below changes the annotation from a lock class per cpu, to a single
> nested lock, as the scheduler never holds more that 2 rq locks at a time
> anyway.
> 
> If there was code requiring holding all rq locks this would not work and
> the original annotation would be the only option, but that not being the
> case, this is a much lighter one.
> 
> Compiles and boots on a 2-way x86_64.
> 
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

I had been wondering this entire debugging session why the
per-rq lock classes were even there, thanks for getting
rid of them :)