Re: [patch 0/9] Fix various __task_cred related invalid RCU assumptions

Paul E. McKenney
2009-12-15T01:23:26Z

On Mon, Dec 14, 2009 at 03:30:39PM +0100, Peter Zijlstra wrote:
> On Mon, 2009-12-14 at 06:16 -0800, Paul E. McKenney wrote:
>
> > > I think you can use lock_is_held(&rcu_lock_map), except you need to deal
> > > with the !debug_locks case, because lockdep stops once debug_locks
> > > becomes false, which means lock_is_held() will return rubbish.
> >
> > OK, so I need to do something like the following, then?
> >
> > debug_locks ? lock_is_held(&rcu_lock_map) : 1
>
> Depending on what the safe return value is, yeah. If you want an assert
> like function, false is usually the safe one.
>
> #define lockdep_assert_held(l) WARN_ON(debug_locks && !lockdep_is_held(l))
>
> is the one in-tree user of this.

Sounds good, thank you for the tip!!!

Thanx, Paul