On Wed, 30 Sep 2020 21:22:42 +0200 Peter Zijlstra <[email protected]> wrote:
> On Wed, Sep 30, 2020 at 03:10:26PM -0400, Steven Rostedt wrote: > > On Wed, 30 Sep 2020 20:13:23 +0200 > > Peter Zijlstra <[email protected]> wrote: > > > > > diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h > > > > index 6a584b3e5c74..3e5bc1dd71c6 100644 > > > > --- a/include/linux/lockdep.h > > > > +++ b/include/linux/lockdep.h > > > > @@ -550,7 +550,8 @@ do { > > > > \ > > > > > > > > #define lockdep_assert_irqs_disabled() > > > > \ > > > > do { > > > > \ > > > > - WARN_ON_ONCE(debug_locks && raw_cpu_read(hardirqs_enabled)); > > > > \ > > > > + WARN_ON_ONCE(debug_locks && raw_cpu_read(hardirqs_enabled) && > > > > \ > > > > + likely(!(current->lockdep_recursion & > > > > LOCKDEP_RECURSION_MASK)));\ > > > > } while (0) > > > > > > Blergh, IIRC there's header hell that way. The sane fix is killing off > > > that trace_*_rcuidle() disease. > > > > Really? > > > > I could run this through all my other tests to see if that is the case. > > That is, to see if it stumbles across header hell. > > I went through a lot of pain to make that per-cpu to avoid using > current. But that might've been driven by > lockdep_assert_preemption_disabled(), which is used in seqlock.h which > in turn is included all over the place. > > That said, there's at least two things we can do: > > - make lockdep_recursion per-cpu too, IIRC we only ever set that when > we have IRQs disabled anyway. > > OR > > - inspired by the above, as can save/clear - restore hardirqs_enabled > when we frob lockdep_recursion. > > Admittedly, the second is somewhat gross :-) I think making lockdep_recursion percpu sounds like the best approach. -- Steve
