Re: [PATCH v7 06/16] lockdep: Detect and handle hist_lock ring buffer overwrite

[Peter Zijlstra]

On Thu, Jul 13, 2017 at 12:29:05PM +0200, Peter Zijlstra wrote:
> On Thu, Jul 13, 2017 at 07:09:53PM +0900, Byungchul Park wrote:
> > On Thu, Jul 13, 2017 at 11:50:52AM +0200, Peter Zijlstra wrote:
> > >   wait_for_completion(&C);
> > >     atomic_inc_return();
> > > 
> > >                                   mutex_lock(A1);
> > >                                   mutex_unlock(A1);
> > > 
> > > 
> > >                                   <IRQ>
> > >                                     spin_lock(B1);
> > >                                     spin_unlock(B1);
> > > 
> > >                                     ...
> > > 
> > >                                     spin_lock(B64);
> > >                                     spin_unlock(B64);
> > >                                   </IRQ>
> > > 
> > > 

Also consider the alternative:

                                        <IRQ>
                                          spin_lock(D);
                                          spin_unlock(D);

                                          complete(&C);
                                        </IRQ>

in which case the context test will also not work.