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

[Byungchul Park]

On Thu, Jul 13, 2017 at 8:12 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> 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.

Context tests are done on xhlock with the release context, _not_
acquisition context. For example, spin_lock(D) and complete(&C) are
in the same context, so the test would pass in this example.

So it works.


-- 
Thanks,
Byungchul