Subject: [PATCH v3] drivers: psci: PSCI checker module

From: [email-masked] (Paul E. McKenney)
Date: Thu, 27 Oct 2016 07:54:46 -0700

On Thu, Oct 27, 2016 at 01:51:57PM +0100, Kevin Brodsky wrote:
> On 27/10/16 10:13, Lorenzo Pieralisi wrote:
> >On Wed, Oct 26, 2016 at 11:11:48AM -0700, Paul E. McKenney wrote:
> >>On Wed, Oct 26, 2016 at 06:35:34PM +0100, Lorenzo Pieralisi wrote:
> >>>On Wed, Oct 26, 2016 at 10:22:52AM -0700, Paul E. McKenney wrote:
> >>>>On Wed, Oct 26, 2016 at 06:10:06PM +0100, Lorenzo Pieralisi wrote:
> >>[ . . . ]
> >>
> >>>>>Thanks a lot for your feedback, thoughts appreciated.
> >>>>Let me ask the question more directly.
> >>>>
> >>>>Why on earth are we trying to run these tests concurrently?
> >>>We must prevent that, no question about that, that's why I started
> >>>this discussion. It is not fine to enable this checker and the
> >>>RCU/LOCK torture hotplug tests at the same time.
> >>>
> >>>>After all, if we just run one at a time in isolation, there is no
> >>>>problem.
> >>>Fine by me, it was to understand if the current assumptions we made
> >>>are correct and they are definitely not. If we enable the PSCI checker
> >>>we must disable the torture rcu/lock hotplug tests either statically or
> >>>dynamically.
> >>What rcutorture, locktorture, and rcuperf do is to invoke
> >>torture_init_begin(), which returns false if one of these tests
> >>is already running.
> >>
> >>Perhaps we should extract this torture-test-exclusion and require
> >>than conflicting torture tests invoke it?
> >Yes if it can be extracted as a check (but it should also prevent the
> >torture tests from running and vice versa), either that or Kconfig
> >dependency (which we could do as a first step, waiting to add the
> >required interface to the torture test code ?).
> >
> >Thanks !
> >Lorenzo
> 
> That sounds like a reasonable idea, but then that would mean that the PSCI checker
> would have to wait until the torture test is finished if it is already running (and
> the other way around).
> 
> I wasn't aware that torture tests were hotplugging CPUs. I think that the most
> sensible thing to do right now is to make CONFIG_PSCI_CHECKER depend on
> !CONFIG_TORTURE_TEST (or maybe specifically !CONFIG_RCU_TORTURE_TEST &&
> !CONFIG_LOCK_TORTURE_TEST). We can try to make them work together afterwards, but for
> the sake of getting this patch merged in a reasonable amount of time, I think we
> should just exclude the conflicting tests at the build level in this patch. I'll also
> update the comment accordingly.

I suggest !CONFIG_TORTURE_TEST, given that there are a couple of other
tests in the offing.

							Thanx, Paul

> Thanks,
> Kevin
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