* Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Sat, Aug 15, 2020 at 10:30:29AM +0200, Ingo Molnar wrote:
> >
> > * Uriel Guajardo <urielguajardojr@xxxxxxxxx> wrote:
> >
> > > From: Uriel Guajardo <urielguajardo@xxxxxxxxxx>
> > >
> > > KUnit will fail tests upon observing a lockdep failure. Because lockdep
> > > turns itself off after its first failure, only fail the first test and
> > > warn users to not expect any future failures from lockdep.
> > >
> > > Similar to lib/locking-selftest [1], we check if the status of
> > > debug_locks has changed after the execution of a test case. However, we
> > > do not reset lockdep afterwards.
> > >
> > > Like the locking selftests, we also fix possible preemption count
> > > corruption from lock bugs.
> >
> > > --- a/lib/kunit/Makefile
> > > +++ b/lib/kunit/Makefile
> >
> > > +void kunit_check_lockdep(struct kunit *test, struct kunit_lockdep *lockdep) {
> > > + int saved_preempt_count = lockdep->preempt_count;
> > > + bool saved_debug_locks = lockdep->debug_locks;
> > > +
> > > + if (DEBUG_LOCKS_WARN_ON(preempt_count() != saved_preempt_count))
> > > + preempt_count_set(saved_preempt_count);
> > > +
> > > +#ifdef CONFIG_TRACE_IRQFLAGS
> > > + if (softirq_count())
> > > + current->softirqs_enabled = 0;
> > > + else
> > > + current->softirqs_enabled = 1;
> > > +#endif
> > > +
> > > + if (saved_debug_locks && !debug_locks) {
> > > + kunit_set_failure(test);
> > > + kunit_warn(test, "Dynamic analysis tool failure from LOCKDEP.");
> > > + kunit_warn(test, "Further tests will have LOCKDEP disabled.");
> > > + }
> >
> >
> > So this basically duplicates what the boot-time locking self-tests do,
> > in a poor fashion?
>
> No, it makes sure that any kunit based self-test fails when it messes up
> it's locking.
We have a flag for whether lockdep is running though, so is this
basically a very complicated way to parse /proc/lockdep_debug? :-)
Thanks,
Ingo
