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References: <20200814205527.1833459-1-urielguajardojr@gmail.com> <20200814205847.GK3982@worktop.programming.kicks-ass.net>
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From:   Uriel Guajardo <urielguajardo@google.com>
Date:   Fri, 14 Aug 2020 16:00:06 -0500
Message-ID: <CAG30Eef1RBj07_=KCJ5G2J0k3_pgL-hM6PiYba0Vf6O16WhnUQ@mail.gmail.com>
Subject: Re: [PATCH v3] kunit: added lockdep support
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Uriel Guajardo <urielguajardojr@gmail.com>,
        Brendan Higgins <brendanhiggins@google.com>, mingo@redhat.com,
        will@kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        KUnit Development <kunit-dev@googlegroups.com>,
        Alan Maguire <alan.maguire@oracle.com>
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On Fri, Aug 14, 2020 at 3:58 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Fri, Aug 14, 2020 at 08:55:27PM +0000, Uriel Guajardo wrote:
> > +
> > +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
>
> This block is pointless. The only way to get softirq tracing out of sync
> is an unbalanced local_bh_disable(), but then the above preempt_count()
> test will trigger and kill IRQ tracing.

Ahh I see. Thank you.

>
> > +
> > +     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.");
> > +     }
> > +}