Re: [PATCH v3] kunit: added lockdep support

[Peter Zijlstra]

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.

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