Re: [PATCH v3] kunit: added lockdep support

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.");
  

• }
  

+}