Re: lockdep null-ptr-deref

[Peter Zijlstra]

On Fri, Oct 02, 2020 at 08:36:02PM +0800, Boqun Feng wrote:

> But what if f2() is called with interrupt disabled? Or f2() disables
> interrupt inside the function, like:
> 
> 	void f2(...)
> 	{
> 		local_irq_disable();
> 		spin_lock(&B);
> 		g(...);
> 		...
> 		local_irq_enable();
> 	}
> 
> In this case, there wouldn't be any LOCK_ENABLED_*_READ usage for
> rwlock_t A. As a result, we won't see it in the lockdep splat.

Hurm, fair enough. So just to make sure, you're arguing for:

-#define LOCK_TRACE_STATES              (XXX_LOCK_USAGE_STATES*4 + 1)
+#define LOCK_TRACE_STATES              (XXX_LOCK_USAGE_STATES*4 + 2)

On top of my earlier patch, right?