[PATCH 1/2] lockdep: add lockdep_assert_not_held()

[Peter Zijlstra]

On Fri, Feb 12, 2021 at 04:28:42PM -0700, Shuah Khan wrote:

> +#define lockdep_assert_not_held(l)	do {			\
> +		WARN_ON(debug_locks && lockdep_is_held(l));	\
> +	} while (0)
> +

This thing isn't as straight forward as you might think, but it'll
mostly work.

Notably this thing will misfire when lockdep_off() is employed. It
certainyl needs a comment to explain the subtleties.