Re: [PATCH 20/28] locking/lockdep: Refactorize check_noncircular and check_redundant

[Peter Zijlstra]

On Wed, Apr 24, 2019 at 06:19:26PM +0800, Yuyang Du wrote:
> These two functions now handle different check results themselves. A new
> check_path function is added to check whether there is a path in the
> dependency graph. No functional change.

This looks good, however I completely forgot we still had the redundant
thing.

It was added for cross-release (which has since been reverted) which
would generate a lot of redundant links (IIRC) but having it makes the
reports more convoluted -- basically, if we had an A-B-C relation, then
A-C will not be added to the graph because it is already covered. This
then means any report will include B, even though a shorter cycle might
have been possible.

Maybe we should make the whole redundant check depend on LOCKDEP_SMALL
for now.