Messages in this thread | | | Date | Thu, 21 Mar 2013 20:36:52 -0700 | Subject | Re: [PATCH 3/3] rbtree_test: add more rbtree integrity checks | From | Michel Lespinasse <> |
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On Mon, Mar 18, 2013 at 4:21 PM, Davidlohr Bueso <davidlohr.bueso@hp.com> wrote: > When checking the rbtree, account for more properties: > > - Both children of a red node are black. > - The tree has at least 2**bh(v)-1 internal nodes.
> - WARN_ON_ONCE(is_red(rb) && > - (!rb_parent(rb) || is_red(rb_parent(rb)))); > + > + if (is_red(rb)) { > + /* > + * root must be black and no path contains two > + * consecutive red nodes. > + */ > + WARN_ON_ONCE(!rb_parent(rb) || is_red(rb_parent(rb))); > + > + /* both children of a red node are black */ > + WARN_ON_ONCE(is_red(rb->rb_left) || is_red(rb->rb_right)); > + }
This seems quite redundant with the previous test - if we're going to visit each children, then at that point we're going to check that they can't be black if their parent (the current node) is black. So I don't see that the tests adds any coverage.
> WARN_ON_ONCE(count != nr_nodes); > + WARN_ON_ONCE(count < (1 << black_path_count(rb_last(&root))) - 1);
I like this last check - it can also be seen as a consequence of the others, but it it's only one line and it nicely sums up what the other properties are for :)
-- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies.
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