Hi,
On 29/04/20 17:32, Peter Zijlstra wrote:
> I've always been bothered by the endless (fragile) boilerplate for
> rbtree, and I recently wrote some rbtree helpers for objtool and
> figured I should lift them into the kernel and use them more widely.
>
> Provide:
>
> partial-order; less() based:
> - rb_add(): add a new entry to the rbtree
> - rb_add_cached(): like rb_add(), but for a rb_root_cached
>
> total-order; cmp() based:
> - rb_find(): find an entry in an rbtree
> - rb_find_first(): find the first (leftmost) matching entry
> - rb_next_match(): continue from rb_find_first()
> - rb_for_each(): for loop with rb_find_first() / rb_next_match()
>
> Also make rb_add_cached() / rb_erase_cached() return true when
> leftmost.
>
> Inlining and constant propagation should see the compiler inline the
> whole thing, including the various compare functions.
>
> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
> ---
> include/linux/rbtree.h | 127
> +++++++++++++++++++++++++++++++++++++++++-
> tools/include/linux/rbtree.h | 129
> ++++++++++++++++++++++++++++++++++++++++++-
> tools/objtool/elf.c | 63 ++-------------------
> 3 files changed, 257 insertions(+), 62 deletions(-)
>
> --- a/include/linux/rbtree.h
> +++ b/include/linux/rbtree.h
> @@ -141,12 +141,18 @@ static inline void rb_insert_color_cache
> rb_insert_color(node, &root->rb_root);
> }
>
> -static inline void rb_erase_cached(struct rb_node *node,
> +static inline bool rb_erase_cached(struct rb_node *node,
> struct rb_root_cached *root)
> {
> - if (root->rb_leftmost == node)
> + bool leftmost = false;
> +
> + if (root->rb_leftmost == node) {
> root->rb_leftmost = rb_next(node);
Think we need
if (root->rb_leftmost)
> + leftmost = true;
DEADLINE crashes w/o that.
> + }
> rb_erase(node, &root->rb_root);
> +
> + return leftmost;
> }
The rest looks good to me.
Thanks,
Juri
