Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753686Ab3DLBOV (ORCPT ); Thu, 11 Apr 2013 21:14:21 -0400 Received: from e8.ny.us.ibm.com ([32.97.182.138]:49580 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752329Ab3DLBOS (ORCPT ); Thu, 11 Apr 2013 21:14:18 -0400 From: Cody P Schafer To: Andrew Morton Cc: Mel Gorman , Linux MM , LKML , Cody P Schafer , Simon Jeons Subject: [RFC PATCH v2 01/25] rbtree: add postorder iteration functions. Date: Thu, 11 Apr 2013 18:13:33 -0700 Message-Id: <1365729237-29711-2-git-send-email-cody@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.2.1 In-Reply-To: <1365729237-29711-1-git-send-email-cody@linux.vnet.ibm.com> References: <1365729237-29711-1-git-send-email-cody@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13041201-9360-0000-0000-000011B4F88D Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2639 Lines: 80 Add postorder iteration functions for rbtree. These are useful for safely freeing an entire rbtree without modifying the tree at all. Signed-off-by: Cody P Schafer --- include/linux/rbtree.h | 4 ++++ lib/rbtree.c | 40 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+) diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h index 0022c1b..2879e96 100644 --- a/include/linux/rbtree.h +++ b/include/linux/rbtree.h @@ -68,6 +68,10 @@ extern struct rb_node *rb_prev(const struct rb_node *); extern struct rb_node *rb_first(const struct rb_root *); extern struct rb_node *rb_last(const struct rb_root *); +/* Postorder iteration - always visit the parent after it's children */ +extern struct rb_node *rb_first_postorder(const struct rb_root *); +extern struct rb_node *rb_next_postorder(const struct rb_node *); + /* Fast replacement of a single node without remove/rebalance/add/rebalance */ extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, struct rb_root *root); diff --git a/lib/rbtree.c b/lib/rbtree.c index c0e31fe..65f4eff 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -518,3 +518,43 @@ void rb_replace_node(struct rb_node *victim, struct rb_node *new, *new = *victim; } EXPORT_SYMBOL(rb_replace_node); + +static struct rb_node *rb_left_deepest_node(const struct rb_node *node) +{ + for (;;) { + if (node->rb_left) + node = node->rb_left; + else if (node->rb_right) + node = node->rb_right; + else + return (struct rb_node *)node; + } +} + +struct rb_node *rb_next_postorder(const struct rb_node *node) +{ + const struct rb_node *parent; + if (!node) + return NULL; + parent = rb_parent(node); + + /* If we're sitting on node, we've already seen our children */ + if (parent && node == parent->rb_left && parent->rb_right) { + /* If we are the parent's left node, go to the parent's right + * node then all the way down to the left */ + return rb_left_deepest_node(parent->rb_right); + } else + /* Otherwise we are the parent's right node, and the parent + * should be next */ + return (struct rb_node *)parent; +} +EXPORT_SYMBOL(rb_next_postorder); + +struct rb_node *rb_first_postorder(const struct rb_root *root) +{ + if (!root->rb_node) + return NULL; + + return rb_left_deepest_node(root->rb_node); +} +EXPORT_SYMBOL(rb_first_postorder); -- 1.8.2.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/