From: Cody P Schafer Subject: [PATCH 1/2] rbtree: fix postorder iteration when the rb_node is not the first element in an entry Date: Mon, 4 Nov 2013 17:40:01 -0800 Message-ID: <1383615602-1784-1-git-send-email-cody@linux.vnet.ibm.com> References: <52784ADF.1040104@linux.vnet.ibm.com> Cc: Andreas Dilger , LKML , EXT4 , Cody P Schafer To: Andrew Morton , Jan Kara Return-path: In-Reply-To: <52784ADF.1040104@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Provide a new helper called rb_next_postorder_entry() to perform NULL checks and container_of() coversions and use it in rbtree_for_each_entry_safe() to fix oopses that occur when rb_node is not the first element in the entry. Additionally, remove the missplaced NULL check from rb_next_postorder(). Signed-off-by: Cody P Schafer --- include/linux/rbtree.h | 20 +++++++++++++++----- lib/rbtree.c | 2 -- 2 files changed, 15 insertions(+), 7 deletions(-) diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h index aa870a4..630eedb 100644 --- a/include/linux/rbtree.h +++ b/include/linux/rbtree.h @@ -86,6 +86,18 @@ static inline void rb_link_node(struct rb_node * node, struct rb_node * parent, } /** + * rb_next_postorder_entry - a helper to check for a NULL entry and advance to + * the next element. + * + * @elem: a 'type *' which is contained in an rbtree + * @field: the field in 'type' which contains the struct rb_node. + */ +#define rb_next_postorder_entry(elem, field) \ + ((elem) ? rb_entry(rb_next_postorder(&(elem)->field), \ + typeof(*(elem)), field) \ + : NULL) + +/** * rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of * given type safe against removal of rb_node entry * @@ -96,11 +108,9 @@ static inline void rb_link_node(struct rb_node * node, struct rb_node * parent, */ #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \ for (pos = rb_entry(rb_first_postorder(root), typeof(*pos), field),\ - n = rb_entry(rb_next_postorder(&pos->field), \ - typeof(*pos), field); \ - &pos->field; \ + n = rb_next_postorder_entry(pos, field); \ + pos; \ pos = n, \ - n = rb_entry(rb_next_postorder(&pos->field), \ - typeof(*pos), field)) + n = rb_next_postorder_entry(pos, field)) #endif /* _LINUX_RBTREE_H */ diff --git a/lib/rbtree.c b/lib/rbtree.c index 65f4eff..08168d0 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -534,8 +534,6 @@ static struct rb_node *rb_left_deepest_node(const 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 */ -- 1.8.4.2