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Subject[patch] avoid kmemcheck warning in epoll
Epoll calls rb_set_parent(n, n) to initialize the rb-tree node, but 
rb_set_parent() accesses node's pointer in its code. This creates a
warning in kmemcheck (reported by Vegard Nossum) about an uninitialized
memory access. The warning is harmless since the following rb-tree node
insert is going to overwrite the node data. In any case I think it's
better to not have that happening at all, and fix it by properly
initializing the data.


Signed-off-by: Davide Libenzi <davidel@xmailserver.org>


- Davide


---
fs/eventpoll.c | 2 +-
include/linux/rbtree.h | 12 ++++++++++++
2 files changed, 13 insertions(+), 1 deletion(-)
Index: linux-2.6.mod/fs/eventpoll.c
===================================================================
--- linux-2.6.mod.orig/fs/eventpoll.c 2008-02-10 12:36:20.000000000 -0800
+++ linux-2.6.mod/fs/eventpoll.c 2008-02-10 12:50:41.000000000 -0800
@@ -260,7 +260,7 @@
/* Special initialization for the RB tree node to detect linkage */
static inline void ep_rb_initnode(struct rb_node *n)
{
- rb_set_parent(n, n);
+ rb_init_node(n, n);
}

/* Removes a node from the RB tree and marks it for a fast is-linked check */
Index: linux-2.6.mod/include/linux/rbtree.h
===================================================================
--- linux-2.6.mod.orig/include/linux/rbtree.h 2008-02-10 12:36:13.000000000 -0800
+++ linux-2.6.mod/include/linux/rbtree.h 2008-02-10 12:51:57.000000000 -0800
@@ -112,6 +112,18 @@
struct rb_node *rb_node;
};

+/**
+ * rb_init_node - Initializes the node internal data
+ *
+ * @node: Pointer to the RB-Tree node
+ * @parent: Pointer to the parent node, or NULL
+ *
+ */
+static inline void rb_init_node(struct rb_node *node, struct rb_node *parent)
+{
+ node->rb_parent_color = (unsigned long) parent;
+ node->rb_left = node->rb_right = NULL;
+}

#define rb_parent(r) ((struct rb_node *)((r)->rb_parent_color & ~3))
#define rb_color(r) ((r)->rb_parent_color & 1)

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