On Sun, 10 Feb 2008 13:32:01 -0800 (PST)
Davide Libenzi <[EMAIL PROTECTED]> wrote:
> 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 <[EMAIL PROTECTED]>
>
>
> - 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;
> +}
Is epoll the only rbtree-using code which exhibits this problem? If so,
what is epoll doing differently from all the others?
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