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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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      Last update: 2008-02-10 22:35    [W:0.041 / U:0.192 seconds]
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