On Tue, 2011-09-20 at 17:29 +0530, Srikar Dronamraju wrote:
> +static struct uprobe *__insert_uprobe(struct uprobe *uprobe)
> +{
> + struct rb_node **p = &uprobes_tree.rb_node;
> + struct rb_node *parent = NULL;
> + struct uprobe *u;
> + int match;
> +
> + while (*p) {
> + parent = *p;
> + u = rb_entry(parent, struct uprobe, rb_node);
> + match = match_uprobe(uprobe, u);
> + if (!match) {
> + atomic_inc(&u->ref);
> + return u;
> + }
> +
> + if (match < 0)
> + p = &parent->rb_left;
> + else
> + p = &parent->rb_right;
> +
> + }
> + u = NULL;
> + rb_link_node(&uprobe->rb_node, parent, p);
> + rb_insert_color(&uprobe->rb_node, &uprobes_tree);
> + /* get access + drop ref */
> + atomic_set(&uprobe->ref, 2);
> + return u;
> +}
If you ever want to make a 'lockless' lookup work you need to set the
refcount of the new object before its fully visible, instead of after.
Now much of a problem now since its fully serialized by that
uprobes_treelock thing.
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