[MINOR] imported the rbtree function from Linux kernel
Those rbtree functions will be used by Sin Yu's new rbtree scheduler.
diff --git a/include/common/rbtree.h b/include/common/rbtree.h
new file mode 100644
index 0000000..107e8d2
--- /dev/null
+++ b/include/common/rbtree.h
@@ -0,0 +1,150 @@
+/*
+ Red Black Trees
+ (C) 1999 Andrea Arcangeli <andrea@suse.de>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ linux/include/linux/rbtree.h
+
+ To use rbtrees you'll have to implement your own insert and search cores.
+ This will avoid us to use callbacks and to drop drammatically performances.
+ I know it's not the cleaner way, but in C (not in C++) to get
+ performances and genericity...
+
+ Some example of insert and search follows here. The search is a plain
+ normal search over an ordered tree. The insert instead must be implemented
+ int two steps: as first thing the code must insert the element in
+ order as a red leaf in the tree, then the support library function
+ rb_insert_color() must be called. Such function will do the
+ not trivial work to rebalance the rbtree if necessary.
+
+-----------------------------------------------------------------------
+static inline struct page * rb_search_page_cache(struct inode * inode,
+ unsigned long offset)
+{
+ struct rb_node * n = inode->i_rb_page_cache.rb_node;
+ struct page * page;
+
+ while (n)
+ {
+ page = rb_entry(n, struct page, rb_page_cache);
+
+ if (offset < page->offset)
+ n = n->rb_left;
+ else if (offset > page->offset)
+ n = n->rb_right;
+ else
+ return page;
+ }
+ return NULL;
+}
+
+static inline struct page * __rb_insert_page_cache(struct inode * inode,
+ unsigned long offset,
+ struct rb_node * node)
+{
+ struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
+ struct rb_node * parent = NULL;
+ struct page * page;
+
+ while (*p)
+ {
+ parent = *p;
+ page = rb_entry(parent, struct page, rb_page_cache);
+
+ if (offset < page->offset)
+ p = &(*p)->rb_left;
+ else if (offset > page->offset)
+ p = &(*p)->rb_right;
+ else
+ return page;
+ }
+
+ rb_link_node(node, parent, p);
+
+ return NULL;
+}
+
+static inline struct page * rb_insert_page_cache(struct inode * inode,
+ unsigned long offset,
+ struct rb_node * node)
+{
+ struct page * ret;
+ if ((ret = __rb_insert_page_cache(inode, offset, node)))
+ goto out;
+ rb_insert_color(node, &inode->i_rb_page_cache);
+ out:
+ return ret;
+}
+-----------------------------------------------------------------------
+*/
+
+#ifndef _LINUX_RBTREE_H
+#define _LINUX_RBTREE_H
+
+/*
+#include <linux/kernel.h>
+#include <linux/stddef.h>
+*/
+
+struct rb_node
+{
+ struct rb_node *rb_parent;
+ int rb_color;
+#define RB_RED 0
+#define RB_BLACK 1
+ struct rb_node *rb_right;
+ struct rb_node *rb_left;
+};
+
+struct rb_root
+{
+ struct rb_node *rb_node;
+};
+
+// Copy from linux kernel 2.6 source (kernel.h, stddef.h)
+#define container_of(ptr, type, member) ({ \
+ const typeof( ((type *)0)->member ) *__mptr = (ptr); \
+ (type *)( (char *)__mptr - offsetof(type,member) );})
+#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+
+
+#define RB_ROOT (struct rb_root) { NULL, }
+#define rb_entry(ptr, type, member) container_of(ptr, type, member)
+
+extern void rb_insert_color(struct rb_node *, struct rb_root *);
+extern void rb_erase(struct rb_node *, struct rb_root *);
+
+/* Find logical next and previous nodes in a tree */
+extern struct rb_node *rb_next(struct rb_node *);
+extern struct rb_node *rb_prev(struct rb_node *);
+extern struct rb_node *rb_first(struct rb_root *);
+extern struct rb_node *rb_last(struct rb_root *);
+
+/* Fast replacement of a single node without remove/rebalance/add/rebalance */
+extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
+ struct rb_root *root);
+
+static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
+ struct rb_node ** rb_link)
+{
+ node->rb_parent = parent;
+ node->rb_color = RB_RED;
+ node->rb_left = node->rb_right = NULL;
+
+ *rb_link = node;
+}
+
+#endif /* _LINUX_RBTREE_H */