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TOMOYO Linux Cross Reference
Linux/include/linux/rbtree.h

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  1 /* SPDX-License-Identifier: GPL-2.0-or-later */
  2 /*
  3   Red Black Trees
  4   (C) 1999  Andrea Arcangeli <andrea@suse.de>
  5   
  6 
  7   linux/include/linux/rbtree.h
  8 
  9   To use rbtrees you'll have to implement your own insert and search cores.
 10   This will avoid us to use callbacks and to drop drammatically performances.
 11   I know it's not the cleaner way,  but in C (not in C++) to get
 12   performances and genericity...
 13 
 14   See Documentation/rbtree.txt for documentation and samples.
 15 */
 16 
 17 #ifndef _LINUX_RBTREE_H
 18 #define _LINUX_RBTREE_H
 19 
 20 #include <linux/kernel.h>
 21 #include <linux/stddef.h>
 22 #include <linux/rcupdate.h>
 23 
 24 struct rb_node {
 25         unsigned long  __rb_parent_color;
 26         struct rb_node *rb_right;
 27         struct rb_node *rb_left;
 28 } __attribute__((aligned(sizeof(long))));
 29     /* The alignment might seem pointless, but allegedly CRIS needs it */
 30 
 31 struct rb_root {
 32         struct rb_node *rb_node;
 33 };
 34 
 35 #define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))
 36 
 37 #define RB_ROOT (struct rb_root) { NULL, }
 38 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
 39 
 40 #define RB_EMPTY_ROOT(root)  (READ_ONCE((root)->rb_node) == NULL)
 41 
 42 /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
 43 #define RB_EMPTY_NODE(node)  \
 44         ((node)->__rb_parent_color == (unsigned long)(node))
 45 #define RB_CLEAR_NODE(node)  \
 46         ((node)->__rb_parent_color = (unsigned long)(node))
 47 
 48 
 49 extern void rb_insert_color(struct rb_node *, struct rb_root *);
 50 extern void rb_erase(struct rb_node *, struct rb_root *);
 51 
 52 
 53 /* Find logical next and previous nodes in a tree */
 54 extern struct rb_node *rb_next(const struct rb_node *);
 55 extern struct rb_node *rb_prev(const struct rb_node *);
 56 extern struct rb_node *rb_first(const struct rb_root *);
 57 extern struct rb_node *rb_last(const struct rb_root *);
 58 
 59 /* Postorder iteration - always visit the parent after its children */
 60 extern struct rb_node *rb_first_postorder(const struct rb_root *);
 61 extern struct rb_node *rb_next_postorder(const struct rb_node *);
 62 
 63 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
 64 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
 65                             struct rb_root *root);
 66 extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
 67                                 struct rb_root *root);
 68 
 69 static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
 70                                 struct rb_node **rb_link)
 71 {
 72         node->__rb_parent_color = (unsigned long)parent;
 73         node->rb_left = node->rb_right = NULL;
 74 
 75         *rb_link = node;
 76 }
 77 
 78 static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
 79                                     struct rb_node **rb_link)
 80 {
 81         node->__rb_parent_color = (unsigned long)parent;
 82         node->rb_left = node->rb_right = NULL;
 83 
 84         rcu_assign_pointer(*rb_link, node);
 85 }
 86 
 87 #define rb_entry_safe(ptr, type, member) \
 88         ({ typeof(ptr) ____ptr = (ptr); \
 89            ____ptr ? rb_entry(____ptr, type, member) : NULL; \
 90         })
 91 
 92 /**
 93  * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
 94  * given type allowing the backing memory of @pos to be invalidated
 95  *
 96  * @pos:        the 'type *' to use as a loop cursor.
 97  * @n:          another 'type *' to use as temporary storage
 98  * @root:       'rb_root *' of the rbtree.
 99  * @field:      the name of the rb_node field within 'type'.
100  *
101  * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
102  * list_for_each_entry_safe() and allows the iteration to continue independent
103  * of changes to @pos by the body of the loop.
104  *
105  * Note, however, that it cannot handle other modifications that re-order the
106  * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
107  * rb_erase() may rebalance the tree, causing us to miss some nodes.
108  */
109 #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
110         for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
111              pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
112                         typeof(*pos), field); 1; }); \
113              pos = n)
114 
115 /*
116  * Leftmost-cached rbtrees.
117  *
118  * We do not cache the rightmost node based on footprint
119  * size vs number of potential users that could benefit
120  * from O(1) rb_last(). Just not worth it, users that want
121  * this feature can always implement the logic explicitly.
122  * Furthermore, users that want to cache both pointers may
123  * find it a bit asymmetric, but that's ok.
124  */
125 struct rb_root_cached {
126         struct rb_root rb_root;
127         struct rb_node *rb_leftmost;
128 };
129 
130 #define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
131 
132 /* Same as rb_first(), but O(1) */
133 #define rb_first_cached(root) (root)->rb_leftmost
134 
135 static inline void rb_insert_color_cached(struct rb_node *node,
136                                           struct rb_root_cached *root,
137                                           bool leftmost)
138 {
139         if (leftmost)
140                 root->rb_leftmost = node;
141         rb_insert_color(node, &root->rb_root);
142 }
143 
144 static inline void rb_erase_cached(struct rb_node *node,
145                                    struct rb_root_cached *root)
146 {
147         if (root->rb_leftmost == node)
148                 root->rb_leftmost = rb_next(node);
149         rb_erase(node, &root->rb_root);
150 }
151 
152 static inline void rb_replace_node_cached(struct rb_node *victim,
153                                           struct rb_node *new,
154                                           struct rb_root_cached *root)
155 {
156         if (root->rb_leftmost == victim)
157                 root->rb_leftmost = new;
158         rb_replace_node(victim, new, &root->rb_root);
159 }
160 
161 #endif  /* _LINUX_RBTREE_H */
162 

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