[NETLINK]: Add properly module refcounting for kernel netlink sockets.
[linux-2.6.git] / lib / rbtree.c
1 /*
2   Red Black Trees
3   (C) 1999  Andrea Arcangeli <andrea@suse.de>
4   (C) 2002  David Woodhouse <dwmw2@infradead.org>
5   
6   This program is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 2 of the License, or
9   (at your option) any later version.
10
11   This program is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program; if not, write to the Free Software
18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19
20   linux/lib/rbtree.c
21 */
22
23 #include <linux/rbtree.h>
24 #include <linux/module.h>
25
26 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
27 {
28         struct rb_node *right = node->rb_right;
29
30         if ((node->rb_right = right->rb_left))
31                 right->rb_left->rb_parent = node;
32         right->rb_left = node;
33
34         if ((right->rb_parent = node->rb_parent))
35         {
36                 if (node == node->rb_parent->rb_left)
37                         node->rb_parent->rb_left = right;
38                 else
39                         node->rb_parent->rb_right = right;
40         }
41         else
42                 root->rb_node = right;
43         node->rb_parent = right;
44 }
45
46 static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
47 {
48         struct rb_node *left = node->rb_left;
49
50         if ((node->rb_left = left->rb_right))
51                 left->rb_right->rb_parent = node;
52         left->rb_right = node;
53
54         if ((left->rb_parent = node->rb_parent))
55         {
56                 if (node == node->rb_parent->rb_right)
57                         node->rb_parent->rb_right = left;
58                 else
59                         node->rb_parent->rb_left = left;
60         }
61         else
62                 root->rb_node = left;
63         node->rb_parent = left;
64 }
65
66 void rb_insert_color(struct rb_node *node, struct rb_root *root)
67 {
68         struct rb_node *parent, *gparent;
69
70         while ((parent = node->rb_parent) && parent->rb_color == RB_RED)
71         {
72                 gparent = parent->rb_parent;
73
74                 if (parent == gparent->rb_left)
75                 {
76                         {
77                                 register struct rb_node *uncle = gparent->rb_right;
78                                 if (uncle && uncle->rb_color == RB_RED)
79                                 {
80                                         uncle->rb_color = RB_BLACK;
81                                         parent->rb_color = RB_BLACK;
82                                         gparent->rb_color = RB_RED;
83                                         node = gparent;
84                                         continue;
85                                 }
86                         }
87
88                         if (parent->rb_right == node)
89                         {
90                                 register struct rb_node *tmp;
91                                 __rb_rotate_left(parent, root);
92                                 tmp = parent;
93                                 parent = node;
94                                 node = tmp;
95                         }
96
97                         parent->rb_color = RB_BLACK;
98                         gparent->rb_color = RB_RED;
99                         __rb_rotate_right(gparent, root);
100                 } else {
101                         {
102                                 register struct rb_node *uncle = gparent->rb_left;
103                                 if (uncle && uncle->rb_color == RB_RED)
104                                 {
105                                         uncle->rb_color = RB_BLACK;
106                                         parent->rb_color = RB_BLACK;
107                                         gparent->rb_color = RB_RED;
108                                         node = gparent;
109                                         continue;
110                                 }
111                         }
112
113                         if (parent->rb_left == node)
114                         {
115                                 register struct rb_node *tmp;
116                                 __rb_rotate_right(parent, root);
117                                 tmp = parent;
118                                 parent = node;
119                                 node = tmp;
120                         }
121
122                         parent->rb_color = RB_BLACK;
123                         gparent->rb_color = RB_RED;
124                         __rb_rotate_left(gparent, root);
125                 }
126         }
127
128         root->rb_node->rb_color = RB_BLACK;
129 }
130 EXPORT_SYMBOL(rb_insert_color);
131
132 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
133                              struct rb_root *root)
134 {
135         struct rb_node *other;
136
137         while ((!node || node->rb_color == RB_BLACK) && node != root->rb_node)
138         {
139                 if (parent->rb_left == node)
140                 {
141                         other = parent->rb_right;
142                         if (other->rb_color == RB_RED)
143                         {
144                                 other->rb_color = RB_BLACK;
145                                 parent->rb_color = RB_RED;
146                                 __rb_rotate_left(parent, root);
147                                 other = parent->rb_right;
148                         }
149                         if ((!other->rb_left ||
150                              other->rb_left->rb_color == RB_BLACK)
151                             && (!other->rb_right ||
152                                 other->rb_right->rb_color == RB_BLACK))
153                         {
154                                 other->rb_color = RB_RED;
155                                 node = parent;
156                                 parent = node->rb_parent;
157                         }
158                         else
159                         {
160                                 if (!other->rb_right ||
161                                     other->rb_right->rb_color == RB_BLACK)
162                                 {
163                                         register struct rb_node *o_left;
164                                         if ((o_left = other->rb_left))
165                                                 o_left->rb_color = RB_BLACK;
166                                         other->rb_color = RB_RED;
167                                         __rb_rotate_right(other, root);
168                                         other = parent->rb_right;
169                                 }
170                                 other->rb_color = parent->rb_color;
171                                 parent->rb_color = RB_BLACK;
172                                 if (other->rb_right)
173                                         other->rb_right->rb_color = RB_BLACK;
174                                 __rb_rotate_left(parent, root);
175                                 node = root->rb_node;
176                                 break;
177                         }
178                 }
179                 else
180                 {
181                         other = parent->rb_left;
182                         if (other->rb_color == RB_RED)
183                         {
184                                 other->rb_color = RB_BLACK;
185                                 parent->rb_color = RB_RED;
186                                 __rb_rotate_right(parent, root);
187                                 other = parent->rb_left;
188                         }
189                         if ((!other->rb_left ||
190                              other->rb_left->rb_color == RB_BLACK)
191                             && (!other->rb_right ||
192                                 other->rb_right->rb_color == RB_BLACK))
193                         {
194                                 other->rb_color = RB_RED;
195                                 node = parent;
196                                 parent = node->rb_parent;
197                         }
198                         else
199                         {
200                                 if (!other->rb_left ||
201                                     other->rb_left->rb_color == RB_BLACK)
202                                 {
203                                         register struct rb_node *o_right;
204                                         if ((o_right = other->rb_right))
205                                                 o_right->rb_color = RB_BLACK;
206                                         other->rb_color = RB_RED;
207                                         __rb_rotate_left(other, root);
208                                         other = parent->rb_left;
209                                 }
210                                 other->rb_color = parent->rb_color;
211                                 parent->rb_color = RB_BLACK;
212                                 if (other->rb_left)
213                                         other->rb_left->rb_color = RB_BLACK;
214                                 __rb_rotate_right(parent, root);
215                                 node = root->rb_node;
216                                 break;
217                         }
218                 }
219         }
220         if (node)
221                 node->rb_color = RB_BLACK;
222 }
223
224 void rb_erase(struct rb_node *node, struct rb_root *root)
225 {
226         struct rb_node *child, *parent;
227         int color;
228
229         if (!node->rb_left)
230                 child = node->rb_right;
231         else if (!node->rb_right)
232                 child = node->rb_left;
233         else
234         {
235                 struct rb_node *old = node, *left;
236
237                 node = node->rb_right;
238                 while ((left = node->rb_left) != NULL)
239                         node = left;
240                 child = node->rb_right;
241                 parent = node->rb_parent;
242                 color = node->rb_color;
243
244                 if (child)
245                         child->rb_parent = parent;
246                 if (parent)
247                 {
248                         if (parent->rb_left == node)
249                                 parent->rb_left = child;
250                         else
251                                 parent->rb_right = child;
252                 }
253                 else
254                         root->rb_node = child;
255
256                 if (node->rb_parent == old)
257                         parent = node;
258                 node->rb_parent = old->rb_parent;
259                 node->rb_color = old->rb_color;
260                 node->rb_right = old->rb_right;
261                 node->rb_left = old->rb_left;
262
263                 if (old->rb_parent)
264                 {
265                         if (old->rb_parent->rb_left == old)
266                                 old->rb_parent->rb_left = node;
267                         else
268                                 old->rb_parent->rb_right = node;
269                 } else
270                         root->rb_node = node;
271
272                 old->rb_left->rb_parent = node;
273                 if (old->rb_right)
274                         old->rb_right->rb_parent = node;
275                 goto color;
276         }
277
278         parent = node->rb_parent;
279         color = node->rb_color;
280
281         if (child)
282                 child->rb_parent = parent;
283         if (parent)
284         {
285                 if (parent->rb_left == node)
286                         parent->rb_left = child;
287                 else
288                         parent->rb_right = child;
289         }
290         else
291                 root->rb_node = child;
292
293  color:
294         if (color == RB_BLACK)
295                 __rb_erase_color(child, parent, root);
296 }
297 EXPORT_SYMBOL(rb_erase);
298
299 /*
300  * This function returns the first node (in sort order) of the tree.
301  */
302 struct rb_node *rb_first(struct rb_root *root)
303 {
304         struct rb_node  *n;
305
306         n = root->rb_node;
307         if (!n)
308                 return NULL;
309         while (n->rb_left)
310                 n = n->rb_left;
311         return n;
312 }
313 EXPORT_SYMBOL(rb_first);
314
315 struct rb_node *rb_last(struct rb_root *root)
316 {
317         struct rb_node  *n;
318
319         n = root->rb_node;
320         if (!n)
321                 return NULL;
322         while (n->rb_right)
323                 n = n->rb_right;
324         return n;
325 }
326 EXPORT_SYMBOL(rb_last);
327
328 struct rb_node *rb_next(struct rb_node *node)
329 {
330         /* If we have a right-hand child, go down and then left as far
331            as we can. */
332         if (node->rb_right) {
333                 node = node->rb_right; 
334                 while (node->rb_left)
335                         node=node->rb_left;
336                 return node;
337         }
338
339         /* No right-hand children.  Everything down and left is
340            smaller than us, so any 'next' node must be in the general
341            direction of our parent. Go up the tree; any time the
342            ancestor is a right-hand child of its parent, keep going
343            up. First time it's a left-hand child of its parent, said
344            parent is our 'next' node. */
345         while (node->rb_parent && node == node->rb_parent->rb_right)
346                 node = node->rb_parent;
347
348         return node->rb_parent;
349 }
350 EXPORT_SYMBOL(rb_next);
351
352 struct rb_node *rb_prev(struct rb_node *node)
353 {
354         /* If we have a left-hand child, go down and then right as far
355            as we can. */
356         if (node->rb_left) {
357                 node = node->rb_left; 
358                 while (node->rb_right)
359                         node=node->rb_right;
360                 return node;
361         }
362
363         /* No left-hand children. Go up till we find an ancestor which
364            is a right-hand child of its parent */
365         while (node->rb_parent && node == node->rb_parent->rb_left)
366                 node = node->rb_parent;
367
368         return node->rb_parent;
369 }
370 EXPORT_SYMBOL(rb_prev);
371
372 void rb_replace_node(struct rb_node *victim, struct rb_node *new,
373                      struct rb_root *root)
374 {
375         struct rb_node *parent = victim->rb_parent;
376
377         /* Set the surrounding nodes to point to the replacement */
378         if (parent) {
379                 if (victim == parent->rb_left)
380                         parent->rb_left = new;
381                 else
382                         parent->rb_right = new;
383         } else {
384                 root->rb_node = new;
385         }
386         if (victim->rb_left)
387                 victim->rb_left->rb_parent = new;
388         if (victim->rb_right)
389                 victim->rb_right->rb_parent = new;
390
391         /* Copy the pointers/colour from the victim to the replacement */
392         *new = *victim;
393 }
394 EXPORT_SYMBOL(rb_replace_node);