1a59d1b8e05ea (Thomas Gleixner 2019-05-27 08:55:05 +0200 1) // SPDX-License-Identifier: GPL-2.0-or-later
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 2) /*
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 3) Red Black Trees
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 4) (C) 1999 Andrea Arcangeli <andrea@suse.de>
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 5) (C) 2002 David Woodhouse <dwmw2@infradead.org>
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 6) (C) 2012 Michel Lespinasse <walken@google.com>
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 7)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 8)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 9) linux/lib/rbtree.c
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 10) */
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 11)
9c079add0d0f4 (Michel Lespinasse 2012-10-08 16:31:33 -0700 12) #include <linux/rbtree_augmented.h>
8bc3bcc93a2b4 (Paul Gortmaker 2011-11-16 21:29:17 -0500 13) #include <linux/export.h>
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 14)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 15) /*
d89775fc929c5 (Alexander A. Klimov 2020-08-11 18:34:50 -0700 16) * red-black trees properties: https://en.wikipedia.org/wiki/Rbtree
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 17) *
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 18) * 1) A node is either red or black
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 19) * 2) The root is black
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 20) * 3) All leaves (NULL) are black
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 21) * 4) Both children of every red node are black
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 22) * 5) Every simple path from root to leaves contains the same number
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 23) * of black nodes.
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 24) *
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 25) * 4 and 5 give the O(log n) guarantee, since 4 implies you cannot have two
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 26) * consecutive red nodes in a path and every red node is therefore followed by
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 27) * a black. So if B is the number of black nodes on every simple path (as per
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 28) * 5), then the longest possible path due to 4 is 2B.
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 29) *
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 30) * We shall indicate color with case, where black nodes are uppercase and red
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 31) * nodes will be lowercase. Unknown color nodes shall be drawn as red within
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 32) * parentheses and have some accompanying text comment.
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 33) */
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 34)
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 35) /*
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 36) * Notes on lockless lookups:
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 37) *
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 38) * All stores to the tree structure (rb_left and rb_right) must be done using
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 39) * WRITE_ONCE(). And we must not inadvertently cause (temporary) loops in the
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 40) * tree structure as seen in program order.
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 41) *
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 42) * These two requirements will allow lockless iteration of the tree -- not
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 43) * correct iteration mind you, tree rotations are not atomic so a lookup might
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 44) * miss entire subtrees.
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 45) *
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 46) * But they do guarantee that any such traversal will only see valid elements
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 47) * and that it will indeed complete -- does not get stuck in a loop.
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 48) *
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 49) * It also guarantees that if the lookup returns an element it is the 'correct'
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 50) * one. But not returning an element does _NOT_ mean it's not present.
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 51) *
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 52) * NOTE:
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 53) *
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 54) * Stores to __rb_parent_color are not important for simple lookups so those
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 55) * are left undone as of now. Nor did I check for loops involving parent
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 56) * pointers.
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 57) */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 58)
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 59) static inline void rb_set_black(struct rb_node *rb)
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 60) {
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 61) rb->__rb_parent_color |= RB_BLACK;
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 62) }
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 63)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 64) static inline struct rb_node *rb_red_parent(struct rb_node *red)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 65) {
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 66) return (struct rb_node *)red->__rb_parent_color;
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 67) }
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 68)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 69) /*
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 70) * Helper function for rotations:
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 71) * - old's parent and color get assigned to new
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 72) * - old gets assigned new as a parent and 'color' as a color.
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 73) */
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 74) static inline void
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 75) __rb_rotate_set_parents(struct rb_node *old, struct rb_node *new,
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 76) struct rb_root *root, int color)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 77) {
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 78) struct rb_node *parent = rb_parent(old);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 79) new->__rb_parent_color = old->__rb_parent_color;
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 80) rb_set_parent_color(old, new, color);
7abc704ae399f (Michel Lespinasse 2012-10-08 16:31:07 -0700 81) __rb_change_child(old, new, parent, root);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 82) }
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 83)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 84) static __always_inline void
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 85) __rb_insert(struct rb_node *node, struct rb_root *root,
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 86) void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 87) {
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 88) struct rb_node *parent = rb_red_parent(node), *gparent, *tmp;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 89)
6d58452dc066d (Michel Lespinasse 2012-10-08 16:30:44 -0700 90) while (true) {
6d58452dc066d (Michel Lespinasse 2012-10-08 16:30:44 -0700 91) /*
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 92) * Loop invariant: node is red.
6d58452dc066d (Michel Lespinasse 2012-10-08 16:30:44 -0700 93) */
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 94) if (unlikely(!parent)) {
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 95) /*
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 96) * The inserted node is root. Either this is the
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 97) * first node, or we recursed at Case 1 below and
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 98) * are no longer violating 4).
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 99) */
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 100) rb_set_parent_color(node, NULL, RB_BLACK);
6d58452dc066d (Michel Lespinasse 2012-10-08 16:30:44 -0700 101) break;
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 102) }
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 103)
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 104) /*
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 105) * If there is a black parent, we are done.
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 106) * Otherwise, take some corrective action as,
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 107) * per 4), we don't want a red root or two
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 108) * consecutive red nodes.
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 109) */
2aadf7fc7df9e (Davidlohr Bueso 2017-09-08 16:14:39 -0700 110) if(rb_is_black(parent))
6d58452dc066d (Michel Lespinasse 2012-10-08 16:30:44 -0700 111) break;
6d58452dc066d (Michel Lespinasse 2012-10-08 16:30:44 -0700 112)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 113) gparent = rb_red_parent(parent);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 114)
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 115) tmp = gparent->rb_right;
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 116) if (parent != tmp) { /* parent == gparent->rb_left */
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 117) if (tmp && rb_is_red(tmp)) {
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 118) /*
35dc67d7d922b (Davidlohr Bueso 2017-09-08 16:14:42 -0700 119) * Case 1 - node's uncle is red (color flips).
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 120) *
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 121) * G g
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 122) * / \ / \
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 123) * p u --> P U
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 124) * / /
1b9c53e849aa6 (Wei Yang 2014-08-08 14:22:14 -0700 125) * n n
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 126) *
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 127) * However, since g's parent might be red, and
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 128) * 4) does not allow this, we need to recurse
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 129) * at g.
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 130) */
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 131) rb_set_parent_color(tmp, gparent, RB_BLACK);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 132) rb_set_parent_color(parent, gparent, RB_BLACK);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 133) node = gparent;
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 134) parent = rb_parent(node);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 135) rb_set_parent_color(node, parent, RB_RED);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 136) continue;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 137) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 138)
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 139) tmp = parent->rb_right;
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 140) if (node == tmp) {
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 141) /*
35dc67d7d922b (Davidlohr Bueso 2017-09-08 16:14:42 -0700 142) * Case 2 - node's uncle is black and node is
35dc67d7d922b (Davidlohr Bueso 2017-09-08 16:14:42 -0700 143) * the parent's right child (left rotate at parent).
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 144) *
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 145) * G G
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 146) * / \ / \
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 147) * p U --> n U
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 148) * \ /
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 149) * n p
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 150) *
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 151) * This still leaves us in violation of 4), the
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 152) * continuation into Case 3 will fix that.
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 153) */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 154) tmp = node->rb_left;
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 155) WRITE_ONCE(parent->rb_right, tmp);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 156) WRITE_ONCE(node->rb_left, parent);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 157) if (tmp)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 158) rb_set_parent_color(tmp, parent,
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 159) RB_BLACK);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 160) rb_set_parent_color(parent, node, RB_RED);
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 161) augment_rotate(parent, node);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 162) parent = node;
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 163) tmp = node->rb_right;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 164) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 165)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 166) /*
35dc67d7d922b (Davidlohr Bueso 2017-09-08 16:14:42 -0700 167) * Case 3 - node's uncle is black and node is
35dc67d7d922b (Davidlohr Bueso 2017-09-08 16:14:42 -0700 168) * the parent's left child (right rotate at gparent).
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 169) *
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 170) * G P
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 171) * / \ / \
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 172) * p U --> n g
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 173) * / \
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 174) * n U
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 175) */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 176) WRITE_ONCE(gparent->rb_left, tmp); /* == parent->rb_right */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 177) WRITE_ONCE(parent->rb_right, gparent);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 178) if (tmp)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 179) rb_set_parent_color(tmp, gparent, RB_BLACK);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 180) __rb_rotate_set_parents(gparent, parent, root, RB_RED);
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 181) augment_rotate(gparent, parent);
1f0528653e41e (Michel Lespinasse 2012-10-08 16:30:42 -0700 182) break;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 183) } else {
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 184) tmp = gparent->rb_left;
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 185) if (tmp && rb_is_red(tmp)) {
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 186) /* Case 1 - color flips */
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 187) rb_set_parent_color(tmp, gparent, RB_BLACK);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 188) rb_set_parent_color(parent, gparent, RB_BLACK);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 189) node = gparent;
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 190) parent = rb_parent(node);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 191) rb_set_parent_color(node, parent, RB_RED);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 192) continue;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 193) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 194)
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 195) tmp = parent->rb_left;
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 196) if (node == tmp) {
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 197) /* Case 2 - right rotate at parent */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 198) tmp = node->rb_right;
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 199) WRITE_ONCE(parent->rb_left, tmp);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 200) WRITE_ONCE(node->rb_right, parent);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 201) if (tmp)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 202) rb_set_parent_color(tmp, parent,
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 203) RB_BLACK);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 204) rb_set_parent_color(parent, node, RB_RED);
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 205) augment_rotate(parent, node);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 206) parent = node;
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 207) tmp = node->rb_left;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 208) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 209)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 210) /* Case 3 - left rotate at gparent */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 211) WRITE_ONCE(gparent->rb_right, tmp); /* == parent->rb_left */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 212) WRITE_ONCE(parent->rb_left, gparent);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 213) if (tmp)
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 214) rb_set_parent_color(tmp, gparent, RB_BLACK);
5bc9188aa207d (Michel Lespinasse 2012-10-08 16:30:47 -0700 215) __rb_rotate_set_parents(gparent, parent, root, RB_RED);
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 216) augment_rotate(gparent, parent);
1f0528653e41e (Michel Lespinasse 2012-10-08 16:30:42 -0700 217) break;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 218) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 219) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 220) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 221)
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 222) /*
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 223) * Inline version for rb_erase() use - we want to be able to inline
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 224) * and eliminate the dummy_rotate callback there
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 225) */
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 226) static __always_inline void
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 227) ____rb_erase_color(struct rb_node *parent, struct rb_root *root,
9c079add0d0f4 (Michel Lespinasse 2012-10-08 16:31:33 -0700 228) void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 229) {
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 230) struct rb_node *node = NULL, *sibling, *tmp1, *tmp2;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 231)
d6ff1273928eb (Michel Lespinasse 2012-10-08 16:30:50 -0700 232) while (true) {
d6ff1273928eb (Michel Lespinasse 2012-10-08 16:30:50 -0700 233) /*
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 234) * Loop invariants:
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 235) * - node is black (or NULL on first iteration)
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 236) * - node is not the root (parent is not NULL)
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 237) * - All leaf paths going through parent and node have a
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 238) * black node count that is 1 lower than other leaf paths.
d6ff1273928eb (Michel Lespinasse 2012-10-08 16:30:50 -0700 239) */
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 240) sibling = parent->rb_right;
59633abf34e2f (Michel Lespinasse 2012-10-08 16:31:02 -0700 241) if (node != sibling) { /* node == parent->rb_left */
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 242) if (rb_is_red(sibling)) {
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 243) /*
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 244) * Case 1 - left rotate at parent
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 245) *
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 246) * P S
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 247) * / \ / \
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 248) * N s --> p Sr
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 249) * / \ / \
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 250) * Sl Sr N Sl
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 251) */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 252) tmp1 = sibling->rb_left;
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 253) WRITE_ONCE(parent->rb_right, tmp1);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 254) WRITE_ONCE(sibling->rb_left, parent);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 255) rb_set_parent_color(tmp1, parent, RB_BLACK);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 256) __rb_rotate_set_parents(parent, sibling, root,
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 257) RB_RED);
9c079add0d0f4 (Michel Lespinasse 2012-10-08 16:31:33 -0700 258) augment_rotate(parent, sibling);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 259) sibling = tmp1;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 260) }
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 261) tmp1 = sibling->rb_right;
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 262) if (!tmp1 || rb_is_black(tmp1)) {
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 263) tmp2 = sibling->rb_left;
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 264) if (!tmp2 || rb_is_black(tmp2)) {
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 265) /*
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 266) * Case 2 - sibling color flip
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 267) * (p could be either color here)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 268) *
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 269) * (p) (p)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 270) * / \ / \
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 271) * N S --> N s
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 272) * / \ / \
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 273) * Sl Sr Sl Sr
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 274) *
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 275) * This leaves us violating 5) which
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 276) * can be fixed by flipping p to black
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 277) * if it was red, or by recursing at p.
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 278) * p is red when coming from Case 1.
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 279) */
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 280) rb_set_parent_color(sibling, parent,
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 281) RB_RED);
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 282) if (rb_is_red(parent))
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 283) rb_set_black(parent);
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 284) else {
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 285) node = parent;
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 286) parent = rb_parent(node);
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 287) if (parent)
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 288) continue;
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 289) }
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 290) break;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 291) }
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 292) /*
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 293) * Case 3 - right rotate at sibling
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 294) * (p could be either color here)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 295) *
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 296) * (p) (p)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 297) * / \ / \
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 298) * N S --> N sl
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 299) * / \ \
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 300) * sl Sr S
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 301) * \
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 302) * Sr
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 303) *
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 304) * Note: p might be red, and then both
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 305) * p and sl are red after rotation(which
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 306) * breaks property 4). This is fixed in
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 307) * Case 4 (in __rb_rotate_set_parents()
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 308) * which set sl the color of p
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 309) * and set p RB_BLACK)
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 310) *
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 311) * (p) (sl)
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 312) * / \ / \
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 313) * N sl --> P S
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 314) * \ / \
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 315) * S N Sr
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 316) * \
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 317) * Sr
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 318) */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 319) tmp1 = tmp2->rb_right;
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 320) WRITE_ONCE(sibling->rb_left, tmp1);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 321) WRITE_ONCE(tmp2->rb_right, sibling);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 322) WRITE_ONCE(parent->rb_right, tmp2);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 323) if (tmp1)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 324) rb_set_parent_color(tmp1, sibling,
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 325) RB_BLACK);
9c079add0d0f4 (Michel Lespinasse 2012-10-08 16:31:33 -0700 326) augment_rotate(sibling, tmp2);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 327) tmp1 = sibling;
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 328) sibling = tmp2;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 329) }
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 330) /*
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 331) * Case 4 - left rotate at parent + color flips
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 332) * (p and sl could be either color here.
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 333) * After rotation, p becomes black, s acquires
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 334) * p's color, and sl keeps its color)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 335) *
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 336) * (p) (s)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 337) * / \ / \
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 338) * N S --> P Sr
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 339) * / \ / \
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 340) * (sl) sr N (sl)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 341) */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 342) tmp2 = sibling->rb_left;
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 343) WRITE_ONCE(parent->rb_right, tmp2);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 344) WRITE_ONCE(sibling->rb_left, parent);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 345) rb_set_parent_color(tmp1, sibling, RB_BLACK);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 346) if (tmp2)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 347) rb_set_parent(tmp2, parent);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 348) __rb_rotate_set_parents(parent, sibling, root,
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 349) RB_BLACK);
9c079add0d0f4 (Michel Lespinasse 2012-10-08 16:31:33 -0700 350) augment_rotate(parent, sibling);
e125d1471a4f8 (Michel Lespinasse 2012-10-08 16:30:54 -0700 351) break;
d6ff1273928eb (Michel Lespinasse 2012-10-08 16:30:50 -0700 352) } else {
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 353) sibling = parent->rb_left;
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 354) if (rb_is_red(sibling)) {
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 355) /* Case 1 - right rotate at parent */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 356) tmp1 = sibling->rb_right;
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 357) WRITE_ONCE(parent->rb_left, tmp1);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 358) WRITE_ONCE(sibling->rb_right, parent);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 359) rb_set_parent_color(tmp1, parent, RB_BLACK);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 360) __rb_rotate_set_parents(parent, sibling, root,
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 361) RB_RED);
9c079add0d0f4 (Michel Lespinasse 2012-10-08 16:31:33 -0700 362) augment_rotate(parent, sibling);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 363) sibling = tmp1;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 364) }
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 365) tmp1 = sibling->rb_left;
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 366) if (!tmp1 || rb_is_black(tmp1)) {
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 367) tmp2 = sibling->rb_right;
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 368) if (!tmp2 || rb_is_black(tmp2)) {
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 369) /* Case 2 - sibling color flip */
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 370) rb_set_parent_color(sibling, parent,
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 371) RB_RED);
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 372) if (rb_is_red(parent))
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 373) rb_set_black(parent);
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 374) else {
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 375) node = parent;
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 376) parent = rb_parent(node);
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 377) if (parent)
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 378) continue;
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 379) }
46b6135a7402a (Michel Lespinasse 2012-10-08 16:31:11 -0700 380) break;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 381) }
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 382) /* Case 3 - left rotate at sibling */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 383) tmp1 = tmp2->rb_left;
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 384) WRITE_ONCE(sibling->rb_right, tmp1);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 385) WRITE_ONCE(tmp2->rb_left, sibling);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 386) WRITE_ONCE(parent->rb_left, tmp2);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 387) if (tmp1)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 388) rb_set_parent_color(tmp1, sibling,
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 389) RB_BLACK);
9c079add0d0f4 (Michel Lespinasse 2012-10-08 16:31:33 -0700 390) augment_rotate(sibling, tmp2);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 391) tmp1 = sibling;
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 392) sibling = tmp2;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 393) }
ce093a04543c4 (Jie Chen 2016-12-12 16:46:17 -0800 394) /* Case 4 - right rotate at parent + color flips */
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 395) tmp2 = sibling->rb_right;
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 396) WRITE_ONCE(parent->rb_left, tmp2);
d72da4a4d973d (Peter Zijlstra 2015-05-27 11:09:36 +0930 397) WRITE_ONCE(sibling->rb_right, parent);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 398) rb_set_parent_color(tmp1, sibling, RB_BLACK);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 399) if (tmp2)
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 400) rb_set_parent(tmp2, parent);
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 401) __rb_rotate_set_parents(parent, sibling, root,
6280d2356fd8a (Michel Lespinasse 2012-10-08 16:30:57 -0700 402) RB_BLACK);
9c079add0d0f4 (Michel Lespinasse 2012-10-08 16:31:33 -0700 403) augment_rotate(parent, sibling);
e125d1471a4f8 (Michel Lespinasse 2012-10-08 16:30:54 -0700 404) break;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 405) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 406) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 407) }
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 408)
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 409) /* Non-inline version for rb_erase_augmented() use */
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 410) void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 411) void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 412) {
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 413) ____rb_erase_color(parent, root, augment_rotate);
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 414) }
9c079add0d0f4 (Michel Lespinasse 2012-10-08 16:31:33 -0700 415) EXPORT_SYMBOL(__rb_erase_color);
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 416)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 417) /*
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 418) * Non-augmented rbtree manipulation functions.
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 419) *
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 420) * We use dummy augmented callbacks here, and have the compiler optimize them
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 421) * out of the rb_insert_color() and rb_erase() function definitions.
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 422) */
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 423)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 424) static inline void dummy_propagate(struct rb_node *node, struct rb_node *stop) {}
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 425) static inline void dummy_copy(struct rb_node *old, struct rb_node *new) {}
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 426) static inline void dummy_rotate(struct rb_node *old, struct rb_node *new) {}
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 427)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 428) static const struct rb_augment_callbacks dummy_callbacks = {
f231aebfc4cae (Kees Cook 2017-02-24 15:01:04 -0800 429) .propagate = dummy_propagate,
f231aebfc4cae (Kees Cook 2017-02-24 15:01:04 -0800 430) .copy = dummy_copy,
f231aebfc4cae (Kees Cook 2017-02-24 15:01:04 -0800 431) .rotate = dummy_rotate
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 432) };
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 433)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 434) void rb_insert_color(struct rb_node *node, struct rb_root *root)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 435) {
9f973cb38088e (Michel Lespinasse 2019-07-16 16:27:45 -0700 436) __rb_insert(node, root, dummy_rotate);
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 437) }
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 438) EXPORT_SYMBOL(rb_insert_color);
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 439)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 440) void rb_erase(struct rb_node *node, struct rb_root *root)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 441) {
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 442) struct rb_node *rebalance;
9f973cb38088e (Michel Lespinasse 2019-07-16 16:27:45 -0700 443) rebalance = __rb_erase_augmented(node, root, &dummy_callbacks);
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 444) if (rebalance)
3cb7a56344ca4 (Michel Lespinasse 2013-01-11 14:32:20 -0800 445) ____rb_erase_color(rebalance, root, dummy_rotate);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 446) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 447) EXPORT_SYMBOL(rb_erase);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 448)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 449) /*
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 450) * Augmented rbtree manipulation functions.
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 451) *
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 452) * This instantiates the same __always_inline functions as in the non-augmented
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 453) * case, but this time with user-defined callbacks.
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 454) */
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 455)
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 456) void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 457) void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 458) {
9f973cb38088e (Michel Lespinasse 2019-07-16 16:27:45 -0700 459) __rb_insert(node, root, augment_rotate);
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 460) }
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 461) EXPORT_SYMBOL(__rb_insert_augmented);
14b94af0b251a (Michel Lespinasse 2012-10-08 16:31:17 -0700 462)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 463) /*
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 464) * This function returns the first node (in sort order) of the tree.
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 465) */
f4b477c473323 (Artem Bityutskiy 2009-01-10 11:12:09 +0000 466) struct rb_node *rb_first(const struct rb_root *root)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 467) {
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 468) struct rb_node *n;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 469)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 470) n = root->rb_node;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 471) if (!n)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 472) return NULL;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 473) while (n->rb_left)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 474) n = n->rb_left;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 475) return n;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 476) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 477) EXPORT_SYMBOL(rb_first);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 478)
f4b477c473323 (Artem Bityutskiy 2009-01-10 11:12:09 +0000 479) struct rb_node *rb_last(const struct rb_root *root)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 480) {
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 481) struct rb_node *n;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 482)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 483) n = root->rb_node;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 484) if (!n)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 485) return NULL;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 486) while (n->rb_right)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 487) n = n->rb_right;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 488) return n;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 489) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 490) EXPORT_SYMBOL(rb_last);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 491)
f4b477c473323 (Artem Bityutskiy 2009-01-10 11:12:09 +0000 492) struct rb_node *rb_next(const struct rb_node *node)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 493) {
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 494) struct rb_node *parent;
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 495)
4c199a93a2d36 (Michel Lespinasse 2012-10-08 16:30:32 -0700 496) if (RB_EMPTY_NODE(node))
10fd48f2376db (Jens Axboe 2006-07-11 21:15:52 +0200 497) return NULL;
10fd48f2376db (Jens Axboe 2006-07-11 21:15:52 +0200 498)
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 499) /*
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 500) * If we have a right-hand child, go down and then left as far
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 501) * as we can.
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 502) */
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 503) if (node->rb_right) {
cd9e61ed1eebb (Davidlohr Bueso 2017-09-08 16:14:36 -0700 504) node = node->rb_right;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 505) while (node->rb_left)
8d994cada27c5 (chenqiwu 2020-04-06 20:10:31 -0700 506) node = node->rb_left;
f4b477c473323 (Artem Bityutskiy 2009-01-10 11:12:09 +0000 507) return (struct rb_node *)node;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 508) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 509)
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 510) /*
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 511) * No right-hand children. Everything down and left is smaller than us,
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 512) * so any 'next' node must be in the general direction of our parent.
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 513) * Go up the tree; any time the ancestor is a right-hand child of its
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 514) * parent, keep going up. First time it's a left-hand child of its
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 515) * parent, said parent is our 'next' node.
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 516) */
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 517) while ((parent = rb_parent(node)) && node == parent->rb_right)
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 518) node = parent;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 519)
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 520) return parent;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 521) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 522) EXPORT_SYMBOL(rb_next);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 523)
f4b477c473323 (Artem Bityutskiy 2009-01-10 11:12:09 +0000 524) struct rb_node *rb_prev(const struct rb_node *node)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 525) {
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 526) struct rb_node *parent;
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 527)
4c199a93a2d36 (Michel Lespinasse 2012-10-08 16:30:32 -0700 528) if (RB_EMPTY_NODE(node))
10fd48f2376db (Jens Axboe 2006-07-11 21:15:52 +0200 529) return NULL;
10fd48f2376db (Jens Axboe 2006-07-11 21:15:52 +0200 530)
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 531) /*
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 532) * If we have a left-hand child, go down and then right as far
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 533) * as we can.
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 534) */
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 535) if (node->rb_left) {
cd9e61ed1eebb (Davidlohr Bueso 2017-09-08 16:14:36 -0700 536) node = node->rb_left;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 537) while (node->rb_right)
8d994cada27c5 (chenqiwu 2020-04-06 20:10:31 -0700 538) node = node->rb_right;
f4b477c473323 (Artem Bityutskiy 2009-01-10 11:12:09 +0000 539) return (struct rb_node *)node;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 540) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 541)
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 542) /*
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 543) * No left-hand children. Go up till we find an ancestor which
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 544) * is a right-hand child of its parent.
7ce6ff9e5de99 (Michel Lespinasse 2012-10-08 16:31:01 -0700 545) */
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 546) while ((parent = rb_parent(node)) && node == parent->rb_left)
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 547) node = parent;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 548)
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 549) return parent;
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 550) }
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 551) EXPORT_SYMBOL(rb_prev);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 552)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 553) void rb_replace_node(struct rb_node *victim, struct rb_node *new,
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 554) struct rb_root *root)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 555) {
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 556) struct rb_node *parent = rb_parent(victim);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 557)
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 558) /* Copy the pointers/colour from the victim to the replacement */
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 559) *new = *victim;
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 560)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 561) /* Set the surrounding nodes to point to the replacement */
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 562) if (victim->rb_left)
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 563) rb_set_parent(victim->rb_left, new);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 564) if (victim->rb_right)
55a981027fc39 (David Woodhouse 2006-04-21 13:35:51 +0100 565) rb_set_parent(victim->rb_right, new);
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 566) __rb_change_child(victim, new, parent, root);
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 567) }
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 568) EXPORT_SYMBOL(rb_replace_node);
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 569)
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 570) void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 571) struct rb_root *root)
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 572) {
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 573) struct rb_node *parent = rb_parent(victim);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 574)
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 575) /* Copy the pointers/colour from the victim to the replacement */
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 576) *new = *victim;
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 577)
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 578) /* Set the surrounding nodes to point to the replacement */
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 579) if (victim->rb_left)
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 580) rb_set_parent(victim->rb_left, new);
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 581) if (victim->rb_right)
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 582) rb_set_parent(victim->rb_right, new);
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 583)
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 584) /* Set the parent's pointer to the new node last after an RCU barrier
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 585) * so that the pointers onwards are seen to be set correctly when doing
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 586) * an RCU walk over the tree.
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 587) */
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 588) __rb_change_child_rcu(victim, new, parent, root);
^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 589) }
c1adf20052d80 (David Howells 2016-07-01 07:53:51 +0100 590) EXPORT_SYMBOL(rb_replace_node_rcu);
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 591)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 592) static struct rb_node *rb_left_deepest_node(const struct rb_node *node)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 593) {
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 594) for (;;) {
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 595) if (node->rb_left)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 596) node = node->rb_left;
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 597) else if (node->rb_right)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 598) node = node->rb_right;
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 599) else
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 600) return (struct rb_node *)node;
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 601) }
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 602) }
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 603)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 604) struct rb_node *rb_next_postorder(const struct rb_node *node)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 605) {
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 606) const struct rb_node *parent;
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 607) if (!node)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 608) return NULL;
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 609) parent = rb_parent(node);
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 610)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 611) /* If we're sitting on node, we've already seen our children */
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 612) if (parent && node == parent->rb_left && parent->rb_right) {
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 613) /* If we are the parent's left node, go to the parent's right
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 614) * node then all the way down to the left */
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 615) return rb_left_deepest_node(parent->rb_right);
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 616) } else
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 617) /* Otherwise we are the parent's right node, and the parent
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 618) * should be next */
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 619) return (struct rb_node *)parent;
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 620) }
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 621) EXPORT_SYMBOL(rb_next_postorder);
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 622)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 623) struct rb_node *rb_first_postorder(const struct rb_root *root)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 624) {
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 625) if (!root->rb_node)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 626) return NULL;
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 627)
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 628) return rb_left_deepest_node(root->rb_node);
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 629) }
9dee5c51516d2 (Cody P Schafer 2013-09-11 14:25:10 -0700 630) EXPORT_SYMBOL(rb_first_postorder);
VisionFive2 Linux kernel
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