^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) Red Black Trees
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) (C) 1999 Andrea Arcangeli <andrea@suse.de>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) (C) 2002 David Woodhouse <dwmw2@infradead.org>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) (C) 2012 Michel Lespinasse <walken@google.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) linux/lib/rbtree.c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <linux/rbtree_augmented.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include <linux/export.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) * red-black trees properties: https://en.wikipedia.org/wiki/Rbtree
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) * 1) A node is either red or black
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) * 2) The root is black
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) * 3) All leaves (NULL) are black
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) * 4) Both children of every red node are black
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) * 5) Every simple path from root to leaves contains the same number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) * of black nodes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) * 4 and 5 give the O(log n) guarantee, since 4 implies you cannot have two
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) * consecutive red nodes in a path and every red node is therefore followed by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) * a black. So if B is the number of black nodes on every simple path (as per
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) * 5), then the longest possible path due to 4 is 2B.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) * We shall indicate color with case, where black nodes are uppercase and red
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) * nodes will be lowercase. Unknown color nodes shall be drawn as red within
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) * parentheses and have some accompanying text comment.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) * Notes on lockless lookups:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) * All stores to the tree structure (rb_left and rb_right) must be done using
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) * WRITE_ONCE(). And we must not inadvertently cause (temporary) loops in the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) * tree structure as seen in program order.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) * These two requirements will allow lockless iteration of the tree -- not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) * correct iteration mind you, tree rotations are not atomic so a lookup might
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) * miss entire subtrees.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) * But they do guarantee that any such traversal will only see valid elements
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) * and that it will indeed complete -- does not get stuck in a loop.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) * It also guarantees that if the lookup returns an element it is the 'correct'
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) * one. But not returning an element does _NOT_ mean it's not present.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) * NOTE:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) * Stores to __rb_parent_color are not important for simple lookups so those
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) * are left undone as of now. Nor did I check for loops involving parent
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) * pointers.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) static inline void rb_set_black(struct rb_node *rb)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) rb->__rb_parent_color |= RB_BLACK;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) static inline struct rb_node *rb_red_parent(struct rb_node *red)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) return (struct rb_node *)red->__rb_parent_color;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) * Helper function for rotations:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) * - old's parent and color get assigned to new
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) * - old gets assigned new as a parent and 'color' as a color.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) static inline void
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) __rb_rotate_set_parents(struct rb_node *old, struct rb_node *new,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) struct rb_root *root, int color)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) struct rb_node *parent = rb_parent(old);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) new->__rb_parent_color = old->__rb_parent_color;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) rb_set_parent_color(old, new, color);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) __rb_change_child(old, new, parent, root);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) static __always_inline void
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) __rb_insert(struct rb_node *node, struct rb_root *root,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) struct rb_node *parent = rb_red_parent(node), *gparent, *tmp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) while (true) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) * Loop invariant: node is red.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) if (unlikely(!parent)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) * The inserted node is root. Either this is the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) * first node, or we recursed at Case 1 below and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) * are no longer violating 4).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) rb_set_parent_color(node, NULL, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) * If there is a black parent, we are done.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) * Otherwise, take some corrective action as,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) * per 4), we don't want a red root or two
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) * consecutive red nodes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) if(rb_is_black(parent))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) gparent = rb_red_parent(parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) tmp = gparent->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) if (parent != tmp) { /* parent == gparent->rb_left */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) if (tmp && rb_is_red(tmp)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) * Case 1 - node's uncle is red (color flips).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) * G g
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) * p u --> P U
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) * / /
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) * n n
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) * However, since g's parent might be red, and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) * 4) does not allow this, we need to recurse
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) * at g.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) rb_set_parent_color(tmp, gparent, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) rb_set_parent_color(parent, gparent, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) node = gparent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) parent = rb_parent(node);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) rb_set_parent_color(node, parent, RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) tmp = parent->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) if (node == tmp) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) * Case 2 - node's uncle is black and node is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) * the parent's right child (left rotate at parent).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) * G G
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) * p U --> n U
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) * \ /
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) * n p
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) * This still leaves us in violation of 4), the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) * continuation into Case 3 will fix that.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) tmp = node->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) WRITE_ONCE(parent->rb_right, tmp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) WRITE_ONCE(node->rb_left, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) if (tmp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) rb_set_parent_color(tmp, parent,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) rb_set_parent_color(parent, node, RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) augment_rotate(parent, node);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) parent = node;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) tmp = node->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) * Case 3 - node's uncle is black and node is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) * the parent's left child (right rotate at gparent).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) * G P
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) * p U --> n g
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) * / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) * n U
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) WRITE_ONCE(gparent->rb_left, tmp); /* == parent->rb_right */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) WRITE_ONCE(parent->rb_right, gparent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) if (tmp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) rb_set_parent_color(tmp, gparent, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) __rb_rotate_set_parents(gparent, parent, root, RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) augment_rotate(gparent, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) } else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) tmp = gparent->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) if (tmp && rb_is_red(tmp)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) /* Case 1 - color flips */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) rb_set_parent_color(tmp, gparent, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) rb_set_parent_color(parent, gparent, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) node = gparent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) parent = rb_parent(node);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) rb_set_parent_color(node, parent, RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) tmp = parent->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) if (node == tmp) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) /* Case 2 - right rotate at parent */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) tmp = node->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) WRITE_ONCE(parent->rb_left, tmp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) WRITE_ONCE(node->rb_right, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) if (tmp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) rb_set_parent_color(tmp, parent,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) rb_set_parent_color(parent, node, RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) augment_rotate(parent, node);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) parent = node;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) tmp = node->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) /* Case 3 - left rotate at gparent */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) WRITE_ONCE(gparent->rb_right, tmp); /* == parent->rb_left */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) WRITE_ONCE(parent->rb_left, gparent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) if (tmp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) rb_set_parent_color(tmp, gparent, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) __rb_rotate_set_parents(gparent, parent, root, RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) augment_rotate(gparent, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) * Inline version for rb_erase() use - we want to be able to inline
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) * and eliminate the dummy_rotate callback there
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) static __always_inline void
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) ____rb_erase_color(struct rb_node *parent, struct rb_root *root,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) struct rb_node *node = NULL, *sibling, *tmp1, *tmp2;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) while (true) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) * Loop invariants:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) * - node is black (or NULL on first iteration)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) * - node is not the root (parent is not NULL)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) * - All leaf paths going through parent and node have a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) * black node count that is 1 lower than other leaf paths.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) sibling = parent->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) if (node != sibling) { /* node == parent->rb_left */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) if (rb_is_red(sibling)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) * Case 1 - left rotate at parent
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) * P S
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) * N s --> p Sr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) * Sl Sr N Sl
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) tmp1 = sibling->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) WRITE_ONCE(parent->rb_right, tmp1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) WRITE_ONCE(sibling->rb_left, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) rb_set_parent_color(tmp1, parent, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) __rb_rotate_set_parents(parent, sibling, root,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) augment_rotate(parent, sibling);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) sibling = tmp1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) tmp1 = sibling->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) if (!tmp1 || rb_is_black(tmp1)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) tmp2 = sibling->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) if (!tmp2 || rb_is_black(tmp2)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) * Case 2 - sibling color flip
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) * (p could be either color here)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) * (p) (p)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) * N S --> N s
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) * Sl Sr Sl Sr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) * This leaves us violating 5) which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) * can be fixed by flipping p to black
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) * if it was red, or by recursing at p.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) * p is red when coming from Case 1.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) rb_set_parent_color(sibling, parent,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) if (rb_is_red(parent))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) rb_set_black(parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) node = parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) parent = rb_parent(node);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) if (parent)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) * Case 3 - right rotate at sibling
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) * (p could be either color here)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) * (p) (p)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) * N S --> N sl
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) * / \ \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) * sl Sr S
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) * \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) * Sr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) * Note: p might be red, and then both
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) * p and sl are red after rotation(which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) * breaks property 4). This is fixed in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) * Case 4 (in __rb_rotate_set_parents()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) * which set sl the color of p
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) * and set p RB_BLACK)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) * (p) (sl)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) * N sl --> P S
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) * \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) * S N Sr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316) * \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) * Sr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319) tmp1 = tmp2->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) WRITE_ONCE(sibling->rb_left, tmp1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) WRITE_ONCE(tmp2->rb_right, sibling);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) WRITE_ONCE(parent->rb_right, tmp2);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323) if (tmp1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324) rb_set_parent_color(tmp1, sibling,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326) augment_rotate(sibling, tmp2);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) tmp1 = sibling;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328) sibling = tmp2;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331) * Case 4 - left rotate at parent + color flips
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332) * (p and sl could be either color here.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333) * After rotation, p becomes black, s acquires
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334) * p's color, and sl keeps its color)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336) * (p) (s)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338) * N S --> P Sr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) * / \ / \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340) * (sl) sr N (sl)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) tmp2 = sibling->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343) WRITE_ONCE(parent->rb_right, tmp2);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344) WRITE_ONCE(sibling->rb_left, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) rb_set_parent_color(tmp1, sibling, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346) if (tmp2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) rb_set_parent(tmp2, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) __rb_rotate_set_parents(parent, sibling, root,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349) RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) augment_rotate(parent, sibling);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352) } else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353) sibling = parent->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) if (rb_is_red(sibling)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) /* Case 1 - right rotate at parent */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356) tmp1 = sibling->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357) WRITE_ONCE(parent->rb_left, tmp1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358) WRITE_ONCE(sibling->rb_right, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359) rb_set_parent_color(tmp1, parent, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 360) __rb_rotate_set_parents(parent, sibling, root,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 361) RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 362) augment_rotate(parent, sibling);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 363) sibling = tmp1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 364) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 365) tmp1 = sibling->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 366) if (!tmp1 || rb_is_black(tmp1)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 367) tmp2 = sibling->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 368) if (!tmp2 || rb_is_black(tmp2)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 369) /* Case 2 - sibling color flip */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 370) rb_set_parent_color(sibling, parent,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 371) RB_RED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 372) if (rb_is_red(parent))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 373) rb_set_black(parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 374) else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 375) node = parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 376) parent = rb_parent(node);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 377) if (parent)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 378) continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 379) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 380) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 381) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 382) /* Case 3 - left rotate at sibling */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 383) tmp1 = tmp2->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 384) WRITE_ONCE(sibling->rb_right, tmp1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 385) WRITE_ONCE(tmp2->rb_left, sibling);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 386) WRITE_ONCE(parent->rb_left, tmp2);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 387) if (tmp1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 388) rb_set_parent_color(tmp1, sibling,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 389) RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 390) augment_rotate(sibling, tmp2);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 391) tmp1 = sibling;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 392) sibling = tmp2;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 393) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 394) /* Case 4 - right rotate at parent + color flips */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 395) tmp2 = sibling->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 396) WRITE_ONCE(parent->rb_left, tmp2);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 397) WRITE_ONCE(sibling->rb_right, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 398) rb_set_parent_color(tmp1, sibling, RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 399) if (tmp2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 400) rb_set_parent(tmp2, parent);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 401) __rb_rotate_set_parents(parent, sibling, root,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 402) RB_BLACK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 403) augment_rotate(parent, sibling);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 404) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 405) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 406) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 407) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 408)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 409) /* Non-inline version for rb_erase_augmented() use */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 410) void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 411) void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 412) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 413) ____rb_erase_color(parent, root, augment_rotate);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 414) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 415) EXPORT_SYMBOL(__rb_erase_color);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 416)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 417) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 418) * Non-augmented rbtree manipulation functions.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 419) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 420) * We use dummy augmented callbacks here, and have the compiler optimize them
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 421) * out of the rb_insert_color() and rb_erase() function definitions.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 422) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 423)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 424) static inline void dummy_propagate(struct rb_node *node, struct rb_node *stop) {}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 425) static inline void dummy_copy(struct rb_node *old, struct rb_node *new) {}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 426) static inline void dummy_rotate(struct rb_node *old, struct rb_node *new) {}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 427)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 428) static const struct rb_augment_callbacks dummy_callbacks = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 429) .propagate = dummy_propagate,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 430) .copy = dummy_copy,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 431) .rotate = dummy_rotate
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 432) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 433)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 434) void rb_insert_color(struct rb_node *node, struct rb_root *root)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 435) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 436) __rb_insert(node, root, dummy_rotate);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 437) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 438) EXPORT_SYMBOL(rb_insert_color);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 439)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 440) void rb_erase(struct rb_node *node, struct rb_root *root)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 441) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 442) struct rb_node *rebalance;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 443) rebalance = __rb_erase_augmented(node, root, &dummy_callbacks);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 444) if (rebalance)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 445) ____rb_erase_color(rebalance, root, dummy_rotate);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 446) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 447) EXPORT_SYMBOL(rb_erase);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 448)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 449) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 450) * Augmented rbtree manipulation functions.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 451) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 452) * This instantiates the same __always_inline functions as in the non-augmented
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 453) * case, but this time with user-defined callbacks.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 454) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 455)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 456) void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 457) void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 458) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 459) __rb_insert(node, root, augment_rotate);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 460) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 461) EXPORT_SYMBOL(__rb_insert_augmented);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 462)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 463) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 464) * This function returns the first node (in sort order) of the tree.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 465) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 466) struct rb_node *rb_first(const struct rb_root *root)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 467) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 468) struct rb_node *n;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 469)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 470) n = root->rb_node;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 471) if (!n)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 472) return NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 473) while (n->rb_left)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 474) n = n->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 475) return n;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 476) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 477) EXPORT_SYMBOL(rb_first);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 478)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 479) struct rb_node *rb_last(const struct rb_root *root)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 480) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 481) struct rb_node *n;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 482)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 483) n = root->rb_node;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 484) if (!n)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 485) return NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 486) while (n->rb_right)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 487) n = n->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 488) return n;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 489) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 490) EXPORT_SYMBOL(rb_last);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 491)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 492) struct rb_node *rb_next(const struct rb_node *node)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 493) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 494) struct rb_node *parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 495)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 496) if (RB_EMPTY_NODE(node))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 497) return NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 498)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 499) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 500) * If we have a right-hand child, go down and then left as far
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 501) * as we can.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 502) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 503) if (node->rb_right) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 504) node = node->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 505) while (node->rb_left)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 506) node = node->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 507) return (struct rb_node *)node;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 508) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 509)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 510) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 511) * No right-hand children. Everything down and left is smaller than us,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 512) * so any 'next' node must be in the general direction of our parent.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 513) * Go up the tree; any time the ancestor is a right-hand child of its
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 514) * parent, keep going up. First time it's a left-hand child of its
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 515) * parent, said parent is our 'next' node.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 516) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 517) while ((parent = rb_parent(node)) && node == parent->rb_right)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 518) node = parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 519)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 520) return parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 521) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 522) EXPORT_SYMBOL(rb_next);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 523)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 524) struct rb_node *rb_prev(const struct rb_node *node)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 525) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 526) struct rb_node *parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 527)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 528) if (RB_EMPTY_NODE(node))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 529) return NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 530)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 531) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 532) * If we have a left-hand child, go down and then right as far
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 533) * as we can.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 534) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 535) if (node->rb_left) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 536) node = node->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 537) while (node->rb_right)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 538) node = node->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 539) return (struct rb_node *)node;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 540) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 541)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 542) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 543) * No left-hand children. Go up till we find an ancestor which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 544) * is a right-hand child of its parent.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 545) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 546) while ((parent = rb_parent(node)) && node == parent->rb_left)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 547) node = parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 548)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 549) return parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 550) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 551) EXPORT_SYMBOL(rb_prev);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 552)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 553) void rb_replace_node(struct rb_node *victim, struct rb_node *new,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 554) struct rb_root *root)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 555) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 556) struct rb_node *parent = rb_parent(victim);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 557)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 558) /* Copy the pointers/colour from the victim to the replacement */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 559) *new = *victim;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 560)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 561) /* Set the surrounding nodes to point to the replacement */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 562) if (victim->rb_left)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 563) rb_set_parent(victim->rb_left, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 564) if (victim->rb_right)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 565) rb_set_parent(victim->rb_right, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 566) __rb_change_child(victim, new, parent, root);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 567) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 568) EXPORT_SYMBOL(rb_replace_node);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 569)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 570) void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 571) struct rb_root *root)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 572) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 573) struct rb_node *parent = rb_parent(victim);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 574)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 575) /* Copy the pointers/colour from the victim to the replacement */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 576) *new = *victim;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 577)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 578) /* Set the surrounding nodes to point to the replacement */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 579) if (victim->rb_left)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 580) rb_set_parent(victim->rb_left, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 581) if (victim->rb_right)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 582) rb_set_parent(victim->rb_right, new);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 583)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 584) /* Set the parent's pointer to the new node last after an RCU barrier
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 585) * so that the pointers onwards are seen to be set correctly when doing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 586) * an RCU walk over the tree.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 587) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 588) __rb_change_child_rcu(victim, new, parent, root);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 589) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 590) EXPORT_SYMBOL(rb_replace_node_rcu);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 591)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 592) static struct rb_node *rb_left_deepest_node(const struct rb_node *node)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 593) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 594) for (;;) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 595) if (node->rb_left)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 596) node = node->rb_left;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 597) else if (node->rb_right)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 598) node = node->rb_right;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 599) else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 600) return (struct rb_node *)node;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 601) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 602) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 603)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 604) struct rb_node *rb_next_postorder(const struct rb_node *node)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 605) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 606) const struct rb_node *parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 607) if (!node)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 608) return NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 609) parent = rb_parent(node);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 610)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 611) /* If we're sitting on node, we've already seen our children */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 612) if (parent && node == parent->rb_left && parent->rb_right) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 613) /* If we are the parent's left node, go to the parent's right
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 614) * node then all the way down to the left */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 615) return rb_left_deepest_node(parent->rb_right);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 616) } else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 617) /* Otherwise we are the parent's right node, and the parent
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 618) * should be next */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 619) return (struct rb_node *)parent;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 620) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 621) EXPORT_SYMBOL(rb_next_postorder);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 622)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 623) struct rb_node *rb_first_postorder(const struct rb_root *root)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 624) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 625) if (!root->rb_node)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 626) return NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 627)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 628) return rb_left_deepest_node(root->rb_node);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 629) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 630) EXPORT_SYMBOL(rb_first_postorder);
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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