mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
![Wei Yang](/assets/img/avatar_default.png)
Both in Case 2 and 3, we exchange n and s. This mean no matter whether child2 is NULL or not, successor's parent should be assigned to node's. This patch takes this step out to make it explicit and reduce the ambiguity. Besides, this step reduces some symbol size like rb_erase(). KERN_CONFIG upstream patched OPT_FOR_PERF 877 870 OPT_FOR_SIZE 635 621 Link: http://lkml.kernel.org/r/20191028021442.5450-1-richardw.yang@linux.intel.com Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Michel Lespinasse <walken@google.com> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
318 lines
9.6 KiB
C
318 lines
9.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
|
|
/*
|
|
Red Black Trees
|
|
(C) 1999 Andrea Arcangeli <andrea@suse.de>
|
|
(C) 2002 David Woodhouse <dwmw2@infradead.org>
|
|
(C) 2012 Michel Lespinasse <walken@google.com>
|
|
|
|
|
|
linux/include/linux/rbtree_augmented.h
|
|
*/
|
|
|
|
#ifndef _LINUX_RBTREE_AUGMENTED_H
|
|
#define _LINUX_RBTREE_AUGMENTED_H
|
|
|
|
#include <linux/compiler.h>
|
|
#include <linux/rbtree.h>
|
|
#include <linux/rcupdate.h>
|
|
|
|
/*
|
|
* Please note - only struct rb_augment_callbacks and the prototypes for
|
|
* rb_insert_augmented() and rb_erase_augmented() are intended to be public.
|
|
* The rest are implementation details you are not expected to depend on.
|
|
*
|
|
* See Documentation/rbtree.txt for documentation and samples.
|
|
*/
|
|
|
|
struct rb_augment_callbacks {
|
|
void (*propagate)(struct rb_node *node, struct rb_node *stop);
|
|
void (*copy)(struct rb_node *old, struct rb_node *new);
|
|
void (*rotate)(struct rb_node *old, struct rb_node *new);
|
|
};
|
|
|
|
extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
|
|
void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
|
|
|
|
/*
|
|
* Fixup the rbtree and update the augmented information when rebalancing.
|
|
*
|
|
* On insertion, the user must update the augmented information on the path
|
|
* leading to the inserted node, then call rb_link_node() as usual and
|
|
* rb_insert_augmented() instead of the usual rb_insert_color() call.
|
|
* If rb_insert_augmented() rebalances the rbtree, it will callback into
|
|
* a user provided function to update the augmented information on the
|
|
* affected subtrees.
|
|
*/
|
|
static inline void
|
|
rb_insert_augmented(struct rb_node *node, struct rb_root *root,
|
|
const struct rb_augment_callbacks *augment)
|
|
{
|
|
__rb_insert_augmented(node, root, augment->rotate);
|
|
}
|
|
|
|
static inline void
|
|
rb_insert_augmented_cached(struct rb_node *node,
|
|
struct rb_root_cached *root, bool newleft,
|
|
const struct rb_augment_callbacks *augment)
|
|
{
|
|
if (newleft)
|
|
root->rb_leftmost = node;
|
|
rb_insert_augmented(node, &root->rb_root, augment);
|
|
}
|
|
|
|
/*
|
|
* Template for declaring augmented rbtree callbacks (generic case)
|
|
*
|
|
* RBSTATIC: 'static' or empty
|
|
* RBNAME: name of the rb_augment_callbacks structure
|
|
* RBSTRUCT: struct type of the tree nodes
|
|
* RBFIELD: name of struct rb_node field within RBSTRUCT
|
|
* RBAUGMENTED: name of field within RBSTRUCT holding data for subtree
|
|
* RBCOMPUTE: name of function that recomputes the RBAUGMENTED data
|
|
*/
|
|
|
|
#define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \
|
|
RBSTRUCT, RBFIELD, RBAUGMENTED, RBCOMPUTE) \
|
|
static inline void \
|
|
RBNAME ## _propagate(struct rb_node *rb, struct rb_node *stop) \
|
|
{ \
|
|
while (rb != stop) { \
|
|
RBSTRUCT *node = rb_entry(rb, RBSTRUCT, RBFIELD); \
|
|
if (RBCOMPUTE(node, true)) \
|
|
break; \
|
|
rb = rb_parent(&node->RBFIELD); \
|
|
} \
|
|
} \
|
|
static inline void \
|
|
RBNAME ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \
|
|
{ \
|
|
RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
|
|
RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
|
|
new->RBAUGMENTED = old->RBAUGMENTED; \
|
|
} \
|
|
static void \
|
|
RBNAME ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \
|
|
{ \
|
|
RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
|
|
RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
|
|
new->RBAUGMENTED = old->RBAUGMENTED; \
|
|
RBCOMPUTE(old, false); \
|
|
} \
|
|
RBSTATIC const struct rb_augment_callbacks RBNAME = { \
|
|
.propagate = RBNAME ## _propagate, \
|
|
.copy = RBNAME ## _copy, \
|
|
.rotate = RBNAME ## _rotate \
|
|
};
|
|
|
|
/*
|
|
* Template for declaring augmented rbtree callbacks,
|
|
* computing RBAUGMENTED scalar as max(RBCOMPUTE(node)) for all subtree nodes.
|
|
*
|
|
* RBSTATIC: 'static' or empty
|
|
* RBNAME: name of the rb_augment_callbacks structure
|
|
* RBSTRUCT: struct type of the tree nodes
|
|
* RBFIELD: name of struct rb_node field within RBSTRUCT
|
|
* RBTYPE: type of the RBAUGMENTED field
|
|
* RBAUGMENTED: name of RBTYPE field within RBSTRUCT holding data for subtree
|
|
* RBCOMPUTE: name of function that returns the per-node RBTYPE scalar
|
|
*/
|
|
|
|
#define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD, \
|
|
RBTYPE, RBAUGMENTED, RBCOMPUTE) \
|
|
static inline bool RBNAME ## _compute_max(RBSTRUCT *node, bool exit) \
|
|
{ \
|
|
RBSTRUCT *child; \
|
|
RBTYPE max = RBCOMPUTE(node); \
|
|
if (node->RBFIELD.rb_left) { \
|
|
child = rb_entry(node->RBFIELD.rb_left, RBSTRUCT, RBFIELD); \
|
|
if (child->RBAUGMENTED > max) \
|
|
max = child->RBAUGMENTED; \
|
|
} \
|
|
if (node->RBFIELD.rb_right) { \
|
|
child = rb_entry(node->RBFIELD.rb_right, RBSTRUCT, RBFIELD); \
|
|
if (child->RBAUGMENTED > max) \
|
|
max = child->RBAUGMENTED; \
|
|
} \
|
|
if (exit && node->RBAUGMENTED == max) \
|
|
return true; \
|
|
node->RBAUGMENTED = max; \
|
|
return false; \
|
|
} \
|
|
RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \
|
|
RBSTRUCT, RBFIELD, RBAUGMENTED, RBNAME ## _compute_max)
|
|
|
|
|
|
#define RB_RED 0
|
|
#define RB_BLACK 1
|
|
|
|
#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
|
|
|
|
#define __rb_color(pc) ((pc) & 1)
|
|
#define __rb_is_black(pc) __rb_color(pc)
|
|
#define __rb_is_red(pc) (!__rb_color(pc))
|
|
#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
|
|
#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
|
|
#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
|
|
|
|
static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
|
|
{
|
|
rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
|
|
}
|
|
|
|
static inline void rb_set_parent_color(struct rb_node *rb,
|
|
struct rb_node *p, int color)
|
|
{
|
|
rb->__rb_parent_color = (unsigned long)p | color;
|
|
}
|
|
|
|
static inline void
|
|
__rb_change_child(struct rb_node *old, struct rb_node *new,
|
|
struct rb_node *parent, struct rb_root *root)
|
|
{
|
|
if (parent) {
|
|
if (parent->rb_left == old)
|
|
WRITE_ONCE(parent->rb_left, new);
|
|
else
|
|
WRITE_ONCE(parent->rb_right, new);
|
|
} else
|
|
WRITE_ONCE(root->rb_node, new);
|
|
}
|
|
|
|
static inline void
|
|
__rb_change_child_rcu(struct rb_node *old, struct rb_node *new,
|
|
struct rb_node *parent, struct rb_root *root)
|
|
{
|
|
if (parent) {
|
|
if (parent->rb_left == old)
|
|
rcu_assign_pointer(parent->rb_left, new);
|
|
else
|
|
rcu_assign_pointer(parent->rb_right, new);
|
|
} else
|
|
rcu_assign_pointer(root->rb_node, new);
|
|
}
|
|
|
|
extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
|
|
void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
|
|
|
|
static __always_inline struct rb_node *
|
|
__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
|
|
const struct rb_augment_callbacks *augment)
|
|
{
|
|
struct rb_node *child = node->rb_right;
|
|
struct rb_node *tmp = node->rb_left;
|
|
struct rb_node *parent, *rebalance;
|
|
unsigned long pc;
|
|
|
|
if (!tmp) {
|
|
/*
|
|
* Case 1: node to erase has no more than 1 child (easy!)
|
|
*
|
|
* Note that if there is one child it must be red due to 5)
|
|
* and node must be black due to 4). We adjust colors locally
|
|
* so as to bypass __rb_erase_color() later on.
|
|
*/
|
|
pc = node->__rb_parent_color;
|
|
parent = __rb_parent(pc);
|
|
__rb_change_child(node, child, parent, root);
|
|
if (child) {
|
|
child->__rb_parent_color = pc;
|
|
rebalance = NULL;
|
|
} else
|
|
rebalance = __rb_is_black(pc) ? parent : NULL;
|
|
tmp = parent;
|
|
} else if (!child) {
|
|
/* Still case 1, but this time the child is node->rb_left */
|
|
tmp->__rb_parent_color = pc = node->__rb_parent_color;
|
|
parent = __rb_parent(pc);
|
|
__rb_change_child(node, tmp, parent, root);
|
|
rebalance = NULL;
|
|
tmp = parent;
|
|
} else {
|
|
struct rb_node *successor = child, *child2;
|
|
|
|
tmp = child->rb_left;
|
|
if (!tmp) {
|
|
/*
|
|
* Case 2: node's successor is its right child
|
|
*
|
|
* (n) (s)
|
|
* / \ / \
|
|
* (x) (s) -> (x) (c)
|
|
* \
|
|
* (c)
|
|
*/
|
|
parent = successor;
|
|
child2 = successor->rb_right;
|
|
|
|
augment->copy(node, successor);
|
|
} else {
|
|
/*
|
|
* Case 3: node's successor is leftmost under
|
|
* node's right child subtree
|
|
*
|
|
* (n) (s)
|
|
* / \ / \
|
|
* (x) (y) -> (x) (y)
|
|
* / /
|
|
* (p) (p)
|
|
* / /
|
|
* (s) (c)
|
|
* \
|
|
* (c)
|
|
*/
|
|
do {
|
|
parent = successor;
|
|
successor = tmp;
|
|
tmp = tmp->rb_left;
|
|
} while (tmp);
|
|
child2 = successor->rb_right;
|
|
WRITE_ONCE(parent->rb_left, child2);
|
|
WRITE_ONCE(successor->rb_right, child);
|
|
rb_set_parent(child, successor);
|
|
|
|
augment->copy(node, successor);
|
|
augment->propagate(parent, successor);
|
|
}
|
|
|
|
tmp = node->rb_left;
|
|
WRITE_ONCE(successor->rb_left, tmp);
|
|
rb_set_parent(tmp, successor);
|
|
|
|
pc = node->__rb_parent_color;
|
|
tmp = __rb_parent(pc);
|
|
__rb_change_child(node, successor, tmp, root);
|
|
|
|
if (child2) {
|
|
rb_set_parent_color(child2, parent, RB_BLACK);
|
|
rebalance = NULL;
|
|
} else {
|
|
unsigned long pc2 = successor->__rb_parent_color;
|
|
rebalance = __rb_is_black(pc2) ? parent : NULL;
|
|
}
|
|
successor->__rb_parent_color = pc;
|
|
tmp = successor;
|
|
}
|
|
|
|
augment->propagate(tmp, NULL);
|
|
return rebalance;
|
|
}
|
|
|
|
static __always_inline void
|
|
rb_erase_augmented(struct rb_node *node, struct rb_root *root,
|
|
const struct rb_augment_callbacks *augment)
|
|
{
|
|
struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
|
|
if (rebalance)
|
|
__rb_erase_color(rebalance, root, augment->rotate);
|
|
}
|
|
|
|
static __always_inline void
|
|
rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root,
|
|
const struct rb_augment_callbacks *augment)
|
|
{
|
|
if (root->rb_leftmost == node)
|
|
root->rb_leftmost = rb_next(node);
|
|
rb_erase_augmented(node, &root->rb_root, augment);
|
|
}
|
|
|
|
#endif /* _LINUX_RBTREE_AUGMENTED_H */
|