343 lines
8.6 KiB
C
343 lines
8.6 KiB
C
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/*
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* NUMA support for s390
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*
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* A tree structure used for machine topology mangling
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*
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* Copyright IBM Corp. 2015
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*/
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#include <linux/kernel.h>
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#include <linux/cpumask.h>
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#include <linux/list.h>
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#include <linux/list_sort.h>
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#include <linux/slab.h>
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#include <asm/numa.h>
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#include "toptree.h"
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/**
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* toptree_alloc - Allocate and initialize a new tree node.
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* @level: The node's vertical level; level 0 contains the leaves.
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* @id: ID number, explicitly not unique beyond scope of node's siblings
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*
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* Allocate a new tree node and initialize it.
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*
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* RETURNS:
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* Pointer to the new tree node or NULL on error
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*/
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struct toptree *toptree_alloc(int level, int id)
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{
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struct toptree *res = kzalloc(sizeof(struct toptree), GFP_KERNEL);
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if (!res)
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return res;
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INIT_LIST_HEAD(&res->children);
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INIT_LIST_HEAD(&res->sibling);
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cpumask_clear(&res->mask);
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res->level = level;
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res->id = id;
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return res;
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}
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/**
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* toptree_remove - Remove a tree node from a tree
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* @cand: Pointer to the node to remove
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*
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* The node is detached from its parent node. The parent node's
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* masks will be updated to reflect the loss of the child.
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*/
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static void toptree_remove(struct toptree *cand)
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{
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struct toptree *oldparent;
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list_del_init(&cand->sibling);
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oldparent = cand->parent;
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cand->parent = NULL;
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toptree_update_mask(oldparent);
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}
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/**
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* toptree_free - discard a tree node
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* @cand: Pointer to the tree node to discard
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*
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* Checks if @cand is attached to a parent node. Detaches it
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* cleanly using toptree_remove. Possible children are freed
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* recursively. In the end @cand itself is freed.
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*/
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void toptree_free(struct toptree *cand)
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{
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struct toptree *child, *tmp;
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if (cand->parent)
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toptree_remove(cand);
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toptree_for_each_child_safe(child, tmp, cand)
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toptree_free(child);
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kfree(cand);
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}
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/**
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* toptree_update_mask - Update node bitmasks
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* @cand: Pointer to a tree node
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*
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* The node's cpumask will be updated by combining all children's
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* masks. Then toptree_update_mask is called recursively for the
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* parent if applicable.
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*
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* NOTE:
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* This must not be called on leaves. If called on a leaf, its
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* CPU mask is cleared and lost.
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*/
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void toptree_update_mask(struct toptree *cand)
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{
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struct toptree *child;
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cpumask_clear(&cand->mask);
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list_for_each_entry(child, &cand->children, sibling)
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cpumask_or(&cand->mask, &cand->mask, &child->mask);
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if (cand->parent)
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toptree_update_mask(cand->parent);
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}
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/**
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* toptree_insert - Insert a tree node into tree
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* @cand: Pointer to the node to insert
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* @target: Pointer to the node to which @cand will added as a child
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*
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* Insert a tree node into a tree. Masks will be updated automatically.
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*
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* RETURNS:
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* 0 on success, -1 if NULL is passed as argument or the node levels
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* don't fit.
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*/
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static int toptree_insert(struct toptree *cand, struct toptree *target)
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{
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if (!cand || !target)
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return -1;
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if (target->level != (cand->level + 1))
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return -1;
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list_add_tail(&cand->sibling, &target->children);
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cand->parent = target;
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toptree_update_mask(target);
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return 0;
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}
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/**
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* toptree_move_children - Move all child nodes of a node to a new place
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* @cand: Pointer to the node whose children are to be moved
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* @target: Pointer to the node to which @cand's children will be attached
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*
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* Take all child nodes of @cand and move them using toptree_move.
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*/
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static void toptree_move_children(struct toptree *cand, struct toptree *target)
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{
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struct toptree *child, *tmp;
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toptree_for_each_child_safe(child, tmp, cand)
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toptree_move(child, target);
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}
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/**
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* toptree_unify - Merge children with same ID
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* @cand: Pointer to node whose direct children should be made unique
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*
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* When mangling the tree it is possible that a node has two or more children
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* which have the same ID. This routine merges these children into one and
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* moves all children of the merged nodes into the unified node.
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*/
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void toptree_unify(struct toptree *cand)
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{
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struct toptree *child, *tmp, *cand_copy;
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/* Threads cannot be split, cores are not split */
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if (cand->level < 2)
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return;
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cand_copy = toptree_alloc(cand->level, 0);
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toptree_for_each_child_safe(child, tmp, cand) {
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struct toptree *tmpchild;
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if (!cpumask_empty(&child->mask)) {
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tmpchild = toptree_get_child(cand_copy, child->id);
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toptree_move_children(child, tmpchild);
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}
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toptree_free(child);
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}
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toptree_move_children(cand_copy, cand);
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toptree_free(cand_copy);
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toptree_for_each_child(child, cand)
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toptree_unify(child);
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}
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/**
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* toptree_move - Move a node to another context
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* @cand: Pointer to the node to move
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* @target: Pointer to the node where @cand should go
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*
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* In the easiest case @cand is exactly on the level below @target
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* and will be immediately moved to the target.
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*
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* If @target's level is not the direct parent level of @cand,
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* nodes for the missing levels are created and put between
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* @cand and @target. The "stacking" nodes' IDs are taken from
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* @cand's parents.
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*
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* After this it is likely to have redundant nodes in the tree
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* which are addressed by means of toptree_unify.
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*/
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void toptree_move(struct toptree *cand, struct toptree *target)
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{
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struct toptree *stack_target, *real_insert_point, *ptr, *tmp;
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if (cand->level + 1 == target->level) {
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toptree_remove(cand);
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toptree_insert(cand, target);
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return;
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}
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real_insert_point = NULL;
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ptr = cand;
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stack_target = NULL;
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do {
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tmp = stack_target;
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stack_target = toptree_alloc(ptr->level + 1,
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ptr->parent->id);
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toptree_insert(tmp, stack_target);
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if (!real_insert_point)
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real_insert_point = stack_target;
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ptr = ptr->parent;
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} while (stack_target->level < (target->level - 1));
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toptree_remove(cand);
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toptree_insert(cand, real_insert_point);
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toptree_insert(stack_target, target);
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}
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/**
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* toptree_get_child - Access a tree node's child by its ID
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* @cand: Pointer to tree node whose child is to access
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* @id: The desired child's ID
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*
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* @cand's children are searched for a child with matching ID.
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* If no match can be found, a new child with the desired ID
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* is created and returned.
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*/
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struct toptree *toptree_get_child(struct toptree *cand, int id)
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{
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struct toptree *child;
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toptree_for_each_child(child, cand)
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if (child->id == id)
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return child;
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child = toptree_alloc(cand->level-1, id);
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toptree_insert(child, cand);
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return child;
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}
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/**
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* toptree_first - Find the first descendant on specified level
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* @context: Pointer to tree node whose descendants are to be used
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* @level: The level of interest
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*
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* RETURNS:
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* @context's first descendant on the specified level, or NULL
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* if there is no matching descendant
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*/
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struct toptree *toptree_first(struct toptree *context, int level)
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{
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struct toptree *child, *tmp;
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if (context->level == level)
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return context;
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if (!list_empty(&context->children)) {
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list_for_each_entry(child, &context->children, sibling) {
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tmp = toptree_first(child, level);
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if (tmp)
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return tmp;
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}
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}
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return NULL;
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}
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/**
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* toptree_next_sibling - Return next sibling
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* @cur: Pointer to a tree node
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*
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* RETURNS:
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* If @cur has a parent and is not the last in the parent's children list,
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* the next sibling is returned. Or NULL when there are no siblings left.
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*/
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static struct toptree *toptree_next_sibling(struct toptree *cur)
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{
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if (cur->parent == NULL)
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return NULL;
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if (cur == list_last_entry(&cur->parent->children,
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struct toptree, sibling))
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return NULL;
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return (struct toptree *) list_next_entry(cur, sibling);
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}
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/**
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* toptree_next - Tree traversal function
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* @cur: Pointer to current element
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* @context: Pointer to the root node of the tree or subtree to
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* be traversed.
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* @level: The level of interest.
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*
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* RETURNS:
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* Pointer to the next node on level @level
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* or NULL when there is no next node.
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*/
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struct toptree *toptree_next(struct toptree *cur, struct toptree *context,
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int level)
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{
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struct toptree *cur_context, *tmp;
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if (!cur)
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return NULL;
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if (context->level == level)
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return NULL;
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tmp = toptree_next_sibling(cur);
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if (tmp != NULL)
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return tmp;
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cur_context = cur;
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while (cur_context->level < context->level - 1) {
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/* Step up */
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cur_context = cur_context->parent;
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/* Step aside */
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tmp = toptree_next_sibling(cur_context);
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if (tmp != NULL) {
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/* Step down */
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tmp = toptree_first(tmp, level);
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if (tmp != NULL)
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return tmp;
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}
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}
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return NULL;
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}
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/**
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* toptree_count - Count descendants on specified level
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* @context: Pointer to node whose descendants are to be considered
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* @level: Only descendants on the specified level will be counted
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*
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* RETURNS:
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* Number of descendants on the specified level
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*/
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int toptree_count(struct toptree *context, int level)
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{
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struct toptree *cur;
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int cnt = 0;
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toptree_for_each(cur, context, level)
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cnt++;
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return cnt;
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}
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