1 files changed, 342 insertions, 0 deletions
diff --git a/arch/s390/numa/toptree.c b/arch/s390/numa/toptree.c
new file mode 100644
index 000000000000..902d350d859a
--- /dev/null
+++ b/arch/s390/numa/toptree.c
@@ -0,0 +1,342 @@
+/*
+ * NUMA support for s390
+ *
+ * A tree structure used for machine topology mangling
+ *
+ * Copyright IBM Corp. 2015
+ */
+
+#include <linux/kernel.h>
+#include <linux/cpumask.h>
+#include <linux/list.h>
+#include <linux/list_sort.h>
+#include <linux/slab.h>
+#include <asm/numa.h>
+
+#include "toptree.h"
+
+/**
+ * toptree_alloc - Allocate and initialize a new tree node.
+ * @level: The node's vertical level; level 0 contains the leaves.
+ * @id: ID number, explicitly not unique beyond scope of node's siblings
+ *
+ * Allocate a new tree node and initialize it.
+ *
+ * RETURNS:
+ * Pointer to the new tree node or NULL on error
+ */
+struct toptree *toptree_alloc(int level, int id)
+{
+	struct toptree *res = kzalloc(sizeof(struct toptree), GFP_KERNEL);
+
+	if (!res)
+		return res;
+
+	INIT_LIST_HEAD(&res->children);
+	INIT_LIST_HEAD(&res->sibling);
+	cpumask_clear(&res->mask);
+	res->level = level;
+	res->id = id;
+	return res;
+}
+
+/**
+ * toptree_remove - Remove a tree node from a tree
+ * @cand: Pointer to the node to remove
+ *
+ * The node is detached from its parent node. The parent node's
+ * masks will be updated to reflect the loss of the child.
+ */
+static void toptree_remove(struct toptree *cand)
+{
+	struct toptree *oldparent;
+
+	list_del_init(&cand->sibling);
+	oldparent = cand->parent;
+	cand->parent = NULL;
+	toptree_update_mask(oldparent);
+}
+
+/**
+ * toptree_free - discard a tree node
+ * @cand: Pointer to the tree node to discard
+ *
+ * Checks if @cand is attached to a parent node. Detaches it
+ * cleanly using toptree_remove. Possible children are freed
+ * recursively. In the end @cand itself is freed.
+ */
+void toptree_free(struct toptree *cand)
+{
+	struct toptree *child, *tmp;
+
+	if (cand->parent)
+		toptree_remove(cand);
+	toptree_for_each_child_safe(child, tmp, cand)
+		toptree_free(child);
+	kfree(cand);
+}
+
+/**
+ * toptree_update_mask - Update node bitmasks
+ * @cand: Pointer to a tree node
+ *
+ * The node's cpumask will be updated by combining all children's
+ * masks. Then toptree_update_mask is called recursively for the
+ * parent if applicable.
+ *
+ * NOTE:
+ * This must not be called on leaves. If called on a leaf, its
+ * CPU mask is cleared and lost.
+ */
+void toptree_update_mask(struct toptree *cand)
+{
+	struct toptree *child;
+
+	cpumask_clear(&cand->mask);
+	list_for_each_entry(child, &cand->children, sibling)
+		cpumask_or(&cand->mask, &cand->mask, &child->mask);
+	if (cand->parent)
+		toptree_update_mask(cand->parent);
+}
+
+/**
+ * toptree_insert - Insert a tree node into tree
+ * @cand: Pointer to the node to insert
+ * @target: Pointer to the node to which @cand will added as a child
+ *
+ * Insert a tree node into a tree. Masks will be updated automatically.
+ *
+ * RETURNS:
+ * 0 on success, -1 if NULL is passed as argument or the node levels
+ * don't fit.
+ */
+static int toptree_insert(struct toptree *cand, struct toptree *target)
+{
+	if (!cand || !target)
+		return -1;
+	if (target->level != (cand->level + 1))
+		return -1;
+	list_add_tail(&cand->sibling, &target->children);
+	cand->parent = target;
+	toptree_update_mask(target);
+	return 0;
+}
+
+/**
+ * toptree_move_children - Move all child nodes of a node to a new place
+ * @cand: Pointer to the node whose children are to be moved
+ * @target: Pointer to the node to which @cand's children will be attached
+ *
+ * Take all child nodes of @cand and move them using toptree_move.
+ */
+static void toptree_move_children(struct toptree *cand, struct toptree *target)
+{
+	struct toptree *child, *tmp;
+
+	toptree_for_each_child_safe(child, tmp, cand)
+		toptree_move(child, target);
+}
+
+/**
+ * toptree_unify - Merge children with same ID
+ * @cand: Pointer to node whose direct children should be made unique
+ *
+ * When mangling the tree it is possible that a node has two or more children
+ * which have the same ID. This routine merges these children into one and
+ * moves all children of the merged nodes into the unified node.
+ */
+void toptree_unify(struct toptree *cand)
+{
+	struct toptree *child, *tmp, *cand_copy;
+
+	/* Threads cannot be split, cores are not split */
+	if (cand->level < 2)
+		return;
+
+	cand_copy = toptree_alloc(cand->level, 0);
+	toptree_for_each_child_safe(child, tmp, cand) {
+		struct toptree *tmpchild;
+
+		if (!cpumask_empty(&child->mask)) {
+			tmpchild = toptree_get_child(cand_copy, child->id);
+			toptree_move_children(child, tmpchild);
+		}
+		toptree_free(child);
+	}
+	toptree_move_children(cand_copy, cand);
+	toptree_free(cand_copy);
+
+	toptree_for_each_child(child, cand)
+		toptree_unify(child);
+}
+
+/**
+ * toptree_move - Move a node to another context
+ * @cand: Pointer to the node to move
+ * @target: Pointer to the node where @cand should go
+ *
+ * In the easiest case @cand is exactly on the level below @target
+ * and will be immediately moved to the target.
+ *
+ * If @target's level is not the direct parent level of @cand,
+ * nodes for the missing levels are created and put between
+ * @cand and @target. The "stacking" nodes' IDs are taken from
+ * @cand's parents.
+ *
+ * After this it is likely to have redundant nodes in the tree
+ * which are addressed by means of toptree_unify.
+ */
+void toptree_move(struct toptree *cand, struct toptree *target)
+{
+	struct toptree *stack_target, *real_insert_point, *ptr, *tmp;
+
+	if (cand->level + 1 == target->level) {
+		toptree_remove(cand);
+		toptree_insert(cand, target);
+		return;
+	}
+
+	real_insert_point = NULL;
+	ptr = cand;
+	stack_target = NULL;
+
+	do {
+		tmp = stack_target;
+		stack_target = toptree_alloc(ptr->level + 1,
+					     ptr->parent->id);
+		toptree_insert(tmp, stack_target);
+		if (!real_insert_point)
+			real_insert_point = stack_target;
+		ptr = ptr->parent;
+	} while (stack_target->level < (target->level - 1));
+
+	toptree_remove(cand);
+	toptree_insert(cand, real_insert_point);
+	toptree_insert(stack_target, target);
+}
+
+/**
+ * toptree_get_child - Access a tree node's child by its ID
+ * @cand: Pointer to tree node whose child is to access
+ * @id: The desired child's ID
+ *
+ * @cand's children are searched for a child with matching ID.
+ * If no match can be found, a new child with the desired ID
+ * is created and returned.
+ */
+struct toptree *toptree_get_child(struct toptree *cand, int id)
+{
+	struct toptree *child;
+
+	toptree_for_each_child(child, cand)
+		if (child->id == id)
+			return child;
+	child = toptree_alloc(cand->level-1, id);
+	toptree_insert(child, cand);
+	return child;
+}
+
+/**
+ * toptree_first - Find the first descendant on specified level
+ * @context: Pointer to tree node whose descendants are to be used
+ * @level: The level of interest
+ *
+ * RETURNS:
+ * @context's first descendant on the specified level, or NULL
+ * if there is no matching descendant
+ */
+struct toptree *toptree_first(struct toptree *context, int level)
+{
+	struct toptree *child, *tmp;
+
+	if (context->level == level)
+		return context;
+
+	if (!list_empty(&context->children)) {
+		list_for_each_entry(child, &context->children, sibling) {
+			tmp = toptree_first(child, level);
+			if (tmp)
+				return tmp;
+		}
+	}
+	return NULL;
+}
+
+/**
+ * toptree_next_sibling - Return next sibling
+ * @cur: Pointer to a tree node
+ *
+ * RETURNS:
+ * If @cur has a parent and is not the last in the parent's children list,
+ * the next sibling is returned. Or NULL when there are no siblings left.
+ */
+static struct toptree *toptree_next_sibling(struct toptree *cur)
+{
+	if (cur->parent == NULL)
+		return NULL;
+
+	if (cur == list_last_entry(&cur->parent->children,
+				   struct toptree, sibling))
+		return NULL;
+	return (struct toptree *) list_next_entry(cur, sibling);
+}
+
+/**
+ * toptree_next - Tree traversal function
+ * @cur: Pointer to current element
+ * @context: Pointer to the root node of the tree or subtree to
+ * be traversed.
+ * @level: The level of interest.
+ *
+ * RETURNS:
+ * Pointer to the next node on level @level
+ * or NULL when there is no next node.
+ */
+struct toptree *toptree_next(struct toptree *cur, struct toptree *context,
+			     int level)
+{
+	struct toptree *cur_context, *tmp;
+
+	if (!cur)
+		return NULL;
+
+	if (context->level == level)
+		return NULL;
+
+	tmp = toptree_next_sibling(cur);
+	if (tmp != NULL)
+		return tmp;
+
+	cur_context = cur;
+	while (cur_context->level < context->level - 1) {
+		/* Step up */
+		cur_context = cur_context->parent;
+		/* Step aside */
+		tmp = toptree_next_sibling(cur_context);
+		if (tmp != NULL) {
+			/* Step down */
+			tmp = toptree_first(tmp, level);
+			if (tmp != NULL)
+				return tmp;
+		}
+	}
+	return NULL;
+}
+
+/**
+ * toptree_count - Count descendants on specified level
+ * @context: Pointer to node whose descendants are to be considered
+ * @level: Only descendants on the specified level will be counted
+ *
+ * RETURNS:
+ * Number of descendants on the specified level
+ */
+int toptree_count(struct toptree *context, int level)
+{
+	struct toptree *cur;
+	int cnt = 0;
+
+	toptree_for_each(cur, context, level)
+		cnt++;
+	return cnt;
+}