Unverified Commit d12ea806 authored by Christian Brauner's avatar Christian Brauner
Browse files

nstree: add helper to operate on struct ns_tree_{node,root} 

Add helpers that work on the combined rbtree and rculist combined.
This will make the code a lot more managable and legible.

Link: https://patch.msgid.link/20251110-work-namespace-nstree-fixes-v1-4-e8a9264e0fb9@kernel.org


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 1c64fb02

include/linux/nstree.h

+8 −0
Original line number Diff line number Diff line
@@ -22,6 +22,14 @@ extern struct ns_tree time_ns_tree; 
extern struct ns_tree user_ns_tree;

extern struct ns_tree uts_ns_tree;



void ns_tree_node_init(struct ns_tree_node *node);

void ns_tree_root_init(struct ns_tree_root *root);

bool ns_tree_node_empty(const struct ns_tree_node *node);

struct rb_node *ns_tree_node_add(struct ns_tree_node *node,

				  struct ns_tree_root *root,

				  int (*cmp)(struct rb_node *, const struct rb_node *));

void ns_tree_node_del(struct ns_tree_node *node, struct ns_tree_root *root);



#define to_ns_tree(__ns)					\

	_Generic((__ns),					\

		struct cgroup_namespace *: &(cgroup_ns_tree),	\

kernel/nstree.c

+85 −0
Original line number Diff line number Diff line
@@ -73,6 +73,91 @@ struct ns_tree time_ns_tree = { 
	.type = CLONE_NEWTIME,

};



/**

 * ns_tree_node_init - Initialize a namespace tree node

 * @node: The node to initialize

 *

 * Initializes both the rbtree node and list entry.

 */

void ns_tree_node_init(struct ns_tree_node *node)

{

	RB_CLEAR_NODE(&node->ns_node);

	INIT_LIST_HEAD(&node->ns_list_entry);

}



/**

 * ns_tree_root_init - Initialize a namespace tree root

 * @root: The root to initialize

 *

 * Initializes both the rbtree root and list head.

 */

void ns_tree_root_init(struct ns_tree_root *root)

{

	root->ns_rb = RB_ROOT;

	INIT_LIST_HEAD(&root->ns_list_head);

}



/**

 * ns_tree_node_empty - Check if a namespace tree node is empty

 * @node: The node to check

 *

 * Returns true if the node is not in any tree.

 */

bool ns_tree_node_empty(const struct ns_tree_node *node)

{

	return RB_EMPTY_NODE(&node->ns_node);

}



/**

 * ns_tree_node_add - Add a node to a namespace tree

 * @node: The node to add

 * @root: The tree root to add to

 * @cmp: Comparison function for rbtree insertion

 *

 * Adds the node to both the rbtree and the list, maintaining sorted order.

 * The list is maintained in the same order as the rbtree to enable efficient

 * iteration.

 *

 * Returns: NULL if insertion succeeded, existing node if duplicate found

 */

struct rb_node *ns_tree_node_add(struct ns_tree_node *node,

				  struct ns_tree_root *root,

				  int (*cmp)(struct rb_node *, const struct rb_node *))

{

	struct rb_node *ret, *prev;



	/* Add to rbtree */

	ret = rb_find_add_rcu(&node->ns_node, &root->ns_rb, cmp);



	/* Add to list in sorted order */

	prev = rb_prev(&node->ns_node);

	if (!prev) {

		/* No previous node, add at head */

		list_add_rcu(&node->ns_list_entry, &root->ns_list_head);

	} else {

		/* Add after previous node */

		struct ns_tree_node *prev_node;

		prev_node = rb_entry(prev, struct ns_tree_node, ns_node);

		list_add_rcu(&node->ns_list_entry, &prev_node->ns_list_entry);

	}



	return ret;

}



/**

 * ns_tree_node_del - Remove a node from a namespace tree

 * @node: The node to remove

 * @root: The tree root to remove from

 *

 * Removes the node from both the rbtree and the list atomically.

 */

void ns_tree_node_del(struct ns_tree_node *node, struct ns_tree_root *root)

{

	rb_erase(&node->ns_node, &root->ns_rb);

	RB_CLEAR_NODE(&node->ns_node);

	list_bidir_del_rcu(&node->ns_list_entry);

}



static inline struct ns_common *node_to_ns(const struct rb_node *node)

{

	if (!node)