[RFC PATCH 07/20] kho: allow destroying KHO radix tree

[Jork Loeser <jloeser@linux.microsoft.com>]

From: "Pratyush Yadav (Google)" <pratyush@kernel.org>

Add kho_radix_destroy_tree() which allows destroying the radix tree and
freeing all its pages.

Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Jork Loeser <jloeser@linux.microsoft.com>
---
 include/linux/kho_radix_tree.h     |  3 +++
 kernel/liveupdate/kexec_handover.c | 34 ++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/include/linux/kho_radix_tree.h b/include/linux/kho_radix_tree.h
index 6c0f7d82716b..617395a6647a 100644
--- a/include/linux/kho_radix_tree.h
+++ b/include/linux/kho_radix_tree.h
@@ -54,6 +54,7 @@ int kho_radix_add_key(struct kho_radix_tree *tree, unsigned long key);
 void kho_radix_del_key(struct kho_radix_tree *tree, unsigned long key);
 int kho_radix_walk_tree(struct kho_radix_tree *tree,
 			const struct kho_radix_walk_cb *cb, void *data);
+void kho_radix_destroy_tree(struct kho_radix_tree *tree);
 
 #else  /* #ifdef CONFIG_KEXEC_HANDOVER */
 
@@ -71,6 +72,8 @@ static inline int kho_radix_walk_tree(struct kho_radix_tree *tree,
 	return -EOPNOTSUPP;
 }
 
+static inline void kho_radix_destroy_tree(struct kho_radix_tree *tree) { }
+
 #endif /* #ifdef CONFIG_KEXEC_HANDOVER */
 
 #endif	/* _LINUX_KHO_RADIX_TREE_H */
diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
index 5c201e605b96..3f3ea71baa1a 100644
--- a/kernel/liveupdate/kexec_handover.c
+++ b/kernel/liveupdate/kexec_handover.c
@@ -286,6 +286,40 @@ void kho_radix_del_key(struct kho_radix_tree *tree, unsigned long key)
 }
 EXPORT_SYMBOL_GPL(kho_radix_del_key);
 
+static void __kho_radix_destroy_tree(struct kho_radix_node *root,
+				     unsigned int level)
+{
+	unsigned long i;
+
+	if (level == 0) {
+		kho_radix_free_node(root);
+		return;
+	}
+
+	for (i = 0; i < PAGE_SIZE / sizeof(phys_addr_t); i++) {
+		if (root->table[i])
+			__kho_radix_destroy_tree(phys_to_virt(root->table[i]),
+						 level - 1);
+	}
+
+	kho_radix_free_node(root);
+}
+
+/**
+ * kho_radix_destroy_tree - Destroy the radix tree
+ * @tree: The radix tree to destroy
+ *
+ * Walk @tree and free all its nodes.
+ */
+void kho_radix_destroy_tree(struct kho_radix_tree *tree)
+{
+	if (!tree->root)
+		return;
+
+	__kho_radix_destroy_tree(tree->root, KHO_TREE_MAX_DEPTH - 1);
+}
+EXPORT_SYMBOL_GPL(kho_radix_destroy_tree);
+
 static int kho_radix_walk_leaf(struct kho_radix_leaf *leaf, unsigned long key,
 			       const struct kho_radix_walk_cb *cb, void *data)
 {
-- 
2.43.0