[RFC PATCH 08/20] kho: add kho_radix_init_tree()

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

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

Move the initialization logic of the radix tree into
kho_radix_init_tree() instead of having users open-code it. Makes the
boundaries cleaner and reduces code duplication when a new user of the
radix tree will be added in a future commit.

Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Jork Loeser <jloeser@linux.microsoft.com>
---
 include/linux/kho_radix_tree.h     |  7 ++++++
 kernel/liveupdate/kexec_handover.c | 37 ++++++++++++++++++++++++++++--
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/include/linux/kho_radix_tree.h b/include/linux/kho_radix_tree.h
index 617395a6647a..c0840ecb230c 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);
+int kho_radix_init_tree(struct kho_radix_tree *tree, struct kho_radix_node *root);
 void kho_radix_destroy_tree(struct kho_radix_tree *tree);
 
 #else  /* #ifdef CONFIG_KEXEC_HANDOVER */
@@ -72,6 +73,12 @@ static inline int kho_radix_walk_tree(struct kho_radix_tree *tree,
 	return -EOPNOTSUPP;
 }
 
+static inline int kho_radix_init_tree(struct kho_radix_tree *tree,
+				      struct kho_radix_node *root)
+{
+	return 0;
+}
+
 static inline void kho_radix_destroy_tree(struct kho_radix_tree *tree) { }
 
 #endif /* #ifdef CONFIG_KEXEC_HANDOVER */
diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
index 3f3ea71baa1a..b2d1572808eb 100644
--- a/kernel/liveupdate/kexec_handover.c
+++ b/kernel/liveupdate/kexec_handover.c
@@ -305,6 +305,34 @@ static void __kho_radix_destroy_tree(struct kho_radix_node *root,
 	kho_radix_free_node(root);
 }
 
+/**
+ * kho_radix_init_tree - initialize the radix tree.
+ * @tree:   the tree to initialize.
+ * @root:   root table of the radix tree.
+ *
+ * Initialize the radix tree with the given root node. If root is %NULL, an
+ * empty root table is allocated. If root is not %NULL, it is the caller's
+ * responsibility to make sure the root is valid and in the correct format.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+int kho_radix_init_tree(struct kho_radix_tree *tree, struct kho_radix_node *root)
+{
+	/* Already initialized. */
+	if (tree->root)
+		return 0;
+
+	if (!root)
+		root = kho_radix_alloc_node();
+	if (!root)
+		return -ENOMEM;
+
+	tree->root = root;
+	mutex_init(&tree->lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kho_radix_init_tree);
+
 /**
  * kho_radix_destroy_tree - Destroy the radix tree
  * @tree: The radix tree to destroy
@@ -1467,9 +1495,14 @@ static int __init kho_mem_retrieve(const void *fdt)
 	const struct kho_radix_walk_cb cb = {
 		.key = kho_preserved_memory_reserve,
 	};
+	phys_addr_t mem_map_phys;
+	int err;
+
+	mem_map_phys = kho_get_mem_map_phys(fdt);
+	err = kho_radix_init_tree(&kho_in.radix_tree, phys_to_virt(mem_map_phys));
+	if (err)
+		return err;
 
-	kho_in.radix_tree.root = phys_to_virt(kho_get_mem_map_phys(fdt));
-	mutex_init(&kho_in.radix_tree.lock);
 	return kho_radix_walk_tree(&kho_in.radix_tree, &cb, NULL);
 }
 
-- 
2.43.0