From 2b1106a407cc592cbce7d7bda146d9b99d482df3 Mon Sep 17 00:00:00 2001
From: Flavio Ceolin <flavio.ceolin@intel.com>
Date: Fri, 14 Jul 2023 12:24:33 -0700
Subject: [PATCH] kernel: userspace: Use only list for dynamic objs

Since the rbtree is using as list because we no longer
can assume that the object pointer is the address of the
data field in the dynamic object struct, lets just use
the already existent dlist for tracking dynamic kernel
objects.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
---
 kernel/userspace.c | 38 ++++++++------------------------------
 1 file changed, 8 insertions(+), 30 deletions(-)

diff --git a/kernel/userspace.c b/kernel/userspace.c
index 17680d042c9b68..f9a5be98a27ec5 100644
--- a/kernel/userspace.c
+++ b/kernel/userspace.c
@@ -47,7 +47,7 @@ LOG_MODULE_DECLARE(os, CONFIG_KERNEL_LOG_LEVEL);
  * not.
  */
 #ifdef CONFIG_DYNAMIC_OBJECTS
-static struct k_spinlock lists_lock;       /* kobj rbtree/dlist */
+static struct k_spinlock lists_lock;       /* kobj dlist */
 static struct k_spinlock objfree_lock;     /* k_object_free */
 
 #ifdef CONFIG_GEN_PRIV_STACKS
@@ -167,8 +167,7 @@ uint8_t *z_priv_stack_find(k_thread_stack_t *stack)
 
 struct dyn_obj_base {
 	struct z_object kobj;
-	sys_dnode_t dobj_list;
-	struct rbnode node; /* must be immediately before data member */
+	sys_dnode_t dobj_list; /* must be immediately before data member */
 };
 
 struct dyn_obj {
@@ -192,16 +191,6 @@ extern struct z_object *z_object_gperf_find(const void *obj);
 extern void z_object_gperf_wordlist_foreach(_wordlist_cb_func_t func,
 					     void *context);
 
-static bool node_lessthan(struct rbnode *a, struct rbnode *b);
-
-/*
- * Red/black tree of allocated kernel objects, for reasonably fast lookups
- * based on object pointer values.
- */
-static struct rbtree obj_rb_tree = {
-	.lessthan_fn = node_lessthan
-};
-
 /*
  * Linked list of allocated kernel objects, for iteration over all allocated
  * objects (and potentially deleting them during iteration).
@@ -209,8 +198,7 @@ static struct rbtree obj_rb_tree = {
 static sys_dlist_t obj_list = SYS_DLIST_STATIC_INIT(&obj_list);
 
 /*
- * TODO: Write some hash table code that will replace both obj_rb_tree
- * and obj_list.
+ * TODO: Write some hash table code that will replace obj_list.
  */
 
 static size_t obj_size_get(enum k_objects otype)
@@ -250,15 +238,9 @@ static size_t obj_align_get(enum k_objects otype)
 	return ret;
 }
 
-static bool node_lessthan(struct rbnode *a, struct rbnode *b)
-{
-	return a < b;
-}
-
 static struct dyn_obj_base *dyn_object_find(void *obj)
 {
-	struct rbnode *node;
-	struct dyn_obj_base *ret;
+	struct dyn_obj_base *node;
 	k_spinlock_key_t key;
 
 	/* For any dynamically allocated kernel object, the object
@@ -268,20 +250,19 @@ static struct dyn_obj_base *dyn_object_find(void *obj)
 	 */
 	key = k_spin_lock(&lists_lock);
 
-	RB_FOR_EACH(&obj_rb_tree, node) {
-		ret = CONTAINER_OF(node, struct dyn_obj_base, node);
-		if (ret->kobj.name == obj) {
+	SYS_DLIST_FOR_EACH_CONTAINER(&obj_list, node, dobj_list) {
+		if (node->kobj.name == obj) {
 			goto end;
 		}
 	}
 
 	/* No object found */
-	ret = NULL;
+	node = NULL;
 
  end:
 	k_spin_unlock(&lists_lock, key);
 
-	return ret;
+	return node;
 }
 
 /**
@@ -407,7 +388,6 @@ static struct z_object *dynamic_object_create(enum k_objects otype, size_t align
 
 	k_spinlock_key_t key = k_spin_lock(&lists_lock);
 
-	rb_insert(&obj_rb_tree, &dyn->node);
 	sys_dlist_append(&obj_list, &dyn->dobj_list);
 	k_spin_unlock(&lists_lock, key);
 
@@ -502,7 +482,6 @@ void k_object_free(void *obj)
 
 	dyn = dyn_object_find(obj);
 	if (dyn != NULL) {
-		rb_remove(&obj_rb_tree, &dyn->node);
 		sys_dlist_remove(&dyn->dobj_list);
 
 		if (dyn->kobj.type == K_OBJ_THREAD) {
@@ -612,7 +591,6 @@ static void unref_check(struct z_object *ko, uintptr_t index)
 		break;
 	}
 
-	rb_remove(&obj_rb_tree, &dyn->node);
 	sys_dlist_remove(&dyn->dobj_list);
 	k_free(dyn);
 out: