lib: allow listnode memory to be managed by the app

In most cases this memory is pre-allocated along with the base element.
Similarly it is stored in the base element to allow efficient del
without lookup (main reason for using DLL vs. SLL).

So (in most cases) there should be no need to manage the element/data
and listnode memories separately.

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>

1 files changed, 15 insertions, 5 deletions

diff --git a/lib/linklist.h b/lib/linklist.h
index 00cb9f8714..94a1a1604a 100644
--- a/lib/linklist.h
+++ b/lib/linklist.h
@@ -43,6 +43,12 @@ struct list {
 	/* invariant: count is the number of listnodes in the list */
 	unsigned int count;
 
+	uint8_t flags;
+/* Indicates that listnode memory is managed by the application and
+ * doesn't need to be freed by this library via listnode_delete etc.
+ */
+#define LINKLIST_FLAG_NODE_MEM_BY_APP (1 << 0)
+
 	/*
 	 * Returns -1 if val1 < val2, 0 if equal?, 1 if val1 > val2.
 	 * Used as definition of sorted for listnode_add_sort
@@ -60,10 +66,14 @@ struct list {
 #define listhead(X) ((X) ? ((X)->head) : NULL)
 #define listhead_unchecked(X) ((X)->head)
 #define listtail(X) ((X) ? ((X)->tail) : NULL)
+#define listtail_unchecked(X) ((X)->tail)
 #define listcount(X) ((X)->count)
 #define list_isempty(X) ((X)->head == NULL && (X)->tail == NULL)
 /* return X->data only if X and X->data are not NULL */
 #define listgetdata(X) (assert(X), assert((X)->data != NULL), (X)->data)
+/* App is going to manage listnode memory */
+#define listset_app_node_mem(X) ((X)->flags |= LINKLIST_FLAG_NODE_MEM_BY_APP)
+#define listnode_init(X, val) ((X)->data = (val))
 
 /*
  * Create a new linked list.
@@ -95,7 +105,7 @@ extern struct listnode *listnode_add(struct list *list, void *data);
  *    list to operate on
  *
  * data
- *    element to add
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  */
 extern void listnode_add_head(struct list *list, void *data);
 
@@ -112,7 +122,7 @@ extern void listnode_add_head(struct list *list, void *data);
  *    list to operate on
  *
  * val
- *    element to add
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  */
 extern void listnode_add_sort(struct list *list, void *val);
 
@@ -128,7 +138,7 @@ extern void listnode_add_sort(struct list *list, void *val);
  *    listnode to insert after
  *
  * data
- *    data to insert
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  *
  * Returns:
  *    pointer to newly created listnode that contains the inserted data
@@ -148,7 +158,7 @@ extern struct listnode *listnode_add_after(struct list *list,
  *    listnode to insert before
  *
  * data
- *    data to insert
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  *
  * Returns:
  *    pointer to newly created listnode that contains the inserted data
@@ -313,7 +323,7 @@ extern void list_filter_out_nodes(struct list *list, bool (*cond)(void *data));
  *    list to operate on
  *
  * val
- *    element to add
+ *    If MEM_BY_APP is set this is listnode. Otherwise it is element to add.
  */
 
 extern bool listnode_add_sort_nodup(struct list *list, void *val);