tools/xenstore: add helpers to free struct buffered_data

Add two helpers for freeing struct buffered_data: free_buffered_data()
for freeing one instance and conn_free_buffered_data() for freeing all
instances for a connection.

This is avoiding duplicated code and will help later when more actions
are needed when freeing a struct buffered_data.

This is part of XSA-326.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
(cherry picked from commit ead062a68a)

tools/xenstore/xenstored_core.c

@@ -208,6 +208,21 @@ void reopen_log(void)
 	}
 }
 
+static void free_buffered_data(struct buffered_data *out,
+			       struct connection *conn)
+{
+	list_del(&out->list);
+	talloc_free(out);
+}
+
+void conn_free_buffered_data(struct connection *conn)
+{
+	struct buffered_data *out;
+
+	while ((out = list_top(&conn->out_list, struct buffered_data, list)))
+		free_buffered_data(out, conn);
+}
+
 static bool write_messages(struct connection *conn)
 {
 	int ret;
@@ -251,8 +266,7 @@ static bool write_messages(struct connection *conn)
 
 	trace_io(conn, out, 1);
 
-	list_del(&out->list);
-	talloc_free(out);
+	free_buffered_data(out, conn);
 
 	return true;
 }
@@ -1391,18 +1405,12 @@ static struct {
  */
 static void ignore_connection(struct connection *conn)
 {
-	struct buffered_data *out, *tmp;
-
 	trace("CONN %p ignored\n", conn);
 
 	conn->is_ignored = true;
 	conn_delete_all_watches(conn);
 	conn_delete_all_transactions(conn);
-
-	list_for_each_entry_safe(out, tmp, &conn->out_list, list) {
-		list_del(&out->list);
-		talloc_free(out);
-	}
+	conn_free_buffered_data(conn);
 
 	talloc_free(conn->in);
 	conn->in = NULL;

tools/xenstore/xenstored_core.h

@@ -226,6 +226,8 @@ extern xengnttab_handle **xgt_handle;
 
 int remember_string(struct hashtable *hash, const char *str);
 
+void conn_free_buffered_data(struct connection *conn);
+
 #endif /* _XENSTORED_CORE_H */
 
 /*

tools/xenstore/xenstored_domain.c

@@ -402,15 +402,10 @@ static struct domain *find_domain_by_domid(unsigned int domid)
 static void domain_conn_reset(struct domain *domain)
 {
 	struct connection *conn = domain->conn;
-	struct buffered_data *out;
 
 	conn_delete_all_watches(conn);
 	conn_delete_all_transactions(conn);
-
-	while ((out = list_top(&conn->out_list, struct buffered_data, list))) {
-		list_del(&out->list);
-		talloc_free(out);
-	}
+	conn_free_buffered_data(conn);
 
 	talloc_free(conn->in);