From b306cab8be88ff4ac7c1280ceee66dfbaa0ec239 Mon Sep 17 00:00:00 2001
From: likewise <likewise>
Date: Fri, 6 Jun 2003 08:34:37 +0000
Subject: [PATCH] Additional documentation on the subtle difference of a 'pbuf
 chain' and a 'packet queue'.

---
 src/core/pbuf.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/core/pbuf.c b/src/core/pbuf.c
index d57d7721..cc9019c7 100644
--- a/src/core/pbuf.c
+++ b/src/core/pbuf.c
@@ -13,11 +13,18 @@
  * Multiple packets may be queued, also using this singly linked list.
  * This is called a "packet queue". So, a packet queue consists of one
  * or more pbuf chains, each of which consist of one or more pbufs.
+ * The differences between a pbuf chain and a packet queue are very
+ * subtle. Currently, queues are only supported in a limited section
+ * of lwIP, this is the etharp queueing code. Outside of this section
+ * no packet queues are supported as of yet.
  *
  * The last pbuf of a packet has a ->tot_len field that equals the
  * ->len field. It can be found by traversing the list. If the last
  * pbuf of a packet has a ->next field other than NULL, more packets
  * are on the queue.
+ *
+ * Therefore, looping through a pbuf of a single packet, has an
+ * loop end condition (tot_len == p->len), NOT (next == NULL).
  */
 
 /*