If the first list was empty, ml_join() did not not clear the second

list after transferring all elements away.  Reorder the conditionals
to make sure that ml_init() is always called for a non empty second
list.  This makes all cases consistent and is less surprising.
OK dlg@

diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
index 704bc98..a230b8e 100644 (file)
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: uipc_mbuf.c,v 1.203 2015/04/13 08:45:48 mpi Exp $     */
+/*     $OpenBSD: uipc_mbuf.c,v 1.204 2015/05/31 20:10:44 bluhm Exp $   */
 /*     $NetBSD: uipc_mbuf.c,v 1.15.4.1 1996/06/13 17:11:44 cgd Exp $   */
 
 /*
@@ -1266,10 +1266,11 @@ ml_enqueue(struct mbuf_list *ml, struct mbuf *m)
 void
 ml_join(struct mbuf_list *mla, struct mbuf_list *mlb)
 {
-       if (mla->ml_tail == NULL)
-               *mla = *mlb;
-       else if (mlb->ml_tail != NULL) {
-               mla->ml_tail->m_nextpkt = mlb->ml_head;
+       if (!ml_empty(mlb)) {
+               if (ml_empty(mla))
+                       mla->ml_head = mlb->ml_head;
+               else
+                       mla->ml_tail->m_nextpkt = mlb->ml_head;
                mla->ml_tail = mlb->ml_tail;
                mla->ml_len += mlb->ml_len;