Index: src/sys/pci/if_xl.c
===================================================================
RCS file: /home/ncvs/src/sys/pci/if_xl.c,v
retrieving revision 1.130
diff -u -r1.130 if_xl.c
--- src/sys/pci/if_xl.c	22 Feb 2003 14:46:31 -0000	1.130
+++ src/sys/pci/if_xl.c	22 Feb 2003 16:48:06 -0000
@@ -2148,11 +2148,14 @@
 			break;
 
 		sc->xl_cdata.xl_tx_head = cur_tx->xl_next;
-		bus_dmamap_sync(sc->xl_mtag, cur_tx->xl_map,
-		    BUS_DMASYNC_POSTWRITE);
-		bus_dmamap_unload(sc->xl_mtag, cur_tx->xl_map);
-		m_freem(cur_tx->xl_mbuf);
-		cur_tx->xl_mbuf = NULL;
+		if (cur_tx->xl_mbuf != NULL) {
+			bus_dmamap_sync(sc->xl_mtag, cur_tx->xl_map
+			    BUS_DMASYNC_POSTWRITE);
+			bus_dmamap_unload(sc->xl_mtag, cur_tx->xl_map);
+			m_freem(cur_tx->xl_mbuf);
+			cur_tx->xl_mbuf = NULL;
+		}
+		
 		ifp->if_opackets++;
 
 		cur_tx->xl_next = sc->xl_cdata.xl_tx_free;