Index: dev/ata/ata-disk.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/ata/ata-disk.c,v
retrieving revision 1.60.2.27
diff -u -r1.60.2.27 ata-disk.c
--- dev/ata/ata-disk.c	5 Sep 2003 18:27:38 -0000	1.60.2.27
+++ dev/ata/ata-disk.c	21 Oct 2003 13:15:27 -0000
@@ -521,8 +521,16 @@
 	    }
 
 	    /* start transfer, return and wait for interrupt */
-	    ata_dmastart(adp->device, request->data, request->bytecount,
+	    ret = ata_dmastart(adp->device, request->data, request->bytecount,
 			 request->flags & ADR_F_READ);
+	    /*
+	     * another transfer is already active, bail out.
+	     */
+	    if (ret == EINPROGRESS) {
+		    ata_prtdev(adp->device, "transfer active on this device!");
+		    goto transfer_failed;
+	    }
+
 	    return ATA_OP_CONTINUES;
 	}
 
Index: dev/ata/ata-dma.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/ata/ata-dma.c,v
retrieving revision 1.35.2.33
diff -u -r1.35.2.33 ata-dma.c
--- dev/ata/ata-dma.c	5 Sep 2003 07:29:10 -0000	1.35.2.33
+++ dev/ata/ata-dma.c	21 Oct 2003 13:15:27 -0000
@@ -128,6 +128,7 @@
     struct ata_dmastate *ds;
 
     ds = &atadev->dmastate;
+    ds->flags = 0;
     if (ds->mdmatab) {
 	bus_dmamap_unload(ds->cdmatag, ds->cdmamap);
 	bus_dmamem_free(ds->cdmatag, ds->dmatab, ds->cdmamap);
@@ -1369,9 +1370,12 @@
     struct ata_channel *ch = atadev->channel;
     struct ata_dmastate *ds = &atadev->dmastate;
     struct ata_dmasetup_data_cb_args cba;
-
+#if 0
     if (ds->flags & ATA_DS_ACTIVE)
 	    panic("ata_dmasetup: transfer active on this device!");
+#endif
+    if (ds->flags & ATA_DS_ACTIVE)
+	    return EINPROGRESS;
 
     cba.dmatab = ds->dmatab;
     bus_dmamap_sync(ds->cdmatag, ds->cdmamap, BUS_DMASYNC_PREWRITE);