Fix several issues with the busdma(9) KPI use in the e1000 drivers.

The problems do not affect bouncing busdma in a visible way, but are
critical for the dmar backend.

- The bus_dmamap_create(9) is not documented to take BUS_DMA_NOWAIT flag.
- Unload descriptor map after receive.
- Do not reset descriptor map to NULL, bus_dmamap_load(9) requires
  valid map, and also this leaks the map.

Reported and tested by:	pho
Approved by:	jfv
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks

1 files changed, 2 insertions, 4 deletions

diff --git a/sys/dev/e1000/if_lem.c b/sys/dev/e1000/if_lem.c
index 676bf8fe1e85..1df8de951ab6 100644
--- a/sys/dev/e1000/if_lem.c
+++ b/sys/dev/e1000/if_lem.c
@@ -3183,8 +3183,7 @@ lem_allocate_receive_structures(struct adapter *adapter)
 	}
 
 	/* Create the spare map (used by getbuf) */
-	error = bus_dmamap_create(adapter->rxtag, BUS_DMA_NOWAIT,
-	     &adapter->rx_sparemap);
+	error = bus_dmamap_create(adapter->rxtag, 0, &adapter->rx_sparemap);
 	if (error) {
 		device_printf(dev, "%s: bus_dmamap_create failed: %d\n",
 		    __func__, error);
@@ -3193,8 +3192,7 @@ lem_allocate_receive_structures(struct adapter *adapter)
 
 	rx_buffer = adapter->rx_buffer_area;
 	for (i = 0; i < adapter->num_rx_desc; i++, rx_buffer++) {
-		error = bus_dmamap_create(adapter->rxtag, BUS_DMA_NOWAIT,
-		    &rx_buffer->map);
+		error = bus_dmamap_create(adapter->rxtag, 0, &rx_buffer->map);
 		if (error) {
 			device_printf(dev, "%s: bus_dmamap_create failed: %d\n",
 			    __func__, error);