Check the return values of contigmalloc(9) as well as bus_dma(9)

functions and stop attaching of dcons(4) and dcons_crom(4) if
they indicate failure. This fixes a panic seen on sparc64 machines
with no free physical memory in the requested 32-bit region but
still doesn't make dcons(4)/dcons_crom(4) these work. I think
the latter can be fixed by simply specifying ~0UL as the upper
limit for contigmalloc(9) and letting the bounce pages and the
IOMMU respectively handle limitations of the DMA engine. I didn't
want to change that without the consensus of simokawa@ though,
who unfortunately didn't reply so far.

MFC after:	1 week

1 files changed, 12 insertions, 3 deletions

diff --git a/sys/dev/dcons/dcons_crom.c b/sys/dev/dcons/dcons_crom.c
index 0b2b707..ee263e9 100644
--- a/sys/dev/dcons/dcons_crom.c
+++ b/sys/dev/dcons/dcons_crom.c
@@ -205,7 +205,10 @@ dcons_crom_attach(device_t dev)
 	return (-1);
 #else
 	struct dcons_crom_softc *sc;
+	int error;
 
+	if (dcons_conf->buf == NULL)
+		return (ENXIO);
         sc = (struct dcons_crom_softc *) device_get_softc(dev);
 	sc->fd.fc = device_get_ivars(dev);
 	sc->fd.dev = dev;
@@ -213,7 +216,7 @@ dcons_crom_attach(device_t dev)
 	sc->fd.post_busreset = (void *) dcons_crom_post_busreset;
 
 	/* map dcons buffer */
-	bus_dma_tag_create(
+	error = bus_dma_tag_create(
 		/*parent*/ sc->fd.fc->dmat,
 		/*alignment*/ sizeof(u_int32_t),
 		/*boundary*/ 0,
@@ -229,10 +232,16 @@ dcons_crom_attach(device_t dev)
 		/*lockarg*/&Giant,
 #endif
 		&sc->dma_tag);
-	bus_dmamap_create(sc->dma_tag, BUS_DMA_COHERENT, &sc->dma_map);
-	bus_dmamap_load(sc->dma_tag, sc->dma_map,
+	if (error != 0)
+		return (error);
+	error = bus_dmamap_create(sc->dma_tag, BUS_DMA_COHERENT, &sc->dma_map);
+	if (error != 0)
+		return (error);
+	error = bus_dmamap_load(sc->dma_tag, sc->dma_map,
 	    (void *)dcons_conf->buf, dcons_conf->size,
 	    dmamap_cb, sc, 0);
+	if (error != 0)
+		return (error);
 	sc->ehand = EVENTHANDLER_REGISTER(dcons_poll, dcons_crom_poll,
 			 (void *)sc, 0);
 	return (0);