The bounce zone sees its page number increased if multiple dma maps use it in

the same dma tag. However, it can happen multiple dma tags share the same
bounce zone too, so add a per-bounce zone map counter, and check it instead of
the dma tag map counter, to know if we have to alloc more pages.

Reported by:	miwi
Reviewed by:	scottl

1 files changed, 6 insertions, 1 deletions

diff --git a/sys/i386/i386/busdma_machdep.c b/sys/i386/i386/busdma_machdep.c
index 04844f9..d4aa9b5 100644
--- a/sys/i386/i386/busdma_machdep.c
+++ b/sys/i386/i386/busdma_machdep.c
@@ -98,6 +98,7 @@ struct bounce_zone {
 	int		active_bpages;
 	int		total_bounced;
 	int		total_deferred;
+	int		map_count;
 	bus_size_t	alignment;
 	bus_size_t	boundary;
 	bus_addr_t	lowaddr;
@@ -431,7 +432,7 @@ bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
 		else
 			maxpages = MIN(MAX_BPAGES, Maxmem -atop(dmat->lowaddr));
 		if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
-		 || (dmat->map_count > 0 && bz->total_bpages < maxpages)) {
+		 || (bz->map_count > 0 && bz->total_bpages < maxpages)) {
 			int pages;
 
 			pages = MAX(atop(dmat->maxsize), 1);
@@ -447,6 +448,7 @@ bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
 				error = 0;
 			}
 		}
+		bz->map_count++;
 	} else {
 		*mapp = NULL;
 	}
@@ -470,6 +472,8 @@ bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
 			    __func__, dmat, EBUSY);
 			return (EBUSY);
 		}
+		if (dmat->bounce_zone)
+			dmat->bounce_zone->map_count--;
 		free(map, M_DEVBUF);
 	}
 	dmat->map_count--;
@@ -1007,6 +1011,7 @@ alloc_bounce_zone(bus_dma_tag_t dmat)
 	bz->lowaddr = dmat->lowaddr;
 	bz->alignment = dmat->alignment;
 	bz->boundary = dmat->boundary;
+	bz->map_count = 0;
 	snprintf(bz->zoneid, 8, "zone%d", busdma_zonecount);
 	busdma_zonecount++;
 	snprintf(bz->lowaddrid, 18, "%#jx", (uintmax_t)bz->lowaddr);