Use atomic operations to increment and decrement the refcount

in busdma tags.  There are currently no tags shared accross
different drivers so this isn't needed at the moment, but it
will be required when we'll have a proper newbus method to get
the parent busdma tag.

1 files changed, 4 insertions, 4 deletions

diff --git a/sys/alpha/alpha/busdma_machdep.c b/sys/alpha/alpha/busdma_machdep.c
index 2075053..0b9ed6d 100644
--- a/sys/alpha/alpha/busdma_machdep.c
+++ b/sys/alpha/alpha/busdma_machdep.c
@@ -42,6 +42,7 @@
 #include <vm/vm_page.h>
 #include <vm/vm_map.h>
 
+#include <machine/atomic.h>
 #include <machine/bus.h>
 #include <machine/sgmap.h>
 #include <machine/md_var.h>
@@ -179,9 +180,8 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 			newtag->filterarg = parent->filterarg;
 			newtag->parent = parent->parent;
 		}
-		if (newtag->parent != NULL) {
-			parent->ref_count++;
-		}
+		if (newtag->parent != NULL)
+			atomic_add_int(&parent->ref_count, 1);
 	}
 	
 	if (newtag->lowaddr < ptoa(Maxmem) && (flags & BUS_DMA_ALLOCNOW) != 0) {
@@ -228,7 +228,7 @@ bus_dma_tag_destroy(bus_dma_tag_t dmat)
 			bus_dma_tag_t parent;
 
 			parent = dmat->parent;
-			dmat->ref_count--;
+			atomic_subtract_int(&dmat->ref_count, 1);
 			if (dmat->ref_count == 0) {
 				free(dmat, M_DEVBUF);
 			}