diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c
index 6dd1780a5885ddadddafe2efddc273dbba440908..41269ad84d169800af81371d168d7d8a4073d5a3 100644
--- a/drivers/parisc/sba_iommu.c
+++ b/drivers/parisc/sba_iommu.c
@@ -1063,7 +1063,7 @@ sba_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
 	spin_unlock_irqrestore(&ioc->res_lock, flags);
 #endif
 
-	while (sg_dma_len(sglist) && nents--) {
+	while (nents && sg_dma_len(sglist)) {
 
 		sba_unmap_page(dev, sg_dma_address(sglist), sg_dma_len(sglist),
 				direction, 0);
@@ -1072,6 +1072,7 @@ sba_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
 		ioc->usingle_calls--;	/* kluge since call is unmap_sg() */
 #endif
 		++sglist;
+		nents--;
 	}
 
 	DBG_RUN_SG("%s() DONE (nents %d)\n", __func__,  nents);