diff --git a/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c b/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
index f630d4bf71..fab1ea6bc3 100644
--- a/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
+++ b/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
@@ -191,12 +191,13 @@ static int increase_reservation(unsigned long nr_pages)
 	rc = HYPERVISOR_memory_op(
 		XENMEM_increase_reservation, &reservation);
 	if (rc < nr_pages) {
+		int ret;
 		/* We hit the Xen hard limit: reprobe. */
 		reservation.extent_start = mfn_list;
 		reservation.nr_extents   = rc;
-		BUG_ON(HYPERVISOR_memory_op(
-			XENMEM_decrease_reservation,
-			&reservation) != rc);
+		ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
+				&reservation);
+		BUG_ON(ret != rc);
 		hard_limit = current_pages + rc - driver_pages;
 		goto out;
 	}
@@ -213,11 +214,14 @@ static int increase_reservation(unsigned long nr_pages)
 		xen_machphys_update(mfn_list[i], pfn);
             
 		/* Link back into the page tables if not highmem. */
-		if (pfn < max_low_pfn)
-			BUG_ON(HYPERVISOR_update_va_mapping(
+		if (pfn < max_low_pfn) {
+			int ret;
+			ret = HYPERVISOR_update_va_mapping(
 				(unsigned long)__va(pfn << PAGE_SHIFT),
 				pfn_pte_ma(mfn_list[i], PAGE_KERNEL),
-				0));
+				0);
+			BUG_ON(ret);
+		}
 
 		/* Relinquish the page back to the allocator. */
 		ClearPageReserved(page);
@@ -242,6 +246,7 @@ static int decrease_reservation(unsigned long nr_pages)
 	struct page   *page;
 	void          *v;
 	int            need_sleep = 0;
+	int ret;
 	struct xen_memory_reservation reservation = {
 		.address_bits = 0,
 		.extent_order = 0,
@@ -268,8 +273,9 @@ static int decrease_reservation(unsigned long nr_pages)
 		if (!PageHighMem(page)) {
 			v = phys_to_virt(pfn << PAGE_SHIFT);
 			scrub_pages(v, 1);
-			BUG_ON(HYPERVISOR_update_va_mapping(
-				(unsigned long)v, __pte_ma(0), 0));
+			ret = HYPERVISOR_update_va_mapping(
+				(unsigned long)v, __pte_ma(0), 0);
+			BUG_ON(ret);
 		}
 #ifdef CONFIG_XEN_SCRUB_PAGES
 		else {
@@ -295,8 +301,8 @@ static int decrease_reservation(unsigned long nr_pages)
 
 	reservation.extent_start = mfn_list;
 	reservation.nr_extents   = nr_pages;
-	BUG_ON(HYPERVISOR_memory_op(
-		XENMEM_decrease_reservation, &reservation) != nr_pages);
+	ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+	BUG_ON(ret != nr_pages);
 
 	current_pages -= nr_pages;
 	totalram_pages = current_pages;
@@ -501,6 +507,7 @@ static int dealloc_pte_fn(
 	pte_t *pte, struct page *pte_page, unsigned long addr, void *data)
 {
 	unsigned long mfn = pte_mfn(*pte);
+	int ret;
 	struct xen_memory_reservation reservation = {
 		.extent_start = &mfn,
 		.nr_extents   = 1,
@@ -510,8 +517,8 @@ static int dealloc_pte_fn(
 	set_pte_at(&init_mm, addr, pte, __pte_ma(0));
 	phys_to_machine_mapping[__pa(addr) >> PAGE_SHIFT] =
 		INVALID_P2M_ENTRY;
-	BUG_ON(HYPERVISOR_memory_op(
-		XENMEM_decrease_reservation, &reservation) != 1);
+	ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+	BUG_ON(ret != 1);
 	return 0;
 }
 
@@ -519,6 +526,7 @@ struct page *balloon_alloc_empty_page_range(unsigned long nr_pages)
 {
 	unsigned long vstart, flags;
 	unsigned int  order = get_order(nr_pages * PAGE_SIZE);
+	int ret;
 
 	vstart = __get_free_pages(GFP_KERNEL, order);
 	if (vstart == 0)
@@ -527,8 +535,9 @@ struct page *balloon_alloc_empty_page_range(unsigned long nr_pages)
 	scrub_pages(vstart, 1 << order);
 
 	balloon_lock(flags);
-	BUG_ON(generic_page_range(
-		&init_mm, vstart, PAGE_SIZE << order, dealloc_pte_fn, NULL));
+	ret = generic_page_range(
+		&init_mm, vstart, PAGE_SIZE << order, dealloc_pte_fn, NULL);
+	BUG_ON(ret);
 	current_pages -= 1UL << order;
 	balloon_unlock(flags);
 
diff --git a/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c b/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
index c9d812695e..3dc929f0a7 100644
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
@@ -108,6 +108,7 @@ static void fast_flush_area(int idx, int nr_pages)
 	struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 	unsigned int i, invcount = 0;
 	u16 handle;
+	int ret;
 
 	for (i = 0; i < nr_pages; i++) {
 		handle = pending_handle(idx, i);
@@ -120,8 +121,9 @@ static void fast_flush_area(int idx, int nr_pages)
 		invcount++;
 	}
 
-	BUG_ON(HYPERVISOR_grant_table_op(
-		GNTTABOP_unmap_grant_ref, unmap, invcount));
+	ret = HYPERVISOR_grant_table_op(
+		GNTTABOP_unmap_grant_ref, unmap, invcount);
+	BUG_ON(ret);
 }
 
 
@@ -338,6 +340,7 @@ static void dispatch_rw_block_io(blkif_t *blkif, blkif_request_t *req)
 	struct bio *bio = NULL, *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 	int nbio = 0;
 	request_queue_t *q;
+	int ret;
 
 	/* Check that number of segments is sane. */
 	nseg = req->nr_segments;
@@ -367,8 +370,8 @@ static void dispatch_rw_block_io(blkif_t *blkif, blkif_request_t *req)
 			map[i].flags |= GNTMAP_readonly;
 	}
 
-	BUG_ON(HYPERVISOR_grant_table_op(
-		GNTTABOP_map_grant_ref, map, nseg));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg);
+	BUG_ON(ret);
 
 	for (i = 0; i < nseg; i++) {
 		if (unlikely(map[i].handle < 0)) {
@@ -493,6 +496,7 @@ static int __init blkif_init(void)
 {
 	int i;
 	struct page *page;
+	int ret;
 
 	blkif_interface_init();
 
@@ -509,7 +513,8 @@ static int __init blkif_init(void)
 	spin_lock_init(&blkio_schedule_list_lock);
 	INIT_LIST_HEAD(&blkio_schedule_list);
 
-	BUG_ON(kernel_thread(blkio_schedule, 0, CLONE_FS | CLONE_FILES) < 0);
+	ret = kernel_thread(blkio_schedule, 0, CLONE_FS | CLONE_FILES);
+	BUG_ON(ret < 0);
 
 	blkif_xenbus_init();
 
diff --git a/linux-2.6-xen-sparse/drivers/xen/blkback/interface.c b/linux-2.6-xen-sparse/drivers/xen/blkback/interface.c
index ee1889a09a..be6f935191 100644
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/interface.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/interface.c
@@ -31,6 +31,7 @@ blkif_t *alloc_blkif(domid_t domid)
 static int map_frontend_page(blkif_t *blkif, unsigned long shared_page)
 {
 	struct gnttab_map_grant_ref op;
+	int ret;
 
 	op.host_addr = (unsigned long)blkif->blk_ring_area->addr;
 	op.flags     = GNTMAP_host_map;
@@ -38,8 +39,9 @@ static int map_frontend_page(blkif_t *blkif, unsigned long shared_page)
 	op.dom       = blkif->domid;
 
 	lock_vm_area(blkif->blk_ring_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
 	unlock_vm_area(blkif->blk_ring_area);
+	BUG_ON(ret);
 
 	if (op.handle < 0) {
 		DPRINTK(" Grant table operation failure !\n");
@@ -55,14 +57,16 @@ static int map_frontend_page(blkif_t *blkif, unsigned long shared_page)
 static void unmap_frontend_page(blkif_t *blkif)
 {
 	struct gnttab_unmap_grant_ref op;
+	int ret;
 
 	op.host_addr    = (unsigned long)blkif->blk_ring_area->addr;
 	op.handle       = blkif->shmem_handle;
 	op.dev_bus_addr = 0;
 
 	lock_vm_area(blkif->blk_ring_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1);
 	unlock_vm_area(blkif->blk_ring_area);
+	BUG_ON(ret);
 }
 
 int blkif_map(blkif_t *blkif, unsigned long shared_page, unsigned int evtchn)
diff --git a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
index 671f16038c..3485d84424 100644
--- a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
@@ -305,6 +305,7 @@ static irqreturn_t blkif_int(int irq, void *dev_id, struct pt_regs *ptregs)
 
 	for (i = info->ring.rsp_cons; i != rp; i++) {
 		unsigned long id;
+		int ret;
 
 		bret = RING_GET_RESPONSE(&info->ring, i);
 		id   = bret->id;
@@ -321,9 +322,10 @@ static irqreturn_t blkif_int(int irq, void *dev_id, struct pt_regs *ptregs)
 				DPRINTK("Bad return from blkdev data "
 					"request: %x\n", bret->status);
 
-			BUG_ON(end_that_request_first(
+			ret = end_that_request_first(
 				req, (bret->status == BLKIF_RSP_OKAY),
-				req->hard_nr_sectors));
+				req->hard_nr_sectors);
+			BUG_ON(ret);
 			end_that_request_last(req);
 			break;
 		default:
diff --git a/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c b/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c
index dacedfc227..03a4fcb970 100644
--- a/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c
@@ -413,6 +413,7 @@ static void fast_flush_area(int idx, int nr_pages)
 	unsigned int i, op = 0;
 	struct grant_handle_pair *handle;
 	unsigned long ptep;
+	int ret;
 
 	for ( i = 0; i < nr_pages; i++)
 	{
@@ -440,8 +441,8 @@ static void fast_flush_area(int idx, int nr_pages)
 		BLKTAP_INVALIDATE_HANDLE(handle);
 	}
 
-	BUG_ON(HYPERVISOR_grant_table_op(
-		GNTTABOP_unmap_grant_ref, unmap, op));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, op);
+	BUG_ON(ret);
 
 	if (blktap_vma != NULL)
 		zap_page_range(blktap_vma, 
@@ -673,6 +674,7 @@ static void dispatch_rw_block_io(blkif_t *blkif, blkif_request_t *req)
 	struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST*2];
 	int op, ret;
 	unsigned int nseg;
+	int retval;
 
 	/* Check that number of segments is sane. */
 	nseg = req->nr_segments;
@@ -740,8 +742,8 @@ static void dispatch_rw_block_io(blkif_t *blkif, blkif_request_t *req)
 		op++;
 	}
 
-	BUG_ON(HYPERVISOR_grant_table_op(
-		GNTTABOP_map_grant_ref, map, op));
+	retval = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, op);
+	BUG_ON(retval);
 
 	op = 0;
 	for (i = 0; i < (req->nr_segments*2); i += 2) {
@@ -877,7 +879,8 @@ static int __init blkif_init(void)
 	spin_lock_init(&blkio_schedule_list_lock);
 	INIT_LIST_HEAD(&blkio_schedule_list);
 
-	BUG_ON(kernel_thread(blkio_schedule, 0, CLONE_FS | CLONE_FILES) < 0);
+	i = kernel_thread(blkio_schedule, 0, CLONE_FS | CLONE_FILES);
+	BUG_ON(i<0);
 
 	blkif_xenbus_init();
 
diff --git a/linux-2.6-xen-sparse/drivers/xen/blktap/interface.c b/linux-2.6-xen-sparse/drivers/xen/blktap/interface.c
index 1394922ac7..dcaedf875e 100644
--- a/linux-2.6-xen-sparse/drivers/xen/blktap/interface.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blktap/interface.c
@@ -31,6 +31,7 @@ blkif_t *alloc_blkif(domid_t domid)
 static int map_frontend_page(blkif_t *blkif, unsigned long shared_page)
 {
 	struct gnttab_map_grant_ref op;
+	int ret;
 
 	op.host_addr = (unsigned long)blkif->blk_ring_area->addr;
 	op.flags     = GNTMAP_host_map;
@@ -38,8 +39,9 @@ static int map_frontend_page(blkif_t *blkif, unsigned long shared_page)
 	op.dom       = blkif->domid;
 
 	lock_vm_area(blkif->blk_ring_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
 	unlock_vm_area(blkif->blk_ring_area);
+	BUG_ON(ret);
 
 	if (op.handle < 0) {
 		DPRINTK(" Grant table operation failure !\n");
@@ -55,14 +57,16 @@ static int map_frontend_page(blkif_t *blkif, unsigned long shared_page)
 static void unmap_frontend_page(blkif_t *blkif)
 {
 	struct gnttab_unmap_grant_ref op;
+	int ret;
 
 	op.host_addr    = (unsigned long)blkif->blk_ring_area->addr;
 	op.handle       = blkif->shmem_handle;
 	op.dev_bus_addr = 0;
 
 	lock_vm_area(blkif->blk_ring_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1);
 	unlock_vm_area(blkif->blk_ring_area);
+	BUG_ON(ret);
 }
 
 int blkif_map(blkif_t *blkif, unsigned long shared_page, unsigned int evtchn)
diff --git a/linux-2.6-xen-sparse/drivers/xen/evtchn/evtchn.c b/linux-2.6-xen-sparse/drivers/xen/evtchn/evtchn.c
index d3a805fb72..42f4a8f70a 100644
--- a/linux-2.6-xen-sparse/drivers/xen/evtchn/evtchn.c
+++ b/linux-2.6-xen-sparse/drivers/xen/evtchn/evtchn.c
@@ -282,6 +282,7 @@ static int evtchn_ioctl(struct inode *inode, struct file *file,
 
 	case IOCTL_EVTCHN_UNBIND: {
 		struct ioctl_evtchn_unbind unbind;
+		int ret;
 
 		rc = -EFAULT;
 		if (copy_from_user(&unbind, (void *)arg, sizeof(unbind)))
@@ -306,7 +307,8 @@ static int evtchn_ioctl(struct inode *inode, struct file *file,
 
 		op.cmd = EVTCHNOP_close;
 		op.u.close.port = unbind.port;
-		BUG_ON(HYPERVISOR_event_channel_op(&op));
+		ret = HYPERVISOR_event_channel_op(&op);
+		BUG_ON(ret);
 
 		rc = 0;
 		break;
@@ -399,6 +401,7 @@ static int evtchn_release(struct inode *inode, struct file *filp)
 
 	for (i = 0; i < NR_EVENT_CHANNELS; i++)
 	{
+		int ret;
 		if (port_user[i] != u)
 			continue;
 
@@ -407,7 +410,8 @@ static int evtchn_release(struct inode *inode, struct file *filp)
 
 		op.cmd = EVTCHNOP_close;
 		op.u.close.port = i;
-		BUG_ON(HYPERVISOR_event_channel_op(&op));
+		ret = HYPERVISOR_event_channel_op(&op);
+		BUG_ON(ret);
 	}
 
 	spin_unlock_irq(&port_user_lock);
diff --git a/linux-2.6-xen-sparse/drivers/xen/netback/interface.c b/linux-2.6-xen-sparse/drivers/xen/netback/interface.c
index 404eb98831..7cfd3c944c 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/interface.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/interface.c
@@ -115,6 +115,7 @@ static int map_frontend_pages(
 	netif_t *netif, grant_ref_t tx_ring_ref, grant_ref_t rx_ring_ref)
 {
 	struct gnttab_map_grant_ref op;
+	int ret;
 
 	op.host_addr = (unsigned long)netif->comms_area->addr;
 	op.flags     = GNTMAP_host_map;
@@ -122,8 +123,9 @@ static int map_frontend_pages(
 	op.dom       = netif->domid;
     
 	lock_vm_area(netif->comms_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
 	unlock_vm_area(netif->comms_area);
+	BUG_ON(ret);
 
 	if (op.handle < 0) { 
 		DPRINTK(" Gnttab failure mapping tx_ring_ref!\n");
@@ -139,8 +141,9 @@ static int map_frontend_pages(
 	op.dom       = netif->domid;
 
 	lock_vm_area(netif->comms_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
 	unlock_vm_area(netif->comms_area);
+	BUG_ON(ret);
 
 	if (op.handle < 0) { 
 		DPRINTK(" Gnttab failure mapping rx_ring_ref!\n");
@@ -156,22 +159,25 @@ static int map_frontend_pages(
 static void unmap_frontend_pages(netif_t *netif)
 {
 	struct gnttab_unmap_grant_ref op;
+	int ret;
 
 	op.host_addr    = (unsigned long)netif->comms_area->addr;
 	op.handle       = netif->tx_shmem_handle;
 	op.dev_bus_addr = 0;
 
 	lock_vm_area(netif->comms_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1);
 	unlock_vm_area(netif->comms_area);
+	BUG_ON(ret);
 
 	op.host_addr    = (unsigned long)netif->comms_area->addr + PAGE_SIZE;
 	op.handle       = netif->rx_shmem_handle;
 	op.dev_bus_addr = 0;
 
 	lock_vm_area(netif->comms_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1);
 	unlock_vm_area(netif->comms_area);
+	BUG_ON(ret);
 }
 
 int netif_map(netif_t *netif, unsigned long tx_ring_ref,
diff --git a/linux-2.6-xen-sparse/drivers/xen/netback/netback.c b/linux-2.6-xen-sparse/drivers/xen/netback/netback.c
index 656ed94ded..2eee002ec6 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/netback.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/netback.c
@@ -112,9 +112,12 @@ static void free_mfn(unsigned long mfn)
 	spin_lock_irqsave(&mfn_lock, flags);
 	if ( alloc_index != MAX_MFN_ALLOC )
 		mfn_list[alloc_index++] = mfn;
-	else
-		BUG_ON(HYPERVISOR_memory_op(XENMEM_decrease_reservation,
-					    &reservation) != 1);
+	else {
+		int ret;
+		ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
+					    &reservation);
+		BUG_ON(ret != 1);
+	}
 	spin_unlock_irqrestore(&mfn_lock, flags);
 }
 #endif
@@ -159,13 +162,15 @@ int netif_be_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	 */
 	if (skb_shared(skb) || skb_cloned(skb) || !is_xen_skb(skb)) {
 		int hlen = skb->data - skb->head;
+		int ret;
 		struct sk_buff *nskb = dev_alloc_skb(hlen + skb->len);
 		if ( unlikely(nskb == NULL) )
 			goto drop;
 		skb_reserve(nskb, hlen);
 		__skb_put(nskb, skb->len);
-		BUG_ON(skb_copy_bits(skb, -hlen, nskb->data - hlen,
-				     skb->len + hlen));
+		ret = skb_copy_bits(skb, -hlen, nskb->data - hlen,
+				     skb->len + hlen);
+		BUG_ON(ret);
 		nskb->dev = skb->dev;
 		nskb->proto_csum_valid = skb->proto_csum_valid;
 		dev_kfree_skb(skb);
@@ -218,6 +223,7 @@ static void net_rx_action(unsigned long unused)
 	struct sk_buff *skb;
 	u16 notify_list[NETIF_RX_RING_SIZE];
 	int notify_nr = 0;
+	int ret;
 
 	skb_queue_head_init(&rxq);
 
@@ -279,7 +285,8 @@ static void net_rx_action(unsigned long unused)
 	mcl++;
 
 	mcl[-2].args[MULTI_UVMFLAGS_INDEX] = UVMF_TLB_FLUSH|UVMF_ALL;
-	BUG_ON(HYPERVISOR_multicall(rx_mcl, mcl - rx_mcl) != 0);
+	ret = HYPERVISOR_multicall(rx_mcl, mcl - rx_mcl);
+	BUG_ON(ret != 0);
 
 	mcl = rx_mcl;
 	if( HYPERVISOR_grant_table_op(GNTTABOP_transfer, grant_rx_op, 
@@ -421,6 +428,7 @@ inline static void net_tx_action_dealloc(void)
 	u16 pending_idx;
 	PEND_RING_IDX dc, dp;
 	netif_t *netif;
+	int ret;
 
 	dc = dealloc_cons;
 	dp = dealloc_prod;
@@ -436,8 +444,9 @@ inline static void net_tx_action_dealloc(void)
 		gop->handle       = grant_tx_ref[pending_idx];
 		gop++;
 	}
-	BUG_ON(HYPERVISOR_grant_table_op(
-		GNTTABOP_unmap_grant_ref, tx_unmap_ops, gop - tx_unmap_ops));
+	ret = HYPERVISOR_grant_table_op(
+		GNTTABOP_unmap_grant_ref, tx_unmap_ops, gop - tx_unmap_ops);
+	BUG_ON(ret);
 
 	while (dealloc_cons != dp) {
 		pending_idx = dealloc_ring[MASK_PEND_IDX(dealloc_cons++)];
@@ -477,6 +486,7 @@ static void net_tx_action(unsigned long unused)
 	NETIF_RING_IDX i;
 	gnttab_map_grant_ref_t *mop;
 	unsigned int data_len;
+	int ret;
 
 	if (dealloc_cons != dealloc_prod)
 		net_tx_action_dealloc();
@@ -599,8 +609,9 @@ static void net_tx_action(unsigned long unused)
 	if (mop == tx_map_ops)
 		return;
 
-	BUG_ON(HYPERVISOR_grant_table_op(
-		GNTTABOP_map_grant_ref, tx_map_ops, mop - tx_map_ops));
+	ret = HYPERVISOR_grant_table_op(
+		GNTTABOP_map_grant_ref, tx_map_ops, mop - tx_map_ops);
+	BUG_ON(ret);
 
 	mop = tx_map_ops;
 	while ((skb = __skb_dequeue(&tx_queue)) != NULL) {
diff --git a/linux-2.6-xen-sparse/drivers/xen/tpmback/interface.c b/linux-2.6-xen-sparse/drivers/xen/tpmback/interface.c
index 98db181306..6dc05d217b 100644
--- a/linux-2.6-xen-sparse/drivers/xen/tpmback/interface.c
+++ b/linux-2.6-xen-sparse/drivers/xen/tpmback/interface.c
@@ -78,6 +78,7 @@ tpmif_find(domid_t domid, long int instance)
 static int
 map_frontend_page(tpmif_t *tpmif, unsigned long shared_page)
 {
+	int ret;
 	struct gnttab_map_grant_ref op = {
 		.host_addr = (unsigned long)tpmif->tx_area->addr,
 		.flags = GNTMAP_host_map,
@@ -86,8 +87,9 @@ map_frontend_page(tpmif_t *tpmif, unsigned long shared_page)
 	};
 
 	lock_vm_area(tpmif->tx_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
 	unlock_vm_area(tpmif->tx_area);
+	BUG_ON(ret);
 
 	if (op.handle < 0) {
 		DPRINTK(" Grant table operation failure !\n");
@@ -104,14 +106,16 @@ static void
 unmap_frontend_page(tpmif_t *tpmif)
 {
 	struct gnttab_unmap_grant_ref op;
+	int ret;
 
 	op.host_addr    = (unsigned long)tpmif->tx_area->addr;
 	op.handle       = tpmif->shmem_handle;
 	op.dev_bus_addr = 0;
 
 	lock_vm_area(tpmif->tx_area);
-	BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1);
 	unlock_vm_area(tpmif->tx_area);
+	BUG_ON(ret);
 }
 
 int
diff --git a/linux-2.6-xen-sparse/drivers/xen/util.c b/linux-2.6-xen-sparse/drivers/xen/util.c
index 8df067f29e..be2b155cf1 100644
--- a/linux-2.6-xen-sparse/drivers/xen/util.c
+++ b/linux-2.6-xen-sparse/drivers/xen/util.c
@@ -34,7 +34,9 @@ struct vm_struct *alloc_vm_area(unsigned long size)
 
 void free_vm_area(struct vm_struct *area)
 {
-	BUG_ON(remove_vm_area(area->addr) != area);
+	struct vm_struct *ret;
+	ret = remove_vm_area(area->addr);
+	BUG_ON(ret != area);
 	kfree(area);
 }
 
diff --git a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
index e5c9de1139..c3d349b385 100644
--- a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
+++ b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
@@ -737,6 +737,7 @@ static int __init xenbus_probe_init(void)
 
 		unsigned long page;
 		evtchn_op_t op = { 0 };
+		int ret;
 
 
 		/* Allocate page. */
@@ -757,7 +758,8 @@ static int __init xenbus_probe_init(void)
 		op.u.alloc_unbound.dom        = DOMID_SELF;
 		op.u.alloc_unbound.remote_dom = 0; 
 
-		BUG_ON(HYPERVISOR_event_channel_op(&op)); 
+		ret = HYPERVISOR_event_channel_op(&op);
+		BUG_ON(ret); 
 		xen_start_info->store_evtchn = op.u.alloc_unbound.port;
 
 		/* And finally publish the above info in /proc/xen */