diff --git a/drivers/xen/xen-pciback/conf_space.c b/drivers/xen/xen-pciback/conf_space.c
index 6855bf552126..9e9286d0872e 100644
--- a/drivers/xen/xen-pciback/conf_space.c
+++ b/drivers/xen/xen-pciback/conf_space.c
@@ -148,7 +148,7 @@ int xen_pcibk_config_read(struct pci_dev *dev, int offset, int size,
 	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 	const struct config_field_entry *cfg_entry;
 	const struct config_field *field;
-	int req_start, req_end, field_start, field_end;
+	int field_start, field_end;
 	/* if read fails for any reason, return 0
 	 * (as if device didn't respond) */
 	u32 value = 0, tmp_val;
@@ -178,12 +178,10 @@ int xen_pcibk_config_read(struct pci_dev *dev, int offset, int size,
 	list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
 		field = cfg_entry->field;
 
-		req_start = offset;
-		req_end = offset + size;
 		field_start = OFFSET(cfg_entry);
 		field_end = OFFSET(cfg_entry) + field->size;
 
-		 if (req_end > field_start && field_end > req_start) {
+		if (offset + size > field_start && field_end > offset) {
 			err = conf_space_read(dev, cfg_entry, field_start,
 					      &tmp_val);
 			if (err)
@@ -191,7 +189,7 @@ int xen_pcibk_config_read(struct pci_dev *dev, int offset, int size,
 
 			value = merge_value(value, tmp_val,
 					    get_mask(field->size),
-					    field_start - req_start);
+					    field_start - offset);
 		}
 	}
 
@@ -211,7 +209,7 @@ int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
 	const struct config_field_entry *cfg_entry;
 	const struct config_field *field;
 	u32 tmp_val;
-	int req_start, req_end, field_start, field_end;
+	int field_start, field_end;
 
 	if (unlikely(verbose_request))
 		printk(KERN_DEBUG
@@ -224,19 +222,17 @@ int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
 	list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
 		field = cfg_entry->field;
 
-		req_start = offset;
-		req_end = offset + size;
 		field_start = OFFSET(cfg_entry);
 		field_end = OFFSET(cfg_entry) + field->size;
 
-		 if (req_end > field_start && field_end > req_start) {
+		if (offset + size > field_start && field_end > offset) {
 			err = conf_space_read(dev, cfg_entry, field_start,
 					      &tmp_val);
 			if (err)
 				break;
 
 			tmp_val = merge_value(tmp_val, value, get_mask(size),
-					      req_start - field_start);
+					      offset - field_start);
 
 			err = conf_space_write(dev, cfg_entry, field_start,
 					       tmp_val);