diff --git a/arch/sparc/include/asm/vio.h b/arch/sparc/include/asm/vio.h
index fb124feb363b..8174f6cdbbbb 100644
--- a/arch/sparc/include/asm/vio.h
+++ b/arch/sparc/include/asm/vio.h
@@ -300,6 +300,21 @@ static inline u32 vio_dring_avail(struct vio_dring_state *dr,
 		((dr->prod - dr->cons) & (ring_size - 1)) - 1);
 }
 
+static inline u32 vio_dring_next(struct vio_dring_state *dr, u32 index)
+{
+	if (++index == dr->num_entries)
+		index = 0;
+	return index;
+}
+
+static inline u32 vio_dring_prev(struct vio_dring_state *dr, u32 index)
+{
+	if (index == 0)
+		return dr->num_entries - 1;
+	else
+		return index - 1;
+}
+
 #define VIO_MAX_TYPE_LEN	32
 #define VIO_MAX_COMPAT_LEN	64
 
diff --git a/drivers/block/sunvdc.c b/drivers/block/sunvdc.c
index 089ff9035de6..65cec156cfb4 100644
--- a/drivers/block/sunvdc.c
+++ b/drivers/block/sunvdc.c
@@ -269,7 +269,7 @@ static void vdc_end_one(struct vdc_port *port, struct vio_dring_state *dr,
 
 	ldc_unmap(port->vio.lp, desc->cookies, desc->ncookies);
 	desc->hdr.state = VIO_DESC_FREE;
-	dr->cons = (index + 1) & (VDC_TX_RING_SIZE - 1);
+	dr->cons = vio_dring_next(dr, index);
 
 	req = rqe->req;
 	if (req == NULL) {
@@ -472,7 +472,7 @@ static int __send_request(struct request *req)
 		printk(KERN_ERR PFX "vdc_tx_trigger() failure, err=%d\n", err);
 	} else {
 		port->req_id++;
-		dr->prod = (dr->prod + 1) & (VDC_TX_RING_SIZE - 1);
+		dr->prod = vio_dring_next(dr, dr->prod);
 	}
 
 	return err;
@@ -626,7 +626,7 @@ static int generic_request(struct vdc_port *port, u8 op, void *buf, int len)
 	err = __vdc_tx_trigger(port);
 	if (err >= 0) {
 		port->req_id++;
-		dr->prod = (dr->prod + 1) & (VDC_TX_RING_SIZE - 1);
+		dr->prod = vio_dring_next(dr, dr->prod);
 		spin_unlock_irqrestore(&port->vio.lock, flags);
 
 		wait_for_completion(&comp.com);
diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c
index 90c86cd3be14..45c408ef67d0 100644
--- a/drivers/net/ethernet/sun/sunvnet.c
+++ b/drivers/net/ethernet/sun/sunvnet.c
@@ -466,23 +466,6 @@ static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr,
 	return err;
 }
 
-static u32 next_idx(u32 idx, struct vio_dring_state *dr)
-{
-	if (++idx == dr->num_entries)
-		idx = 0;
-	return idx;
-}
-
-static u32 prev_idx(u32 idx, struct vio_dring_state *dr)
-{
-	if (idx == 0)
-		idx = dr->num_entries - 1;
-	else
-		idx--;
-
-	return idx;
-}
-
 static struct vio_net_desc *get_rx_desc(struct vnet_port *port,
 					struct vio_dring_state *dr,
 					u32 index)
@@ -556,7 +539,8 @@ static int vnet_walk_rx(struct vnet_port *port, struct vio_dring_state *dr,
 	int ack_start = -1, ack_end = -1;
 	bool send_ack = true;
 
-	end = (end == (u32) -1) ? prev_idx(start, dr) : next_idx(end, dr);
+	end = (end == (u32) -1) ? vio_dring_prev(dr, start)
+				: vio_dring_next(dr, end);
 
 	viodbg(DATA, "vnet_walk_rx start[%08x] end[%08x]\n", start, end);
 
@@ -570,7 +554,7 @@ static int vnet_walk_rx(struct vnet_port *port, struct vio_dring_state *dr,
 		if (ack_start == -1)
 			ack_start = start;
 		ack_end = start;
-		start = next_idx(start, dr);
+		start = vio_dring_next(dr, start);
 		if (ack && start != end) {
 			err = vnet_send_ack(port, dr, ack_start, ack_end,
 					    VIO_DRING_ACTIVE);
@@ -584,7 +568,7 @@ static int vnet_walk_rx(struct vnet_port *port, struct vio_dring_state *dr,
 		}
 	}
 	if (unlikely(ack_start == -1))
-		ack_start = ack_end = prev_idx(start, dr);
+		ack_start = ack_end = vio_dring_prev(dr, start);
 	if (send_ack) {
 		port->napi_resume = false;
 		return vnet_send_ack(port, dr, ack_start, ack_end,
@@ -633,7 +617,7 @@ static int idx_is_pending(struct vio_dring_state *dr, u32 end)
 			found = 1;
 			break;
 		}
-		idx = next_idx(idx, dr);
+		idx = vio_dring_next(dr, idx);
 	}
 	return found;
 }
@@ -663,7 +647,7 @@ static int vnet_ack(struct vnet_port *port, void *msgbuf)
 	/* sync for race conditions with vnet_start_xmit() and tell xmit it
 	 * is time to send a trigger.
 	 */
-	dr->cons = next_idx(end, dr);
+	dr->cons = vio_dring_next(dr, end);
 	desc = vio_dring_entry(dr, dr->cons);
 	if (desc->hdr.state == VIO_DESC_READY && !port->start_cons) {
 		/* vnet_start_xmit() just populated this dring but missed
@@ -784,7 +768,7 @@ static int vnet_event_napi(struct vnet_port *port, int budget)
 			pkt->tag.stype = VIO_SUBTYPE_INFO;
 			pkt->tag.stype_env = VIO_DRING_DATA;
 			pkt->seq = dr->rcv_nxt;
-			pkt->start_idx = next_idx(port->napi_stop_idx, dr);
+			pkt->start_idx = vio_dring_next(dr, port->napi_stop_idx);
 			pkt->end_idx = -1;
 			goto napi_resume;
 		}