net: mvpp2: fix refilling BM pools in RX path

In hitherto code in case of RX buffer allocation error during refill,
original buffer is pushed to the network stack, but the amount of
available buffer pointers in BM pool is decreased.

This commit fixes the situation by moving refill call before skb_put(),
and returning original buffer pointer to the pool in case of an error.
Signed-off-by: Marcin Wojtas <mw@semihalf.com>

Fixes: 3f518509 ("ethernet: Add new driver for Marvell Armada 375
network unit")

Cc: <stable@vger.kernel.org> # v3.18+
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvpp2.c

@@ -5099,7 +5099,8 @@ static int mvpp2_rx(struct mvpp2_port *port, int rx_todo,
 		    struct mvpp2_rx_queue *rxq)
 {
 	struct net_device *dev = port->dev;
-	int rx_received, rx_filled, i;
+	int rx_received;
+	int rx_done = 0;
 	u32 rcvd_pkts = 0;
 	u32 rcvd_bytes = 0;
 
@@ -5108,17 +5109,18 @@ static int mvpp2_rx(struct mvpp2_port *port, int rx_todo,
 	if (rx_todo > rx_received)
 		rx_todo = rx_received;
 
-	rx_filled = 0;
-	for (i = 0; i < rx_todo; i++) {
+	while (rx_done < rx_todo) {
 		struct mvpp2_rx_desc *rx_desc = mvpp2_rxq_next_desc_get(rxq);
 		struct mvpp2_bm_pool *bm_pool;
 		struct sk_buff *skb;
+		dma_addr_t phys_addr;
 		u32 bm, rx_status;
 		int pool, rx_bytes, err;
 
-		rx_filled++;
+		rx_done++;
 		rx_status = rx_desc->status;
 		rx_bytes = rx_desc->data_size - MVPP2_MH_SIZE;
+		phys_addr = rx_desc->buf_phys_addr;
 
 		bm = mvpp2_bm_cookie_build(rx_desc);
 		pool = mvpp2_bm_cookie_pool_get(bm);
@@ -5135,8 +5137,10 @@ static int mvpp2_rx(struct mvpp2_port *port, int rx_todo,
 		 * comprised by the RX descriptor.
 		 */
 		if (rx_status & MVPP2_RXD_ERR_SUMMARY) {
+		err_drop_frame:
 			dev->stats.rx_errors++;
 			mvpp2_rx_error(port, rx_desc);
+			/* Return the buffer to the pool */
 			mvpp2_pool_refill(port, bm, rx_desc->buf_phys_addr,
 					  rx_desc->buf_cookie);
 			continue;
@@ -5144,7 +5148,13 @@ static int mvpp2_rx(struct mvpp2_port *port, int rx_todo,
 
 		skb = (struct sk_buff *)rx_desc->buf_cookie;
 
-		dma_unmap_single(dev->dev.parent, rx_desc->buf_phys_addr,
+		err = mvpp2_rx_refill(port, bm_pool, bm, 0);
+		if (err) {
+			netdev_err(port->dev, "failed to refill BM pools\n");
+			goto err_drop_frame;
+		}
+
+		dma_unmap_single(dev->dev.parent, phys_addr,
 				 bm_pool->buf_size, DMA_FROM_DEVICE);
 
 		rcvd_pkts++;
@@ -5157,12 +5167,6 @@ static int mvpp2_rx(struct mvpp2_port *port, int rx_todo,
 		mvpp2_rx_csum(port, rx_status, skb);
 
 		napi_gro_receive(&port->napi, skb);
-
-		err = mvpp2_rx_refill(port, bm_pool, bm, 0);
-		if (err) {
-			netdev_err(port->dev, "failed to refill BM pools\n");
-			rx_filled--;
-		}
 	}
 
 	if (rcvd_pkts) {
@@ -5176,7 +5180,7 @@ static int mvpp2_rx(struct mvpp2_port *port, int rx_todo,
 
 	/* Update Rx queue management counters */
 	wmb();
-	mvpp2_rxq_status_update(port, rxq->id, rx_todo, rx_filled);
+	mvpp2_rxq_status_update(port, rxq->id, rx_done, rx_done);
 
 	return rx_todo;
 }