net: arc_emac: fix sk_buff leak

EMAC could be disabled, while there is some sb_buff
in use. That buffers got lost for linux.

In order to reproduce run on device during active ethernet work:
    ifconfig eth0 down

Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/arc/emac_main.c b/drivers/net/ethernet/arc/emac_main.c
index 4f6e5be184dfbcc197317d9a6728f0ad3e258338..6446af1403f70be8101625ed9a8b03d3de17b792 100644 (file)
--- a/drivers/net/ethernet/arc/emac_main.c
+++ b/drivers/net/ethernet/arc/emac_main.c
@@ -517,6 +517,64 @@ static void arc_emac_set_rx_mode(struct net_device *ndev)
        }
 }
 
+/**
+ * arc_free_tx_queue - free skb from tx queue
+ * @ndev:      Pointer to the network device.
+ *
+ * This function must be called while EMAC disable
+ */
+static void arc_free_tx_queue(struct net_device *ndev)
+{
+       struct arc_emac_priv *priv = netdev_priv(ndev);
+       unsigned int i;
+
+       for (i = 0; i < TX_BD_NUM; i++) {
+               struct arc_emac_bd *txbd = &priv->txbd[i];
+               struct buffer_state *tx_buff = &priv->tx_buff[i];
+
+               if (tx_buff->skb) {
+                       dma_unmap_single(&ndev->dev, dma_unmap_addr(tx_buff, addr),
+                                        dma_unmap_len(tx_buff, len), DMA_TO_DEVICE);
+
+                       /* return the sk_buff to system */
+                       dev_kfree_skb_irq(tx_buff->skb);
+               }
+
+               txbd->info = 0;
+               txbd->data = 0;
+               tx_buff->skb = NULL;
+       }
+}
+
+/**
+ * arc_free_rx_queue - free skb from rx queue
+ * @ndev:      Pointer to the network device.
+ *
+ * This function must be called while EMAC disable
+ */
+static void arc_free_rx_queue(struct net_device *ndev)
+{
+       struct arc_emac_priv *priv = netdev_priv(ndev);
+       unsigned int i;
+
+       for (i = 0; i < RX_BD_NUM; i++) {
+               struct arc_emac_bd *rxbd = &priv->rxbd[i];
+               struct buffer_state *rx_buff = &priv->rx_buff[i];
+
+               if (rx_buff->skb) {
+                       dma_unmap_single(&ndev->dev, dma_unmap_addr(rx_buff, addr),
+                                       dma_unmap_len(rx_buff, len), DMA_FROM_DEVICE);
+
+                       /* return the sk_buff to system */
+                       dev_kfree_skb_irq(rx_buff->skb);
+               }
+
+               rxbd->info = 0;
+               rxbd->data = 0;
+               rx_buff->skb = NULL;
+       }
+}
+
 /**
  * arc_emac_stop - Close the network device.
  * @ndev:      Pointer to the network device.
@@ -538,6 +596,10 @@ static int arc_emac_stop(struct net_device *ndev)
        /* Disable EMAC */
        arc_reg_clr(priv, R_CTRL, EN_MASK);
 
+       /* Return the sk_buff to system */
+       arc_free_tx_queue(ndev);
+       arc_free_rx_queue(ndev);
+
        return 0;
 }