Revert "net: fec: fix the warning found by dma debug"

This reverts commit 2b995f63987013bacde99168218f9c7b252bdcf1.

Панов Андрей reported the following regression:

"Commit 2b995f63987013bacde99168218f9c7b252bdcf1 in 4.0.0-rc3 introduces a
nasty bug in transmit, corrupting packets.

To reproduce:

$ dd if=/dev/zero of=zeros bs=1M count=20
$ md5sum -b zeros
8f4e33f3dc3e414ff94e5fb6905cba8c *zeros

This checksum is correct.

Copy file "zeros" to another host with NFS, and it gets corrupted, checksum is
changed.
File should be big, small amounts of transmit isn't affected.

I use an i.MX6 Quad board.

If this commit is reverted, all works fine."

Reported-by: Панов Андрей <rockford@yandex.ru>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 23 deletions

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 787db5026191..78e1ce09b1ab 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1189,13 +1189,12 @@ static void
 fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
 {
         struct  fec_enet_private *fep;
-        struct bufdesc *bdp, *bdp_t;
+        struct bufdesc *bdp;
         unsigned short status;
         struct  sk_buff *skb;
         struct fec_enet_priv_tx_q *txq;
         struct netdev_queue *nq;
         int     index = 0;
-        int     i, bdnum;
         int     entries_free;
 
         fep = netdev_priv(ndev);
@@ -1216,29 +1215,18 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
                 if (bdp == txq->cur_tx)
                         break;
 
-                bdp_t = bdp;
-                bdnum = 1;
-                index = fec_enet_get_bd_index(txq->tx_bd_base, bdp_t, fep);
-                skb = txq->tx_skbuff[index];
-                while (!skb) {
-                        bdp_t = fec_enet_get_nextdesc(bdp_t, fep, queue_id);
-                        index = fec_enet_get_bd_index(txq->tx_bd_base, bdp_t, fep);
-                        skb = txq->tx_skbuff[index];
-                        bdnum++;
-                }
-                if (skb_shinfo(skb)->nr_frags &&
-                    (status = bdp_t->cbd_sc) & BD_ENET_TX_READY)
-                        break;
+                index = fec_enet_get_bd_index(txq->tx_bd_base, bdp, fep);
 
-                for (i = 0; i < bdnum; i++) {
-                        if (!IS_TSO_HEADER(txq, bdp->cbd_bufaddr))
-                                dma_unmap_single(&fep->pdev->dev, bdp->cbd_bufaddr,
-                                                 bdp->cbd_datlen, DMA_TO_DEVICE);
-                        bdp->cbd_bufaddr = 0;
-                        if (i < bdnum - 1)
-                                bdp = fec_enet_get_nextdesc(bdp, fep, queue_id);
-                }
+                skb = txq->tx_skbuff[index];
                 txq->tx_skbuff[index] = NULL;
+                if (!IS_TSO_HEADER(txq, bdp->cbd_bufaddr))
+                        dma_unmap_single(&fep->pdev->dev, bdp->cbd_bufaddr,
+                                        bdp->cbd_datlen, DMA_TO_DEVICE);
+                bdp->cbd_bufaddr = 0;
+                if (!skb) {
+                        bdp = fec_enet_get_nextdesc(bdp, fep, queue_id);
+                        continue;
+                }
 
                 /* Check for errors. */
                 if (status & (BD_ENET_TX_HB | BD_ENET_TX_LC |