gianfar: fix headroom expansion code

The code that was added to increase headroom was wrong.
It doesn't handle the case where gfar_add_fcb() changes the skb.
Better to do check at start of transmit (outside of lock), where
error handling is better anyway.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index 9d81e7a..a7a6737 100644 (file)
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -1239,19 +1239,9 @@ static int gfar_enet_open(struct net_device *dev)
        return err;
 }
 
-static inline struct txfcb *gfar_add_fcb(struct sk_buff **skbp)
+static inline struct txfcb *gfar_add_fcb(struct sk_buff *skb)
 {
-       struct txfcb *fcb;
-       struct sk_buff *skb = *skbp;
-
-       if (unlikely(skb_headroom(skb) < GMAC_FCB_LEN)) {
-               struct sk_buff *old_skb = skb;
-               skb = skb_realloc_headroom(old_skb, GMAC_FCB_LEN);
-               if (!skb)
-                       return NULL;
-               dev_kfree_skb_any(old_skb);
-       }
-       fcb = (struct txfcb *)skb_push(skb, GMAC_FCB_LEN);
+       struct txfcb *fcb = (struct txfcb *)skb_push(skb, GMAC_FCB_LEN);
        cacheable_memzero(fcb, GMAC_FCB_LEN);
 
        return fcb;
@@ -1320,6 +1310,20 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
        base = priv->tx_bd_base;
 
+       /* make space for additional header */
+       if (skb_headroom(skb) < GMAC_FCB_LEN) {
+               struct sk_buff *skb_new;
+
+               skb_new = skb_realloc_headroom(skb, GMAC_FCB_LEN);
+               if (!skb_new) {
+                       dev->stats.tx_errors++;
+                       kfree(skb);
+                       return NETDEV_TX_OK;
+               }
+               kfree_skb(skb);
+               skb = skb_new;
+       }
+
        /* total number of fragments in the SKB */
        nr_frags = skb_shinfo(skb)->nr_frags;
 
@@ -1372,20 +1376,18 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
        /* Set up checksumming */
        if (CHECKSUM_PARTIAL == skb->ip_summed) {
-               fcb = gfar_add_fcb(&skb);
-               if (likely(fcb != NULL)) {
-                       lstatus |= BD_LFLAG(TXBD_TOE);
-                       gfar_tx_checksum(skb, fcb);
-               }
+               fcb = gfar_add_fcb(skb);
+               lstatus |= BD_LFLAG(TXBD_TOE);
+               gfar_tx_checksum(skb, fcb);
        }
 
        if (priv->vlgrp && vlan_tx_tag_present(skb)) {
-               if (unlikely(NULL == fcb))
-                       fcb = gfar_add_fcb(&skb);
-               if (likely(fcb != NULL)) {
+               if (unlikely(NULL == fcb)) {
+                       fcb = gfar_add_fcb(skb);
                        lstatus |= BD_LFLAG(TXBD_TOE);
-                       gfar_tx_vlan(skb, fcb);
                }
+
+               gfar_tx_vlan(skb, fcb);
        }
 
        /* setup the TxBD length and buffer pointer for the first BD */
@@ -1433,7 +1435,7 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
        /* Unlock priv */
        spin_unlock_irqrestore(&priv->txlock, flags);
 
-       return 0;
+       return NETDEV_TX_OK;
 }
 
 /* Stops the kernel queue, and halts the controller */