[NET]: Clean up skb_linearize

The linearisation operation doesn't need to be super-optimised.  So we can
replace __skb_linearize with __pskb_pull_tail which does the same thing but
is more general.

Also, most users of skb_linearize end up testing whether the skb is linear
or not so it helps to make skb_linearize do just that.

Some callers of skb_linearize also use it to copy cloned data, so it's
useful to have a new function skb_linearize_cow to copy the data if it's
either non-linear or cloned.

Last but not least, I've removed the gfp argument since nobody uses it
anymore.  If it's ever needed we can easily add it back.

Misc bugs fixed by this patch:

* via-velocity error handling (also, no SG => no frags)

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 8 insertions, 4 deletions

diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index 411f4d809c47..625ff61c9988 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -1200,7 +1200,7 @@ static int mv643xx_eth_start_xmit(struct sk_buff *skb, struct net_device *dev)
         }
 
         if (has_tiny_unaligned_frags(skb)) {
-                if ((skb_linearize(skb, GFP_ATOMIC) != 0)) {
+                if (__skb_linearize(skb)) {
                         stats->tx_dropped++;
                         printk(KERN_DEBUG "%s: failed to linearize tiny "
                                         "unaligned fragment\n", dev->name);
diff --git a/drivers/net/via-velocity.c b/drivers/net/via-velocity.c
index ed1f837c8fda..2eb6b5f9ba0d 100644
--- a/drivers/net/via-velocity.c
+++ b/drivers/net/via-velocity.c
@@ -1899,6 +1899,13 @@ static int velocity_xmit(struct sk_buff *skb, struct net_device *dev)
 
         int pktlen = skb->len;
 
+#ifdef VELOCITY_ZERO_COPY_SUPPORT
+        if (skb_shinfo(skb)->nr_frags > 6 && __skb_linearize(skb)) {
+                kfree_skb(skb);
+                return 0;
+        }
+#endif
+
         spin_lock_irqsave(&vptr->lock, flags);
 
         index = vptr->td_curr[qnum];
@@ -1914,8 +1921,6 @@ static int velocity_xmit(struct sk_buff *skb, struct net_device *dev)
          */
         if (pktlen < ETH_ZLEN) {
                 /* Cannot occur until ZC support */
-                if(skb_linearize(skb, GFP_ATOMIC))
-                        return 0; 
                 pktlen = ETH_ZLEN;
                 memcpy(tdinfo->buf, skb->data, skb->len);
                 memset(tdinfo->buf + skb->len, 0, ETH_ZLEN - skb->len);
@@ -1933,7 +1938,6 @@ static int velocity_xmit(struct sk_buff *skb, struct net_device *dev)
                 int nfrags = skb_shinfo(skb)->nr_frags;
                 tdinfo->skb = skb;
                 if (nfrags > 6) {
-                        skb_linearize(skb, GFP_ATOMIC);
                         memcpy(tdinfo->buf, skb->data, skb->len);
                         tdinfo->skb_dma[0] = tdinfo->buf_dma;
                         td_ptr->tdesc0.pktsize =