On Wed, 2015-04-29 at 17:56 +0300, Madalin Bucur wrote:
> This introduces the Freescale Data Path Acceleration Architecture
> (DPAA) Ethernet driver (dpaa_eth) that builds upon the DPAA QMan,
> BMan, PAMU and FMan drivers to deliver Ethernet connectivity on
> the Freescale DPAA QorIQ platforms.
...
> + /* We're going to store the skb backpointer at the beginning
> + * of the data buffer, so we need a privately owned skb
> + */
> +
> + /* Code borrowed from skb_unshare(). */
> + if (skb_cloned(skb)) {
> + struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC);
> +
> + /* Finally, create a contig FD from this skb */
> + skb_to_contig_fd(priv, skb, &fd, countptr, &offset);
> +
> + kfree_skb(skb);
> + skb = nskb;
> + /* skb_copy() has now linearized the skbuff. */
> + }
> +
You know that TCP packets are clones, right ?
This code is killing performance.
TCP allows the headers part being modified by a driver if needed.
You should use skb_header_cloned() instead.
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