net/usbnet: reserve headroom on rx skbs
Eric Dumazet [Wed, 14 Mar 2012 06:56:25 +0000 (06:56 +0000)]
network drivers should reserve some headroom on incoming skbs so that we
dont need expensive reallocations, eg forwarding packets in tunnels.

This NET_SKB_PAD padding is done in various helpers, like
__netdev_alloc_skb_ip_align() in this patch, combining NET_SKB_PAD and
NET_IP_ALIGN magic.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Oliver Neukum <oneukum@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/usbnet.c

index 81b96e3..59681f0 100644 (file)
@@ -328,13 +328,13 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
        unsigned long           lockflags;
        size_t                  size = dev->rx_urb_size;
 
-       if ((skb = alloc_skb (size + NET_IP_ALIGN, flags)) == NULL) {
+       skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
+       if (!skb) {
                netif_dbg(dev, rx_err, dev->net, "no rx skb\n");
                usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
                usb_free_urb (urb);
                return -ENOMEM;
        }
-       skb_reserve (skb, NET_IP_ALIGN);
 
        entry = (struct skb_data *) skb->cb;
        entry->urb = urb;