[PATCH] net/usbnet: reserve headroom on rx skbs

[Eric Dumazet <eric.dumazet@gmail.com>]

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>
---
 drivers/net/usb/usbnet.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 83dcc53..5903aea 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -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;