From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH 1/2] tun: reserves space for network in skb Date: Wed, 08 Jun 2011 17:33:07 -0700 Message-ID: <20110609003321.904295399@vyatta.com> References: <20110609003306.651532958@vyatta.com> Cc: netdev@vger.kernel.org To: "David S. Miller" Return-path: Received: from suva.vyatta.com ([76.74.103.44]:34274 "EHLO suva.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751481Ab1FIBQ2 (ORCPT ); Wed, 8 Jun 2011 21:16:28 -0400 Content-Disposition: inline; filename=tun-tap-pad.patch Sender: netdev-owner@vger.kernel.org List-ID: The tun driver allocates skb's to hold data from user and then passes the data into the network stack as received data. Most network devices allocate the receive skb with routines like dev_alloc_skb() that reserves additional space for use by network protocol stack but tun does not. Because of the lack of padding, when the packet is passed through bridge netfilter a new skb has to be allocated. Signed-off-by: Stephen Hemminger --- a/drivers/net/tun.c 2011-05-13 12:37:11.619318207 -0700 +++ b/drivers/net/tun.c 2011-05-13 16:43:25.643040523 -0700 @@ -584,7 +584,7 @@ static __inline__ ssize_t tun_get_user(s { struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) }; struct sk_buff *skb; - size_t len = count, align = 0; + size_t len = count, align = NET_SKB_PAD; struct virtio_net_hdr gso = { 0 }; int offset = 0; @@ -614,7 +614,7 @@ static __inline__ ssize_t tun_get_user(s } if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) { - align = NET_IP_ALIGN; + align += NET_IP_ALIGN; if (unlikely(len < ETH_HLEN || (gso.hdr_len && gso.hdr_len < ETH_HLEN))) return -EINVAL;