From mboxrd@z Thu Jan 1 00:00:00 1970 From: William Tu Subject: [net-next 1/3] ip_gre: fix mtu and headroom size Date: Mon, 9 Oct 2017 13:47:45 -0700 Message-ID: <1507582067-36718-2-git-send-email-u9012063@gmail.com> References: <1507582067-36718-1-git-send-email-u9012063@gmail.com> Cc: Tom Herbert To: netdev@vger.kernel.org Return-path: Received: from mail-pf0-f196.google.com ([209.85.192.196]:35742 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754295AbdJIUsE (ORCPT ); Mon, 9 Oct 2017 16:48:04 -0400 Received: by mail-pf0-f196.google.com with SMTP id i23so30357973pfi.2 for ; Mon, 09 Oct 2017 13:48:03 -0700 (PDT) In-Reply-To: <1507582067-36718-1-git-send-email-u9012063@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: The ip_gre_calc_hlen() already counts gre's base header len (4-byte) plus optional header's len, so tunnel->hlen has the entire gre headeri + options len. Thus, remove the -4 and +4 when calculating the needed_headroom and mtu. Fixes: 4565e9919cda ("gre: Setup and TX path for gre/UDP foo-over-udp encapsulation") Signed-off-by: William Tu Cc: Tom Herbert --- net/ipv4/ip_gre.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index c105a315b1a3..286065c35959 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -947,8 +947,8 @@ static void __gre_tunnel_init(struct net_device *dev) t_hlen = tunnel->hlen + sizeof(struct iphdr); - dev->needed_headroom = LL_MAX_HEADER + t_hlen + 4; - dev->mtu = ETH_DATA_LEN - t_hlen - 4; + dev->needed_headroom = LL_MAX_HEADER + t_hlen; + dev->mtu = ETH_DATA_LEN - t_hlen; dev->features |= GRE_FEATURES; dev->hw_features |= GRE_FEATURES; -- 2.7.4