From patchwork Mon Oct 9 20:47:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: William Tu X-Patchwork-Id: 823504 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="FL6Urmkd"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3y9slL2WKmz9t5R for ; Tue, 10 Oct 2017 07:48:14 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755060AbdJIUsN (ORCPT ); Mon, 9 Oct 2017 16:48:13 -0400 Received: from mail-pf0-f193.google.com ([209.85.192.193]:35762 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754188AbdJIUsF (ORCPT ); Mon, 9 Oct 2017 16:48:05 -0400 Received: by mail-pf0-f193.google.com with SMTP id i23so30358057pfi.2 for ; Mon, 09 Oct 2017 13:48:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=DeUMbNhFltfOQHupEAhMf2hnG7RZkZLAb1cXD5ENx3E=; b=FL6Urmkds2oOO7BuDyuozk6jp0Pm3HeZZxLS1Q9c7vLT5rLzW+FHajCbXSd7K7vWQs JgCkDmfA/4pfNb9Fu6pbhaX7E+tijWOgCzjAqYSLckvveypE38iGv3CLFFJnuGKXPRE2 +FrxUkyEECLFiPSQ+3ewP6k/lTC4qld7PCz8jIbJqdEmXARxHFSqbo9b01Xnhqcx151e BUr8irfGM9Vf+sIZOmXQ3QQJ2fbkLywia0UgK46u7gRnHa1DtKGRpJe4fx1JEc2CfXi1 E425WnPKu+cRj7c+ihlxMwYcGj1cK0R8DDf5MDhrFB/x7YByjyr5NQG69mQ0tc/CASzY hlWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=DeUMbNhFltfOQHupEAhMf2hnG7RZkZLAb1cXD5ENx3E=; b=QJfsVecJOrd1Np5o/Sqs9TPtsPh7XGA621pZ7EcLov98NepxNCUGzs7Bzzovw9vQSw iIhMl8E6CQu8aZgLrBZi604Y9Cy043eGTziI6da+zNL0/lDEo+o8E1aGsELoEPzBAOOK V3PU/zM5agaFOBXzz/vEB9NgBzkm8zi02Skj3M954He1E86L0v+mPvkCbHp2wrhiNmYy M2BjvQgSGKqq6lvyDbs1tu4juiQIhGFTuDsI6H11zSizNQVCJBYqKzz1UnnDegRC8AtL tZCRWIwDH5ftS6a/NNYyA7sKf6UWpW568ioYuQAqh1tkA3xi3bMf1KP3DLEsxzetj+pw TNSw== X-Gm-Message-State: AMCzsaVE/vZ4wORn5MF2NodvvOYP91Cdn3CRy18BpbVFfsolAmir5Vcs fubXMCma0LI0wLoCjE1ERaU2tiGF X-Google-Smtp-Source: AOwi7QCSZPaPZQdTVG48ox7SAiz0uH39gnSAir8QdxdqLPYx0RdKSkQgCmunizhoNkRx7zIP7f0wFQ== X-Received: by 10.98.178.86 with SMTP id x83mr11248784pfe.332.1507582084489; Mon, 09 Oct 2017 13:48:04 -0700 (PDT) Received: from sc9-mailhost3.vmware.com ([208.91.1.34]) by smtp.gmail.com with ESMTPSA id p71sm17861098pfl.56.2017.10.09.13.48.03 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 09 Oct 2017 13:48:03 -0700 (PDT) From: William Tu To: netdev@vger.kernel.org Cc: Xin Long Subject: [net-next 2/3] ip_gre: fix erspan tunnel mtu calculation Date: Mon, 9 Oct 2017 13:47:46 -0700 Message-Id: <1507582067-36718-3-git-send-email-u9012063@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1507582067-36718-1-git-send-email-u9012063@gmail.com> References: <1507582067-36718-1-git-send-email-u9012063@gmail.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Remove the unnecessary -4 and +4 bytes at mtu and headroom calculation. In addition, erspan uses fixed 8-byte gre header, so add ERSPAN_GREHDR_LEN macro for better readability. Now tunnel->hlen = grehdr(8) + erspanhdr(8) = 16 byte. The mtu should be ETH_DATA_LEN - 16 - iph(20) = 1464. After the ip_tunnel_bind_dev(), the mtu is adjusted to 1464 - 14 (dev->hard_header_len) = 1450. The maximum skb->len the erspan tunnel can carry without being truncated is 1450 + 14 = 1464 byte. Signed-off-by: William Tu Cc: Xin Long --- include/net/erspan.h | 1 + net/ipv4/ip_gre.c | 11 +++++------ 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/include/net/erspan.h b/include/net/erspan.h index ca94fc86865e..e28294e248d0 100644 --- a/include/net/erspan.h +++ b/include/net/erspan.h @@ -28,6 +28,7 @@ */ #define ERSPAN_VERSION 0x1 +#define ERSPAN_GREHDR_LEN 8 /* ERSPAN has fixed 8-byte GRE header */ #define VER_MASK 0xf000 #define VLAN_MASK 0x0fff diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 286065c35959..6e6e4c4811cc 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -569,8 +569,7 @@ static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev, key = &tun_info->key; - /* ERSPAN has fixed 8 byte GRE header */ - tunnel_hlen = 8 + sizeof(struct erspanhdr); + tunnel_hlen = ERSPAN_GREHDR_LEN + sizeof(struct erspanhdr); rt = prepare_fb_xmit(skb, dev, &fl, tunnel_hlen); if (!rt) @@ -591,7 +590,7 @@ static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev, erspan_build_header(skb, tunnel_id_to_key32(key->tun_id), ntohl(md->index), truncate); - gre_build_header(skb, 8, TUNNEL_SEQ, + gre_build_header(skb, ERSPAN_GREHDR_LEN, TUNNEL_SEQ, htons(ETH_P_ERSPAN), 0, htonl(tunnel->o_seqno++)); df = key->tun_flags & TUNNEL_DONT_FRAGMENT ? htons(IP_DF) : 0; @@ -1242,14 +1241,14 @@ static int erspan_tunnel_init(struct net_device *dev) struct ip_tunnel *tunnel = netdev_priv(dev); int t_hlen; - tunnel->tun_hlen = 8; + tunnel->tun_hlen = ERSPAN_GREHDR_LEN; tunnel->parms.iph.protocol = IPPROTO_GRE; tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen + sizeof(struct erspanhdr); 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; dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;