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[81.170.137.65]) by smtp.gmail.com with ESMTPSA id b26sm2535171lff.162.2021.02.01.22.52.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Feb 2021 22:52:09 -0800 (PST) From: Jonas Bonn To: laforge@gnumonks.org, kuba@kernel.org, netdev@vger.kernel.org, pablo@netfilter.org Cc: Jonas Bonn Subject: [PATCH net-next 2/7] gtp: set initial MTU Date: Tue, 2 Feb 2021 07:51:54 +0100 Message-Id: <20210202065159.227049-3-jonas@norrbonn.se> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210202065159.227049-1-jonas@norrbonn.se> References: <20210202065159.227049-1-jonas@norrbonn.se> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The GTP link is brought up with a default MTU of zero. This can lead to some rather unexpected behaviour for users who are more accustomed to interfaces coming online with reasonable defaults. This patch sets an initial MTU for the GTP link of 1500 less worst-case tunnel overhead. Signed-off-by: Jonas Bonn Acked-by: Harald Welte --- drivers/net/gtp.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 4c04e271f184..5a048f050a9c 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -612,11 +612,16 @@ static const struct net_device_ops gtp_netdev_ops = { static void gtp_link_setup(struct net_device *dev) { + unsigned int max_gtp_header_len = sizeof(struct iphdr) + + sizeof(struct udphdr) + + sizeof(struct gtp0_header); + dev->netdev_ops = >p_netdev_ops; dev->needs_free_netdev = true; dev->hard_header_len = 0; dev->addr_len = 0; + dev->mtu = ETH_DATA_LEN - max_gtp_header_len; /* Zero header length. */ dev->type = ARPHRD_NONE; @@ -626,11 +631,7 @@ static void gtp_link_setup(struct net_device *dev) dev->features |= NETIF_F_LLTX; netif_keep_dst(dev); - /* Assume largest header, ie. GTPv0. */ - dev->needed_headroom = LL_MAX_HEADER + - sizeof(struct iphdr) + - sizeof(struct udphdr) + - sizeof(struct gtp0_header); + dev->needed_headroom = LL_MAX_HEADER + max_gtp_header_len; } static int gtp_hashtable_new(struct gtp_dev *gtp, int hsize); -- 2.27.0