diff mbox series

[net-next,v2,2/7] gtp: set initial MTU

Message ID 20210203070805.281321-3-jonas@norrbonn.se (mailing list archive)
State Accepted
Delegated to: Netdev Maintainers
Headers show
Series GTP | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 2 maintainers not CCed: davem@davemloft.net osmocom-net-gprs@lists.osmocom.org
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 28 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Jonas Bonn Feb. 3, 2021, 7:08 a.m. UTC 
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 <jonas@norrbonn.se>
Acked-by: Harald Welte <laforge@gnumonks.org>
---
 drivers/net/gtp.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)
diff mbox series

Patch

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		= &gtp_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);