From: Ed Swierk <eswierk@arastra.com>
Date: Sun, 16 Sep 2007 19:21:38 +0000 (-0700)
Subject: [TAP]: Configurable interface MTU.
X-Git-Tag: firefly_0821_release~26070^2~483
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4885a50476b95fa0f4caad179a80783508c2fe86;p=firefly-linux-kernel-4.4.55.git

[TAP]: Configurable interface MTU.

Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d279151f065d..d8b8e68ef70b 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -172,6 +172,18 @@ tun_net_mclist(struct net_device *dev)
 	}
 }
 
+#define MIN_MTU 68
+#define MAX_MTU 65535
+
+static int
+tun_net_change_mtu(struct net_device *dev, int new_mtu)
+{
+	if (new_mtu < MIN_MTU || new_mtu + dev->hard_header_len > MAX_MTU)
+		return -EINVAL;
+	dev->mtu = new_mtu;
+	return 0;
+}
+
 /* Initialize net device. */
 static void tun_net_init(struct net_device *dev)
 {
@@ -183,6 +195,7 @@ static void tun_net_init(struct net_device *dev)
 		dev->hard_header_len = 0;
 		dev->addr_len = 0;
 		dev->mtu = 1500;
+		dev->change_mtu = tun_net_change_mtu;
 
 		/* Zero header length */
 		dev->type = ARPHRD_NONE;
@@ -195,6 +208,7 @@ static void tun_net_init(struct net_device *dev)
 		dev->set_multicast_list = tun_net_mclist;
 
 		ether_setup(dev);
+		dev->change_mtu = tun_net_change_mtu;
 
 		/* random address already created for us by tun_set_iff, use it */
 		memcpy(dev->dev_addr, tun->dev_addr, min(sizeof(tun->dev_addr), sizeof(dev->dev_addr)) );