From d2bef6a0a9564f43f366ae792d91c2e3b6b03f07 Mon Sep 17 00:00:00 2001
From: Breno Leitao <leitao@linux.vnet.ibm.com>
Date: Tue, 2 Sep 2008 17:28:58 -0700
Subject: [PATCH] --- yaml --- r: 109443 b: refs/heads/master c:
 06770843c2f0f929a6e0c758dc433902a01aabfb h: refs/heads/master i:   109441:
 3af6b5ae63a15a3c241e359b04df3260c8fb93be   109439:
 7ae2b0cf74feb28b7b62d2d55cbcb59b8a35ed73 v: v3

---
 [refs]                   |  2 +-
 trunk/net/ipv4/devinet.c | 15 ++++++++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 61c1b1e420e8..cc4a45d20b8a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9d7d74029e0f5fde3b88b39892b9b9cfdf4ea10a
+refs/heads/master: 06770843c2f0f929a6e0c758dc433902a01aabfb
diff --git a/trunk/net/ipv4/devinet.c b/trunk/net/ipv4/devinet.c
index 91d3d96805d0..b12dae2b0b2d 100644
--- a/trunk/net/ipv4/devinet.c
+++ b/trunk/net/ipv4/devinet.c
@@ -1029,6 +1029,11 @@ static void inetdev_changename(struct net_device *dev, struct in_device *in_dev)
 	}
 }
 
+static inline bool inetdev_valid_mtu(unsigned mtu)
+{
+	return mtu >= 68;
+}
+
 /* Called only under RTNL semaphore */
 
 static int inetdev_event(struct notifier_block *this, unsigned long event,
@@ -1048,6 +1053,10 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 				IN_DEV_CONF_SET(in_dev, NOXFRM, 1);
 				IN_DEV_CONF_SET(in_dev, NOPOLICY, 1);
 			}
+		} else if (event == NETDEV_CHANGEMTU) {
+			/* Re-enabling IP */
+			if (inetdev_valid_mtu(dev->mtu))
+				in_dev = inetdev_init(dev);
 		}
 		goto out;
 	}
@@ -1058,7 +1067,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 		dev->ip_ptr = NULL;
 		break;
 	case NETDEV_UP:
-		if (dev->mtu < 68)
+		if (!inetdev_valid_mtu(dev->mtu))
 			break;
 		if (dev->flags & IFF_LOOPBACK) {
 			struct in_ifaddr *ifa;
@@ -1080,9 +1089,9 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 		ip_mc_down(in_dev);
 		break;
 	case NETDEV_CHANGEMTU:
-		if (dev->mtu >= 68)
+		if (inetdev_valid_mtu(dev->mtu))
 			break;
-		/* MTU falled under 68, disable IP */
+		/* disable IP when MTU is not enough */
 	case NETDEV_UNREGISTER:
 		inetdev_destroy(in_dev);
 		break;