[patch 27/36] IPV6: Restore IPv6 when MTU is big enough

[Greg KH <gregkh@suse.de>]

2.6.22-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>

[IPV6]: Restore IPv6 when MTU is big enough

[ Upstream commit: d31c7b8fa303eb81311f27b80595b8d2cbeef950 ]

Avaid provided test application, so bug got fixed.

IPv6 addrconf removes ipv6 inner device from netdev each time cmu
changes and new value is less than IPV6_MIN_MTU (1280 bytes).
When mtu is changed and new value is greater than IPV6_MIN_MTU,
it does not add ipv6 addresses and inner device bac.

This patch fixes that.

Tested with Avaid's application, which works ok now.

Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 net/ipv6/addrconf.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2285,6 +2285,9 @@ static int addrconf_notify(struct notifi
 				break;
 			}
 
+			if (!idev && dev->mtu >= IPV6_MIN_MTU)
+				idev = ipv6_add_dev(dev);
+
 			if (idev)
 				idev->if_flags |= IF_READY;
 		} else {
@@ -2349,12 +2352,18 @@ static int addrconf_notify(struct notifi
 		break;
 
 	case NETDEV_CHANGEMTU:
-		if ( idev && dev->mtu >= IPV6_MIN_MTU) {
+		if (idev && dev->mtu >= IPV6_MIN_MTU) {
 			rt6_mtu_change(dev, dev->mtu);
 			idev->cnf.mtu6 = dev->mtu;
 			break;
 		}
 
+		if (!idev && dev->mtu >= IPV6_MIN_MTU) {
+			idev = ipv6_add_dev(dev);
+			if (idev)
+				break;
+		}
+
 		/* MTU falled under IPV6_MIN_MTU. Stop IPv6 on this interface. */
 
 	case NETDEV_DOWN:

-- 
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