From: Li Wei Date: Tue, 6 Dec 2011 21:23:45 +0000 (+0000) Subject: ipv6: Fix for adding multicast route for loopback device automatically. X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=4af04aba93f47699e7ac33e7cfd4da22550e6114;p=linux-beck.git ipv6: Fix for adding multicast route for loopback device automatically. There is no obvious reason to add a default multicast route for loopback devices, otherwise there would be a route entry whose dst.error set to -ENETUNREACH that would blocking all multicast packets. ==================== [ more detailed explanation ] The problem is that the resulting routing table depends on the sequence of interface's initialization and in some situation, that would block all muticast packets. Suppose there are two interfaces on my computer (lo and eth0), if we initailize 'lo' before 'eth0', the resuting routing table(for multicast) would be # ip -6 route show | grep ff00:: unreachable ff00::/8 dev lo metric 256 error -101 ff00::/8 dev eth0 metric 256 When sending multicasting packets, routing subsystem will return the first route entry which with a error set to -101(ENETUNREACH). I know the kernel will set the default ipv6 address for 'lo' when it is up and won't set the default multicast route for it, but there is no reason to stop 'init' program from setting address for 'lo', and that is exactly what systemd did. I am sure there is something wrong with kernel or systemd, currently I preferred kernel caused this problem. ==================== Signed-off-by: Li Wei Signed-off-by: David S. Miller --- diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index cf88df82e2c2..36806def8cfd 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -1805,7 +1805,8 @@ static struct inet6_dev *addrconf_add_dev(struct net_device *dev) return ERR_PTR(-EACCES); /* Add default multicast route */ - addrconf_add_mroute(dev); + if (!(dev->flags & IFF_LOOPBACK)) + addrconf_add_mroute(dev); /* Add link local route */ addrconf_add_lroute(dev);