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| author | Maciej Żenczykowski <maze@google.com> | 2016-11-04 22:51:54 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-11-09 19:19:32 +0100 |
| commit | fb56be83e43d0bb0cc9e8c35a6a9cac853231ba2 (patch) | |
| tree | 2df54004541ac2397e6035d9301804b36c3b8ea3 /net/ipv6/route.c | |
| parent | sock: fix sendmmsg for partial sendmsg (diff) | |
| download | linux-fb56be83e43d0bb0cc9e8c35a6a9cac853231ba2.tar.xz linux-fb56be83e43d0bb0cc9e8c35a6a9cac853231ba2.zip | |
net-ipv6: on device mtu change do not add mtu to mtu-less routes
Routes can specify an mtu explicitly or inherit the mtu from
the underlying device - this inheritance is implemented in
dst->ops->mtu handlers ip6_mtu() and ip6_blackhole_mtu().
Currently changing the mtu of a device adds mtu explicitly
to routes using that device.
ie.
# ip link set dev lo mtu 65536
# ip -6 route add local 2000::1 dev lo
# ip -6 route get 2000::1
local 2000::1 dev lo table local src ... metric 1024 pref medium
# ip link set dev lo mtu 65535
# ip -6 route get 2000::1
local 2000::1 dev lo table local src ... metric 1024 mtu 65535 pref medium
# ip link set dev lo mtu 65536
# ip -6 route get 2000::1
local 2000::1 dev lo table local src ... metric 1024 mtu 65536 pref medium
# ip -6 route del local 2000::1
After this patch the route entry no longer changes unless it already has an mtu.
There is no need: this inheritance is already done in ip6_mtu()
# ip link set dev lo mtu 65536
# ip -6 route add local 2000::1 dev lo
# ip -6 route add local 2000::2 dev lo mtu 2000
# ip -6 route get 2000::1; ip -6 route get 2000::2
local 2000::1 dev lo table local src ... metric 1024 pref medium
local 2000::2 dev lo table local src ... metric 1024 mtu 2000 pref medium
# ip link set dev lo mtu 65535
# ip -6 route get 2000::1; ip -6 route get 2000::2
local 2000::1 dev lo table local src ... metric 1024 pref medium
local 2000::2 dev lo table local src ... metric 1024 mtu 2000 pref medium
# ip link set dev lo mtu 1501
# ip -6 route get 2000::1; ip -6 route get 2000::2
local 2000::1 dev lo table local src ... metric 1024 pref medium
local 2000::2 dev lo table local src ... metric 1024 mtu 1501 pref medium
# ip link set dev lo mtu 65536
# ip -6 route get 2000::1; ip -6 route get 2000::2
local 2000::1 dev lo table local src ... metric 1024 pref medium
local 2000::2 dev lo table local src ... metric 1024 mtu 65536 pref medium
# ip -6 route del local 2000::1
# ip -6 route del local 2000::2
This is desirable because changing device mtu and then resetting it
to the previous value shouldn't change the user visible routing table.
Signed-off-by: Maciej Żenczykowski <maze@google.com>
CC: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/route.c')
| -rw-r--r-- | net/ipv6/route.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 7403d90dcb38..1b57e11e6e0d 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -2761,6 +2761,7 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg) PMTU discouvery. */ if (rt->dst.dev == arg->dev && + dst_metric_raw(&rt->dst, RTAX_MTU) && !dst_metric_locked(&rt->dst, RTAX_MTU)) { if (rt->rt6i_flags & RTF_CACHE) { /* For RTF_CACHE with rt6i_pmtu == 0 |