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authorPaolo Abeni <pabeni@redhat.com>2019-02-20 18:18:12 +0100
committerDavid S. Miller <davem@davemloft.net>2019-02-22 11:45:25 -0800
commitf5b51fe804ec2a6edce0f8f6b11ea57283f5857b (patch)
tree981c1f44beabf65f1e20d84a710e3905c0ae2f2f
parentaaaf59851abba6900d37bd6e8be9968e72a0a187 (diff)
ipv6: route: purge exception on removal
When a netdevice is unregistered, we flush the relevant exception via rt6_sync_down_dev() -> fib6_ifdown() -> fib6_del() -> fib6_del_route(). Finally, we end-up calling rt6_remove_exception(), where we release the relevant dst, while we keep the references to the related fib6_info and dev. Such references should be released later when the dst will be destroyed. There are a number of caches that can keep the exception around for an unlimited amount of time - namely dst_cache, possibly even socket cache. As a result device registration may hang, as demonstrated by this script: ip netns add cl ip netns add rt ip netns add srv ip netns exec rt sysctl -w net.ipv6.conf.all.forwarding=1 ip link add name cl_veth type veth peer name cl_rt_veth ip link set dev cl_veth netns cl ip -n cl link set dev cl_veth up ip -n cl addr add dev cl_veth 2001::2/64 ip -n cl route add default via 2001::1 ip -n cl link add tunv6 type ip6tnl mode ip6ip6 local 2001::2 remote 2002::1 hoplimit 64 dev cl_veth ip -n cl link set tunv6 up ip -n cl addr add 2013::2/64 dev tunv6 ip link set dev cl_rt_veth netns rt ip -n rt link set dev cl_rt_veth up ip -n rt addr add dev cl_rt_veth 2001::1/64 ip link add name rt_srv_veth type veth peer name srv_veth ip link set dev srv_veth netns srv ip -n srv link set dev srv_veth up ip -n srv addr add dev srv_veth 2002::1/64 ip -n srv route add default via 2002::2 ip -n srv link add tunv6 type ip6tnl mode ip6ip6 local 2002::1 remote 2001::2 hoplimit 64 dev srv_veth ip -n srv link set tunv6 up ip -n srv addr add 2013::1/64 dev tunv6 ip link set dev rt_srv_veth netns rt ip -n rt link set dev rt_srv_veth up ip -n rt addr add dev rt_srv_veth 2002::2/64 ip netns exec srv netserver & sleep 0.1 ip netns exec cl ping6 -c 4 2013::1 ip netns exec cl netperf -H 2013::1 -t TCP_STREAM -l 3 & sleep 1 ip -n rt link set dev rt_srv_veth mtu 1400 wait %2 ip -n cl link del cl_veth This commit addresses the issue purging all the references held by the exception at time, as we currently do for e.g. ipv6 pcpu dst entries. v1 -> v2: - re-order the code to avoid accessing dst and net after dst_dev_put() Fixes: 93531c674315 ("net/ipv6: separate handling of FIB entries from dst based routes") Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv6/route.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 74b9b6fd4168..047c47224dba 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1274,18 +1274,29 @@ static DEFINE_SPINLOCK(rt6_exception_lock);
static void rt6_remove_exception(struct rt6_exception_bucket *bucket,
struct rt6_exception *rt6_ex)
{
+ struct fib6_info *from;
struct net *net;
if (!bucket || !rt6_ex)
return;
net = dev_net(rt6_ex->rt6i->dst.dev);
+ net->ipv6.rt6_stats->fib_rt_cache--;
+
+ /* purge completely the exception to allow releasing the held resources:
+ * some [sk] cache may keep the dst around for unlimited time
+ */
+ from = rcu_dereference_protected(rt6_ex->rt6i->from,
+ lockdep_is_held(&rt6_exception_lock));
+ rcu_assign_pointer(rt6_ex->rt6i->from, NULL);
+ fib6_info_release(from);
+ dst_dev_put(&rt6_ex->rt6i->dst);
+
hlist_del_rcu(&rt6_ex->hlist);
dst_release(&rt6_ex->rt6i->dst);
kfree_rcu(rt6_ex, rcu);
WARN_ON_ONCE(!bucket->depth);
bucket->depth--;
- net->ipv6.rt6_stats->fib_rt_cache--;
}
/* Remove oldest rt6_ex in bucket and free the memory