Re: [ovs-dev] [PATCH net] Revert "openvswitch: switch to per-action label counting in conntrack"

[Jianbo Liu via dev]

On 3/12/2025 10:25 PM, Aaron Conole wrote:

Xin Long <lucien....@gmail.com> writes:

Currently, ovs_ct_set_labels() is only called for confirmed conntrack
entries (ct) within ovs_ct_commit(). However, if the conntrack entry
does not have the labels_ext extension, attempting to allocate it in
ovs_ct_get_conn_labels() for a confirmed entry triggers a warning in
nf_ct_ext_add():

   WARN_ON(nf_ct_is_confirmed(ct));

This happens when the conntrack entry is created externally before OVS
increments net->ct.labels_used. The issue has become more likely since
commit fcb1aa5163b1 ("openvswitch: switch to per-action label counting
in conntrack"), which changed to use per-action label counting and
increment net->ct.labels_used when a flow with ct action is added.

Since there’s no straightforward way to fully resolve this issue at the
moment, this reverts the commit to avoid breaking existing use cases.

Fixes: fcb1aa5163b1 ("openvswitch: switch to per-action label counting in 
conntrack")
Reported-by: Jianbo Liu <jian...@nvidia.com>
Signed-off-by: Xin Long <lucien....@gmail.com>
---

I did a quick test using the case provided by Jianbo and I wasn't able
to generate the warning.  If possible, I'd like Jianbo to confirm that
it works as well.

Yes, it works. The warning is gone after applying this revert. Thanks!

Acked-by: Aaron Conole <acon...@redhat.com>

  net/openvswitch/conntrack.c | 30 ++++++++++++++++++------------
  net/openvswitch/datapath.h  |  3 +++
  2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index 3bb4810234aa..e573e9221302 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -1368,8 +1368,11 @@ bool ovs_ct_verify(struct net *net, enum ovs_key_attr 
attr)
            attr == OVS_KEY_ATTR_CT_MARK)
                return true;
        if (IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS) &&
-           attr == OVS_KEY_ATTR_CT_LABELS)
-               return true;
+           attr == OVS_KEY_ATTR_CT_LABELS) {
+               struct ovs_net *ovs_net = net_generic(net, ovs_net_id);
+
+               return ovs_net->xt_label;
+       }

return false;

  }
@@ -1378,7 +1381,6 @@ int ovs_ct_copy_action(struct net *net, const struct 
nlattr *attr,
                       const struct sw_flow_key *key,
                       struct sw_flow_actions **sfa,  bool log)
  {
-       unsigned int n_bits = sizeof(struct ovs_key_ct_labels) * BITS_PER_BYTE;
        struct ovs_conntrack_info ct_info;
        const char *helper = NULL;
        u16 family;
@@ -1407,12 +1409,6 @@ int ovs_ct_copy_action(struct net *net, const struct 
nlattr *attr,
                return -ENOMEM;
        }

- if (nf_connlabels_get(net, n_bits - 1)) {

-               nf_ct_tmpl_free(ct_info.ct);
-               OVS_NLERR(log, "Failed to set connlabel length");
-               return -EOPNOTSUPP;
-       }
-
        if (ct_info.timeout[0]) {
                if (nf_ct_set_timeout(net, ct_info.ct, family, key->ip.proto,
                                      ct_info.timeout))
@@ -1581,7 +1577,6 @@ static void __ovs_ct_free_action(struct 
ovs_conntrack_info *ct_info)
        if (ct_info->ct) {
                if (ct_info->timeout[0])
                        nf_ct_destroy_timeout(ct_info->ct);
-               nf_connlabels_put(nf_ct_net(ct_info->ct));
                nf_ct_tmpl_free(ct_info->ct);
        }
  }
@@ -2006,9 +2001,17 @@ struct genl_family dp_ct_limit_genl_family 
__ro_after_init = {

int ovs_ct_init(struct net *net)

  {
-#if    IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
+       unsigned int n_bits = sizeof(struct ovs_key_ct_labels) * BITS_PER_BYTE;
        struct ovs_net *ovs_net = net_generic(net, ovs_net_id);

+ if (nf_connlabels_get(net, n_bits - 1)) {

+               ovs_net->xt_label = false;
+               OVS_NLERR(true, "Failed to set connlabel length");
+       } else {
+               ovs_net->xt_label = true;
+       }
+
+#if    IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
        return ovs_ct_limit_init(net, ovs_net);
  #else
        return 0;
@@ -2017,9 +2020,12 @@ int ovs_ct_init(struct net *net)

void ovs_ct_exit(struct net *net)

  {
-#if    IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
        struct ovs_net *ovs_net = net_generic(net, ovs_net_id);

+#if IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)

        ovs_ct_limit_exit(net, ovs_net);
  #endif
+
+       if (ovs_net->xt_label)
+               nf_connlabels_put(net);
  }
diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h
index 365b9bb7f546..9ca6231ea647 100644
--- a/net/openvswitch/datapath.h
+++ b/net/openvswitch/datapath.h
@@ -160,6 +160,9 @@ struct ovs_net {
  #if   IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
        struct ovs_ct_limit_info *ct_limit_info;
  #endif
+
+       /* Module reference for configuring conntrack. */
+       bool xt_label;
  };

/**

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