Re: [PATCHv3 net-next 06/10] openvswitch: Allow matching on conntrack mark

[Joe Stringer]

On 12 August 2015 at 16:00, Pravin Shelar <pshelar@xxxxxxxxxx> wrote:
> On Tue, Aug 11, 2015 at 3:59 PM, Joe Stringer <joestringer@xxxxxxxxxx> wrote:
>> From: Justin Pettit <jpettit@xxxxxxxxxx>
>>
>> Allow matching and setting the conntrack mark field. As with conntrack
>> state and zone, these are populated by executing the ct() action. Unlike
>> these, the ct_mark is also a writable field. The set_field() action may
>> be used to modify the mark, which will take effect on the most recent
>> conntrack entry.
>>
>> E.g.: actions:ct(zone=0),ct(zone=1),set_field(1->ct_mark)
>>
>> This will perform conntrack lookup in zone 0, then lookup in zone 1,
>> then modify the mark for the entry in zone 1. The mark for the entry in
>> zone 0 is unchanged. The conntrack entry itself must be committed using
>> the "commit" flag in the conntrack action flags for this change to persist.
>>
>> Signed-off-by: Justin Pettit <jpettit@xxxxxxxxxx>
>> Signed-off-by: Joe Stringer <joestringer@xxxxxxxxxx>
>> ---
> ...
>
>>
>> +int ovs_ct_set_mark(struct sk_buff *skb, struct sw_flow_key *key,
>> +                   u32 ct_mark, u32 mask)
>> +{
>> +#ifdef CONFIG_NF_CONNTRACK_MARK
>> +       enum ip_conntrack_info ctinfo;
>> +       struct nf_conn *ct;
>> +       u32 new_mark;
>> +
>> +       /* This must happen directly after lookup/commit. */
>> +       ct = nf_ct_get(skb, &ctinfo);
>> +       if (!ct)
>> +               return -EINVAL;
>> +
>> +       new_mark = ct_mark | (ct->mark & ~(mask));
>> +       if (ct->mark != new_mark) {
>> +               ct->mark = new_mark;
>> +               nf_conntrack_event_cache(IPCT_MARK, ct);
>> +               key->ct.mark = ct_mark;
>> +       }
>> +
>
> Is it fine to set just set mark and not initialize reset of key->ct members?

I don't quite follow. This action acts upon the current connection,
and modifies its metadata. key->ct should already be populated with
the existing connection info.
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