Re: [ovs-dev] [PATCHv11 net-next 2/2] openvswitch: Add support for unique flow IDs.

[Joe Stringer <joestringer@nicira.com>]

On 9 December 2014 at 22:11, Pravin Shelar <pshelar@nicira.com> wrote:
> On Tue, Dec 9, 2014 at 4:25 PM, Joe Stringer <joestringer@nicira.com> wrote:
>> On 9 December 2014 at 10:32, Pravin Shelar <pshelar@nicira.com> wrote:
>>> On Tue, Dec 2, 2014 at 6:56 PM, Joe Stringer <joestringer@nicira.com> wrote:
>>>> @@ -424,10 +475,9 @@ static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
>>>>         ovs_flow_mask_key(&masked_key, unmasked, mask);
>>>>         hash = flow_hash(&masked_key, key_start, key_end);
>>>>         head = find_bucket(ti, hash);
>>>> -       hlist_for_each_entry_rcu(flow, head, hash_node[ti->node_ver]) {
>>>> -               if (flow->mask == mask && flow->hash == hash &&
>>>> -                   flow_cmp_masked_key(flow, &masked_key,
>>>> -                                         key_start, key_end))
>>>> +       hlist_for_each_entry_rcu(flow, head, flow_hash.node[ti->node_ver]) {
>>>> +               if (flow->mask == mask && flow->flow_hash.hash == hash &&
>>>> +                   flow_cmp_masked_key(flow, &masked_key, key_start, key_end))
>>>>                         return flow;
>>>>         }
>>>>         return NULL;
>>>> @@ -469,7 +519,40 @@ struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,
>>>>         /* Always called under ovs-mutex. */
>>>>         list_for_each_entry(mask, &tbl->mask_list, list) {
>>>>                 flow = masked_flow_lookup(ti, match->key, mask);
>>>> -               if (flow && ovs_flow_cmp_unmasked_key(flow, match))  /* Found */
>>>> +               if (flow && !flow->ufid &&
>>> why not NULL check for flow->unmasked_key here rather than ufid?
>>
>> In this version, I tried to consistently use flow->ufid as the switch
>> for whether UFID exists or not. In the next version, this statement
>> would refer to flow->id->ufid_len.
>>
>> The current approach means that ovs_flow_tbl_lookup_exact() is really
>> ovs_flow_tbl_lookup_unmasked_key(). Do you think this should remain
>> specific to unmasked key or should it be made to check that the
>> identifier (ufid OR unmasked key) is the same?
>
> It is easier to read code if we check for flow->unmasked_key here.
> ovs_flow_cmp_unmasked_key() has assert on ufid anyways.

With the change to put UFID/unmasked key in the same struct, there
will be no such pointer to check, only ufid_len.

However, we could shift this check at the start of the function instead.