[ovs-dev] [PACKET_OUT v2] ofproto-dpif: treat non-datapath ports as local port for OFPT_PACKET_OUT

[YAMAMOTO Takashi]

> On Wed, Apr 30, 2014 at 11:59 PM, YAMAMOTO Takashi
> <yamamoto at valinux.co.jp> wrote:
>>>> Something like this (I have not tested either scenario):
>>>>
>>>>   I think this will fail to match but that may not be obvious to users:
>>>>   packet_out: in_port=CONTROLLER actions=goto_table:1
>>>>   table 1: match=in_port=CONTROLLER actions=normal
>>>>
>>>>   I think this will match but that may not be obvious to users:
>>>>   packet_out: in_port=CONTROLLER actions=goto_table:1
>>>>   table 1: match=in_port=LOCAL actions=normal
>>>>
>>>>   Where CONTROLLER could be any port covered by this patch.
>>>>
>>> Only ODP ports are changed to LOCAL, so simple rule matches as
>>> outlined should work.
>>> However, this scenario is valid when recirculation is involved. I am
>>> not sure what we should
>>> do about this edge case either.
>>
>> how about having a userspace-only special variant of RECIRC action,
>> which can specify in_port as (ofproto, ofp port) and thus can be
>> used even when odp port is not available?
>>
>> if a translation detects the condition (ie. recirculation is necessary
>> but in_port does not have the corresponding odp port), it can use
>> the userspace variant with SLOW_ACTION instead of normal RECIRC.
> 
> Not all actions can be executed in the user space. Hash action can
> only be executed
> in datapath. User space, by design, can not predict the hash value
> computed by the
> datapath.

then HASH action ought to be handle specially.  (like OUTPUT?)

the current code seems broken in that regard.
if some SLOW_ACTIONs are involved, the upcall hander would
use DPIF_OP_EXECUTE with needs_help=true, which ends up with
dpif_execute_with_help, to execute actions, which might include
HASH and RECIRC.  but dpif_execute_helper_cb can't handle these
actions.  ie. OVS_NOT_REACHED in dpif_execute_helper_cb seems
actually reachable.

YAMAMOTO Takashi

>>
>> YAMAMOTO Takashi
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