> On Aug 29, 2016, at 2:07 PM, Ben Pfaff <[email protected]> wrote:
>
> On Mon, Aug 22, 2016 at 04:31:28PM -0700, Jarno Rajahalme wrote:
>> OVS implementation of buffering packets that are sent to the
>> controller is not compliant with the OpenFlow specifications after
>> OpenFlow 1.0, which is possibly true since OpenFlow 1.0 is not really
>> specifying the packet buffering behavior.
>>
>> OVS implementation executes the buffered packet against the actions of
>> the modified or added rule, whereas OpenFlow (since 1.1) specifies
>> that the packet should be matched against the flow table 0 and
>> processed accordingly.
>>
>> Rather than fix this behavior, and potentially break OVS users, we
>> propose to remove the feature altogether. After all, such packet
>> buffering is an optional OpenFlow feature, and as such any possible
>> users should continue to work without this feature.
>>
>> This patch also makes OVS check the received 'buffer_id' values more
>> rigorously, and fixes some internal users accordingly.
>>
>> Signed-off-by: Jarno Rajahalme <[email protected]>
>
> I believe that this came out of a bug report. Will you credit the bug
> reporter?
>
I noticed this when checking back to OpenFlow specs when developing the split
late/execute for buffered packets and packet outs, so there is no bug report.
I'll state “Found by inspection” in the commit message.
> I think that we will probably start getting a question about "what
> happened to the buffers?" so it might be worthwhile to add a question
> and answer to the FAQ about that.
>
Done.
> The change to lib/learn.c seems unnecessary.
>
Right, it was a combination of two changes made at different times cancelling
out each other.
> I'd be inclined to also remove the buffer_id parameters from the
> functions that ofputil_encode_packet_in_private() calls. They're always
> going to be UINT32_MAX now.
>
I should leave the NXPINT_BUFFER_ID definition be even though we now never
encode it, however?
> In ofputil_encode_packet_in_private(), here:
> if (check_buffer_id && fm->buffer_id != UINT32_MAX) {
> error = OFPERR_OFPBRC_BUFFER_UNKNOWN;
> }
> I would add "!error &&" to the condition, because I think that this
> error is less important than the others.
>
This was in ofproto.c:ofproto_flow_mod_init(), but I changed this like you
suggested.
> The changes to ofctrl.c should not be necessary, because the
> encode_flow_mod() function that all of the cases use already sets
> buffer_id to UINT32_MAX.
>
Right, reverted.
> Acked-by: Ben Pfaff <[email protected] <mailto:[email protected]>>
Thanks for the thorough review! Pushed to master with these revisions.
Jarno
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