On 25 November 2015 at 15:12, Joe Stringer <[email protected]> wrote: > On 25 November 2015 at 15:06, Jarno Rajahalme <[email protected]> wrote: >> >>> On Nov 25, 2015, at 2:58 PM, Joe Stringer <[email protected]> wrote: >>> >>> On 25 November 2015 at 11:23, Jarno Rajahalme <[email protected] >>> <mailto:[email protected]>> wrote: >>>> >>>> On Nov 25, 2015, at 11:11 AM, Jarno Rajahalme <[email protected]> wrote: >>>> >>>> >>>> On Nov 25, 2015, at 10:52 AM, Joe Stringer <[email protected]> wrote: >>>> >>>> On 25 November 2015 at 10:31, Jarno Rajahalme <[email protected]> wrote: >>>> >>>> >>>> On Nov 24, 2015, at 5:02 PM, Joe Stringer <[email protected]> wrote: >>>> >>>> On 24 November 2015 at 13:41, Jarno Rajahalme <[email protected]> wrote: >>>> >>>> Sometimes xlate_actions() fails due to too deep recursion, too many >>>> MPLS labels, or missing recirculation context. Make xlate_actions() >>>> clear out the produced odp actions in these cases to make it easy for >>>> the caller to install a drop flow (instead or installing a flow with >>>> partially translated actions). Also, return a specific error code, so >>>> that the error can be properly propagated where meaningful. >>>> >>>> Before this patch it was possible that the revalidation installed a >>>> flow with a recirculation ID with an invalid recirc ID (== 0), due to >>>> the introduction of in-place modification in commit 43b2f131a229 >>>> (ofproto: Allow in-place modifications of datapath flows). >>>> >>>> Signed-off-by: Jarno Rajahalme <[email protected]> >>>> >>>> >>>> Should this also set the error when receiving packets on a mirror port >>>> in xlate_actions()? Or when receiving tagged VLAN traffic that doesn't >>>> correspond to the port's vlan tag? Or when a group has no live bucket? >>>> Are there any other cases that should also be covered? (I just scanned >>>> across ofproto/ofproto-dpif-xlate.c looking for cases where we're >>>> already logging that we drop the packet, but maybe there's a reasoning >>>> behind not including these - if so, please enlighten me) >>>> >>>> >>>> No reasoning for missing those, I just did not notice them. Thanks for >>>> pointing them out. >>>> >>>> >>>> OK, I thought it may have been something like "expected errors" vs. >>>> "unexpected errors". >>>> >>>> >>>> Looking into these I noticed this to be the case. Must discern whether to >>>> fail just the individual action v.s. the whole pipeline. >>>> >>>> >>>> How about this incremental to cover two cases here (rest are “expected >>>> errors” IMO): >>>> >>>> diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c >>>> index 36a6fbc..2908339 100644 >>>> --- a/ofproto/ofproto-dpif-xlate.c >>>> +++ b/ofproto/ofproto-dpif-xlate.c >>>> @@ -336,6 +336,10 @@ const char *xlate_strerror(enum xlate_error error) >>>> return "Recirculation conflict"; >>>> case XLATE_TOO_MANY_MPLS_LABELS: >>>> return "Too many MPLS labels"; >>>> + case XLATE_BUCKET_CHAINING_TOO_DEEP: >>>> + return "Bucket chaining too deep"; >>>> + case XLATE_NO_INPUT_BUNDLE: >>>> + return "No input bundle"; >>>> } >>>> return "Unknown error"; >>>> } >>>> @@ -1444,10 +1448,9 @@ bucket_is_alive(const struct xlate_ctx *ctx, >>>> struct ofputil_bucket *bucket, int depth) >>>> { >>>> if (depth >= MAX_LIVENESS_RECURSION) { >>>> - static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1); >>>> - >>>> - VLOG_WARN_RL(&rl, "bucket chaining exceeded %d links", >>>> - MAX_LIVENESS_RECURSION); >>>> + XLATE_REPORT_ERROR(ctx, "bucket chaining exceeded %d links", >>>> + MAX_LIVENESS_RECURSION); >>>> + ctx->error = XLATE_BUCKET_CHAINING_TOO_DEEP; >>>> return false; >>>> } >>>> >>>> @@ -2323,7 +2326,8 @@ xlate_normal(struct xlate_ctx *ctx) >>>> in_xbundle = lookup_input_bundle(ctx->xbridge, flow->in_port.ofp_port, >>>> ctx->xin->packet != NULL, &in_port); >>>> if (!in_xbundle) { >>>> - xlate_report(ctx, "no input bundle, dropping"); >>>> + XLATE_REPORT_ERROR(ctx, "no input bundle, dropping"); >>>> + ctx->error = XLATE_NO_INPUT_BUNDLE; >>>> return; >>>> } >>>> >>>> >>>> The last one is debatable, as setting the error fails the whole translation >>>> rather than just the normal action. But this is most likely an >>>> configuration >>>> error, so maybe failing the whole pipeline (and installing a drop flow) is >>>> the right thing to do here? >>> >>> Jarno and I discussed this offline, and I'll try to summarise here. >>> Broadly speaking, we're talking about the decision between failing an >>> individual (piece of an) action or completely failing the action >>> processing for the flow. And I think arguably the approach should be >>> that if it is a serious error such as running out of resources or an >>> internal conflict of recirc IDs, then we should fail the entire action >>> processing. In this case it will have two user-visible effects: >>> 1) ofproto/trace will tell the user which serious condition is being >>> triggered that causes dropping of the flow >>> 2) OpenFlow controllers attempting packet_out could be notified that >>> the error occurred (rather than silently failing like currently) >>> >>> However, in the two cases in the incremental patch here, the actions >>> inherently have some ambiguity as to whether they successfully execute >>> (eg output) or not. The more obvious case is in the bucket_is_alive() >>> logic, where recursion will cause a bucket to be not used. If a bucket >>> is not live in the spec, this doesn't mean that the entire flow should >>> stop processing. In the case of normal, I'd argue it's very similar in >>> that 'normal' doesn't specifically attempt to output to a particular >>> port; sending packets out to different ports may fail for different >>> reasons, but this shouldn't prevent later actions in the actions list >>> from being executed. >>> >>> I think the latter cases should be reported for ofproto/trace, though. >>> >>> Looking back across this thread, it looks not far off your reasoning >>> described earlier so I think we're converging on the same view. Does >>> this sound like a fair approach? >>> >>> -- >>> >>> In the mirror case, the point is moot because do_xlate_actions() isn't >>> even called in that case, so it's purely a matter of whether we want >>> to return the error up the stack or not. Maybe that should be reported >>> for ofproto/trace as well. >>> >>> I didn't see any other cases that might need handling through this. >> >> So the only ask I see here is that more of the cases of individual actions >> bailing out should have xlate_report() calls on them. To me this sounds like >> a different patch, not directly related to erroring out the whole >> translation. As such I hope to get an Ack on the original patch of this now >> lengthy discussion… > > I agree. > > Acked-by: Joe Stringer <[email protected]>
Ah, mismatch between my sender email an the ack. Here: Acked-by: Joe Stringer <[email protected]> _______________________________________________ dev mailing list [email protected] http://openvswitch.org/mailman/listinfo/dev
