On 25 November 2015 at 15:06, Jarno Rajahalme <ja...@ovn.org> wrote: > >> On Nov 25, 2015, at 2:58 PM, Joe Stringer <j...@ovn.org> wrote: >> >> On 25 November 2015 at 11:23, Jarno Rajahalme <ja...@ovn.org >> <mailto:ja...@ovn.org>> wrote: >>> >>> On Nov 25, 2015, at 11:11 AM, Jarno Rajahalme <ja...@ovn.org> wrote: >>> >>> >>> On Nov 25, 2015, at 10:52 AM, Joe Stringer <j...@ovn.org> wrote: >>> >>> On 25 November 2015 at 10:31, Jarno Rajahalme <ja...@ovn.org> wrote: >>> >>> >>> On Nov 24, 2015, at 5:02 PM, Joe Stringer <j...@ovn.org> wrote: >>> >>> On 24 November 2015 at 13:41, Jarno Rajahalme <ja...@ovn.org> 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 <ja...@ovn.org> >>> >>> >>> 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 <j...@ovn.org> _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
