> 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… Jarno _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev