Signed-off-by: Ben Pfaff <b...@ovn.org> --- ofproto/ofproto-dpif-xlate.c | 267 +++++++++++++++++++++++-------------------- 1 file changed, 143 insertions(+), 124 deletions(-)
diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c index f48c5ac..009d8e5 100644 --- a/ofproto/ofproto-dpif-xlate.c +++ b/ofproto/ofproto-dpif-xlate.c @@ -210,36 +210,58 @@ struct xlate_ctx { bool exit; /* No further actions should be processed. */ mirror_mask_t mirrors; /* Bitmap of associated mirrors. */ - /* These are used for non-bond recirculation. The recirculation IDs are - * stored in xout and must be associated with a datapath flow (ukey), - * otherwise they will be freed when the xout is uninitialized. + /* Freezing Translation + * ==================== * + * At some point during translation, the code may recognize the need to halt + * and checkpoint the translation in a way that it can be restarted again + * later. We call the checkpointing process "freezing" and the restarting + * process "thawing". * - * Steps in Recirculation Translation - * ================================== + * The use cases for freezing are: * - * At some point during translation, the code recognizes the need for - * recirculation. For example, recirculation is necessary when, after - * popping the last MPLS label, an action or a match tries to examine or - * modify a field that has been newly revealed following the MPLS label. + * - "Recirculation", where the translation process discovers that it + * doesn't have enough information to complete translation without + * actually executing the actions that have already been translated, + * which provides the additionally needed information. In these + * situations, translation freezes translation and assigns the frozen + * data a unique "recirculation ID", which it associates with the data + * in a table in userspace (see ofproto-dpif-rid.h). It also adds a + * OVS_ACTION_ATTR_RECIRC action specifying that ID to the datapath + * actions. When a packet hits that action, the datapath looks its + * flow up again using the ID. If there's a miss, it comes back to + * userspace, which find the recirculation table entry for the ID, + * thaws the associated frozen data, and continues translation from + * that point given the additional information that is now known. * - * The simplest part of the work to be done is to commit existing changes to - * the packet, which produces datapath actions corresponding to the changes, - * and after this, add an OVS_ACTION_ATTR_RECIRC datapath action. + * The archetypal example is MPLS. As MPLS is implemented in + * OpenFlow, the protocol that follows the last MPLS label becomes + * known only when that label is popped by an OpenFlow action. That + * means that Open vSwitch can't extract the headers beyond the MPLS + * labels until the pop action is executed. Thus, at that point + * translation uses the recirculation process to extract the headers + * beyond the MPLS labels. * - * The main problem here is preserving state. When the datapath executes - * OVS_ACTION_ATTR_RECIRC, it will upcall to userspace to get a translation - * for the post-recirculation actions. At this point userspace has to - * resume the translation where it left off, which means that it has to - * execute the following: + * (OVS also uses OVS_ACTION_ATTR_RECIRC to implement hashing for + * output to bonds. OVS pre-populates all the datapath flows for bond + * output in the datapath, though, which means that the elaborate + * process of coming back to userspace for a second round of + * translation isn't needed, and so bonds don't follow the above + * process.) * - * - The action that prompted recirculation, and any actions following - * it within the same flow. * - * - If the action that prompted recirculation was invoked within a - * NXAST_RESUBMIT, then any actions following the resubmit. These - * "resubmit"s can be nested, so this has to go all the way up the - * control stack. + * The main problem of freezing translation is preserving state, so that + * when the translation is thawed later it resumes from where it left off, + * without disruption. In particular, actions must be preserved as follows: + * + * - If we're freezing because an action needed more information, the + * action that prompted it. + * + * - Any actions remaining to be translated within the current flow. + * + * - If translation was frozen within a NXAST_RESUBMIT, then any actions + * following the resubmit action. Resubmit actions can be nested, so + * this has to go all the way up the control stack. * * - The OpenFlow 1.1+ action set. * @@ -248,47 +270,47 @@ struct xlate_ctx { * * - Metadata fields (input port, registers, OF1.1+ metadata, ...). * - * - Action set, stack + * - The stack used by NXAST_STACK_PUSH and NXAST_STACK_POP actions. * * - The table ID and cookie of the flow being translated at each level - * of the control stack (since OFPAT_CONTROLLER actions send these to - * the controller). + * of the control stack, because these can become visible through + * OFPAT_CONTROLLER actions (and other ways). * * Translation allows for the control of this state preservation via these - * members. When a need for recirculation is identified, the translation - * process: + * members. When a need to freeze translation is identified, the + * translation process: * - * 1. Sets 'recirculating' to true. + * 1. Sets 'freezing' to true. * * 2. Sets 'exit' to true to tell later steps that we're exiting from the * translation process. * - * 3. Adds an OFPACT_UNROLL_XLATE action to 'recirculate_actions', and - * points recirculate_actions.header to the action to make it easy to - * find it later. This action holds the current table ID and cookie so - * that they can be restored during a post-recirculation upcall - * translation. + * 3. Adds an OFPACT_UNROLL_XLATE action to 'frozen_actions', and points + * frozen_actions.header to the action to make it easy to find it later. + * This action holds the current table ID and cookie so that they can be + * restored during a post-recirculation upcall translation. * * 4. Adds the action that prompted recirculation and any actions following - * it within the same flow to 'recirculate_actions', so that they can be + * it within the same flow to 'frozen_actions', so that they can be * executed during a post-recirculation upcall translation. * * 5. Returns. * * 6. The action that prompted recirculation might be nested in a stack of * nested "resubmit"s that have actions remaining. Each of these notices - * that we're exiting and recirculating and responds by adding more - * OFPACT_UNROLL_XLATE actions to 'recirculate_actions', as necessary, - * and any actions that were yet unprocessed. + * that we're exiting and freezing and responds by adding more + * OFPACT_UNROLL_XLATE actions to 'frozen_actions', as necessary, + * followed by any actions that were yet unprocessed. * - * The caller stores all the state produced by this process associated with - * the recirculation ID. For post-recirculation upcall translation, the - * caller passes it back in for the new translation to execute. The - * process yielded a set of ofpacts that can be translated directly, so it - * is not much of a special case at that point. + * If we're freezing because of recirculation, the caller generates a + * recirculation ID and associates all the state produced by this process + * with it. For post-recirculation upcall translation, the caller passes it + * back in for the new translation to execute. The process yielded a set of + * ofpacts that can be translated directly, so it is not much of a special + * case at that point. */ - bool recirculating; - struct ofpbuf recirculate_actions; + bool freezing; + struct ofpbuf frozen_actions; /* True if a packet was but is no longer MPLS (due to an MPLS pop action). * This is a trigger for recirculation in cases where translating an action @@ -298,7 +320,7 @@ struct xlate_ctx { /* True if conntrack has been performed on this packet during processing * on the current bridge. This is used to determine whether conntrack - * state from the datapath should be honored after recirculation. */ + * state from the datapath should be honored after thawing. */ bool conntracked; /* Pointer to an embedded NAT action in a conntrack action, or NULL. */ @@ -343,25 +365,25 @@ static void xlate_action_set(struct xlate_ctx *ctx); static void xlate_commit_actions(struct xlate_ctx *ctx); static void -ctx_trigger_recirculation(struct xlate_ctx *ctx) +ctx_trigger_freeze(struct xlate_ctx *ctx) { ctx->exit = true; - ctx->recirculating = true; + ctx->freezing = true; } static bool -ctx_first_recirculation_action(const struct xlate_ctx *ctx) +ctx_first_frozen_action(const struct xlate_ctx *ctx) { - return !ctx->recirculate_actions.size; + return !ctx->frozen_actions.size; } static void -ctx_cancel_recirculation(struct xlate_ctx *ctx) +ctx_cancel_freeze(struct xlate_ctx *ctx) { - if (ctx->recirculating) { - ctx->recirculating = false; - ofpbuf_clear(&ctx->recirculate_actions); - ctx->recirculate_actions.header = NULL; + if (ctx->freezing) { + ctx->freezing = false; + ofpbuf_clear(&ctx->frozen_actions); + ctx->frozen_actions.header = NULL; } } @@ -2982,10 +3004,10 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port, if (!process_special(ctx, peer) && may_receive(peer, ctx)) { if (xport_stp_forward_state(peer) && xport_rstp_forward_state(peer)) { xlate_table_action(ctx, flow->in_port.ofp_port, 0, true, true); - if (!ctx->recirculating) { + if (!ctx->freezing) { xlate_action_set(ctx); } - if (ctx->recirculating) { + if (ctx->freezing) { compose_recirculate_action(ctx); } } else { @@ -3000,8 +3022,8 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port, ctx->base_flow = old_base_flow; ctx->odp_actions->size = old_size; - /* Undo changes that may have been done for recirculation. */ - ctx_cancel_recirculation(ctx); + /* Undo changes that may have been done for freezing. */ + ctx_cancel_freeze(ctx); } } @@ -3025,9 +3047,8 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port, /* The fact that the peer bridge exits (for any reason) does not mean * that the original bridge should exit. Specifically, if the peer - * bridge recirculates (which typically modifies the packet), the - * original bridge must continue processing with the original, not the - * recirculated packet! */ + * bridge freezes translation, the original bridge must continue + * processing with the original, not the frozen packet! */ ctx->exit = false; /* Peer bridge errors do not propagate back. */ @@ -3239,7 +3260,7 @@ xlate_table_action(struct xlate_ctx *ctx, ofp_port_t in_port, uint8_t table_id, { /* Check if we need to recirculate before matching in a table. */ if (ctx->was_mpls) { - ctx_trigger_recirculation(ctx); + ctx_trigger_freeze(ctx); return; } if (xlate_resubmit_resource_check(ctx)) { @@ -3315,7 +3336,7 @@ xlate_group_bucket(struct xlate_ctx *ctx, struct ofputil_bucket *bucket) ofpbuf_uninit(&action_list); /* Check if need to recirculate. */ - if (ctx->recirculating) { + if (ctx->freezing) { compose_recirculate_action(ctx); } @@ -3341,9 +3362,8 @@ xlate_group_bucket(struct xlate_ctx *ctx, struct ofputil_bucket *bucket) /* The fact that the group bucket exits (for any reason) does not mean that * the translation after the group action should exit. Specifically, if - * the group bucket recirculates (which typically modifies the packet), the - * actions after the group action must continue processing with the - * original, not the recirculated packet! */ + * the group bucket freezes translation, the actions after the group action + * must continue processing with the original, not the frozen packet! */ ctx->exit = false; } @@ -3623,7 +3643,7 @@ compose_recirculate_action__(struct xlate_ctx *ctx, uint8_t table) recirc_metadata_from_flow(&md, &ctx->xin->flow); - ovs_assert(ctx->recirculating); + ovs_assert(ctx->freezing); struct recirc_state state = { .table_id = table, @@ -3633,8 +3653,8 @@ compose_recirculate_action__(struct xlate_ctx *ctx, uint8_t table) .n_stack = ctx->stack.size / sizeof(union mf_subvalue), .mirrors = ctx->mirrors, .conntracked = ctx->conntracked, - .ofpacts = ctx->recirculate_actions.data, - .ofpacts_len = ctx->recirculate_actions.size, + .ofpacts = ctx->frozen_actions.data, + .ofpacts_len = ctx->frozen_actions.size, .action_set = ctx->action_set.data, .action_set_len = ctx->action_set.size, }; @@ -3654,11 +3674,11 @@ compose_recirculate_action__(struct xlate_ctx *ctx, uint8_t table) nl_msg_put_u32(ctx->odp_actions, OVS_ACTION_ATTR_RECIRC, id); - /* Undo changes done by recirculation. */ - ctx_cancel_recirculation(ctx); + /* Undo changes done by freezing. */ + ctx_cancel_freeze(ctx); } -/* Called only when we're recirculating. */ +/* Called only when we're freezing. */ static void compose_recirculate_action(struct xlate_ctx *ctx) { @@ -3673,7 +3693,7 @@ compose_recirculate_action(struct xlate_ctx *ctx) static void compose_recirculate_and_fork(struct xlate_ctx *ctx, uint8_t table) { - ctx->recirculating = true; + ctx->freezing = true; compose_recirculate_action__(ctx, table); } @@ -4125,29 +4145,29 @@ xlate_action_set(struct xlate_ctx *ctx) } static void -recirc_put_unroll_xlate(struct xlate_ctx *ctx) +freeze_put_unroll_xlate(struct xlate_ctx *ctx) { - struct ofpact_unroll_xlate *unroll = ctx->recirculate_actions.header; + struct ofpact_unroll_xlate *unroll = ctx->frozen_actions.header; /* Restore the table_id and rule cookie for a potential PACKET * IN if needed. */ if (!unroll || (ctx->table_id != unroll->rule_table_id || ctx->rule_cookie != unroll->rule_cookie)) { - unroll = ofpact_put_UNROLL_XLATE(&ctx->recirculate_actions); + unroll = ofpact_put_UNROLL_XLATE(&ctx->frozen_actions); unroll->rule_table_id = ctx->table_id; unroll->rule_cookie = ctx->rule_cookie; - ctx->recirculate_actions.header = unroll; + ctx->frozen_actions.header = unroll; } } -/* Copy actions 'a' through 'end' to ctx->recirculate_actions, which will be - * executed after recirculation. UNROLL_XLATE action is inserted, if not - * already done so, before actions that may depend on the current table ID or - * flow cookie. */ +/* Copy actions 'a' through 'end' to ctx->frozen_actions, which will be + * executed after thawing. Inserts an UNROLL_XLATE action, if none is already + * present, before any action that may depend on the current table ID or flow + * cookie. */ static void -recirc_unroll_actions(const struct ofpact *a, const struct ofpact *end, +freeze_unroll_actions(const struct ofpact *a, const struct ofpact *end, struct xlate_ctx *ctx) { for (; a < end; a = ofpact_next(a)) { @@ -4160,14 +4180,14 @@ recirc_unroll_actions(const struct ofpact *a, const struct ofpact *end, case OFPACT_DEC_TTL: /* These actions may generate asynchronous messages, which include * table ID and flow cookie information. */ - recirc_put_unroll_xlate(ctx); + freeze_put_unroll_xlate(ctx); break; case OFPACT_RESUBMIT: if (ofpact_get_RESUBMIT(a)->table_id == 0xff) { /* This resubmit action is relative to the current table, so we * need to track what table that is.*/ - recirc_put_unroll_xlate(ctx); + freeze_put_unroll_xlate(ctx); } break; @@ -4221,13 +4241,13 @@ recirc_unroll_actions(const struct ofpact *a, const struct ofpact *end, continue; } /* Copy the action over. */ - ofpbuf_put(&ctx->recirculate_actions, a, OFPACT_ALIGN(a->len)); + ofpbuf_put(&ctx->frozen_actions, a, OFPACT_ALIGN(a->len)); } } #define CHECK_MPLS_RECIRCULATION() \ if (ctx->was_mpls) { \ - ctx_trigger_recirculation(ctx); \ + ctx_trigger_freeze(ctx); \ break; \ } #define CHECK_MPLS_RECIRCULATION_IF(COND) \ @@ -4416,8 +4436,8 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len, if (ctx->exit) { /* Check if need to store the remaining actions for later * execution. */ - if (ctx->recirculating) { - recirc_unroll_actions(a, ofpact_end(ofpacts, ofpacts_len), + if (ctx->freezing) { + freeze_unroll_actions(a, ofpact_end(ofpacts, ofpacts_len), ctx); } break; @@ -4551,7 +4571,7 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len, break; case OFPACT_RESUBMIT: - /* Recirculation complicates resubmit. There are two cases: + /* Freezing complicates resubmit. There are two cases: * * - If mpls_pop has been executed, then the flow table lookup * as part of resubmit might depend on fields that can only @@ -4563,14 +4583,14 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len, * the post-recirculation actions. * * - Otherwise, some action in the flow entry found by resubmit - * might trigger recirculation. If that happens, then we do - * not want to execute the resubmit again after - * recirculation, so we want to skip back to the head of the - * loop to avoid that, only adding any actions that follow - * the resubmit to the post-recirculation actions. + * might trigger freezing. If that happens, then we do not + * want to execute the resubmit again during thawing, so we + * want to skip back to the head of the loop to avoid that, + * only adding any actions that follow the resubmit to the + * frozen actions. */ if (ctx->was_mpls) { - ctx_trigger_recirculation(ctx); + ctx_trigger_freeze(ctx); break; } xlate_ofpact_resubmit(ctx, ofpact_get_RESUBMIT(a)); @@ -4785,15 +4805,15 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len, break; case OFPACT_DEBUG_RECIRC: - ctx_trigger_recirculation(ctx); + ctx_trigger_freeze(ctx); a = ofpact_next(a); break; } /* Check if need to store this and the remaining actions for later * execution. */ - if (!ctx->error && ctx->exit && ctx_first_recirculation_action(ctx)) { - recirc_unroll_actions(a, ofpact_end(ofpacts, ofpacts_len), ctx); + if (!ctx->error && ctx->exit && ctx_first_frozen_action(ctx)) { + freeze_unroll_actions(a, ofpact_end(ofpacts, ofpacts_len), ctx); break; } } @@ -5070,7 +5090,7 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) union mf_subvalue stack_stub[1024 / sizeof(union mf_subvalue)]; uint64_t action_set_stub[1024 / 8]; - uint64_t recirculate_actions_stub[1024 / 8]; + uint64_t frozen_actions_stub[1024 / 8]; struct flow_wildcards scratch_wc; uint64_t actions_stub[256 / 8]; struct ofpbuf scratch_actions = OFPBUF_STUB_INITIALIZER(actions_stub); @@ -5100,8 +5120,8 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) .error = XLATE_OK, .mirrors = 0, - .recirculating = false, - .recirculate_actions = OFPBUF_STUB_INITIALIZER(recirculate_actions_stub), + .freezing = false, + .frozen_actions = OFPBUF_STUB_INITIALIZER(frozen_actions_stub), .was_mpls = false, .conntracked = false, @@ -5144,7 +5164,7 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) if (xin->recirc) { const struct recirc_state *state = xin->recirc; - xlate_report(&ctx, "Restoring state post-recirculation:"); + xlate_report(&ctx, "Thawing frozen state:"); if (xin->ofpacts_len > 0 || ctx.rule) { static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1); @@ -5166,16 +5186,16 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) if (OVS_UNLIKELY(!new_bridge)) { /* Drop the packet if the bridge cannot be found. */ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1); - VLOG_WARN_RL(&rl, "Recirculation bridge no longer exists."); - xlate_report(&ctx, "- Recirculation bridge no longer exists."); + VLOG_WARN_RL(&rl, "Frozen bridge no longer exists."); + xlate_report(&ctx, "- Frozen bridge no longer exists."); ctx.error = XLATE_BRIDGE_NOT_FOUND; goto exit; } ctx.xbridge = new_bridge; } - /* Set the post-recirculation table id. Note: A table lookup is done - * only if there are no post-recirculation actions. */ + /* Set the thawed table id. Note: A table lookup is done only if there + * are no frozen actions. */ ctx.table_id = state->table_id; xlate_report(&ctx, "- Resuming from table %"PRIu8, ctx.table_id); @@ -5184,8 +5204,7 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) } /* Restore pipeline metadata. May change flow's in_port and other - * metadata to the values that existed when recirculation was - * triggered. */ + * metadata to the values that existed when freezing was triggered. */ recirc_metadata_to_flow(&state->metadata, flow); /* Restore stack, if any. */ @@ -5207,8 +5226,8 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) state->action_set_len); } - /* Restore recirculation actions. If there are no actions, processing - * will start with a lookup in the table set above. */ + /* Restore frozen actions. If there are no actions, processing will + * start with a lookup in the table set above. */ xin->ofpacts = state->ofpacts; xin->ofpacts_len = state->ofpacts_len; if (state->ofpacts_len) { @@ -5252,7 +5271,7 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) struct xport *in_port = get_ofp_port(xbridge, ctx.base_flow.in_port.ofp_port); - /* Tunnel stats only for non-recirculated packets. */ + /* Tunnel stats only for not-thawed packets. */ if (!xin->recirc && in_port && in_port->is_tunnel) { if (ctx.xin->resubmit_stats) { netdev_vport_inc_rx(in_port->netdev, ctx.xin->resubmit_stats); @@ -5272,8 +5291,8 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) if (!xin->recirc && process_special(&ctx, in_port)) { /* process_special() did all the processing for this packet. * - * We do not perform special processing on recirculated packets, as - * recirculated packets are not really received by the bridge.*/ + * We do not perform special processing on thawed packets, since that + * was done before they were frozen and should not be redone. */ } else if (in_port && in_port->xbundle && xbundle_mirror_out(xbridge, in_port->xbundle)) { if (ctx.xin->packet != NULL) { @@ -5283,7 +5302,7 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) ctx.xbridge->name, in_port->xbundle->name); } } else { - /* Sampling is done only for packets really received by the bridge. */ + /* Sampling is done on initial reception; don't redo after thawing. */ unsigned int user_cookie_offset = 0; if (!xin->recirc) { user_cookie_offset = compose_sflow_action(&ctx); @@ -5316,25 +5335,25 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) } /* We've let OFPP_NORMAL and the learning action look at the - * packet, so cancel all actions and recirculation if forwarding is + * packet, so cancel all actions and freezing if forwarding is * disabled. */ if (in_port && (!xport_stp_forward_state(in_port) || !xport_rstp_forward_state(in_port))) { ctx.odp_actions->size = sample_actions_len; - ctx_cancel_recirculation(&ctx); + ctx_cancel_freeze(&ctx); ofpbuf_clear(&ctx.action_set); } - if (!ctx.recirculating) { + if (!ctx.freezing) { xlate_action_set(&ctx); } - if (ctx.recirculating) { + if (ctx.freezing) { compose_recirculate_action(&ctx); } } /* Output only fully processed packets. */ - if (!ctx.recirculating + if (!ctx.freezing && xbridge->has_in_band && in_band_must_output_to_local_port(flow) && !actions_output_to_local_port(&ctx)) { @@ -5358,9 +5377,9 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) ctx.xout->slow |= SLOW_ACTION; } - /* Do netflow only for packets really received by the bridge and not sent - * to the controller. We consider packets sent to the controller to be - * part of the control plane rather than the data plane. */ + /* Do netflow only for packets on initial reception, that are not sent to + * the controller. We consider packets sent to the controller to be part + * of the control plane rather than the data plane. */ if (!xin->recirc && xbridge->netflow && !(xout->slow & SLOW_CONTROLLER)) { if (ctx.xin->resubmit_stats) { netflow_flow_update(xbridge->netflow, flow, @@ -5384,7 +5403,7 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout) exit: ofpbuf_uninit(&ctx.stack); ofpbuf_uninit(&ctx.action_set); - ofpbuf_uninit(&ctx.recirculate_actions); + ofpbuf_uninit(&ctx.frozen_actions); ofpbuf_uninit(&scratch_actions); /* Make sure we return a "drop flow" in case of an error. */ -- 2.1.3 _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev