lib/learning-switch.c

   1 /*
   2  * Copyright (c) 2008-2017 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include "learning-switch.h"
  19
  20 #include <errno.h>
  21 #include <inttypes.h>
  22 #include <sys/types.h>
  23 #include <netinet/in.h>
  24 #include <stdlib.h>
  25 #include <time.h>
  26
  27 #include "byte-order.h"
  28 #include "classifier.h"
  29 #include "dp-packet.h"
  30 #include "flow.h"
  31 #include "openvswitch/hmap.h"
  32 #include "mac-learning.h"
  33 #include "openflow/openflow.h"
  34 #include "openvswitch/ofp-actions.h"
  35 #include "openvswitch/ofp-connection.h"
  36 #include "openvswitch/ofp-errors.h"
  37 #include "openvswitch/ofp-flow.h"
  38 #include "openvswitch/ofp-match.h"
  39 #include "openvswitch/ofp-msgs.h"
  40 #include "openvswitch/ofp-print.h"
  41 #include "openvswitch/ofp-util.h"
  42 #include "openvswitch/ofp-packet.h"
  43 #include "openvswitch/ofp-port.h"
  44 #include "openvswitch/ofp-switch.h"
  45 #include "openvswitch/ofpbuf.h"
  46 #include "openvswitch/vconn.h"
  47 #include "openvswitch/vlog.h"
  48 #include "openvswitch/poll-loop.h"
  49 #include "openvswitch/rconn.h"
  50 #include "openvswitch/shash.h"
  51 #include "simap.h"
  52 #include "timeval.h"
  53
  54 VLOG_DEFINE_THIS_MODULE(learning_switch);
  55
  56 struct lswitch_port {
  57     struct hmap_node hmap_node; /* Hash node for port number. */
  58     ofp_port_t port_no;         /* OpenFlow port number. */
  59     uint32_t queue_id;          /* OpenFlow queue number. */
  60 };
  61
  62 enum lswitch_state {
  63     S_CONNECTING,               /* Waiting for connection to complete. */
  64     S_FEATURES_REPLY,           /* Waiting for features reply. */
  65     S_SWITCHING,                /* Switching flows. */
  66 };
  67
  68 struct lswitch {
  69     struct rconn *rconn;
  70     enum lswitch_state state;
  71
  72     /* If nonnegative, the switch sets up flows that expire after the given
  73      * number of seconds (or never expire, if the value is OFP_FLOW_PERMANENT).
  74      * Otherwise, the switch processes every packet. */
  75     int max_idle;
  76
  77     enum ofputil_protocol protocol;
  78     unsigned long long int datapath_id;
  79     struct mac_learning *ml;    /* NULL to act as hub instead of switch. */
  80     struct flow_wildcards wc;   /* Wildcards to apply to flows. */
  81     bool action_normal;         /* Use OFPP_NORMAL? */
  82
  83     /* Queue distribution. */
  84     uint32_t default_queue;     /* Default OpenFlow queue, or UINT32_MAX. */
  85     struct hmap queue_numbers;  /* Map from port number to lswitch_port. */
  86     struct shash queue_names;   /* Map from port name to lswitch_port. */
  87
  88     /* Number of outgoing queued packets on the rconn. */
  89     struct rconn_packet_counter *queued;
  90
  91     /* If true, do not reply to any messages from the switch (for debugging
  92      * fail-open mode). */
  93     bool mute;
  94
  95     /* Optional "flow mod" requests to send to the switch at connection time,
  96      * to set up the flow table. */
  97     const struct ofputil_flow_mod *default_flows;
  98     size_t n_default_flows;
  99     enum ofputil_protocol usable_protocols;
 100 };
 101
 102 /* The log messages here could actually be useful in debugging, so keep the
 103  * rate limit relatively high. */
 104 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(30, 300);
 105
 106 static void queue_tx(struct lswitch *, struct ofpbuf *);
 107 static void send_features_request(struct lswitch *);
 108
 109 static void lswitch_process_packet(struct lswitch *, const struct ofpbuf *);
 110 static enum ofperr process_switch_features(struct lswitch *,
 111                                            struct ofp_header *);
 112 static void process_packet_in(struct lswitch *, const struct ofp_header *);
 113 static void process_echo_request(struct lswitch *, const struct ofp_header *);
 114
 115 static ofp_port_t get_mac_entry_ofp_port(const struct mac_learning *ml,
 116                                          const struct mac_entry *)
 117     OVS_REQ_RDLOCK(ml->rwlock);
 118 static void set_mac_entry_ofp_port(struct mac_learning *ml,
 119                                    struct mac_entry *, ofp_port_t)
 120     OVS_REQ_WRLOCK(ml->rwlock);
 121
 122 /* Creates and returns a new learning switch whose configuration is given by
 123  * 'cfg'.
 124  *
 125  * 'rconn' is used to send out an OpenFlow features request. */
 126 struct lswitch *
 127 lswitch_create(struct rconn *rconn, const struct lswitch_config *cfg)
 128 {
 129     struct lswitch *sw;
 130     uint32_t ofpfw;
 131
 132     sw = xzalloc(sizeof *sw);
 133     sw->rconn = rconn;
 134     sw->state = S_CONNECTING;
 135     sw->max_idle = cfg->max_idle;
 136     sw->datapath_id = 0;
 137     sw->ml = (cfg->mode == LSW_LEARN
 138               ? mac_learning_create(MAC_ENTRY_DEFAULT_IDLE_TIME)
 139               : NULL);
 140     sw->action_normal = cfg->mode == LSW_NORMAL;
 141
 142     switch (cfg->wildcards) {
 143     case 0:
 144         ofpfw = 0;
 145         break;
 146
 147     case UINT32_MAX:
 148         /* Try to wildcard as many fields as possible, but we cannot
 149          * wildcard all fields.  We need in_port to detect moves.  We need
 150          * Ethernet source and dest and VLAN VID to do L2 learning. */
 151         ofpfw = (OFPFW10_DL_TYPE | OFPFW10_DL_VLAN_PCP
 152                  | OFPFW10_NW_SRC_ALL | OFPFW10_NW_DST_ALL
 153                  | OFPFW10_NW_TOS | OFPFW10_NW_PROTO
 154                  | OFPFW10_TP_SRC | OFPFW10_TP_DST);
 155         break;
 156
 157     default:
 158         ofpfw = cfg->wildcards;
 159         break;
 160     }
 161     ofputil_wildcard_from_ofpfw10(ofpfw, &sw->wc);
 162
 163     sw->default_queue = cfg->default_queue;
 164     hmap_init(&sw->queue_numbers);
 165     shash_init(&sw->queue_names);
 166     if (cfg->port_queues) {
 167         struct simap_node *node;
 168
 169         SIMAP_FOR_EACH (node, cfg->port_queues) {
 170             struct lswitch_port *port = xmalloc(sizeof *port);
 171             hmap_node_nullify(&port->hmap_node);
 172             port->queue_id = node->data;
 173             shash_add(&sw->queue_names, node->name, port);
 174         }
 175     }
 176
 177     sw->default_flows = cfg->default_flows;
 178     sw->n_default_flows = cfg->n_default_flows;
 179     sw->usable_protocols = cfg->usable_protocols;
 180
 181     sw->queued = rconn_packet_counter_create();
 182
 183     return sw;
 184 }
 185
 186 static void
 187 lswitch_handshake(struct lswitch *sw)
 188 {
 189     enum ofputil_protocol protocol;
 190     enum ofp_version version;
 191
 192     send_features_request(sw);
 193
 194     version = rconn_get_version(sw->rconn);
 195     protocol = ofputil_protocol_from_ofp_version(version);
 196     if (version >= OFP13_VERSION) {
 197         /* OpenFlow 1.3 and later by default drop packets that miss in the flow
 198          * table.  Set up a flow to send packets to the controller by
 199          * default. */
 200         struct ofpact_output output;
 201         struct ofpbuf *msg;
 202         int error;
 203
 204         ofpact_init_OUTPUT(&output);
 205         output.port = OFPP_CONTROLLER;
 206         output.max_len = OFP_DEFAULT_MISS_SEND_LEN;
 207
 208         struct ofputil_flow_mod fm = {
 209             .priority = 0,
 210             .table_id = 0,
 211             .command = OFPFC_ADD,
 212             .buffer_id = UINT32_MAX,
 213             .out_port = OFPP_NONE,
 214             .out_group = OFPG_ANY,
 215             .ofpacts = &output.ofpact,
 216             .ofpacts_len = sizeof output,
 217         };
 218         minimatch_init_catchall(&fm.match);
 219         msg = ofputil_encode_flow_mod(&fm, protocol);
 220         minimatch_destroy(&fm.match);
 221
 222         error = rconn_send(sw->rconn, msg, NULL);
 223         if (error) {
 224             VLOG_INFO_RL(&rl, "%s: failed to add default flow (%s)",
 225                          rconn_get_name(sw->rconn), ovs_strerror(error));
 226         }
 227     }
 228     if (sw->default_flows) {
 229         struct ofpbuf *msg = NULL;
 230         int error = 0;
 231         size_t i;
 232
 233         /* If the initial protocol isn't good enough for default_flows, then
 234          * pick one that will work and encode messages to set up that
 235          * protocol.
 236          *
 237          * This could be improved by actually negotiating a mutually acceptable
 238          * flow format with the switch, but that would require an asynchronous
 239          * state machine.  This version ought to work fine in practice. */
 240         if (!(protocol & sw->usable_protocols)) {
 241             enum ofputil_protocol want = rightmost_1bit(sw->usable_protocols);
 242             while (!error) {
 243                 msg = ofputil_encode_set_protocol(protocol, want, &protocol);
 244                 if (!msg) {
 245                     break;
 246                 }
 247                 error = rconn_send(sw->rconn, msg, NULL);
 248             }
 249         }
 250         if (protocol & sw->usable_protocols) {
 251             for (i = 0; !error && i < sw->n_default_flows; i++) {
 252                 msg = ofputil_encode_flow_mod(&sw->default_flows[i], protocol);
 253                 error = rconn_send(sw->rconn, msg, NULL);
 254             }
 255
 256             if (error) {
 257                 VLOG_INFO_RL(&rl, "%s: failed to queue default flows (%s)",
 258                              rconn_get_name(sw->rconn), ovs_strerror(error));
 259             }
 260         } else {
 261             VLOG_INFO_RL(&rl, "%s: failed to set usable protocol",
 262                          rconn_get_name(sw->rconn));
 263         }
 264     }
 265     sw->protocol = protocol;
 266 }
 267
 268 bool
 269 lswitch_is_alive(const struct lswitch *sw)
 270 {
 271     return rconn_is_alive(sw->rconn);
 272 }
 273
 274 /* Destroys 'sw'. */
 275 void
 276 lswitch_destroy(struct lswitch *sw)
 277 {
 278     if (sw) {
 279         struct lswitch_port *node;
 280
 281         rconn_destroy(sw->rconn);
 282         HMAP_FOR_EACH_POP (node, hmap_node, &sw->queue_numbers) {
 283             free(node);
 284         }
 285         shash_destroy(&sw->queue_names);
 286         mac_learning_unref(sw->ml);
 287         rconn_packet_counter_destroy(sw->queued);
 288         free(sw);
 289     }
 290 }
 291
 292 /* Takes care of necessary 'sw' activity, except for receiving packets (which
 293  * the caller must do). */
 294 void
 295 lswitch_run(struct lswitch *sw)
 296 {
 297     int i;
 298
 299     if (sw->ml) {
 300         ovs_rwlock_wrlock(&sw->ml->rwlock);
 301         mac_learning_run(sw->ml);
 302         ovs_rwlock_unlock(&sw->ml->rwlock);
 303     }
 304
 305     rconn_run(sw->rconn);
 306
 307     if (sw->state == S_CONNECTING) {
 308         if (rconn_is_connected(sw->rconn)) {
 309             lswitch_handshake(sw);
 310             sw->state = S_FEATURES_REPLY;
 311         }
 312         return;
 313     }
 314
 315     for (i = 0; i < 50; i++) {
 316         struct ofpbuf *msg;
 317
 318         msg = rconn_recv(sw->rconn);
 319         if (!msg) {
 320             break;
 321         }
 322
 323         if (!sw->mute) {
 324             lswitch_process_packet(sw, msg);
 325         }
 326         ofpbuf_delete(msg);
 327     }
 328 }
 329
 330 void
 331 lswitch_wait(struct lswitch *sw)
 332 {
 333     if (sw->ml) {
 334         ovs_rwlock_rdlock(&sw->ml->rwlock);
 335         mac_learning_wait(sw->ml);
 336         ovs_rwlock_unlock(&sw->ml->rwlock);
 337     }
 338     rconn_run_wait(sw->rconn);
 339     rconn_recv_wait(sw->rconn);
 340 }
 341
 342 /* Processes 'msg', which should be an OpenFlow received on 'rconn', according
 343  * to the learning switch state in 'sw'.  The most likely result of processing
 344  * is that flow-setup and packet-out OpenFlow messages will be sent out on
 345  * 'rconn'.  */
 346 static void
 347 lswitch_process_packet(struct lswitch *sw, const struct ofpbuf *msg)
 348 {
 349     enum ofptype type;
 350     struct ofpbuf b;
 351
 352     b = *msg;
 353     if (ofptype_pull(&type, &b)) {
 354         return;
 355     }
 356
 357     if (sw->state == S_FEATURES_REPLY
 358         && type != OFPTYPE_ECHO_REQUEST
 359         && type != OFPTYPE_FEATURES_REPLY) {
 360         return;
 361     }
 362
 363     if (type == OFPTYPE_ECHO_REQUEST) {
 364         process_echo_request(sw, msg->data);
 365     } else if (type == OFPTYPE_FEATURES_REPLY) {
 366         if (sw->state == S_FEATURES_REPLY) {
 367             if (!process_switch_features(sw, msg->data)) {
 368                 sw->state = S_SWITCHING;
 369             } else {
 370                 rconn_disconnect(sw->rconn);
 371             }
 372         }
 373     } else if (type == OFPTYPE_PACKET_IN) {
 374         process_packet_in(sw, msg->data);
 375     } else if (type == OFPTYPE_FLOW_REMOVED) {
 376         /* Nothing to do. */
 377     } else if (VLOG_IS_DBG_ENABLED()) {
 378         char *s = ofp_to_string(msg->data, msg->size, NULL, NULL, 2);
 379         VLOG_DBG_RL(&rl, "%016llx: OpenFlow packet ignored: %s",
 380                     sw->datapath_id, s);
 381         free(s);
 382     }
 383 }
 384 \f
 385 static void
 386 send_features_request(struct lswitch *sw)
 387 {
 388     struct ofpbuf *b;
 389     int ofp_version = rconn_get_version(sw->rconn);
 390
 391     ovs_assert(ofp_version > 0 && ofp_version < 0xff);
 392
 393     /* Send OFPT_FEATURES_REQUEST. */
 394     b = ofpraw_alloc(OFPRAW_OFPT_FEATURES_REQUEST, ofp_version, 0);
 395     queue_tx(sw, b);
 396
 397     /* Send OFPT_SET_CONFIG. */
 398     struct ofputil_switch_config config = {
 399         .miss_send_len = OFP_DEFAULT_MISS_SEND_LEN
 400     };
 401     queue_tx(sw, ofputil_encode_set_config(&config, ofp_version));
 402 }
 403
 404 static void
 405 queue_tx(struct lswitch *sw, struct ofpbuf *b)
 406 {
 407     int retval = rconn_send_with_limit(sw->rconn, b, sw->queued, 10);
 408     if (retval && retval != ENOTCONN) {
 409         if (retval == EAGAIN) {
 410             VLOG_INFO_RL(&rl, "%016llx: %s: tx queue overflow",
 411                          sw->datapath_id, rconn_get_name(sw->rconn));
 412         } else {
 413             VLOG_WARN_RL(&rl, "%016llx: %s: send: %s",
 414                          sw->datapath_id, rconn_get_name(sw->rconn),
 415                          ovs_strerror(retval));
 416         }
 417     }
 418 }
 419
 420 static enum ofperr
 421 process_switch_features(struct lswitch *sw, struct ofp_header *oh)
 422 {
 423     struct ofputil_switch_features features;
 424     struct ofputil_phy_port port;
 425
 426     struct ofpbuf b = ofpbuf_const_initializer(oh, ntohs(oh->length));
 427     enum ofperr error = ofputil_pull_switch_features(&b, &features);
 428     if (error) {
 429         VLOG_ERR("received invalid switch feature reply (%s)",
 430                  ofperr_to_string(error));
 431         return error;
 432     }
 433
 434     sw->datapath_id = features.datapath_id;
 435
 436     while (!ofputil_pull_phy_port(oh->version, &b, &port)) {
 437         struct lswitch_port *lp = shash_find_data(&sw->queue_names, port.name);
 438         if (lp && hmap_node_is_null(&lp->hmap_node)) {
 439             lp->port_no = port.port_no;
 440             hmap_insert(&sw->queue_numbers, &lp->hmap_node,
 441                         hash_ofp_port(lp->port_no));
 442         }
 443     }
 444     return 0;
 445 }
 446
 447 static ofp_port_t
 448 lswitch_choose_destination(struct lswitch *sw, const struct flow *flow)
 449 {
 450     ofp_port_t out_port;
 451
 452     /* Learn the source MAC. */
 453     if (sw->ml) {
 454         ovs_rwlock_wrlock(&sw->ml->rwlock);
 455         if (mac_learning_may_learn(sw->ml, flow->dl_src, 0)) {
 456             struct mac_entry *mac = mac_learning_insert(sw->ml, flow->dl_src,
 457                                                         0);
 458             if (get_mac_entry_ofp_port(sw->ml, mac)
 459                 != flow->in_port.ofp_port) {
 460                 VLOG_DBG_RL(&rl, "%016llx: learned that "ETH_ADDR_FMT" is on "
 461                             "port %"PRIu32, sw->datapath_id,
 462                             ETH_ADDR_ARGS(flow->dl_src),
 463                             flow->in_port.ofp_port);
 464
 465                 set_mac_entry_ofp_port(sw->ml, mac, flow->in_port.ofp_port);
 466             }
 467         }
 468         ovs_rwlock_unlock(&sw->ml->rwlock);
 469     }
 470
 471     /* Drop frames for reserved multicast addresses. */
 472     if (eth_addr_is_reserved(flow->dl_dst)) {
 473         return OFPP_NONE;
 474     }
 475
 476     out_port = OFPP_FLOOD;
 477     if (sw->ml) {
 478         struct mac_entry *mac;
 479
 480         ovs_rwlock_rdlock(&sw->ml->rwlock);
 481         mac = mac_learning_lookup(sw->ml, flow->dl_dst, 0);
 482         if (mac) {
 483             out_port = get_mac_entry_ofp_port(sw->ml, mac);
 484             if (out_port == flow->in_port.ofp_port) {
 485                 /* Don't send a packet back out its input port. */
 486                 ovs_rwlock_unlock(&sw->ml->rwlock);
 487                 return OFPP_NONE;
 488             }
 489         }
 490         ovs_rwlock_unlock(&sw->ml->rwlock);
 491     }
 492
 493     /* Check if we need to use "NORMAL" action. */
 494     if (sw->action_normal && out_port != OFPP_FLOOD) {
 495         return OFPP_NORMAL;
 496     }
 497
 498     return out_port;
 499 }
 500
 501 static uint32_t
 502 get_queue_id(const struct lswitch *sw, ofp_port_t in_port)
 503 {
 504     const struct lswitch_port *port;
 505
 506     HMAP_FOR_EACH_WITH_HASH (port, hmap_node, hash_ofp_port(in_port),
 507                              &sw->queue_numbers) {
 508         if (port->port_no == in_port) {
 509             return port->queue_id;
 510         }
 511     }
 512
 513     return sw->default_queue;
 514 }
 515
 516 static void
 517 process_packet_in(struct lswitch *sw, const struct ofp_header *oh)
 518 {
 519     struct ofputil_packet_in pi;
 520     uint32_t buffer_id;
 521     uint32_t queue_id;
 522     ofp_port_t out_port;
 523
 524     uint64_t ofpacts_stub[64 / 8];
 525     struct ofpbuf ofpacts;
 526
 527     struct ofputil_packet_out po;
 528     enum ofperr error;
 529
 530     struct dp_packet pkt;
 531     struct flow flow;
 532
 533     error = ofputil_decode_packet_in(oh, true, NULL, NULL, &pi, NULL,
 534                                      &buffer_id, NULL);
 535     if (error) {
 536         VLOG_WARN_RL(&rl, "failed to decode packet-in: %s",
 537                      ofperr_to_string(error));
 538         return;
 539     }
 540
 541     /* Ignore packets sent via output to OFPP_CONTROLLER.  This library never
 542      * uses such an action.  You never know what experiments might be going on,
 543      * though, and it seems best not to interfere with them. */
 544     if (pi.reason != OFPR_NO_MATCH) {
 545         return;
 546     }
 547
 548     /* Extract flow data from 'pi' into 'flow'. */
 549     dp_packet_use_const(&pkt, pi.packet, pi.packet_len);
 550     flow_extract(&pkt, &flow);
 551     flow.in_port.ofp_port = pi.flow_metadata.flow.in_port.ofp_port;
 552     flow.tunnel.tun_id = pi.flow_metadata.flow.tunnel.tun_id;
 553
 554     /* Choose output port. */
 555     out_port = lswitch_choose_destination(sw, &flow);
 556
 557     /* Make actions. */
 558     queue_id = get_queue_id(sw, pi.flow_metadata.flow.in_port.ofp_port);
 559     ofpbuf_use_stack(&ofpacts, ofpacts_stub, sizeof ofpacts_stub);
 560     if (out_port == OFPP_NONE) {
 561         /* No actions. */
 562     } else if (queue_id == UINT32_MAX
 563                || ofp_to_u16(out_port) >= ofp_to_u16(OFPP_MAX)) {
 564         ofpact_put_OUTPUT(&ofpacts)->port = out_port;
 565     } else {
 566         struct ofpact_enqueue *enqueue = ofpact_put_ENQUEUE(&ofpacts);
 567         enqueue->port = out_port;
 568         enqueue->queue = queue_id;
 569     }
 570
 571     /* Prepare packet_out in case we need one. */
 572     po.buffer_id = buffer_id;
 573     if (buffer_id == UINT32_MAX) {
 574         po.packet = dp_packet_data(&pkt);
 575         po.packet_len = dp_packet_size(&pkt);
 576     } else {
 577         po.packet = NULL;
 578         po.packet_len = 0;
 579     }
 580     match_set_in_port(&po.flow_metadata,
 581                       pi.flow_metadata.flow.in_port.ofp_port);
 582     po.ofpacts = ofpacts.data;
 583     po.ofpacts_len = ofpacts.size;
 584
 585     /* Send the packet, and possibly the whole flow, to the output port. */
 586     if (sw->max_idle >= 0 && (!sw->ml || out_port != OFPP_FLOOD)) {
 587         /* The output port is known, or we always flood everything, so add a
 588          * new flow. */
 589         struct ofputil_flow_mod fm = {
 590             .priority = 1, /* Must be > 0 because of table-miss flow entry. */
 591             .table_id = 0xff,
 592             .command = OFPFC_ADD,
 593             .idle_timeout = sw->max_idle,
 594             .buffer_id = buffer_id,
 595             .out_port = OFPP_NONE,
 596             .ofpacts = ofpacts.data,
 597             .ofpacts_len = ofpacts.size,
 598         };
 599
 600         struct match match;
 601         match_init(&match, &flow, &sw->wc);
 602         ofputil_normalize_match_quiet(&match);
 603         minimatch_init(&fm.match, &match);
 604
 605         struct ofpbuf *buffer = ofputil_encode_flow_mod(&fm, sw->protocol);
 606
 607         minimatch_destroy(&fm.match);
 608
 609         queue_tx(sw, buffer);
 610
 611         /* If the switch didn't buffer the packet, we need to send a copy. */
 612         if (buffer_id == UINT32_MAX && out_port != OFPP_NONE) {
 613             queue_tx(sw, ofputil_encode_packet_out(&po, sw->protocol));
 614         }
 615     } else {
 616         /* We don't know that MAC, or we don't set up flows.  Send along the
 617          * packet without setting up a flow. */
 618         if (buffer_id != UINT32_MAX || out_port != OFPP_NONE) {
 619             queue_tx(sw, ofputil_encode_packet_out(&po, sw->protocol));
 620         }
 621     }
 622 }
 623
 624 static void
 625 process_echo_request(struct lswitch *sw, const struct ofp_header *rq)
 626 {
 627     queue_tx(sw, ofputil_encode_echo_reply(rq));
 628 }
 629
 630 static ofp_port_t
 631 get_mac_entry_ofp_port(const struct mac_learning *ml,
 632                        const struct mac_entry *e)
 633     OVS_REQ_RDLOCK(ml->rwlock)
 634 {
 635     void *port = mac_entry_get_port(ml, e);
 636     return (OVS_FORCE ofp_port_t) (uintptr_t) port;
 637 }
 638
 639 static void
 640 set_mac_entry_ofp_port(struct mac_learning *ml,
 641                        struct mac_entry *e, ofp_port_t ofp_port)
 642     OVS_REQ_WRLOCK(ml->rwlock)
 643 {
 644     mac_entry_set_port(ml, e, (void *) (OVS_FORCE uintptr_t) ofp_port);
 645 }