Merge branch 'mainstream'
[sliver-openvswitch.git] / ofproto / ofproto-dpif.c
index 80e97e0..be7f807 100644 (file)
@@ -52,6 +52,7 @@
 #include "ofproto-dpif-governor.h"
 #include "ofproto-dpif-ipfix.h"
 #include "ofproto-dpif-mirror.h"
+#include "ofproto-dpif-monitor.h"
 #include "ofproto-dpif-sflow.h"
 #include "ofproto-dpif-upcall.h"
 #include "ofproto-dpif-xlate.h"
@@ -361,8 +362,6 @@ ofport_dpif_cast(const struct ofport *ofport)
 }
 
 static void port_run(struct ofport_dpif *);
-static void port_run_fast(struct ofport_dpif *);
-static void port_wait(struct ofport_dpif *);
 static int set_bfd(struct ofport *, const struct smap *);
 static int set_cfm(struct ofport *, const struct cfm_settings *);
 static void ofport_update_peer(struct ofport_dpif *);
@@ -470,8 +469,9 @@ struct ofproto_dpif {
     struct classifier facets;     /* Contains 'struct facet's. */
     long long int consistency_rl;
 
-    struct netdev_stats stats; /* To account packets generated and consumed in
-                                * userspace. */
+    struct ovs_mutex stats_mutex;
+    struct netdev_stats stats OVS_GUARDED; /* To account packets generated and
+                                            * consumed in userspace. */
 
     /* Spanning tree. */
     struct stp *stp;
@@ -526,9 +526,6 @@ static int expire(struct dpif_backer *);
 /* NetFlow. */
 static void send_netflow_active_timeouts(struct ofproto_dpif *);
 
-/* Utilities. */
-static int send_packet(const struct ofport_dpif *, struct ofpbuf *packet);
-
 /* Global variables. */
 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
 
@@ -548,11 +545,11 @@ ofproto_dpif_flow_mod(struct ofproto_dpif *ofproto,
  * Takes ownership of 'pin' and pin->packet. */
 void
 ofproto_dpif_send_packet_in(struct ofproto_dpif *ofproto,
-                            struct ofputil_packet_in *pin)
+                            struct ofproto_packet_in *pin)
 {
     if (!guarded_list_push_back(&ofproto->pins, &pin->list_node, 1024)) {
         COVERAGE_INC(packet_in_overflow);
-        free(CONST_CAST(void *, pin->packet));
+        free(CONST_CAST(void *, pin->up.packet));
         free(pin);
     }
 }
@@ -1233,6 +1230,7 @@ construct(struct ofproto *ofproto_)
     ofproto->ml = mac_learning_create(MAC_ENTRY_DEFAULT_IDLE_TIME);
     ofproto->mbridge = mbridge_create();
     ofproto->has_bonded_bundles = false;
+    ovs_mutex_init(&ofproto->stats_mutex);
     ovs_mutex_init(&ofproto->vsp_mutex);
 
     classifier_init(&ofproto->facets);
@@ -1361,7 +1359,7 @@ destruct(struct ofproto *ofproto_)
 {
     struct ofproto_dpif *ofproto = ofproto_dpif_cast(ofproto_);
     struct rule_dpif *rule, *next_rule;
-    struct ofputil_packet_in *pin, *next_pin;
+    struct ofproto_packet_in *pin, *next_pin;
     struct facet *facet, *next_facet;
     struct cls_cursor cursor;
     struct oftable *table;
@@ -1399,7 +1397,7 @@ destruct(struct ofproto *ofproto_)
     guarded_list_pop_all(&ofproto->pins, &pins);
     LIST_FOR_EACH_SAFE (pin, next_pin, list_node, &pins) {
         list_remove(&pin->list_node);
-        free(CONST_CAST(void *, pin->packet));
+        free(CONST_CAST(void *, pin->up.packet));
         free(pin);
     }
     guarded_list_destroy(&ofproto->pins);
@@ -1420,6 +1418,7 @@ destruct(struct ofproto *ofproto_)
     sset_destroy(&ofproto->ghost_ports);
     sset_destroy(&ofproto->port_poll_set);
 
+    ovs_mutex_destroy(&ofproto->stats_mutex);
     ovs_mutex_destroy(&ofproto->vsp_mutex);
 
     close_dpif_backer(ofproto->backer);
@@ -1429,8 +1428,7 @@ static int
 run_fast(struct ofproto *ofproto_)
 {
     struct ofproto_dpif *ofproto = ofproto_dpif_cast(ofproto_);
-    struct ofputil_packet_in *pin, *next_pin;
-    struct ofport_dpif *ofport;
+    struct ofproto_packet_in *pin, *next_pin;
     struct list pins;
 
     /* Do not perform any periodic activity required by 'ofproto' while
@@ -1443,14 +1441,10 @@ run_fast(struct ofproto *ofproto_)
     LIST_FOR_EACH_SAFE (pin, next_pin, list_node, &pins) {
         connmgr_send_packet_in(ofproto->up.connmgr, pin);
         list_remove(&pin->list_node);
-        free(CONST_CAST(void *, pin->packet));
+        free(CONST_CAST(void *, pin->up.packet));
         free(pin);
     }
 
-    HMAP_FOR_EACH (ofport, up.hmap_node, &ofproto->up.ports) {
-        port_run_fast(ofport);
-    }
-
     return 0;
 }
 
@@ -1536,7 +1530,6 @@ static void
 wait(struct ofproto *ofproto_)
 {
     struct ofproto_dpif *ofproto = ofproto_dpif_cast(ofproto_);
-    struct ofport_dpif *ofport;
     struct ofbundle *bundle;
 
     if (ofproto_get_flow_restore_wait()) {
@@ -1549,9 +1542,6 @@ wait(struct ofproto *ofproto_)
     if (ofproto->ipfix) {
         dpif_ipfix_wait(ofproto->ipfix);
     }
-    HMAP_FOR_EACH (ofport, up.hmap_node, &ofproto->up.ports) {
-        port_wait(ofport);
-    }
     HMAP_FOR_EACH (bundle, hmap_node, &ofproto->bundles) {
         bundle_wait(bundle);
     }
@@ -1814,6 +1804,9 @@ port_modified(struct ofport *port_)
         bfd_set_netdev(port->bfd, port->up.netdev);
     }
 
+    ofproto_dpif_monitor_port_update(port, port->bfd, port->cfm,
+                                     port->up.pp.hw_addr);
+
     if (port->is_tunnel && tnl_port_reconfigure(port, port->up.netdev,
                                                 port->odp_port)) {
         ofproto_dpif_cast(port->up.ofproto)->backer->need_revalidate =
@@ -1904,11 +1897,9 @@ static int
 set_cfm(struct ofport *ofport_, const struct cfm_settings *s)
 {
     struct ofport_dpif *ofport = ofport_dpif_cast(ofport_);
-    int error;
+    int error = 0;
 
-    if (!s) {
-        error = 0;
-    } else {
+    if (s) {
         if (!ofport->cfm) {
             struct ofproto_dpif *ofproto;
 
@@ -1918,13 +1909,17 @@ set_cfm(struct ofport *ofport_, const struct cfm_settings *s)
         }
 
         if (cfm_configure(ofport->cfm, s)) {
-            return 0;
+            error = 0;
+            goto out;
         }
 
         error = EINVAL;
     }
     cfm_unref(ofport->cfm);
     ofport->cfm = NULL;
+out:
+    ofproto_dpif_monitor_port_update(ofport, ofport->bfd, ofport->cfm,
+                                     ofport->up.pp.hw_addr);
     return error;
 }
 
@@ -1958,7 +1953,8 @@ set_bfd(struct ofport *ofport_, const struct smap *cfg)
     if (ofport->bfd != old) {
         ofproto->backer->need_revalidate = REV_RECONFIGURE;
     }
-
+    ofproto_dpif_monitor_port_update(ofport, ofport->bfd, ofport->cfm,
+                                     ofport->up.pp.hw_addr);
     return 0;
 }
 
@@ -1996,7 +1992,7 @@ send_bpdu_cb(struct ofpbuf *pkt, int port_num, void *ofproto_)
             VLOG_WARN_RL(&rl, "%s: cannot send BPDU on port %d "
                          "with unknown MAC", ofproto->up.name, port_num);
         } else {
-            send_packet(ofport, pkt);
+            ofproto_dpif_send_packet(ofport, pkt);
         }
     }
     ofpbuf_delete(pkt);
@@ -2592,7 +2588,7 @@ send_pdu_cb(void *port_, const void *pdu, size_t pdu_size)
                                  pdu_size);
         memcpy(packet_pdu, pdu, pdu_size);
 
-        send_packet(port, &packet);
+        ofproto_dpif_send_packet(port, &packet);
         ofpbuf_uninit(&packet);
     } else {
         VLOG_ERR_RL(&rl, "port %s: cannot obtain Ethernet address of iface "
@@ -2629,7 +2625,7 @@ bundle_send_learning_packets(struct ofbundle *bundle)
     LIST_FOR_EACH (learning_packet, list_node, &packets) {
         int ret;
 
-        ret = send_packet(learning_packet->private_p, learning_packet);
+        ret = ofproto_dpif_send_packet(learning_packet->private_p, learning_packet);
         if (ret) {
             error = ret;
             n_errors++;
@@ -2843,28 +2839,6 @@ ofport_update_peer(struct ofport_dpif *ofport)
     free(peer_name);
 }
 
-static void
-port_run_fast(struct ofport_dpif *ofport)
-{
-    if (ofport->cfm && cfm_should_send_ccm(ofport->cfm)) {
-        struct ofpbuf packet;
-
-        ofpbuf_init(&packet, 0);
-        cfm_compose_ccm(ofport->cfm, &packet, ofport->up.pp.hw_addr);
-        send_packet(ofport, &packet);
-        ofpbuf_uninit(&packet);
-    }
-
-    if (ofport->bfd && bfd_should_send_packet(ofport->bfd)) {
-        struct ofpbuf packet;
-
-        ofpbuf_init(&packet, 0);
-        bfd_put_packet(ofport->bfd, &packet, ofport->up.pp.hw_addr);
-        send_packet(ofport, &packet);
-        ofpbuf_uninit(&packet);
-    }
-}
-
 static void
 port_run(struct ofport_dpif *ofport)
 {
@@ -2876,12 +2850,9 @@ port_run(struct ofport_dpif *ofport)
 
     ofport->carrier_seq = carrier_seq;
 
-    port_run_fast(ofport);
-
     if (ofport->cfm) {
         int cfm_opup = cfm_get_opup(ofport->cfm);
 
-        cfm_run(ofport->cfm);
         cfm_enable = !cfm_get_fault(ofport->cfm);
 
         if (cfm_opup >= 0) {
@@ -2890,7 +2861,6 @@ port_run(struct ofport_dpif *ofport)
     }
 
     if (ofport->bfd) {
-        bfd_run(ofport->bfd);
         bfd_enable = bfd_forwarding(ofport->bfd);
     }
 
@@ -2913,18 +2883,6 @@ port_run(struct ofport_dpif *ofport)
     ofport->may_enable = enable;
 }
 
-static void
-port_wait(struct ofport_dpif *ofport)
-{
-    if (ofport->cfm) {
-        cfm_wait(ofport->cfm);
-    }
-
-    if (ofport->bfd) {
-        bfd_wait(ofport->bfd);
-    }
-}
-
 static int
 port_query_by_name(const struct ofproto *ofproto_, const char *devname,
                    struct ofproto_port *ofproto_port)
@@ -3038,10 +2996,11 @@ port_get_stats(const struct ofport *ofport_, struct netdev_stats *stats)
     if (!error && ofport_->ofp_port == OFPP_LOCAL) {
         struct ofproto_dpif *ofproto = ofproto_dpif_cast(ofport->up.ofproto);
 
+        ovs_mutex_lock(&ofproto->stats_mutex);
         /* ofproto->stats.tx_packets represents packets that we created
          * internally and sent to some port (e.g. packets sent with
-         * send_packet()).  Account for them as if they had come from
-         * OFPP_LOCAL and got forwarded. */
+         * ofproto_dpif_send_packet()).  Account for them as if they had
+         * come from OFPP_LOCAL and got forwarded. */
 
         if (stats->rx_packets != UINT64_MAX) {
             stats->rx_packets += ofproto->stats.tx_packets;
@@ -3062,6 +3021,7 @@ port_get_stats(const struct ofport *ofport_, struct netdev_stats *stats)
         if (stats->tx_bytes != UINT64_MAX) {
             stats->tx_bytes += ofproto->stats.rx_bytes;
         }
+        ovs_mutex_unlock(&ofproto->stats_mutex);
     }
 
     return error;
@@ -3836,24 +3796,49 @@ facet_free(struct facet *facet)
     }
 }
 
-/* Executes, within 'ofproto', the 'n_actions' actions in 'actions' on
- * 'packet', which arrived on 'in_port'. */
-static bool
-execute_odp_actions(struct ofproto_dpif *ofproto, const struct flow *flow,
-                    const struct nlattr *odp_actions, size_t actions_len,
-                    struct ofpbuf *packet)
+/* Executes, within 'ofproto', the actions in 'rule' or 'ofpacts' on 'packet'.
+ * 'flow' must reflect the data in 'packet'. */
+int
+ofproto_dpif_execute_actions(struct ofproto_dpif *ofproto,
+                             const struct flow *flow,
+                             struct rule_dpif *rule,
+                             const struct ofpact *ofpacts, size_t ofpacts_len,
+                             struct ofpbuf *packet)
 {
     struct odputil_keybuf keybuf;
+    struct dpif_flow_stats stats;
+    struct xlate_out xout;
+    struct xlate_in xin;
+    ofp_port_t in_port;
     struct ofpbuf key;
     int error;
 
+    ovs_assert((rule != NULL) != (ofpacts != NULL));
+
+    dpif_flow_stats_extract(flow, packet, time_msec(), &stats);
+    if (rule) {
+        rule_dpif_credit_stats(rule, &stats);
+    }
+
+    xlate_in_init(&xin, ofproto, flow, rule, stats.tcp_flags, packet);
+    xin.ofpacts = ofpacts;
+    xin.ofpacts_len = ofpacts_len;
+    xin.resubmit_stats = &stats;
+    xlate_actions(&xin, &xout);
+
     ofpbuf_use_stack(&key, &keybuf, sizeof keybuf);
-    odp_flow_key_from_flow(&key, flow,
-                           ofp_port_to_odp_port(ofproto, flow->in_port.ofp_port));
+    in_port = flow->in_port.ofp_port;
+    if (in_port == OFPP_NONE) {
+        in_port = OFPP_LOCAL;
+    }
+    odp_flow_key_from_flow(&key, flow, ofp_port_to_odp_port(ofproto, in_port));
 
     error = dpif_execute(ofproto->backer->dpif, key.data, key.size,
-                         odp_actions, actions_len, packet);
-    return !error;
+                         xout.odp_actions.data, xout.odp_actions.size, packet,
+                         (xout.slow & SLOW_ACTION) != 0);
+    xlate_out_uninit(&xout);
+
+    return error;
 }
 
 /* Remove 'facet' from its ofproto and free up the associated memory:
@@ -4076,15 +4061,11 @@ facet_check_consistency(struct facet *facet)
 
     struct xlate_out xout;
     struct xlate_in xin;
-
-    struct rule_dpif *rule;
     bool ok;
 
     /* Check the datapath actions for consistency. */
-    rule_dpif_lookup(facet->ofproto, &facet->flow, NULL, &rule);
-    xlate_in_init(&xin, facet->ofproto, &facet->flow, rule, 0, NULL);
+    xlate_in_init(&xin, facet->ofproto, &facet->flow, NULL, 0, NULL);
     xlate_actions(&xin, &xout);
-    rule_dpif_unref(rule);
 
     ok = ofpbuf_equal(&facet->xout.odp_actions, &xout.odp_actions)
         && facet->xout.slow == xout.slow;
@@ -4236,7 +4217,6 @@ flow_push_stats(struct ofproto_dpif *ofproto, struct flow *flow,
                 struct dpif_flow_stats *stats, bool may_learn)
 {
     struct ofport_dpif *in_port;
-    struct rule_dpif *rule;
     struct xlate_in xin;
 
     in_port = get_ofp_port(ofproto, flow->in_port.ofp_port);
@@ -4244,13 +4224,10 @@ flow_push_stats(struct ofproto_dpif *ofproto, struct flow *flow,
         netdev_vport_inc_rx(in_port->up.netdev, stats);
     }
 
-    rule_dpif_lookup(ofproto, flow, NULL, &rule);
-    rule_dpif_credit_stats(rule, stats);
-    xlate_in_init(&xin, ofproto, flow, rule, stats->tcp_flags, NULL);
+    xlate_in_init(&xin, ofproto, flow, NULL, stats->tcp_flags, NULL);
     xin.resubmit_stats = stats;
     xin.may_learn = may_learn;
     xlate_actions_for_side_effects(&xin);
-    rule_dpif_unref(rule);
 }
 
 static void
@@ -4327,9 +4304,15 @@ rule_dpif_credit_stats(struct rule_dpif *rule,
 }
 
 bool
-rule_dpif_fail_open(const struct rule_dpif *rule)
+rule_dpif_is_fail_open(const struct rule_dpif *rule)
 {
-    return rule->up.cr.priority == FAIL_OPEN_PRIORITY;
+    return is_fail_open_rule(&rule->up);
+}
+
+bool
+rule_dpif_is_table_miss(const struct rule_dpif *rule)
+{
+    return rule_is_table_miss(&rule->up);
 }
 
 ovs_be64
@@ -4651,9 +4634,7 @@ rule_dpif_lookup_in_table(struct ofproto_dpif *ofproto,
         cls_rule = classifier_lookup(cls, &ofpc_normal_flow, wc);
     } else if (frag && ofproto->up.frag_handling == OFPC_FRAG_DROP) {
         cls_rule = &ofproto->drop_frags_rule->up.cr;
-        if (wc) {
-            flow_wildcards_init_exact(wc);
-        }
+        /* Frag mask in wc already set above. */
     } else {
         cls_rule = classifier_lookup(cls, flow, wc);
     }
@@ -4780,21 +4761,8 @@ rule_dpif_execute(struct rule_dpif *rule, const struct flow *flow,
                   struct ofpbuf *packet)
 {
     struct ofproto_dpif *ofproto = ofproto_dpif_cast(rule->up.ofproto);
-    struct dpif_flow_stats stats;
-    struct xlate_out xout;
-    struct xlate_in xin;
-
-    dpif_flow_stats_extract(flow, packet, time_msec(), &stats);
-    rule_dpif_credit_stats(rule, &stats);
-
-    xlate_in_init(&xin, ofproto, flow, rule, stats.tcp_flags, packet);
-    xin.resubmit_stats = &stats;
-    xlate_actions(&xin, &xout);
-
-    execute_odp_actions(ofproto, flow, xout.odp_actions.data,
-                        xout.odp_actions.size, packet);
 
-    xlate_out_uninit(&xout);
+    ofproto_dpif_execute_actions(ofproto, flow, rule, NULL, 0, packet);
 }
 
 static enum ofperr
@@ -4825,55 +4793,18 @@ rule_modify_actions(struct rule *rule_, bool reset_counters)
 /* Sends 'packet' out 'ofport'.
  * May modify 'packet'.
  * Returns 0 if successful, otherwise a positive errno value. */
-static int
-send_packet(const struct ofport_dpif *ofport, struct ofpbuf *packet)
+int
+ofproto_dpif_send_packet(const struct ofport_dpif *ofport, struct ofpbuf *packet)
 {
     struct ofproto_dpif *ofproto = ofproto_dpif_cast(ofport->up.ofproto);
-    uint64_t odp_actions_stub[1024 / 8];
-    struct ofpbuf key, odp_actions;
-    struct dpif_flow_stats stats;
-    struct odputil_keybuf keybuf;
-    struct ofpact_output output;
-    struct xlate_out xout;
-    struct xlate_in xin;
-    struct flow flow;
-    union flow_in_port in_port_;
     int error;
 
-    ofpbuf_use_stub(&odp_actions, odp_actions_stub, sizeof odp_actions_stub);
-    ofpbuf_use_stack(&key, &keybuf, sizeof keybuf);
-
-    /* Use OFPP_NONE as the in_port to avoid special packet processing. */
-    in_port_.ofp_port = OFPP_NONE;
-    flow_extract(packet, 0, 0, NULL, &in_port_, &flow);
-    odp_flow_key_from_flow(&key, &flow, ofp_port_to_odp_port(ofproto,
-                                                             OFPP_LOCAL));
-    dpif_flow_stats_extract(&flow, packet, time_msec(), &stats);
-
-    ofpact_init(&output.ofpact, OFPACT_OUTPUT, sizeof output);
-    output.port = ofport->up.ofp_port;
-    output.max_len = 0;
-
-    xlate_in_init(&xin, ofproto, &flow, NULL, 0, packet);
-    xin.ofpacts_len = sizeof output;
-    xin.ofpacts = &output.ofpact;
-    xin.resubmit_stats = &stats;
-    xlate_actions(&xin, &xout);
-
-    error = dpif_execute(ofproto->backer->dpif,
-                         key.data, key.size,
-                         xout.odp_actions.data, xout.odp_actions.size,
-                         packet);
-    xlate_out_uninit(&xout);
-
-    if (error) {
-        VLOG_WARN_RL(&rl, "%s: failed to send packet on port %s (%s)",
-                     ofproto->up.name, netdev_get_name(ofport->up.netdev),
-                     ovs_strerror(error));
-    }
+    error = xlate_send_packet(ofport, packet);
 
+    ovs_mutex_lock(&ofproto->stats_mutex);
     ofproto->stats.tx_packets++;
     ofproto->stats.tx_bytes += packet->size;
+    ovs_mutex_unlock(&ofproto->stats_mutex);
     return error;
 }
 
@@ -4936,30 +4867,9 @@ packet_out(struct ofproto *ofproto_, struct ofpbuf *packet,
            const struct ofpact *ofpacts, size_t ofpacts_len)
 {
     struct ofproto_dpif *ofproto = ofproto_dpif_cast(ofproto_);
-    struct odputil_keybuf keybuf;
-    struct dpif_flow_stats stats;
-    struct xlate_out xout;
-    struct xlate_in xin;
-    struct ofpbuf key;
-
-
-    ofpbuf_use_stack(&key, &keybuf, sizeof keybuf);
-    odp_flow_key_from_flow(&key, flow,
-                           ofp_port_to_odp_port(ofproto,
-                                      flow->in_port.ofp_port));
-
-    dpif_flow_stats_extract(flow, packet, time_msec(), &stats);
-
-    xlate_in_init(&xin, ofproto, flow, NULL, stats.tcp_flags, packet);
-    xin.resubmit_stats = &stats;
-    xin.ofpacts_len = ofpacts_len;
-    xin.ofpacts = ofpacts;
-
-    xlate_actions(&xin, &xout);
-    dpif_execute(ofproto->backer->dpif, key.data, key.size,
-                 xout.odp_actions.data, xout.odp_actions.size, packet);
-    xlate_out_uninit(&xout);
 
+    ofproto_dpif_execute_actions(ofproto, flow, NULL, ofpacts,
+                                 ofpacts_len, packet);
     return 0;
 }
 \f
@@ -5144,7 +5054,7 @@ trace_format_rule(struct ds *result, int level, const struct rule_dpif *rule)
     actions = rule_dpif_get_actions(rule);
 
     ds_put_char_multiple(result, '\t', level);
-    ds_put_cstr(result, "OpenFlow ");
+    ds_put_cstr(result, "OpenFlow actions=");
     ofpacts_format(actions->ofpacts, actions->ofpacts_len, result);
     ds_put_char(result, '\n');
 
@@ -5295,7 +5205,7 @@ ofproto_unixctl_trace(struct unixctl_conn *conn, int argc, const char *argv[],
             goto exit;
         }
         ds_put_format(&result, "Bridge: %s\n", ofproto->up.name);
-    } else if (!parse_ofp_exact_flow(&flow, argv[argc - 1])) {
+    } else if (!parse_ofp_exact_flow(&flow, NULL, argv[argc - 1], NULL)) {
         if (argc != 3) {
             unixctl_command_reply_error(conn, "Must specify bridge name");
             goto exit;
@@ -5399,27 +5309,19 @@ ofproto_trace(struct ofproto_dpif *ofproto, const struct flow *flow,
                            trace.xout.odp_actions.size);
 
         if (trace.xout.slow) {
+            enum slow_path_reason slow;
+
             ds_put_cstr(ds, "\nThis flow is handled by the userspace "
                         "slow path because it:");
-            switch (trace.xout.slow) {
-            case SLOW_CFM:
-                ds_put_cstr(ds, "\n\t- Consists of CFM packets.");
-                break;
-            case SLOW_LACP:
-                ds_put_cstr(ds, "\n\t- Consists of LACP packets.");
-                break;
-            case SLOW_STP:
-                ds_put_cstr(ds, "\n\t- Consists of STP packets.");
-                break;
-            case SLOW_BFD:
-                ds_put_cstr(ds, "\n\t- Consists of BFD packets.");
-                break;
-            case SLOW_CONTROLLER:
-                ds_put_cstr(ds, "\n\t- Sends \"packet-in\" messages "
-                            "to the OpenFlow controller.");
-                break;
-            case __SLOW_MAX:
-                NOT_REACHED();
+
+            slow = trace.xout.slow;
+            while (slow) {
+                enum slow_path_reason bit = rightmost_1bit(slow);
+
+                ds_put_format(ds, "\n\t- %s.",
+                              slow_path_reason_to_explanation(bit));
+
+                slow &= ~bit;
             }
         }