[ovs-dev] [PATCH] ofproto-dpif-xlate: Fix recirculation when in_port is OFPP_CONTROLLER.

Ben Pfaff blp at ovn.org
Fri Mar 20 00:56:26 UTC 2020


Recirculation usually requires finding the pre-recirculation input port.
Packets sent by the controller, with in_port of OFPP_CONTROLLER or
OFPP_NONE, do not have a real input port data structure, only a port
number.  The code in xlate_lookup_ofproto_() mishandled this case,
failing to return the ofproto data structure.  This commit fixes the
problem and adds a test to guard against regression.

Reported-by: Numan Siddique <numans at ovn.org>
Reported-at: https://mail.openvswitch.org/pipermail/ovs-dev/2020-March/368642.html
Signed-off-by: Ben Pfaff <blp at ovn.org>
---
 ofproto/ofproto-dpif-xlate.c | 25 +++++++++++++++++++++----
 tests/ofproto-dpif.at        | 30 ++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
index adf57a5e8929..28dcc67ddac3 100644
--- a/ofproto/ofproto-dpif-xlate.c
+++ b/ofproto/ofproto-dpif-xlate.c
@@ -1520,15 +1520,32 @@ xlate_lookup_ofproto_(const struct dpif_backer *backer,
             return NULL;
         }
 
-        /* If recirculation was initiated due to bond (in_port = OFPP_NONE)
-         * then frozen state is static and xport_uuid is not defined, so xport
-         * cannot be restored from frozen state. */
-        if (recirc_id_node->state.metadata.in_port != OFPP_NONE) {
+        ofp_port_t in_port = recirc_id_node->state.metadata.in_port;
+        if (in_port != OFPP_NONE && in_port != OFPP_CONTROLLER) {
             struct uuid xport_uuid = recirc_id_node->state.xport_uuid;
             xport = xport_lookup_by_uuid(xcfg, &xport_uuid);
             if (xport && xport->xbridge && xport->xbridge->ofproto) {
                 goto out;
             }
+        } else {
+            /* OFPP_NONE and OFPP_CONTROLLER are not real ports.  They indicate
+             * that the packet originated from the controller via an OpenFlow
+             * "packet-out".  The right thing to do is to find just the
+             * ofproto.  There is no xport, which is OK.
+             *
+             * OFPP_NONE can also indicate that a bond caused recirculation. */
+            struct uuid uuid = recirc_id_node->state.ofproto_uuid;
+            const struct xbridge *bridge = xbridge_lookup_by_uuid(xcfg, &uuid);
+            if (bridge && bridge->ofproto) {
+                if (errorp) {
+                    *errorp = NULL;
+                }
+                *xportp = NULL;
+                if (ofp_in_port) {
+                    *ofp_in_port = in_port;
+                }
+                return bridge->ofproto;
+            }
         }
     }
 
diff --git a/tests/ofproto-dpif.at b/tests/ofproto-dpif.at
index ff1cc93707b8..d444cf0844a9 100644
--- a/tests/ofproto-dpif.at
+++ b/tests/ofproto-dpif.at
@@ -5171,6 +5171,36 @@ AT_CHECK_UNQUOTED([tail -1 stdout], [0], [Datapath actions: 2
 OVS_VSWITCHD_STOP
 AT_CLEANUP
 
+# Checks for regression against a bug in which OVS dropped packets
+# with in_port=CONTROLLER when they were recirculated (because
+# CONTROLLER isn't a real port and could not be looked up).
+AT_SETUP([ofproto-dpif - packet-out recirculation])
+OVS_VSWITCHD_START
+add_of_ports br0 1 2
+
+AT_DATA([flows.txt], [dnl
+table=0 ip actions=mod_dl_dst:83:83:83:83:83:83,ct(table=1)
+table=1 ip actions=ct(commit),output:2
+])
+AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
+
+packet=ffffffffffff00102030405008004500001c00000000401100000a000002ffffffff0035111100080000
+AT_CHECK([ovs-ofctl packet-out br0 "in_port=controller packet=$packet actions=table"])
+
+# Dumps out the flow table, extracts the number of packets that have gone
+# through the (single) flow in table 1, and returns success if it's exactly 1.
+#
+# If this remains 0, then the recirculation isn't working properly since the
+# packet never goes through flow in table 1.
+check_flows () {
+    n=$(ovs-ofctl dump-flows br0 table=1 | sed -n 's/.*n_packets=\([[0-9]]\{1,\}\).*/\1/p')
+    echo "n_packets=$n"
+    test "$n" = 1
+}
+OVS_WAIT_UNTIL([check_flows], [ovs dump-flows br0])
+
+OVS_VSWITCHD_STOP
+AT_CLEANUP
 
 AT_SETUP([ofproto-dpif - debug_slow action])
 OVS_VSWITCHD_START
-- 
2.24.1



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