ofproto: Always set MTU for new internal ports.

We only change the MTU of new internal ports if it is bigger than the
bridge minimum.  But when the minimum MTU of the bridge is updated we
change the MTU of all internal ports no matter what.

The behavior is inconsistent, because now the internal ports MTU depends
on the order in which the ports were added.

This commit fixes the problem by _always_ setting the MTU of new
internal ports to the bridge minimum.  I'm not sure what was the logic
behind only adjusting the mtu if it was too big.

A testcase is improved to detect the problem.

VMware-BZ: #1718776
Signed-off-by: Daniele Di Proietto <diproiettod@vmware.com>
Acked-by: Ben Pfaff <blp@ovn.org>

diff --git a/ofproto/ofproto.c b/ofproto/ofproto.c
index da7372de041f985835082b65bbf7828f87f5f796..9d62b72bbf4fca7437c7d10e4b4566f1e03130bc 100644 (file)
--- a/ofproto/ofproto.c
+++ b/ofproto/ofproto.c
@@ -281,6 +281,8 @@ static void meter_insert_rule(struct rule *);
 /* unixctl. */
 static void ofproto_unixctl_init(void);
 
+static int find_min_mtu(struct ofproto *p);
+
 /* All registered ofproto classes, in probe order. */
 static const struct ofproto_class **ofproto_classes;
 static size_t n_ofproto_classes;
@@ -514,7 +516,7 @@ ofproto_create(const char *datapath_name, const char *datapath_type,
     hmap_init(&ofproto->learned_cookies);
     ovs_list_init(&ofproto->expirable);
     ofproto->connmgr = connmgr_create(ofproto, datapath_name, datapath_name);
-    ofproto->min_mtu = INT_MAX;
+    ofproto->min_mtu = find_min_mtu(ofproto);
     cmap_init(&ofproto->groups);
     ovs_mutex_unlock(&ofproto_mutex);
     ofproto->ogf.types = 0xf;
@@ -2750,10 +2752,8 @@ update_mtu(struct ofproto *p, struct ofport *port)
         return;
     }
     if (ofport_is_internal(p, port)) {
-        if (dev_mtu > p->min_mtu) {
-           if (!netdev_set_mtu(port->netdev, p->min_mtu)) {
-               dev_mtu = p->min_mtu;
-           }
+        if (!netdev_set_mtu(port->netdev, p->min_mtu)) {
+            dev_mtu = p->min_mtu;
         }
         port->mtu = dev_mtu;
         return;

diff --git a/tests/ofproto-dpif.at b/tests/ofproto-dpif.at
index d7705da8767cf4202af6d949221bb6e85da93a7d..8e5fde6d73de7d739f1ed8a7474700e1d3a491fb 100644 (file)
--- a/tests/ofproto-dpif.at
+++ b/tests/ofproto-dpif.at
@@ -8863,6 +8863,11 @@ AT_CLEANUP
 AT_SETUP([ofproto - set mtu])
 OVS_VSWITCHD_START
 
+# Check that initial MTU is 1500 for 'br0'.
+AT_CHECK([ovs-vsctl get Interface br0 mtu], [0], [dnl
+1500
+])
+
 add_of_ports br0 1
 
 # Check that initial MTU is 1500 for 'br0' and 'p1'.
@@ -8892,5 +8897,9 @@ AT_CHECK([ovs-vsctl add-port br0 p2 -- set int p2 type=dummy mtu_request=1600])
 AT_CHECK([ovs-vsctl --timeout=10 wait-until Interface p2 mtu=1600])
 AT_CHECK([ovs-vsctl --timeout=10 wait-until Interface br0 mtu=1600])
 
+# New internal port.  The MTU should be updated even for a newly added port.
+AT_CHECK([ovs-vsctl add-port br0 int1 -- set int int1 type=internal])
+AT_CHECK([ovs-vsctl --timeout=10 wait-until Interface int1 mtu=1600])
+
 OVS_VSWITCHD_STOP
 AT_CLEANUP