netdev: Fix carrier status for down interfaces.lts-1.0

Currently netdev_get_carrier() returns both a carrier status and
an error code.  However, usage of the error code was inconsistent:
most callers either ignored it or didn't perform their task if an
error occured, which prevented bond rebalancing.  This makes the
handling consistent by translating an error into a down status in
the netdev library.

Bug #3959

10 files changed, 35 insertions, 30 deletions

diff --git a/lib/netdev-patch.c b/lib/netdev-patch.c
index 7e8b1990e..d2a064332 100644
--- a/lib/netdev-patch.c
+++ b/lib/netdev-patch.c
@@ -200,7 +200,7 @@ const struct netdev_class netdev_patch_class = {
     netdev_vport_get_etheraddr,
     netdev_vport_get_mtu,
     NULL,                       /* get_ifindex */
-    netdev_vport_get_carrier,
+    NULL,                       /* get_carrier */
     netdev_vport_get_stats,
     netdev_vport_set_stats,
 
diff --git a/lib/netdev-provider.h b/lib/netdev-provider.h
index c0ed4ef60..fb610d751 100644
--- a/lib/netdev-provider.h
+++ b/lib/netdev-provider.h
@@ -259,7 +259,11 @@ struct netdev_class {
     int (*get_ifindex)(const struct netdev *netdev);
 
     /* Sets 'carrier' to true if carrier is active (link light is on) on
-     * 'netdev'. */
+     * 'netdev'.
+     *
+     * May be null if device does not provide carrier status (will be always
+     * up as long as device is up).
+     */
     int (*get_carrier)(const struct netdev *netdev, bool *carrier);
 
     /* Retrieves current device stats for 'netdev' into 'stats'.
diff --git a/lib/netdev-tunnel.c b/lib/netdev-tunnel.c
index d0ecd98e2..2c3fca54e 100644
--- a/lib/netdev-tunnel.c
+++ b/lib/netdev-tunnel.c
@@ -256,7 +256,7 @@ const struct netdev_class netdev_gre_class = {
     netdev_vport_get_etheraddr,
     netdev_vport_get_mtu,
     NULL,                       /* get_ifindex */
-    netdev_vport_get_carrier,
+    NULL,                       /* get_carrier */
     netdev_vport_get_stats,
     netdev_vport_set_stats,
 
@@ -316,7 +316,7 @@ const struct netdev_class netdev_capwap_class = {
     netdev_vport_get_etheraddr,
     netdev_vport_get_mtu,
     NULL,                       /* get_ifindex */
-    netdev_vport_get_carrier,
+    NULL,                       /* get_carrier */
     netdev_vport_get_stats,
     netdev_vport_set_stats,
 
diff --git a/lib/netdev-vport.c b/lib/netdev-vport.c
index 0153ac78d..84dda8143 100644
--- a/lib/netdev-vport.c
+++ b/lib/netdev-vport.c
@@ -114,13 +114,6 @@ netdev_vport_get_mtu(const struct netdev *netdev, int *mtup)
 }
 
 int
-netdev_vport_get_carrier(const struct netdev *netdev OVS_UNUSED, bool *carrier)
-{
-    *carrier = true;
-    return 0;
-}
-
-int
 netdev_vport_get_stats(const struct netdev *netdev, struct netdev_stats *stats)
 {
     const char *name = netdev_get_name(netdev);
diff --git a/lib/netdev-vport.h b/lib/netdev-vport.h
index b4016606f..dc65fe78e 100644
--- a/lib/netdev-vport.h
+++ b/lib/netdev-vport.h
@@ -27,7 +27,6 @@ int netdev_vport_set_etheraddr(struct netdev *,
 int netdev_vport_get_etheraddr(const struct netdev *,
                                uint8_t mac[ETH_ADDR_LEN]);
 int netdev_vport_get_mtu(const struct netdev *, int *mtup);
-int netdev_vport_get_carrier(const struct netdev *, bool *carrier);
 int netdev_vport_get_stats(const struct netdev *, struct netdev_stats *);
 int netdev_vport_set_stats(struct netdev *, const struct netdev_stats *);
 int netdev_vport_update_flags(struct netdev *, enum netdev_flags off,
diff --git a/lib/netdev.c b/lib/netdev.c
index 24c2a88fa..db4bb6ef2 100644
--- a/lib/netdev.c
+++ b/lib/netdev.c
@@ -909,19 +909,32 @@ netdev_arp_lookup(const struct netdev *netdev,
     return error;
 }
 
-/* Sets 'carrier' to true if carrier is active (link light is on) on
- * 'netdev'. */
-int
-netdev_get_carrier(const struct netdev *netdev, bool *carrier)
+/* Returns true if carrier is active (link light is on) on 'netdev'. */
+bool
+netdev_get_carrier(const struct netdev *netdev)
 {
-    int error = (netdev_get_dev(netdev)->netdev_class->get_carrier
-                 ? netdev_get_dev(netdev)->netdev_class->get_carrier(netdev,
-                        carrier)
-                 : EOPNOTSUPP);
+    int error;
+    enum netdev_flags flags;
+    bool carrier;
+
+    netdev_get_flags(netdev, &flags);
+    if (!(flags & NETDEV_UP)) {
+        return false;
+    }
+
+    if (!netdev_get_dev(netdev)->netdev_class->get_carrier) {
+        return true;
+    }
+
+    error = netdev_get_dev(netdev)->netdev_class->get_carrier(netdev,
+                                                              &carrier);
     if (error) {
-        *carrier = false;
+        VLOG_DBG("%s: failed to get network device carrier status, assuming "
+                 "down: %s", netdev_get_name(netdev), strerror(error));
+        carrier = false;
     }
-    return error;
+
+    return carrier;
 }
 
 /* Retrieves current device stats for 'netdev'. */
diff --git a/lib/netdev.h b/lib/netdev.h
index cd5c8c300..93997aee7 100644
--- a/lib/netdev.h
+++ b/lib/netdev.h
@@ -127,7 +127,7 @@ int netdev_set_etheraddr(struct netdev *, const uint8_t mac[6]);
 int netdev_get_etheraddr(const struct netdev *, uint8_t mac[6]);
 
 /* PHY interface. */
-int netdev_get_carrier(const struct netdev *, bool *carrier);
+bool netdev_get_carrier(const struct netdev *);
 int netdev_get_features(struct netdev *,
                         uint32_t *current, uint32_t *advertised,
                         uint32_t *supported, uint32_t *peer);
diff --git a/ofproto/ofproto-sflow.c b/ofproto/ofproto-sflow.c
index c74c7360e..f86ca3625 100644
--- a/ofproto/ofproto-sflow.c
+++ b/ofproto/ofproto-sflow.c
@@ -161,10 +161,8 @@ sflow_agent_get_counters(void *os_, SFLPoller *poller,
         counters->ifDirection = 0;
     }
     if (!netdev_get_flags(osp->netdev, &flags) && flags & NETDEV_UP) {
-        bool carrier;
-
         counters->ifStatus = 1; /* ifAdminStatus up. */
-        if (!netdev_get_carrier(osp->netdev, &carrier) && carrier) {
+        if (netdev_get_carrier(osp->netdev)) {
             counters->ifStatus |= 2; /* ifOperStatus us. */
         }
     } else {
diff --git a/ofproto/ofproto.c b/ofproto/ofproto.c
index fb13c7be9..37678a4d5 100644
--- a/ofproto/ofproto.c
+++ b/ofproto/ofproto.c
@@ -1396,7 +1396,6 @@ make_ofport(const struct odp_port *odp_port)
     enum netdev_flags flags;
     struct ofport *ofport;
     struct netdev *netdev;
-    bool carrier;
     int error;
 
     memset(&netdev_options, 0, sizeof netdev_options);
@@ -1423,8 +1422,7 @@ make_ofport(const struct odp_port *odp_port)
     netdev_get_flags(netdev, &flags);
     ofport->opp.config = flags & NETDEV_UP ? 0 : OFPPC_PORT_DOWN;
 
-    netdev_get_carrier(netdev, &carrier);
-    ofport->opp.state = carrier ? 0 : OFPPS_LINK_DOWN;
+    ofport->opp.state = netdev_get_carrier(netdev) ? 0 : OFPPS_LINK_DOWN;
 
     netdev_get_features(netdev,
                         &ofport->opp.curr, &ofport->opp.advertised,
diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
index 598b0016d..687487987 100644
--- a/vswitchd/bridge.c
+++ b/vswitchd/bridge.c
@@ -390,7 +390,7 @@ set_up_iface(const struct ovsrec_interface *iface_cfg, struct iface *iface,
         error = netdev_open(&netdev_options, &iface->netdev);
 
         if (iface->netdev) {
-            netdev_get_carrier(iface->netdev, &iface->enabled);
+            iface->enabled = netdev_get_carrier(iface->netdev);
         }
     } else if (iface->netdev) {
         const char *netdev_type = netdev_get_type(iface->netdev);