UCS/NETLINK: use a designated flag to allow using the default GW

Author: amastbaum

src/ucs/sys/netlink.c

@@ -189,6 +189,8 @@ ucs_netlink_get_route_info(const struct rtattr *rta, int len, int *if_index_p,
         }
     }
 
+    /* In some kernel versions, RTA_DST attribute is not set for default
+     * gateway routes */
     if ((*if_index_p == -1) || ((*dst_in_addr == NULL) && (rtm_dst_len != 0))) {
         return UCS_ERR_INVALID_PARAM;
     }

src/uct/tcp/tcp.h

@@ -295,12 +295,12 @@ typedef enum uct_tcp_device_addr_flags {
      * Device address is extended by additional information:
      * @ref uct_iface_local_addr_ns_t for loopback reachability
      */
-    UCT_TCP_DEVICE_ADDR_FLAG_LOOPBACK      = UCS_BIT(0),
+    UCT_TCP_DEVICE_ADDR_FLAG_LOOPBACK         = UCS_BIT(0),
 
     /**
-     * Interface is IPoIB (IP over InfiniBand)
+     * Allow communication with default gateway
      */
-    UCT_TCP_DEVICE_ADDR_FLAG_LINK_LAYER_IB = UCS_BIT(1)
+    UCT_TCP_DEVICE_ADDR_FLAG_ALLOW_DEFAULT_GW = UCS_BIT(1)
 } uct_tcp_device_addr_flags_t;
 
 

src/uct/tcp/tcp_iface.c

@@ -139,8 +139,8 @@ static ucs_status_t uct_tcp_iface_get_device_address(uct_iface_h tl_iface,
     dev_addr->flags     = 0;
     dev_addr->sa_family = saddr->sa_family;
 
-    if (ucs_netif_is_ipoib(iface->if_name)) {
-        dev_addr->flags |= UCT_TCP_DEVICE_ADDR_FLAG_LINK_LAYER_IB;
+    if (!ucs_netif_is_ipoib(iface->if_name)) {
+        dev_addr->flags |= UCT_TCP_DEVICE_ADDR_FLAG_ALLOW_DEFAULT_GW;
     }
 
     if (ucs_sockaddr_is_inaddr_loopback(saddr)) {
@@ -270,8 +270,8 @@ uct_tcp_iface_is_reachable_v2(const uct_iface_h tl_iface,
     }
 
     /* Default gateway is not relevant for IPoIB interfaces */
-    allow_default_gw = !(tcp_dev_addr->flags &
-                         UCT_TCP_DEVICE_ADDR_FLAG_LINK_LAYER_IB);
+    allow_default_gw = !!(tcp_dev_addr->flags &
+                          UCT_TCP_DEVICE_ADDR_FLAG_ALLOW_DEFAULT_GW);
 
     if (!ucs_netlink_route_exists(ndev_index,
                                   (const struct sockaddr *)&remote_addr,