net/tcp/netdev/mld: correct the netlock handling

Signed-off-by: chao.an <anchao@xiaomi.com>

net/mld/mld_timer.c

@@ -343,6 +343,7 @@ static void mld_polldog_work(FAR void *arg)
 
           fwarn("WARNING: No device associated with ifindex=%d\n",
                 group->ifindex);
+          net_unlock();
           return;
         }
 

net/netdev/netdev_register.c

@@ -375,6 +375,7 @@ int netdev_register(FAR struct net_driver_s *dev, enum net_lltype_e lltype)
       ifindex = get_ifindex();
       if (ifindex < 0)
         {
+          net_unlock();
           return ifindex;
         }
 

net/tcp/tcp_conn.c

@@ -425,6 +425,7 @@ static inline int tcp_ipv4_bind(FAR struct tcp_conn_s *conn,
   if (port < 0)
     {
       nerr("ERROR: tcp_selectport failed: %d\n", port);
+      net_unlock();
       return port;
     }
 
@@ -448,11 +449,10 @@ static inline int tcp_ipv4_bind(FAR struct tcp_conn_s *conn,
 
       conn->lport = 0;
       net_ipv4addr_copy(conn->u.ipv4.laddr, INADDR_ANY);
-      return ret;
     }
 
   net_unlock();
-  return OK;
+  return ret;
 }
 #endif /* CONFIG_NET_IPv4 */
 
@@ -492,6 +492,7 @@ static inline int tcp_ipv6_bind(FAR struct tcp_conn_s *conn,
   if (port < 0)
     {
       nerr("ERROR: tcp_selectport failed: %d\n", port);
+      net_unlock();
       return port;
     }
 
@@ -515,11 +516,10 @@ static inline int tcp_ipv6_bind(FAR struct tcp_conn_s *conn,
 
       conn->lport = 0;
       net_ipv6addr_copy(conn->u.ipv6.laddr, g_ipv6_unspecaddr);
-      return ret;
     }
 
   net_unlock();
-  return OK;
+  return ret;
 }
 #endif /* CONFIG_NET_IPv6 */