network: drop support for old kernels which cannot set prefix route with non-main route table

Not sure when the issue was fixed.
- kernel-3.10 on CentOS 7 has the issue,
- kernel-4.18 on CentOS 8 works fine.

Note, the workaround dropped by the commit is not incomplete:
with an old kernel which has the issue, all non-prefix routes are
configured on the specified route table, but the prefix route is
configured on the main table. That should not work for most cases,
hence, the workaround is mostly meaningless.

1 files changed, 2 insertions, 44 deletions

diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c
index d3fd2571e0..5770b48767 100644
--- a/src/network/networkd-dhcp4.c
+++ b/src/network/networkd-dhcp4.c
@@ -27,8 +27,6 @@
 #include "strv.h"
 #include "sysctl-util.h"
 
-static int dhcp4_request_address_and_routes(Link *link, bool announce);
-
 void network_adjust_dhcp4(Network *network) {
         assert(network);
 
@@ -157,26 +155,6 @@ int dhcp4_check_ready(Link *link) {
         return 0;
 }
 
-static int dhcp4_retry(Link *link) {
-        int r;
-
-        assert(link);
-
-        r = dhcp4_remove_address_and_routes(link, /* only_marked = */ false);
-        if (r < 0)
-                return r;
-
-        r = link_request_static_nexthops(link, true);
-        if (r < 0)
-                return r;
-
-        r = link_request_static_routes(link, true);
-        if (r < 0)
-                return r;
-
-        return dhcp4_request_address_and_routes(link, false);
-}
-
 static int dhcp4_route_handler(sd_netlink *rtnl, sd_netlink_message *m, Request *req, Link *link, Route *route) {
         int r;
 
@@ -184,31 +162,12 @@ static int dhcp4_route_handler(sd_netlink *rtnl, sd_netlink_message *m, Request
         assert(link);
 
         r = sd_netlink_message_get_errno(m);
-        if (r == -ENETUNREACH && !link->dhcp4_route_retrying) {
-
-                /* It seems kernel does not support that the prefix route cannot be configured with
-                 * route table. Let's once drop the config and reconfigure them later. */
-
-                log_link_message_debug_errno(link, m, r, "Could not set DHCPv4 route, retrying later");
-                link->dhcp4_route_failed = true;
-                link->manager->dhcp4_prefix_root_cannot_set_table = true;
-        } else if (r < 0 && r != -EEXIST) {
+        if (r < 0 && r != -EEXIST) {
                 log_link_message_warning_errno(link, m, r, "Could not set DHCPv4 route");
                 link_enter_failed(link);
                 return 1;
         }
 
-        if (link->dhcp4_messages == 0 && link->dhcp4_route_failed) {
-                link->dhcp4_route_failed = false;
-                link->dhcp4_route_retrying = true;
-
-                r = dhcp4_retry(link);
-                if (r < 0)
-                        link_enter_failed(link);
-
-                return 1;
-        }
-
         r = dhcp4_check_ready(link);
         if (r < 0)
                 link_enter_failed(link);
@@ -253,8 +212,7 @@ static int dhcp4_request_route(Route *in, Link *link) {
 
 static bool link_prefixroute(Link *link) {
         return !link->network->dhcp_route_table_set ||
-                link->network->dhcp_route_table == RT_TABLE_MAIN ||
-                link->manager->dhcp4_prefix_root_cannot_set_table;
+                link->network->dhcp_route_table == RT_TABLE_MAIN;
 }
 
 static int dhcp4_request_prefix_route(Link *link) {