networkd: drop DHCPv4 config on stop, keep on restart, by default

keszybz · keszybz · commit 800603524a7a · 2019-10-02T14:01:42.000+02:00
This partially reverts 95355a2. It seems that other parts of link_stop_clients() should be skipped when restarting, but I don't know enough about those other clients to have an opinion if it is better to stop&start them on restart or not. Anyway, that can be done in later patches now that the support for restarts is there. Fixes #13625.
diff --git a/man/systemd.network.xml b/man/systemd.network.xml
@@ -876,8 +876,8 @@
           lease expires. This is contrary to the DHCP specification, but may be the best choice if,
           e.g., the root filesystem relies on this connection. The setting <literal>dhcp</literal>
           implies <literal>dhcp-on-stop</literal>, and <literal>yes</literal> implies
-          <literal>dhcp</literal> and <literal>static</literal>. Defaults to
-          <literal>dhcp-on-stop</literal>.</para>
+          <literal>dhcp</literal> and <literal>static</literal>. Defaults to <literal>no</literal>.
+          </para>
         </listitem>
       </varlistentry>
 
diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
@@ -770,8 +770,12 @@ int link_stop_clients(Link *link, bool may_keep_dhcp) {
 
         dhcp4_release_old_lease(link);
 
-        if (link->dhcp_client && (!may_keep_dhcp || !link->network ||
-                                  !FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP_ON_STOP))) {
+        bool keep_dhcp = may_keep_dhcp &&
+                         link->network &&
+                         (link->manager->restarting ||
+                          FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP_ON_STOP));
+
+        if (link->dhcp_client && !keep_dhcp) {
                 k = sd_dhcp_client_stop(link->dhcp_client);
                 if (k < 0)
                         r = log_link_warning_errno(link, k, "Could not stop DHCPv4 client: %m");
diff --git a/src/network/networkd-network.c b/src/network/networkd-network.c
@@ -268,13 +268,11 @@ int network_verify(Network *network) {
                         /* CriticalConnection=yes also preserve foreign static configurations. */
                         network->keep_configuration = KEEP_CONFIGURATION_YES;
                 else
-                        /* For backward compatibility, we do not release DHCP addresses on manager stop. */
-                        network->keep_configuration = KEEP_CONFIGURATION_DHCP_ON_STOP;
+                        network->keep_configuration = KEEP_CONFIGURATION_NO;
         }
 
         if (network->keep_configuration < 0)
-                /* For backward compatibility, we do not release DHCP addresses on manager stop. */
-                network->keep_configuration = KEEP_CONFIGURATION_DHCP_ON_STOP;
+                network->keep_configuration = KEEP_CONFIGURATION_NO;
 
         LIST_FOREACH_SAFE(addresses, address, address_next, network->static_addresses)
                 if (address_section_verify(address) < 0)
