networkd: introduce refcounting for Links and NetDevs

src/network/networkd-link.c

@@ -37,7 +37,7 @@ static int ipv4ll_address_update(Link *link, bool deprecate);
 static bool ipv4ll_is_bound(sd_ipv4ll *ll);
 
 static int link_new(Manager *manager, sd_rtnl_message *message, Link **ret) {
-        _cleanup_link_free_ Link *link = NULL;
+        _cleanup_link_unref_ Link *link = NULL;
         uint16_t type;
         char *ifname;
         int r, ifindex;
@@ -67,6 +67,7 @@ static int link_new(Manager *manager, sd_rtnl_message *message, Link **ret) {
         if (!link)
                 return -ENOMEM;
 
+        link->n_ref = 1;
         link->manager = manager;
         link->state = LINK_STATE_INITIALIZING;
         link->ifindex = ifindex;
@@ -94,7 +95,7 @@ static int link_new(Manager *manager, sd_rtnl_message *message, Link **ret) {
         return 0;
 }
 
-void link_free(Link *link) {
+static void link_free(Link *link) {
         if (!link)
                 return;
 
@@ -120,6 +121,20 @@ void link_free(Link *link) {
         free(link);
 }
 
+Link *link_unref(Link *link) {
+        if (link && (-- link->n_ref <= 0))
+                link_free(link);
+
+        return NULL;
+}
+
+Link *link_ref(Link *link) {
+        if (link)
+                assert_se(++ link->n_ref >= 2);
+
+        return link;
+}
+
 int link_get(Manager *m, int ifindex, Link **ret) {
         Link *link;
         uint64_t ifindex_64;

src/network/networkd-manager.c

@@ -151,14 +151,14 @@ void manager_free(Manager *m) {
         sd_event_unref(m->event);
 
         while ((link = hashmap_first(m->links)))
-                link_free(link);
+                link_unref(link);
         hashmap_free(m->links);
 
         while ((network = m->networks))
                 network_free(network);
 
         while ((netdev = hashmap_first(m->netdevs)))
-                netdev_free(netdev);
+                netdev_unref(netdev);
         hashmap_free(m->netdevs);
 
         sd_rtnl_unref(m->rtnl);

src/network/networkd-netdev.c

@@ -48,7 +48,7 @@ static const char* const macvlan_mode_table[_NETDEV_MACVLAN_MODE_MAX] = {
 DEFINE_STRING_TABLE_LOOKUP(macvlan_mode, MacVlanMode);
 DEFINE_CONFIG_PARSE_ENUM(config_parse_macvlan_mode, macvlan_mode, MacVlanMode, "Failed to parse macvlan mode");
 
-void netdev_free(NetDev *netdev) {
+static void netdev_free(NetDev *netdev) {
         netdev_enslave_callback *callback;
 
         if (!netdev)
@@ -75,6 +75,20 @@ void netdev_free(NetDev *netdev) {
         free(netdev);
 }
 
+NetDev *netdev_unref(NetDev *netdev) {
+        if (netdev && (-- netdev->n_ref <= 0))
+                netdev_free(netdev);
+
+        return NULL;
+}
+
+NetDev *netdev_ref(NetDev *netdev) {
+        if (netdev)
+                assert_se(++ netdev->n_ref >= 2);
+
+        return netdev;
+}
+
 int netdev_get(Manager *manager, const char *name, NetDev **ret) {
         NetDev *netdev;
 
@@ -413,7 +427,7 @@ int netdev_set_ifindex(NetDev *netdev, sd_rtnl_message *message) {
 }
 
 static int netdev_load_one(Manager *manager, const char *filename) {
-        _cleanup_netdev_free_ NetDev *netdev = NULL;
+        _cleanup_netdev_unref_ NetDev *netdev = NULL;
         _cleanup_fclose_ FILE *file = NULL;
         int r;
 
@@ -437,6 +451,7 @@ static int netdev_load_one(Manager *manager, const char *filename) {
         if (!netdev)
                 return log_oom();
 
+        netdev->n_ref = 1;
         netdev->manager = manager;
         netdev->state = _NETDEV_STATE_INVALID;
         netdev->kind = _NETDEV_KIND_INVALID;
@@ -517,7 +532,7 @@ int netdev_load(Manager *manager) {
         assert(manager);
 
         while ((netdev = hashmap_first(manager->netdevs)))
-                netdev_free(netdev);
+                netdev_unref(netdev);
 
         r = conf_files_list_strv(&files, ".netdev", NULL, network_dirs);
         if (r < 0) {

src/network/networkd.h

@@ -83,6 +83,8 @@ typedef enum NetDevState {
 struct NetDev {
         Manager *manager;
 
+        int n_ref;
+
         char *filename;
 
         Condition *match_host;
@@ -199,6 +201,8 @@ typedef enum LinkState {
 struct Link {
         Manager *manager;
 
+        int n_ref;
+
         uint64_t ifindex;
         char *ifname;
         char *state_file;
@@ -268,10 +272,11 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_free);
 
 int netdev_load(Manager *manager);
 
-void netdev_free(NetDev *netdev);
+NetDev *netdev_unref(NetDev *netdev);
+NetDev *netdev_ref(NetDev *netdev);
 
-DEFINE_TRIVIAL_CLEANUP_FUNC(NetDev*, netdev_free);
-#define _cleanup_netdev_free_ _cleanup_(netdev_freep)
+DEFINE_TRIVIAL_CLEANUP_FUNC(NetDev*, netdev_unref);
+#define _cleanup_netdev_unref_ _cleanup_(netdev_unrefp)
 
 int netdev_get(Manager *manager, const char *name, NetDev **ret);
 int netdev_set_ifindex(NetDev *netdev, sd_rtnl_message *newlink);
@@ -371,7 +376,8 @@ int config_parse_label(const char *unit, const char *filename, unsigned line,
 
 /* Link */
 
-void link_free(Link *link);
+Link *link_unref(Link *link);
+Link *link_ref(Link *link);
 int link_get(Manager *m, int ifindex, Link **ret);
 int link_add(Manager *manager, sd_rtnl_message *message, Link **ret);
 
@@ -386,8 +392,8 @@ bool link_has_carrier(unsigned flags, uint8_t operstate);
 const char* link_state_to_string(LinkState s) _const_;
 LinkState link_state_from_string(const char *s) _pure_;
 
-DEFINE_TRIVIAL_CLEANUP_FUNC(Link*, link_free);
-#define _cleanup_link_free_ _cleanup_(link_freep)
+DEFINE_TRIVIAL_CLEANUP_FUNC(Link*, link_unref);
+#define _cleanup_link_unref_ _cleanup_(link_unrefp)
 
 /* Macros which append INTERFACE= to the message */