udev: event - keep one rtnl per worker, rather than per event

Creating the rtnl context is cheap, but freeing it may not be, due to
synchronous close().

Also drop some excessive logging. We now log about the changing ifname
exactly once.

src/libsystemd/sd-rtnl/rtnl-util.c

@@ -26,7 +26,7 @@
 #include "rtnl-util.h"
 #include "rtnl-internal.h"
 
-int rtnl_set_link_name(sd_rtnl *rtnl, int ifindex, const char *name) {
+int rtnl_set_link_name(sd_rtnl **rtnl, int ifindex, const char *name) {
         _cleanup_rtnl_message_unref_ sd_rtnl_message *message = NULL;
         int r;
 
@@ -34,7 +34,13 @@ int rtnl_set_link_name(sd_rtnl *rtnl, int ifindex, const char *name) {
         assert(ifindex > 0);
         assert(name);
 
-        r = sd_rtnl_message_new_link(rtnl, &message, RTM_SETLINK, ifindex);
+        if (!*rtnl) {
+                r = sd_rtnl_open(rtnl, 0);
+                if (r < 0)
+                        return r;
+        }
+
+        r = sd_rtnl_message_new_link(*rtnl, &message, RTM_SETLINK, ifindex);
         if (r < 0)
                 return r;
 
@@ -42,7 +48,7 @@ int rtnl_set_link_name(sd_rtnl *rtnl, int ifindex, const char *name) {
         if (r < 0)
                 return r;
 
-        r = sd_rtnl_call(rtnl, message, 0, NULL);
+        r = sd_rtnl_call(*rtnl, message, 0, NULL);
         if (r < 0)
                 return r;
 

src/libsystemd/sd-rtnl/rtnl-util.h

@@ -34,7 +34,7 @@ bool rtnl_message_type_is_link(uint16_t type);
 bool rtnl_message_type_is_addr(uint16_t type);
 bool rtnl_message_type_is_route(uint16_t type);
 
-int rtnl_set_link_name(sd_rtnl *rtnl, int ifindex, const char *name);
+int rtnl_set_link_name(sd_rtnl **rtnl, int ifindex, const char *name);
 int rtnl_set_link_properties(sd_rtnl *rtnl, int ifindex, const char *alias, const struct ether_addr *mac, unsigned mtu);
 
 int rtnl_log_parse_error(int r);

src/udev/udev-event.c

@@ -53,6 +53,7 @@ struct udev_event *udev_event_new(struct udev_device *dev) {
 void udev_event_unref(struct udev_event *event) {
         if (event == NULL)
                 return;
+        sd_rtnl_unref(event->rtnl);
         udev_list_cleanup(&event->run_list);
         udev_list_cleanup(&event->seclabel_list);
         free(event->program_result);
@@ -746,30 +747,24 @@ out:
 
 static int rename_netif(struct udev_event *event) {
         struct udev_device *dev = event->dev;
-        _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
         char name[IFNAMSIZ];
         const char *oldname;
         int r;
 
         oldname = udev_device_get_sysname(dev);
 
-        log_debug("changing net interface name from '%s' to '%s'",
-                  oldname, event->name);
-
         strscpy(name, IFNAMSIZ, event->name);
 
-        r = sd_rtnl_open(&rtnl, 0);
-        if (r < 0)
-                return r;
-
-        r = rtnl_set_link_name(rtnl, udev_device_get_ifindex(dev), name);
-        if (r < 0)
-                log_error("error changing net interface name %s to %s: %s",
+        r = rtnl_set_link_name(&event->rtnl, udev_device_get_ifindex(dev), name);
+        if (r < 0) {
+                log_error("error changing net interface name '%s' to '%s': %s",
                           oldname, name, strerror(-r));
-        else
-                print_kmsg("renamed network interface %s to %s\n", oldname, name);
+                return r;
+        }
 
-        return r;
+        print_kmsg("renamed network interface '%s' to '%s'\n", oldname, name);
+
+        return 0;
 }
 
 void udev_event_execute_rules(struct udev_event *event,
@@ -832,8 +827,6 @@ void udev_event_execute_rules(struct udev_event *event,
 
                         r = rename_netif(event);
                         if (r >= 0) {
-                                log_debug("renamed netif to '%s'", event->name);
-
                                 /* remember old name */
                                 udev_device_add_property(dev, "INTERFACE_OLD", udev_device_get_sysname(dev));
 

src/udev/udev.h

@@ -23,6 +23,7 @@
 #include <signal.h>
 
 #include "macro.h"
+#include "sd-rtnl.h"
 #include "libudev.h"
 #include "libudev-private.h"
 #include "util.h"
@@ -44,6 +45,7 @@ struct udev_event {
         int exec_delay;
         usec_t birth_usec;
         int fd_signal;
+        sd_rtnl *rtnl;
         unsigned int builtin_run;
         unsigned int builtin_ret;
         bool sigterm;

src/udev/udevd.c

@@ -48,6 +48,7 @@
 
 #include "udev.h"
 #include "udev-util.h"
+#include "rtnl-util.h"
 #include "sd-daemon.h"
 #include "cgroup-util.h"
 #include "dev-setup.h"
@@ -200,6 +201,7 @@ static void worker_new(struct event *event) {
         case 0: {
                 struct udev_device *dev = NULL;
                 int fd_monitor;
+                _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
                 struct epoll_event ep_signal, ep_monitor;
                 sigset_t mask;
                 int rc = EXIT_SUCCESS;
@@ -301,11 +303,17 @@ static void worker_new(struct event *event) {
                                 }
                         }
 
+                        /* needed for renaming netifs */
+                        udev_event->rtnl = rtnl;
+
                         /* apply rules, create node, symlinks */
                         udev_event_execute_rules(udev_event, event_timeout_usec, rules, &sigmask_orig);
 
                         udev_event_execute_run(udev_event, event_timeout_usec, &sigmask_orig);
 
+                        /* in case rtnl was initialized */
+                        rtnl = sd_rtnl_ref(udev_event->rtnl);
+
                         /* apply/restore inotify watch */
                         if (udev_event->inotify_watch) {
                                 udev_watch_begin(udev, dev);