[systemd] Use cached SystemBus connection. Fixes MER#1694

Usb-moded opens and closes a private peer-to-peer dbus connection for each
systemd unit start/stop it needs to perform. This is relatively heavy
operation and seems to cause problems with systemd v225 during bootup.

Since usb-moded no longer has any reason to communicate with systemd
before it can connect to SystemBus, we can drop the private connections
and use cached SystemBus connection instead.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

src/usb_moded-systemd.c

@@ -35,69 +35,129 @@
 #include "usb_moded-log.h"
 #include "usb_moded-systemd.h"
 
-static DBusConnection * get_systemd_dbus_connection(void)
-{
-  DBusError       error;
-  DBusConnection *conn = 0;
-
-  dbus_error_init(&error);
-
-  conn = dbus_connection_open_private("unix:path=/run/systemd/private", &error);
-  if (!conn) 
-  {
-     if (dbus_error_is_set(&error))
-            log_err("Cannot connect to systemd: %s", error.message);
-     else
-            log_err("Cannot connect to systemd");
-     dbus_error_free(&error);
-     return 0;
-  }
-
-  return conn;
-}
+#define SYSTEMD_DBUS_SERVICE   "org.freedesktop.systemd1"
+#define SYSTEMD_DBUS_PATH      "/org/freedesktop/systemd1"
+#define SYSTEMD_DBUS_INTERFACE "org.freedesktop.systemd1.Manager"
+
+
+/* SystemBus connection ref used for systemd control ipc */
+static DBusConnection *systemd_con = NULL;
+
+// QDBusObjectPath org.freedesktop.systemd1.Manager.StartUnit(QString name, QString mode)
+// QDBusObjectPath org.freedesktop.systemd1.Manager.StopUnit(QString name, QString mode)
+
 
 //  mode = replace
 //  method = StartUnit or StopUnit
 gboolean systemd_control_service(const char *name, const char *method)
 {
+    DBusMessage    *req = NULL;
+    DBusMessage    *rsp = NULL;
+    DBusError       err = DBUS_ERROR_INIT;
+    const char     *arg = "replace";
+    const char     *res = 0;
+
+
+    log_debug("%s(%s) ...", method, name);
+
+    if( !systemd_con ) {
+        log_err("not connected to system bus; skip systemd unit control");
+        goto EXIT;
+    }
+
+    req = dbus_message_new_method_call(SYSTEMD_DBUS_SERVICE,
+                                       SYSTEMD_DBUS_PATH,
+                                       SYSTEMD_DBUS_INTERFACE,
+                                       method);
+    if( !req ) {
+        log_err("failed to construct %s.%s request",
+                SYSTEMD_DBUS_INTERFACE,
+                method);
+        goto EXIT;
+    }
+
+    if( !dbus_message_append_args(req,
+                                  DBUS_TYPE_STRING, &name,
+                                  DBUS_TYPE_STRING, &arg,
+                                  DBUS_TYPE_INVALID))
+    {
+        log_debug("error appending arguments");
+        goto EXIT;
+    }
+
+
+    rsp = dbus_connection_send_with_reply_and_block(systemd_con, req, -1, &err);
+    if( !rsp ) {
+        log_err("no reply to %s.%s request: %s: %s",
+                SYSTEMD_DBUS_INTERFACE,
+                method,
+                err.name, err.message);
+        goto EXIT;
+    }
+
+    if( dbus_set_error_from_message(&err, rsp) ) {
+        log_err("got error reply to %s.%s request: %s: %s",
+                SYSTEMD_DBUS_INTERFACE,
+                method,
+                err.name, err.message);
+        goto EXIT;
+    }
+
+    if( !dbus_message_get_args(rsp, &err,
+                               DBUS_TYPE_OBJECT_PATH, &res,
+                               DBUS_TYPE_INVALID) ) {
+        log_err("failed to parse reply to %s.%s request: %s: %s",
+                SYSTEMD_DBUS_INTERFACE,
+                method,
+                err.name, err.message);
+        goto EXIT;
+    }
+
+EXIT:
+
+    dbus_error_free(&err);
+
+    if( rsp ) dbus_message_unref(rsp);
+    if( req ) dbus_message_unref(req);
+
+    log_debug("%s(%s) -> %s", method, name, res ?: "N/A");
+
+    return res != 0;
+}
+
+/* ========================================================================= *
+ * start/stop systemd control availability
+ * ========================================================================= */
+
+gboolean
+systemd_control_start(void)
+{
+    gboolean ack = FALSE;
+
+    log_debug("starting systemd control");
+
+    /* Get connection ref */
+    if( (systemd_con = usb_moded_dbus_get_connection()) == 0 )
+    {
+        log_err("Could not connect to dbus for systemd control\n");
+        goto cleanup;
+    }
+    ack = TRUE;
 
-  DBusConnection *bus;
-  DBusError error;
-  DBusMessage *msg = NULL, *reply = NULL;
-  gboolean ret = FALSE;
-  const char * replace = "replace";
-
-  dbus_error_init(&error);
-
-  log_debug("Handling %s, with systemd, method %s\n", name, method);
-
-  bus = get_systemd_dbus_connection();
-  if(!bus)
-	return(ret);
-
-  msg = dbus_message_new_method_call("org.freedesktop.systemd1", 
-        "/org/freedesktop/systemd1", "org.freedesktop.systemd1.Manager", method);
-  if(msg)
-  {
-	if(!dbus_message_append_args (msg, DBUS_TYPE_STRING, &name, DBUS_TYPE_STRING, &replace, DBUS_TYPE_INVALID))
-	{
-		log_debug("error appending arguments\n");
-        	dbus_message_unref(msg);	
-		goto quit;
-	}
-	reply = dbus_connection_send_with_reply_and_block(bus, msg, -1, &error);
-	if(reply)
- 	{
-		dbus_message_unref(reply);
-		ret = TRUE;
-	}
-        dbus_message_unref(msg);	
-  }
-
-quit:
-  dbus_connection_close(bus);
-  dbus_connection_unref(bus);
-  dbus_error_free(&error);
-
-  return(ret); 
+cleanup:
+
+    return ack;
+}
+
+void
+systemd_control_stop(void)
+{
+    log_debug("stopping systemd control");
+
+    if(systemd_con)
+    {
+        /* Let go of connection ref */
+        dbus_connection_unref(systemd_con),
+            systemd_con = 0;
+    }
 }

src/usb_moded-systemd.h

@@ -24,3 +24,5 @@
 #define SYSTEMD_START   "StartUnit"
 
 gboolean systemd_control_service(const char *name, const char *method);
+gboolean systemd_control_start(void);
+void     systemd_control_stop(void);

src/usb_moded.c

@@ -54,6 +54,7 @@
 #include "usb_moded-network.h"
 #include "usb_moded-mac.h"
 #include "usb_moded-android.h"
+#include "usb_moded-systemd.h"
 #ifdef MEEGOLOCK
 #include "usb_moded-dsme.h"
 #endif
@@ -1197,6 +1198,11 @@ int main(int argc, char* argv[])
 		goto EXIT;
 	}
 
+	if( !systemd_control_start() ) {
+		log_crit("systemd control could not be started");
+		goto EXIT;
+	}
+
 	/* init daemon into a clean state first, then dbus and hw_abstraction last */
 	usb_moded_init();
 
@@ -1252,6 +1258,7 @@ int main(int argc, char* argv[])
 EXIT:
 	dsme_listener_stop();
 	handle_exit();
+	systemd_control_stop();
 
 	allow_suspend();
 	return result;