dmeventd: use dm_hold_control_dev

Need here to keep  control device opened while there is 'any' dso
plugin loaded - otherwise there would a race closing controlfd
inside lvm2 plugin while some other monitoring thread would
tried to execute another WAITEVENT task.

1 files changed, 13 insertions, 0 deletions

diff --git a/daemons/dmeventd/dmeventd.c b/daemons/dmeventd/dmeventd.c
index 69fe3930c..885aa9de4 100644
--- a/daemons/dmeventd/dmeventd.c
+++ b/daemons/dmeventd/dmeventd.c
@@ -282,6 +282,13 @@ static void _lib_put(struct dso_data *data)
 		dlclose(data->dso_handle);
 		UNLINK_DSO(data);
 		_free_dso_data(data);
+
+		/* Close control device if there is no plugin in-use */
+		if (dm_list_empty(&_dso_registry)) {
+			DEBUGLOG("Unholding control device.");
+			dm_hold_control_dev(0);
+			dm_lib_release();
+		}
 	}
 }
 
@@ -344,6 +351,12 @@ static struct dso_data *_load_dso(struct message_data *data)
 		goto_bad;
 	}
 
+	/* Keep control device open until last user closes */
+	if (dm_list_empty(&_dso_registry)) {
+		DEBUGLOG("Holding control device open.");
+		dm_hold_control_dev(1);
+	}
+
 	/*
 	 * Keep handle to close the library once
 	 * we've got no references to it any more.