Description: do not exit when a DM_COOKIE event is pending.
Author: Herton R. Krzesinski
Ubuntu-Bug: https://bugs.launchpad.net/ubuntu/+source/lvm2/+bug/802626

--- a/libudev/libudev-device.c
+++ b/libudev/libudev-device.c
@@ -89,6 +89,7 @@
 	bool is_initialized;
 	bool sysattr_list_read;
 	bool db_persist;
+	bool dm_cookie_set;
 };
 
 /**
@@ -345,6 +346,27 @@
 	return 0;
 }
 
+/**
+ * udev_device_get_dm_cookie_set:
+ * @udev_device: udev device
+ *
+ * Retrieve the status of DM_COOKIE available for this udev device.
+ *
+ * Returns: true if DM_COOKIE was set for this device, false otherwise
+ **/
+UDEV_EXPORT bool udev_device_get_dm_cookie_set(struct udev_device *udev_device)
+{
+	if (udev_device == NULL)
+		return NULL;
+	return udev_device->dm_cookie_set;
+}
+
+static int udev_device_set_dm_cookie_set(struct udev_device *udev_device)
+{
+	udev_device->dm_cookie_set = true;
+	return 0;
+}
+
 struct udev_list_entry *udev_device_add_property(struct udev_device *udev_device, const char *key, const char *value)
 {
 	udev_device->envp_uptodate = false;
@@ -457,6 +479,9 @@
 		udev_device_set_ifindex(udev_device, strtoull(&property[8], NULL, 10));
 	} else if (strncmp(property, "DEVMODE=", 8) == 0) {
 		udev_device_set_devnode_mode(udev_device, strtoul(&property[8], NULL, 8));
+	} else if (strncmp(property, "DM_COOKIE=", 10) == 0) {
+		udev_device_set_dm_cookie_set(udev_device);
+		udev_device_add_property_from_string(udev_device, property);
 	} else {
 		udev_device_add_property_from_string(udev_device, property);
 	}
--- a/libudev/libudev-private.h
+++ b/libudev/libudev-private.h
@@ -101,6 +101,7 @@
 void udev_device_set_info_loaded(struct udev_device *device);
 bool udev_device_get_db_persist(struct udev_device *udev_device);
 void udev_device_set_db_persist(struct udev_device *udev_device);
+bool udev_device_get_dm_cookie_set(struct udev_device *udev_device);
 
 /* libudev-device-private.c */
 int udev_device_update_db(struct udev_device *udev_device);
--- a/udev/udevd.c
+++ b/udev/udevd.c
@@ -568,6 +568,7 @@
 static void event_queue_start(struct udev *udev)
 {
 	struct udev_list_node *loop;
+	bool force;
 
 	udev_list_node_foreach(loop, &event_list) {
 		struct event *event = node_to_event(loop);
@@ -575,17 +576,23 @@
 		if (event->state != EVENT_QUEUED)
 			continue;
 
+		/* do not schedule any more events if we are exiting,
+		   but we must process any remaining DM_COOKIE events */
+		force = udev_device_get_dm_cookie_set(event->dev);
+		if (udev_exit && !force)
+			continue;
+
 		/* do not start event if parent or child event is still running */
 		if (is_devpath_busy(event)) {
 			dbg(udev, "delay seq %llu (%s)\n", event->seqnum, event->devpath);
 			continue;
 		}
 
-		event_run(event, false);
+		event_run(event, force);
 	}
 }
 
-static void __event_queue_cleanup(struct udev *udev, enum event_state match_type, bool keep_timely)
+static void __event_queue_cleanup(struct udev *udev, enum event_state match_type, bool must_keep)
 {
 	struct udev_list_node *loop, *tmp;
 
@@ -595,9 +602,13 @@
 		if (match_type != EVENT_UNDEF && match_type != event->state)
 			continue;
 
-		/* Keep events which have timelyness requirements
-		 * we will skew these timeouts on coldplug. */
-		if (keep_timely && udev_device_get_timeout(event->dev) > 0)
+		/* Keep events which have timelyness requirements,
+                 * we will skew these timeouts on coldplug. Also,
+                 * dm events with DM_COOKIE set must be kept and
+                 * processed to avoid potential lvm tools deadlock on
+		 * udev_exit */
+		if (must_keep && (udev_device_get_timeout(event->dev) > 0 ||
+		                  udev_device_get_dm_cookie_set(event->dev)))
 			continue;
 
 		event_queue_delete(event, false);
@@ -609,7 +620,7 @@
 	__event_queue_cleanup(udev, match_type, false);
 }
 
-static void event_queue_cleanup_nontimely(struct udev *udev, enum event_state match_type)
+static void event_queue_cleanup_onexit(struct udev *udev, enum event_state match_type)
 {
 	__event_queue_cleanup(udev, match_type, true);
 }
@@ -1635,8 +1646,8 @@
 				fd_inotify = -1;
 			}
 
-			/* discard queued non-timely events and kill workers */
-			event_queue_cleanup_nontimely(udev, EVENT_QUEUED);
+			/* discard most queued events and kill workers */
+			event_queue_cleanup_onexit(udev, EVENT_QUEUED);
 			worker_kill(udev, 0);
 
 			/* exit after all has cleaned up */
@@ -1688,9 +1699,12 @@
 
 			dev = udev_monitor_receive_device(monitor);
 			if (dev != NULL) {
-				/* If we are exiting then only schedule events with
-				 * timeliness requirements. */
-				if (!udev_exit || udev_device_get_timeout(dev) > 0) {
+				/* If we are exiting then only schedule critical
+				 * events (with timeliness requirements or with
+				 * DM_COOKIE set). */
+				if (!udev_exit ||
+				    udev_device_get_timeout(dev) > 0 ||
+				    udev_device_get_dm_cookie_set(dev)) {
 					udev_device_set_usec_initialized(dev, now_usec());
 					if (event_queue_insert(dev) < 0)
 						udev_device_unref(dev);
@@ -1700,7 +1714,7 @@
 		}
 
 		/* start new events */
-		if (!udev_list_node_is_empty(&event_list) && !udev_exit && !stop_exec_queue)
+		if (!udev_list_node_is_empty(&event_list) && !stop_exec_queue)
 			event_queue_start(udev);
 
 		if (is_signal) {