[PATCH] station: fix reentrant FT wiphy radio work insertion

[James Prestwood <prestwoj@gmail.com>]

The failure path for FT was inserting the same work item inside
the 'do_work' callback. This caused duplicate work items to be
inside the radio work queue, and upon destroy the ID would get
zero'ed out. This caused a host of valgrind complaints when this
behavior is triggered.

This can be seen with slight modifiations to the FT test:

src/station.c:station_try_next_transition() 9, target 12:00:00:00:00:02
src/wiphy.c:wiphy_radio_work_insert() Inserting work item 6
src/wiphy.c:wiphy_radio_work_insert() Inserting work item 7
src/wiphy.c:wiphy_radio_work_done() Work item 5 done
src/wiphy.c:wiphy_radio_work_next() Starting work item 6
src/netdev.c:netdev_mlme_notify() MLME notification Remain on Channel(55)
src/ft.c:ft_send_authenticate()
src/netdev.c:netdev_mlme_notify() MLME notification Frame TX Status(60)
src/netdev.c:netdev_mlme_notify() MLME notification Frame Wait Cancel(67)
src/netdev.c:netdev_mlme_notify() MLME notification Cancel Remain on Channel(56)
src/wiphy.c:wiphy_radio_work_done() Work item 6 done

--- Work item 7 is 'station_ft_work_ready()' ---

src/wiphy.c:wiphy_radio_work_next() Starting work item 7
src/station.c:station_debug_event() StationDebug.Event(ft-roam-failed)
src/station.c:station_try_next_transition() 9, target 12:00:00:00:00:03
src/wiphy.c:wiphy_radio_work_insert() Inserting work item 8

--- Here we insert work item 9, which is a duplicate of 7 ---

src/wiphy.c:wiphy_radio_work_insert() Inserting work item 9
src/wiphy.c:wiphy_radio_work_next() Starting work item 8
src/netdev.c:netdev_mlme_notify() MLME notification Remain on Channel(55)
src/ft.c:ft_send_authenticate()
src/netdev.c:netdev_mlme_notify() MLME notification Frame TX Status(60)
src/netdev.c:netdev_mlme_notify() MLME notification Frame Wait Cancel(67)
src/netdev.c:netdev_mlme_notify() MLME notification Cancel Remain on Channel(56)
src/wiphy.c:wiphy_radio_work_done() Work item 8 done

--- And finally, the duplicated work item starts ---

src/wiphy.c:wiphy_radio_work_next() Starting work item 0
src/station.c:station_debug_event() StationDebug.Event(ft-roam-failed)
src/station.c:station_roam_failed() 9
src/station.c:station_roam_trigger_cb() 9
---
 src/station.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/station.c b/src/station.c
index 0d8f7628..3c6e43ce 100644
--- a/src/station.c
+++ b/src/station.c
@@ -122,6 +122,7 @@ struct station {
 
 	uint32_t wiphy_watch;
 
+	struct l_idle *ft_idle;
 	struct wiphy_radio_work_item ft_work;
 
 	bool preparing_roam : 1;
@@ -1739,6 +1740,11 @@ static void station_roam_state_clear(struct station *station)
 		station->roam_freqs = NULL;
 	}
 
+	if (station->ft_idle) {
+		l_idle_remove(station->ft_idle);
+		station->ft_idle = NULL;
+	}
+
 	l_queue_clear(station->roam_bss_list, l_free);
 
 	ft_clear_authentications(netdev_get_ifindex(station->netdev));
@@ -2282,6 +2288,16 @@ static void station_preauthenticate_cb(struct netdev *netdev,
 
 static void station_transition_start(struct station *station);
 
+static void station_transition_idle(struct l_idle *idle, void *user_data)
+{
+	struct station *station = user_data;
+
+	l_idle_remove(station->ft_idle);
+	station->ft_idle = NULL;
+
+	station_transition_start(station);
+}
+
 static bool station_ft_work_ready(struct wiphy_radio_work_item *item)
 {
 	struct station *station = l_container_of(item, struct station, ft_work);
@@ -2300,7 +2316,8 @@ static bool station_ft_work_ready(struct wiphy_radio_work_item *item)
 	if (ret == -ENOENT) {
 		station_debug_event(station, "ft-roam-failed");
 try_next:
-		station_transition_start(station);
+		station->ft_idle = l_idle_create(station_transition_idle,
+							station, NULL);
 		return true;
 	} else if (ret < 0)
 		goto assoc_failed;
-- 
2.25.1