From: Ilan Peer <ilan.peer@xxxxxxxxx>
The following race was possible:
1. The device driver requests HW restart.
2. A scan is requested from user space and is propagated
to the driver. During this flow HW_SCANNING flag is set.
3. The thread that handles the HW restart is scheduled,
and before starting the actual reconfiguration it
checks that HW_SCANNING is not set. The flow does so
without acquiring any lock, and thus the WARN fires.
Fix this by checking that HW_SCANNING is on only after RTNL is
acquired, i.e., user space scan request handling is no longer
in transit.
Signed-off-by: Ilan Peer <ilan.peer@xxxxxxxxx>
Signed-off-by: Luca Coelho <luciano.coelho@xxxxxxxxx>
---
net/mac80211/main.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 62145e5f9628..da3e0ca6aa31 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -256,14 +256,13 @@ static void ieee80211_restart_work(struct work_struct *work)
/* wait for scan work complete */
flush_workqueue(local->workqueue);
flush_work(&local->sched_scan_stopped_work);
+ flush_work(&local->radar_detected_work);
+
+ rtnl_lock();
WARN(test_bit(SCAN_HW_SCANNING, &local->scanning),
"%s called with hardware scan in progress\n", __func__);
- flush_work(&local->radar_detected_work);
- /* we might do interface manipulations, so need both */
- rtnl_lock();
- wiphy_lock(local->hw.wiphy);
list_for_each_entry(sdata, &local->interfaces, list) {
/*
* XXX: there may be more work for other vif types and even
--
2.32.0
