mac80211: fix scheduled scan rtnl deadlock

commit 18db594a1005d908d995a2fc8f5a7bf4286fdca0 upstream.

When changing cfg80211 to use RTNL locking, this caused a
deadlock in mac80211 as it calls cfg80211_sched_scan_stopped()
from a work item that's on a workqueue that is flushed with
the RTNL held.

Fix this by simply using schedule_work(), the work only needs
to finish running before the wiphy is unregistered, no other
synchronisation (e.g. with suspend) is really required since
for suspend userspace is already blocked anyway when we flush
the workqueue so will only pick up the event after resume.

Fixes: 5fe231e87372 ("cfg80211: vastly simplify locking")
Reported-and-tested-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 21d5d44444d04c82fc73c9fd6dee3f58ab56e512..e765f77bb97ac837b2389e340a45c5210dc5e086 100644 (file)
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1047,6 +1047,7 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
 
        cancel_work_sync(&local->restart_work);
        cancel_work_sync(&local->reconfig_filter);
+       flush_work(&local->sched_scan_stopped_work);
 
        ieee80211_clear_tx_pending(local);
        rate_control_deinitialize(local);

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index d2d17a4492245953413c5742d22d2af9e15fd74d..8f2f003afbb89c898a97ff07ee3896308a4ed05c 100644 (file)
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -1089,6 +1089,6 @@ void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
 
        trace_api_sched_scan_stopped(local);
 
-       ieee80211_queue_work(&local->hw, &local->sched_scan_stopped_work);
+       schedule_work(&local->sched_scan_stopped_work);
 }
 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);