Commit 18db594a authored Nov 06, 2013 by Johannes Berg

mac80211: fix scheduled scan rtnl deadlock



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.

Cc: stable@vger.kernel.org
Fixes: 5fe231e8 ("cfg80211: vastly simplify locking")
Reported-and-tested-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

parent 84a3d1c9

net/mac80211/main.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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);

net/mac80211/scan.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1088,6 +1088,6 @@ 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);

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