Commit 0ecfe806 authored Nov 09, 2011 by Johannes Berg Committed by John W. Linville Nov 09, 2011

mac80211: fix race between connection monitor & suspend



When the connection monitor timer fires right before
suspend, the following will happen:
 timer fires -> monitor_work gets queued
 suspend calls ieee80211_sta_quiesce
 ieee80211_sta_quiesce:
  - deletes timer
  - cancels monitor_work synchronously, running it
  [note wrong order of these steps]
 monitor_work runs, re-arming the timer
 later, timer fires while system should be quiesced

This causes a warning:

WARNING: at net/mac80211/util.c:540 ieee80211_can_queue_work+0x35/0x40 [mac80211]()

but is otherwise harmless. I'm not completely sure
this is the scenario Thomas stumbled across, but it
is the only way I can right now see the warning in
a scenario like the one he reported.

Reported-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

parent d929bbc6

net/mac80211/mlme.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2286,6 +2286,7 @@ void ieee80211_sta_quiesce(struct ieee80211_sub_if_data *sdata)

		cancel_work_sync(&ifmgd->request_smps_work);

		cancel_work_sync(&ifmgd->monitor_work);
		cancel_work_sync(&ifmgd->beacon_connection_loss_work);
		if (del_timer_sync(&ifmgd->timer))
		set_bit(TMR_RUNNING_TIMER, &ifmgd->timers_running);
		@@ -2294,7 +2295,6 @@ void ieee80211_sta_quiesce(struct ieee80211_sub_if_data *sdata)
		if (del_timer_sync(&ifmgd->chswitch_timer))
		set_bit(TMR_RUNNING_CHANSW, &ifmgd->timers_running);

		cancel_work_sync(&ifmgd->monitor_work);
		/* these will just be re-established on connection */
		del_timer_sync(&ifmgd->conn_mon_timer);
		del_timer_sync(&ifmgd->bcn_mon_timer);