mac80211: use freezable workqueue for restart work

Requesting hw restart during suspend might result
in the restart work being executed after mac80211
and the hw are suspended.

Solve the race by simply scheduling the restart
work on a freezable workqueue.

Note that there can be some cases of reconfiguration
on resume (besides the hardware restart):

* wowlan is not configured -
    All the interfaces removed were removed on suspend,
    and drv_stop() was called. At this point the driver
    shouldn't expect for hw_restart anyway, so we can
    simply cancel it (on resume).

* wowlan is configured, drv_resume() == 1
    There is no definitive expected behavior in this case,
    as each driver might have different expectations (e.g.
    setting some flags on suspend/restart vs. not handling
    spurious recovery).
    For now, simply let the hw_restart work run again after
    resume, and hope the driver will handle it well (or at
    least initiate another hw restart).

Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 273c96de4910970a0db3cd95c0da75d3a1695c9d..858f6b1cb1494702bbc6e0d8d25f1b4d4b4d1470 100644 (file)
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -281,7 +281,7 @@ void ieee80211_restart_hw(struct ieee80211_hw *hw)
        local->in_reconfig = true;
        barrier();
 
-       schedule_work(&local->restart_work);
+       queue_work(system_freezable_wq, &local->restart_work);
 }
 EXPORT_SYMBOL(ieee80211_restart_hw);
 

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index c5ed42f2f667c8410337b5660d3c5a2ece8b1e8f..7f7ddc527baab0c36c67cb4bc87c10a8aa3e0e39 100644 (file)
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -4,6 +4,7 @@
  * Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
  * Copyright 2007      Johannes Berg <johannes@sipsolutions.net>
  * Copyright 2013-2014  Intel Mobile Communications GmbH
+ * Copyright (C) 2015  Intel Deutschland GmbH
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -1753,6 +1754,16 @@ int ieee80211_reconfig(struct ieee80211_local *local)
        }
 #endif
 
+       /*
+        * In case of hw_restart during suspend (without wowlan),
+        * cancel restart work, as we are reconfiguring the device
+        * anyway.
+        * Note that restart_work is scheduled on a frozen workqueue,
+        * so we can't deadlock in this case.
+        */
+       if (suspended && local->in_reconfig && !reconfig_due_to_wowlan)
+               cancel_work_sync(&local->restart_work);
+
        /*
         * Upon resume hardware can sometimes be goofy due to
         * various platform / driver / bus issues, so restarting