mac80211: backport upstream fixes

Backport most significant upstream fixes (excl. hwsim fixes)
Refreshed all patches.

Contains important fixes for CSA (Channel Switch Announcement)
and A-MSDU frames.

[slightly altered to apply cleanly]
Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/package/kernel/mac80211/patches/390-mac80211-fix-a-race-between-restart-and-CSA-flows.patch b/package/kernel/mac80211/patches/390-mac80211-fix-a-race-between-restart-and-CSA-flows.patch
new file mode 100644
index 0000000000..db2aa0443f
--- /dev/null
+++ b/package/kernel/mac80211/patches/390-mac80211-fix-a-race-between-restart-and-CSA-flows.patch
@@ -0,0 +1,86 @@
+From: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
+Date: Fri, 31 Aug 2018 11:31:06 +0300
+Subject: [PATCH] mac80211: fix a race between restart and CSA flows
+
+We hit a problem with iwlwifi that was caused by a bug in
+mac80211. A bug in iwlwifi caused the firwmare to crash in
+certain cases in channel switch. Because of that bug,
+drv_pre_channel_switch would fail and trigger the restart
+flow.
+Now we had the hw restart worker which runs on the system's
+workqueue and the csa_connection_drop_work worker that runs
+on mac80211's workqueue that can run together. This is
+obviously problematic since the restart work wants to
+reconfigure the connection, while the csa_connection_drop_work
+worker does the exact opposite: it tries to disconnect.
+
+Fix this by cancelling the csa_connection_drop_work worker
+in the restart worker.
+
+Note that this can sound racy: we could have:
+
+driver   iface_work   CSA_work   restart_work
++++++++++++++++++++++++++++++++++++++++++++++
+              |
+ <--drv_cs ---|
+<FW CRASH!>
+-CS FAILED-->
+              |                       |
+              |                 cancel_work(CSA)
+           schedule                   |
+           CSA work                   |
+                         |            |
+                        Race between those 2
+
+But this is not possible because we flush the workqueue
+in the restart worker before we cancel the CSA worker.
+That would be bullet proof if we could guarantee that
+we schedule the CSA worker only from the iface_work
+which runs on the workqueue (and not on the system's
+workqueue), but unfortunately we do have an instance
+in which we schedule the CSA work outside the context
+of the workqueue (ieee80211_chswitch_done).
+
+Note also that we should probably cancel other workers
+like beacon_connection_loss_work and possibly others
+for different types of interfaces, at the very least,
+IBSS should suffer from the exact same problem, but for
+now, do the minimum to fix the actual bug that was actually
+experienced and reproduced.
+
+Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
+Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
+Signed-off-by: Johannes Berg <johannes.berg@intel.com>
+---
+
+--- a/net/mac80211/main.c
++++ b/net/mac80211/main.c
+@@ -255,8 +255,27 @@ static void ieee80211_restart_work(struc
+ 
+ 	flush_work(&local->radar_detected_work);
+ 	rtnl_lock();
+-	list_for_each_entry(sdata, &local->interfaces, list)
++	list_for_each_entry(sdata, &local->interfaces, list) {
++		/*
++		 * XXX: there may be more work for other vif types and even
++		 * for station mode: a good thing would be to run most of
++		 * the iface type's dependent _stop (ieee80211_mg_stop,
++		 * ieee80211_ibss_stop) etc...
++		 * For now, fix only the specific bug that was seen: race
++		 * between csa_connection_drop_work and us.
++		 */
++		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
++			/*
++			 * This worker is scheduled from the iface worker that
++			 * runs on mac80211's workqueue, so we can't be
++			 * scheduling this worker after the cancel right here.
++			 * The exception is ieee80211_chswitch_done.
++			 * Then we can have a race...
++			 */
++			cancel_work_sync(&sdata->u.mgd.csa_connection_drop_work);
++		}
+ 		flush_delayed_work(&sdata->dec_tailroom_needed_wk);
++	}
+ 	ieee80211_scan_cancel(local);
+ 
+ 	/* make sure any new ROC will consider local->in_reconfig */