From 4a199068230bd8074f2e39025a2216390ea5b829 Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Wed, 26 Apr 2017 10:58:53 +0300
Subject: mac80211: disentangle iflist_mtx and chanctx_mtx

At least on iwlwifi, sometimes lockdep complains that we can
lock
 chanctx_mtx -> mvm.mutex -> iflist_mtx
 (due to iterate_interfaces)
and
 iflist_mtx -> chanctx_mtx

Remove the latter dependency in mac80211 by using the RTNL
that we already hold in one case, and can relatively easily
achieve in the other case.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/mac80211/util.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

(limited to 'net/mac80211/util.c')

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 7a37ce78bb38..37dad3dd6bac 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2791,8 +2791,10 @@ void ieee80211_dfs_cac_cancel(struct ieee80211_local *local)
 	struct ieee80211_sub_if_data *sdata;
 	struct cfg80211_chan_def chandef;
 
+	/* for interface list, to avoid linking iflist_mtx and chanctx_mtx */
+	ASSERT_RTNL();
+
 	mutex_lock(&local->mtx);
-	mutex_lock(&local->iflist_mtx);
 	list_for_each_entry(sdata, &local->interfaces, list) {
 		/* it might be waiting for the local->mtx, but then
 		 * by the time it gets it, sdata->wdev.cac_started
@@ -2809,7 +2811,6 @@ void ieee80211_dfs_cac_cancel(struct ieee80211_local *local)
 					   GFP_KERNEL);
 		}
 	}
-	mutex_unlock(&local->iflist_mtx);
 	mutex_unlock(&local->mtx);
 }
 
@@ -2831,7 +2832,9 @@ void ieee80211_dfs_radar_detected_work(struct work_struct *work)
 	}
 	mutex_unlock(&local->chanctx_mtx);
 
+	rtnl_lock();
 	ieee80211_dfs_cac_cancel(local);
+	rtnl_unlock();
 
 	if (num_chanctx > 1)
 		/* XXX: multi-channel is not supported yet */
@@ -2846,7 +2849,7 @@ void ieee80211_radar_detected(struct ieee80211_hw *hw)
 
 	trace_api_radar_detected(local);
 
-	ieee80211_queue_work(hw, &local->radar_detected_work);
+	schedule_work(&local->radar_detected_work);
 }
 EXPORT_SYMBOL(ieee80211_radar_detected);
 
-- 
cgit v1.2.3-70-g09d2