From 856142cdaa483099f50cac70a16898ead8e4094d Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Tue, 24 Nov 2015 15:29:53 +0100
Subject: mac80211: catch queue stop underflow

If some code stops the queues more times than having started
(for when refcounting is used), warn on and reset the counter
to 0 to avoid blocking forever.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 7405802..08af2b3 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -288,10 +288,13 @@ static void __ieee80211_wake_queue(struct ieee80211_hw *hw, int queue,
 	if (!test_bit(reason, &local->queue_stop_reasons[queue]))
 		return;
 
-	if (!refcounted)
+	if (!refcounted) {
 		local->q_stop_reasons[queue][reason] = 0;
-	else
+	} else {
 		local->q_stop_reasons[queue][reason]--;
+		if (WARN_ON(local->q_stop_reasons[queue][reason] < 0))
+			local->q_stop_reasons[queue][reason] = 0;
+	}
 
 	if (local->q_stop_reasons[queue][reason] == 0)
 		__clear_bit(reason, &local->queue_stop_reasons[queue]);
-- 
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