iwlwifi: fix possible recursive locking deadlock

commit f84b29ec
Author: Johannes Berg <johannes.berg@intel.com>
Date:   Tue May 18 02:29:13 2010 -0700

    iwlwifi: queue user-initiated scan when doing internal scan

introduced a potential deadlock because it calls
ieee80211_scan_completed() with the priv->mutex
held, but mac80211 may call back into iwlwifi
which would lead to recursive locking. Move this
out from under the mutex.

Cc: stable@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-core.c

@@ -2000,6 +2000,7 @@ void iwl_mac_remove_interface(struct ieee80211_hw *hw,
 			      struct ieee80211_vif *vif)
 {
 	struct iwl_priv *priv = hw->priv;
+	bool scan_completed = false;
 
 	IWL_DEBUG_MAC80211(priv, "enter\n");
 
@@ -2013,7 +2014,7 @@ void iwl_mac_remove_interface(struct ieee80211_hw *hw,
 	if (priv->vif == vif) {
 		priv->vif = NULL;
 		if (priv->scan_vif == vif) {
-			ieee80211_scan_completed(priv->hw, true);
+			scan_completed = true;
 			priv->scan_vif = NULL;
 			priv->scan_request = NULL;
 		}
@@ -2021,6 +2022,9 @@ void iwl_mac_remove_interface(struct ieee80211_hw *hw,
 	}
 	mutex_unlock(&priv->mutex);
 
+	if (scan_completed)
+		ieee80211_scan_completed(priv->hw, true);
+
 	IWL_DEBUG_MAC80211(priv, "leave\n");
 
 }