mac80211: Add scan race fix

SVN-Revision: 25930

package/mac80211/patches/721-mac80211-fix-scan-race.patch

@@ -0,0 +1,141 @@
+Index: compat-wireless-2011-02-25/net/mac80211/scan.c
+===================================================================
+--- compat-wireless-2011-02-25.orig/net/mac80211/scan.c	2011-03-07 14:43:55.695666042 +0100
++++ compat-wireless-2011-02-25/net/mac80211/scan.c	2011-03-07 14:43:57.594439631 +0100
+@@ -258,10 +258,12 @@ static bool ieee80211_prep_hw_scan(struc
+ 	return true;
+ }
+ 
+-static bool __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
++static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
+ 				       bool was_hw_scan)
+ {
+ 	struct ieee80211_local *local = hw_to_local(hw);
++	bool on_oper_chan;
++	bool enable_beacons = false;
+ 
+ 	lockdep_assert_held(&local->mtx);
+ 
+@@ -275,12 +277,12 @@ static bool __ieee80211_scan_completed(s
+ 		aborted = true;
+ 
+ 	if (WARN_ON(!local->scan_req))
+-		return false;
++		return;
+ 
+ 	if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
+ 		int rc = drv_hw_scan(local, local->scan_sdata, local->hw_scan_req);
+ 		if (rc == 0)
+-			return false;
++			return;
+ 	}
+ 
+ 	kfree(local->hw_scan_req);
+@@ -294,26 +296,13 @@ static bool __ieee80211_scan_completed(s
+ 	local->scanning = 0;
+ 	local->scan_channel = NULL;
+ 
+-	return true;
+-}
+-
+-static void __ieee80211_scan_completed_finish(struct ieee80211_hw *hw,
+-					      bool was_hw_scan)
+-{
+-	struct ieee80211_local *local = hw_to_local(hw);
+-	bool on_oper_chan;
+-	bool enable_beacons = false;
+-
+-	mutex_lock(&local->mtx);
+ 	on_oper_chan = ieee80211_cfg_on_oper_channel(local);
+ 
+ 	WARN_ON(local->scanning & (SCAN_SW_SCANNING | SCAN_HW_SCANNING));
+ 
+-	if (was_hw_scan || !on_oper_chan) {
+-		if (WARN_ON(local->scan_channel))
+-			local->scan_channel = NULL;
++	if (was_hw_scan || !on_oper_chan)
+ 		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
+-	} else
++	else
+ 		/* Set power back to normal operating levels. */
+ 		ieee80211_hw_config(local, 0);
+ 
+@@ -331,7 +320,6 @@ static void __ieee80211_scan_completed_f
+ 	}
+ 
+ 	ieee80211_recalc_idle(local);
+-	mutex_unlock(&local->mtx);
+ 
+ 	ieee80211_mlme_notify_scan_completed(local);
+ 	ieee80211_ibss_notify_scan_completed(local);
+@@ -686,12 +674,14 @@ void ieee80211_scan_work(struct work_str
+ {
+ 	struct ieee80211_local *local =
+ 		container_of(work, struct ieee80211_local, scan_work.work);
+-	struct ieee80211_sub_if_data *sdata = local->scan_sdata;
++	struct ieee80211_sub_if_data *sdata;
+ 	unsigned long next_delay = 0;
+-	bool aborted, hw_scan, finish;
++	bool aborted, hw_scan;
+ 
+ 	mutex_lock(&local->mtx);
+ 
++	sdata = local->scan_sdata;
++
+ 	if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
+ 		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
+ 		goto out_complete;
+@@ -755,17 +745,11 @@ void ieee80211_scan_work(struct work_str
+ 	} while (next_delay == 0);
+ 
+ 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
+-	mutex_unlock(&local->mtx);
+-	return;
++	goto out;
+ 
+ out_complete:
+ 	hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
+-	finish = __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
+-	mutex_unlock(&local->mtx);
+-	if (finish)
+-		__ieee80211_scan_completed_finish(&local->hw, hw_scan);
+-	return;
+-
++	__ieee80211_scan_completed(&local->hw, aborted, hw_scan);
+ out:
+ 	mutex_unlock(&local->mtx);
+ }
+@@ -835,7 +819,6 @@ int ieee80211_request_internal_scan(stru
+ void ieee80211_scan_cancel(struct ieee80211_local *local)
+ {
+ 	bool abortscan;
+-	bool finish = false;
+ 
+ 	/*
+ 	 * We are only canceling software scan, or deferred scan that was not
+@@ -855,14 +838,17 @@ void ieee80211_scan_cancel(struct ieee80
+ 
+ 	mutex_lock(&local->mtx);
+ 	abortscan = local->scan_req && !test_bit(SCAN_HW_SCANNING, &local->scanning);
+-	if (abortscan)
+-		finish = __ieee80211_scan_completed(&local->hw, true, false);
+-	mutex_unlock(&local->mtx);
+-
+ 	if (abortscan) {
+-		/* The scan is canceled, but stop work from being pending */
+-		cancel_delayed_work_sync(&local->scan_work);
++		/*
++		 * The scan is canceled, but stop work from being pending.
++		 *
++		 * If the work is currently running, it must be blocked on
++		 * the mutex, but we'll set scan_sdata = NULL and it'll
++		 * simply exit once it acquires the mutex.
++		 */
++		cancel_delayed_work(&local->scan_work);
++		/* and clean up */
++		__ieee80211_scan_completed(&local->hw, true, false);
+ 	}
+-	if (finish)
+-		__ieee80211_scan_completed_finish(&local->hw, false);
++	mutex_unlock(&local->mtx);
+ }