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Commit 15db0b7f authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
Browse files

mac80211: fix scan cancel on ifdown 



When an interface is taken down while a scan is
pending -- i.e. a scan request was accepted but
not yet acted upon due to other work being in
progress -- we currently do not properly cancel
that scan and end up getting stuck. Fix this by
doing better checks when an interface is taken
down.

Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 6bd5f520

net/mac80211/iface.c

+2 −24
Original line number Diff line number Diff line
@@ -497,30 +497,8 @@ static int ieee80211_stop(struct net_device *dev) 
		}

		/* fall through */

	default:

		if (local->scan_sdata == sdata) {

			if (!local->ops->hw_scan)

				cancel_delayed_work_sync(&local->scan_work);

			/*

			 * The software scan can no longer run now, so we can

			 * clear out the scan_sdata reference. However, the

			 * hardware scan may still be running. The complete

			 * function must be prepared to handle a NULL value.

			 */

			local->scan_sdata = NULL;

			/*

			 * The memory barrier guarantees that another CPU

			 * that is hardware-scanning will now see the fact

			 * that this interface is gone.

			 */

			smp_mb();

			/*

			 * If software scanning, complete the scan but since

			 * the scan_sdata is NULL already don't send out a

			 * scan event to userspace -- the scan is incomplete.

			 */

			if (test_bit(SCAN_SW_SCANNING, &local->scanning))

				ieee80211_scan_completed(&local->hw, true);

		}

		if (local->scan_sdata == sdata)

			ieee80211_scan_cancel(local);



		/*

		 * Disable beaconing for AP and mesh, IBSS can't

net/mac80211/scan.c

+6 −3
Original line number Diff line number Diff line
@@ -280,6 +280,7 @@ void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted) 
	if (local->scan_req != local->int_scan_req)

		cfg80211_scan_done(local->scan_req, aborted);

	local->scan_req = NULL;

	local->scan_sdata = NULL;



	was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);

	local->scanning = 0;
@@ -660,6 +661,7 @@ void ieee80211_scan_work(struct work_struct *work) 
		int rc;



		local->scan_req = NULL;

		local->scan_sdata = NULL;



		rc = __ieee80211_start_scan(sdata, req);

		mutex_unlock(&local->scan_mtx);
@@ -742,7 +744,7 @@ int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata, 


void ieee80211_scan_cancel(struct ieee80211_local *local)

{

	bool swscan;

	bool abortscan;



	cancel_delayed_work_sync(&local->scan_work);
@@ -751,9 +753,10 @@ void ieee80211_scan_cancel(struct ieee80211_local *local) 
	 * queued -- mostly at suspend under RTNL.

	 */

	mutex_lock(&local->scan_mtx);

	swscan = test_bit(SCAN_SW_SCANNING, &local->scanning);

	abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||

		    (!local->scanning && local->scan_req);

	mutex_unlock(&local->scan_mtx);



	if (swscan)

	if (abortscan)

		ieee80211_scan_completed(&local->hw, true);

}