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: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 2 insertions, 24 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index d134bd79972f..f6005adcbf90 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -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