mac80211: assure we also cancel deferred scan request
Stanislaw Gruszka [Wed, 6 Oct 2010 09:22:10 +0000 (11:22 +0200)]
This is partial revert and fix for commit
85f72bc839705294b32b6c16b491c0422f0a71b3 "mac80211: only cancel
software-based scans on suspend"

When cfg80211 request the scan and mac80211 perform some management work,
we defer the scan request. We do not canceling such requests when calling
ieee80211_scan_cancel(), because of SCAN_SW_SCANNING bit check just
before the call. So fix that problem.

Another problem, which commit 85f72bc839705294b32b6c16b491c0422f0a71b3
tries to solve, is we can not cancel HW scan. Hence patch make
ieee80211_scan_cancel() ignore HW scan (see code comments). Keeping
local->mtx lock assures that the deferred scan will not become
"working" HW scan.

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

net/mac80211/main.c
net/mac80211/pm.c
net/mac80211/scan.c

index e371709..915ecf8 100644 (file)
@@ -307,8 +307,7 @@ static void ieee80211_restart_work(struct work_struct *work)
        mutex_unlock(&local->mtx);
 
        rtnl_lock();
-       if (unlikely(test_bit(SCAN_SW_SCANNING, &local->scanning)))
-               ieee80211_scan_cancel(local);
+       ieee80211_scan_cancel(local);
        ieee80211_reconfig(local);
        rtnl_unlock();
 }
index e3e2bce..e373551 100644 (file)
@@ -12,8 +12,7 @@ int __ieee80211_suspend(struct ieee80211_hw *hw)
        struct ieee80211_sub_if_data *sdata;
        struct sta_info *sta;
 
-       if (unlikely(test_bit(SCAN_SW_SCANNING, &local->scanning)))
-               ieee80211_scan_cancel(local);
+       ieee80211_scan_cancel(local);
 
        ieee80211_stop_queues_by_reason(hw,
                        IEEE80211_QUEUE_STOP_REASON_SUSPEND);
index 6964a45..4dbef71 100644 (file)
@@ -793,24 +793,39 @@ int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
        return ret;
 }
 
+/*
+ * Only call this function when a scan can't be queued -- under RTNL.
+ */
 void ieee80211_scan_cancel(struct ieee80211_local *local)
 {
-       bool abortscan;
-       bool finish = false;
-
-       cancel_delayed_work_sync(&local->scan_work);
+       bool abortscan, finish;
 
        /*
-        * Only call this function when a scan can't be
-        * queued -- mostly at suspend under RTNL.
+        * We are only canceling software scan, or deferred scan that was not
+        * yet really started (see __ieee80211_start_scan ).
+        *
+        * Regarding hardware scan:
+        * - we can not call  __ieee80211_scan_completed() as when
+        *   SCAN_HW_SCANNING bit is set this function change
+        *   local->hw_scan_req to operate on 5G band, what race with
+        *   driver which can use local->hw_scan_req
+        *
+        * - we can not cancel scan_work since driver can schedule it
+        *   by ieee80211_scan_completed(..., true) to finish scan
+        *
+        * Hence low lever driver is responsible for canceling HW scan.
         */
+
        mutex_lock(&local->mtx);
-       abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
-                   (!local->scanning && local->scan_req);
+       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 (finish)
-               __ieee80211_scan_completed_finish(&local->hw, false);
+       if (abortscan) {
+               /* The scan is canceled, but stop work from being pending */
+               cancel_delayed_work_sync(&local->scan_work);
+               if (finish)
+                       __ieee80211_scan_completed_finish(&local->hw, false);
+       }
 }