Fix WifiScanner not recovering after Wifi is turned off

WifiScanner implementations could previously get in an inconsistent
state where they had not cleaned up from a previous scan that was
interrupted by turning Wifi off.

Bug: 27620477
Change-Id: I042e35d1aa8ee65e6ebfeb6f62a54c071a7be4ef

4 files changed, 32 insertions, 1 deletions

diff --git a/service/java/com/android/server/wifi/HalWifiScannerImpl.java b/service/java/com/android/server/wifi/HalWifiScannerImpl.java
index c678c7302..ebb5f36ed 100644
--- a/service/java/com/android/server/wifi/HalWifiScannerImpl.java
+++ b/service/java/com/android/server/wifi/HalWifiScannerImpl.java
@@ -75,6 +75,7 @@ public class HalWifiScannerImpl extends WifiScannerImpl implements Handler.Callb
                 } else {
                     Log.w(TAG, "Got single scan failed event without an active scan request");
                 }
+                mWifiNative.resumeBackgroundScan();
                 break;
             case WifiMonitor.SCAN_RESULTS_EVENT:
                 pollLatestSingleScanData();
@@ -174,6 +175,12 @@ public class HalWifiScannerImpl extends WifiScannerImpl implements Handler.Callb
     }
 
     @Override
+    public void cleanup() {
+        mSingleScanEventHandler = null;
+        mWifiNative.resumeBackgroundScan();
+    }
+
+    @Override
     public boolean getScanCapabilities(WifiNative.ScanCapabilities capabilities) {
         return mWifiNative.getScanCapabilities(capabilities);
     }
diff --git a/service/java/com/android/server/wifi/SupplicantWifiScannerImpl.java b/service/java/com/android/server/wifi/SupplicantWifiScannerImpl.java
index 05f602090..91747808a 100644
--- a/service/java/com/android/server/wifi/SupplicantWifiScannerImpl.java
+++ b/service/java/com/android/server/wifi/SupplicantWifiScannerImpl.java
@@ -115,6 +115,19 @@ public class SupplicantWifiScannerImpl extends WifiScannerImpl implements Handle
     }
 
     @Override
+    public void cleanup() {
+        synchronized (mSettingsLock) {
+            mPendingSingleScanSettings = null;
+            mPendingSingleScanEventHandler = null;
+            stopPnoScan();
+            stopBatchedScan();
+            resetHotlist();
+            untrackSignificantWifiChange();
+            mLastScanSettings = null; // finally clear any active scan
+        }
+    }
+
+    @Override
     public boolean getScanCapabilities(WifiNative.ScanCapabilities capabilities) {
         capabilities.max_scan_cache_size = Integer.MAX_VALUE;
         capabilities.max_scan_buckets = MAX_SCAN_BUCKETS;
@@ -213,6 +226,7 @@ public class SupplicantWifiScannerImpl extends WifiScannerImpl implements Handle
             mBackgroundScanPeriodPending = false;
             unscheduleScansLocked();
         }
+        processPendingScans();
     }
 
     @Override
@@ -236,6 +250,7 @@ public class SupplicantWifiScannerImpl extends WifiScannerImpl implements Handle
                 mPendingBackgroundScanEventHandler.onScanPaused(results);
             }
         }
+        processPendingScans();
     }
 
     @Override
@@ -312,7 +327,9 @@ public class SupplicantWifiScannerImpl extends WifiScannerImpl implements Handle
 
     private void unscheduleScansLocked() {
         mAlarmManager.cancel(mScanPeriodListener);
-        mLastScanSettings = null; // make sure that a running scan is marked as ended
+        if (mLastScanSettings != null) {
+            mLastScanSettings.backgroundScanActive = false;
+        }
     }
 
     private void handleScanPeriod() {
diff --git a/service/java/com/android/server/wifi/WifiScannerImpl.java b/service/java/com/android/server/wifi/WifiScannerImpl.java
index 41c356c29..c8d80fde5 100644
--- a/service/java/com/android/server/wifi/WifiScannerImpl.java
+++ b/service/java/com/android/server/wifi/WifiScannerImpl.java
@@ -63,6 +63,12 @@ public abstract class WifiScannerImpl {
     };
 
     /**
+     * Cleanup any ongoing operations. This may be called when the driver is unloaded.
+     * There is no expectation that failure events are returned for ongoing operations.
+     */
+    public abstract void cleanup();
+
+    /**
      * Get the supported scan capabilities.
      *
      * @param capabilities Object that will be filled with the supported capabilities if successful
diff --git a/service/java/com/android/server/wifi/WifiScanningServiceImpl.java b/service/java/com/android/server/wifi/WifiScanningServiceImpl.java
index 8de44f72f..58ddd579f 100644
--- a/service/java/com/android/server/wifi/WifiScanningServiceImpl.java
+++ b/service/java/com/android/server/wifi/WifiScanningServiceImpl.java
@@ -802,6 +802,7 @@ public class WifiScanningServiceImpl extends IWifiScanner.Stub {
             public void exit() {
                 sendPnoScanFailedToAllAndClear(
                         WifiScanner.REASON_UNSPECIFIED, "Scan was interrupted");
+                mScannerImpl.cleanup();
             }
 
             @Override