Merge "UsbDeviceManager: Fix race condition entering USB accessory mode" into klp-dev

1 files changed, 26 insertions, 6 deletions

diff --git a/services/java/com/android/server/usb/UsbDeviceManager.java b/services/java/com/android/server/usb/UsbDeviceManager.java
index 5a60de0..8a5e291 100644
--- a/services/java/com/android/server/usb/UsbDeviceManager.java
+++ b/services/java/com/android/server/usb/UsbDeviceManager.java
@@ -98,6 +98,13 @@ public class UsbDeviceManager {
     // which need debouncing.
     private static final int UPDATE_DELAY = 1000;
 
+    // Time we received a request to enter USB accessory mode
+    private long mAccessoryModeRequestTime = 0;
+
+    // Timeout for entering USB request mode.
+    // Request is cancelled if host does not configure device within 10 seconds.
+    private static final int ACCESSORY_REQUEST_TIMEOUT = 10 * 1000;
+
     private static final String BOOT_MODE_PROPERTY = "ro.bootmode";
 
     private UsbHandler mHandler;
@@ -205,6 +212,8 @@ public class UsbDeviceManager {
     }
 
     private void startAccessoryMode() {
+        if (!mHasUsbAccessory) return;
+
         mAccessoryStrings = nativeGetAccessoryStrings();
         boolean enableAudio = (nativeGetAudioMode() == AUDIO_MODE_SOURCE);
         // don't start accessory mode if our mandatory strings have not been set
@@ -223,6 +232,7 @@ public class UsbDeviceManager {
         }
 
         if (functions != null) {
+            mAccessoryModeRequestTime = SystemClock.elapsedRealtime();
             setCurrentFunctions(functions, false);
         }
     }
@@ -456,6 +466,8 @@ public class UsbDeviceManager {
         }
 
         private void setEnabledFunctions(String functions, boolean makeDefault) {
+            if (DEBUG) Slog.d(TAG, "setEnabledFunctions " + functions
+                    + " makeDefault: " + makeDefault);
 
             // Do not update persystent.sys.usb.config if the device is booted up
             // with OEM specific mode.
@@ -517,9 +529,17 @@ public class UsbDeviceManager {
         }
 
         private void updateCurrentAccessory() {
-            if (!mHasUsbAccessory) return;
+            // We are entering accessory mode if we have received a request from the host
+            // and the request has not timed out yet.
+            boolean enteringAccessoryMode =
+                    mAccessoryModeRequestTime > 0 &&
+                        SystemClock.elapsedRealtime() <
+                            mAccessoryModeRequestTime + ACCESSORY_REQUEST_TIMEOUT;
+
+            if (mConfigured && enteringAccessoryMode) {
+                // successfully entered accessory mode
+                mAccessoryModeRequestTime = 0;
 
-            if (mConfigured) {
                 if (mAccessoryStrings != null) {
                     mCurrentAccessory = new UsbAccessory(mAccessoryStrings);
                     Slog.d(TAG, "entering USB accessory mode: " + mCurrentAccessory);
@@ -530,7 +550,7 @@ public class UsbDeviceManager {
                 } else {
                     Slog.e(TAG, "nativeGetAccessoryStrings failed");
                 }
-            } else if (!mConnected) {
+            } else if (!enteringAccessoryMode) {
                 // make sure accessory mode is off
                 // and restore default functions
                 Slog.d(TAG, "exited USB accessory mode");
@@ -560,6 +580,8 @@ public class UsbDeviceManager {
                 }
             }
 
+            if (DEBUG) Slog.d(TAG, "broadcasting " + intent + " connected: " + mConnected
+                                    + " configured: " + mConfigured);
             mContext.sendStickyBroadcastAsUser(intent, UserHandle.ALL);
         }
 
@@ -599,9 +621,7 @@ public class UsbDeviceManager {
                     if (containsFunction(mCurrentFunctions,
                             UsbManager.USB_FUNCTION_ACCESSORY)) {
                         updateCurrentAccessory();
-                    }
-
-                    if (!mConnected) {
+                    } else if (!mConnected) {
                         // restore defaults when USB is disconnected
                         setEnabledFunctions(mDefaultFunctions, false);
                     }