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Synchronize DeviceStateController on WindowManagerGlobalLock

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The existing way of synchronizing on DeviceStateController.this is
prone to deadlocks. For example, this sequence of events will result in
a deadlock.

ThreadA: 1) Acquire WindowManagerGlobalLock
         4) Acquire DeviceStateController.this

ThreadB) 2) Acquire DeviceStateController.this
         3) Acquire WindowManagerGlobalLock

Instead of using DeviceStateController.this as a lock, we should just
use the existing WindowManagerGlobalLock like the rest of WM code.
This way, since all locking is done on the same global lock, there
shouldn't be a way for this deadlock to occur anymore.

Also, put work onto WindowManagerService's handler so that
DeviceStateController's lock when invoking callbacks is short.

Fixes: 281653024
Test: presubmit
Change-Id: I3c0086856c245a01c951d295a040c93c82c8a485
This commit is contained in:
Kevin Chyn
2023-05-15 23:38:43 +00:00
parent 0f6b4e2348
commit 383b57ab69
4 changed files with 46 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
services/core/java/com/android/server/wm/DeviceStateController.java
View File

@@ -16,11 +16,13 @@
package com.android.server.wm;
import android.annotation.CallbackExecutor;
import android.annotation.NonNull;
import android.content.Context;
import android.hardware.devicestate.DeviceStateManager;
import android.os.Handler;
import android.os.HandlerExecutor;
import android.util.ArrayMap;
import com.android.internal.R;
import com.android.internal.annotations.GuardedBy;
@@ -29,6 +31,8 @@ import com.android.internal.util.ArrayUtils;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Executor;
import java.util.function.Consumer;
/**
@@ -37,6 +41,9 @@ import java.util.function.Consumer;
*/
final class DeviceStateController implements DeviceStateManager.DeviceStateCallback {
// Used to synchronize WindowManager services call paths with DeviceStateManager's callbacks.
@NonNull
private final WindowManagerGlobalLock mWmLock;
@NonNull
private final DeviceStateManager mDeviceStateManager;
@NonNull
@@ -50,10 +57,10 @@ final class DeviceStateController implements DeviceStateManager.DeviceStateCallb
private final int mConcurrentDisplayDeviceState;
@NonNull
private final int[] mReverseRotationAroundZAxisStates;
@GuardedBy("this")
@GuardedBy("mWmLock")
@NonNull
@VisibleForTesting
final List<Consumer<DeviceState>> mDeviceStateCallbacks = new ArrayList<>();
final Map<Consumer<DeviceState>, Executor> mDeviceStateCallbacks = new ArrayMap<>();
private final boolean mMatchBuiltInDisplayOrientationToDefaultDisplay;
@@ -70,7 +77,9 @@ final class DeviceStateController implements DeviceStateManager.DeviceStateCallb
CONCURRENT,
}
DeviceStateController(@NonNull Context context, @NonNull Handler handler) {
DeviceStateController(@NonNull Context context, @NonNull Handler handler,
@NonNull WindowManagerGlobalLock wmLock) {
mWmLock = wmLock;
mDeviceStateManager = context.getSystemService(DeviceStateManager.class);
mOpenDeviceStates = context.getResources()
@@ -94,14 +103,20 @@ final class DeviceStateController implements DeviceStateManager.DeviceStateCallb
}
}
void registerDeviceStateCallback(@NonNull Consumer<DeviceState> callback) {
synchronized (this) {
mDeviceStateCallbacks.add(callback);
/**
* Registers a callback to be notified when the device state changes. Callers should always
* post the work onto their own worker thread to avoid holding the WindowManagerGlobalLock for
* an extended period of time.
*/
void registerDeviceStateCallback(@NonNull Consumer<DeviceState> callback,
@NonNull @CallbackExecutor Executor executor) {
synchronized (mWmLock) {
mDeviceStateCallbacks.put(callback, executor);
}
}
void unregisterDeviceStateCallback(@NonNull Consumer<DeviceState> callback) {
synchronized (this) {
synchronized (mWmLock) {
mDeviceStateCallbacks.remove(callback);
}
}
@@ -144,11 +159,21 @@ final class DeviceStateController implements DeviceStateManager.DeviceStateCallb
if (mCurrentDeviceState == null || !mCurrentDeviceState.equals(deviceState)) {
mCurrentDeviceState = deviceState;
synchronized (this) {
for (Consumer<DeviceState> callback : mDeviceStateCallbacks) {
callback.accept(mCurrentDeviceState);
// Make a copy here because it's possible that the consumer tries to remove a callback
// while we're still iterating through the list, which would end up in a
// ConcurrentModificationException.
final List<Map.Entry<Consumer<DeviceState>, Executor>> entries = new ArrayList<>();
synchronized (mWmLock) {
for (Map.Entry<Consumer<DeviceState>, Executor> entry
: mDeviceStateCallbacks.entrySet()) {
entries.add(entry);
}
}
for (int i = 0; i < entries.size(); i++) {
Map.Entry<Consumer<DeviceState>, Executor> entry = entries.get(i);
entry.getValue().execute(() -> entry.getKey().accept(mCurrentDeviceState));
}
}
}
}

4
services/core/java/com/android/server/wm/DisplayContent.java
View File

@@ -188,6 +188,7 @@ import android.metrics.LogMaker;
import android.os.Bundle;
import android.os.Debug;
import android.os.Handler;
import android.os.HandlerExecutor;
import android.os.IBinder;
import android.os.Message;
import android.os.PowerManager;
@@ -1182,7 +1183,8 @@ class DisplayContent extends RootDisplayArea implements WindowManagerPolicy.Disp
mDisplaySwitchTransitionLauncher.foldStateChanged(newFoldState);
mDisplayRotation.foldStateChanged(newFoldState);
};
mDeviceStateController.registerDeviceStateCallback(mDeviceStateConsumer);
mDeviceStateController.registerDeviceStateCallback(mDeviceStateConsumer,
new HandlerExecutor(mWmService.mH));
mCloseToSquareMaxAspectRatio = mWmService.mContext.getResources().getFloat(
R.dimen.config_closeToSquareDisplayMaxAspectRatio);

3
services/core/java/com/android/server/wm/RootWindowContainer.java
View File

@@ -438,7 +438,8 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
mTaskSupervisor = mService.mTaskSupervisor;
mTaskSupervisor.mRootWindowContainer = this;
mDisplayOffTokenAcquirer = mService.new SleepTokenAcquirerImpl(DISPLAY_OFF_SLEEP_TOKEN_TAG);
mDeviceStateController = new DeviceStateController(service.mContext, service.mH);
mDeviceStateController = new DeviceStateController(service.mContext, service.mH,
service.mGlobalLock);
mDisplayRotationCoordinator = new DisplayRotationCoordinator();
}

9
services/tests/wmtests/src/com/android/server/wm/DeviceStateControllerTests.java
View File

@@ -34,6 +34,8 @@ import androidx.test.filters.SmallTest;
import com.android.internal.R;
import com.google.common.util.concurrent.MoreExecutors;
import org.junit.Before;
import org.junit.Test;
@@ -117,7 +119,7 @@ public class DeviceStateControllerTests {
public void testUnregisterDeviceStateCallback() {
initialize(true /* supportFold */, true /* supportHalfFolded */);
assertEquals(1, mTarget.mDeviceStateCallbacks.size());
assertEquals(mDelegate, mTarget.mDeviceStateCallbacks.get(0));
assertTrue(mTarget.mDeviceStateCallbacks.containsKey(mDelegate));
mTarget.onStateChanged(mOpenDeviceStates[0]);
assertEquals(DeviceStateController.DeviceState.OPEN, mCurrentState);
@@ -194,8 +196,9 @@ public class DeviceStateControllerTests {
when(mMockContext.getResources()).thenReturn((mockRes));
mockFold(mSupportFold, mSupportHalfFold);
Handler mockHandler = mock(Handler.class);
mTarget = new DeviceStateController(mMockContext, mockHandler);
mTarget.registerDeviceStateCallback(mDelegate);
mTarget = new DeviceStateController(mMockContext, mockHandler,
new WindowManagerGlobalLock());
mTarget.registerDeviceStateCallback(mDelegate, MoreExecutors.directExecutor());
}
}
}