Merge "[MediaProjection] Address deadlock between multiple services" into udc-dev (607bd36f) · Commits · e / os / android_frameworks_base

services/core/java/com/android/server/media/projection/MediaProjectionManagerService.java

+27 −14

Original line number	Diff line number	Diff line
		@@ -117,6 +117,10 @@ public final class MediaProjectionManagerService extends SystemService
		// WindowManagerService -> MediaProjectionManagerService -> DisplayManagerService
		// See mediaprojection.md
		private final Object mLock = new Object();
		// A handler for posting tasks that must interact with a service holding another lock,
		// especially for services that will eventually acquire the WindowManager lock.
		@NonNull private final Handler mHandler;

		private final Map<IBinder, IBinder.DeathRecipient> mDeathEaters;
		private final CallbackDelegate mCallbackDelegate;

		@@ -145,6 +149,8 @@ public final class MediaProjectionManagerService extends SystemService
		super(context);
		mContext = context;
		mInjector = injector;
		// Post messages on the main thread; no need for a separate thread.
		mHandler = new Handler(Looper.getMainLooper());
		mClock = injector.createClock();
		mDeathEaters = new ArrayMap<IBinder, IBinder.DeathRecipient>();
		mCallbackDelegate = new CallbackDelegate();
		@@ -238,7 +244,9 @@ public final class MediaProjectionManagerService extends SystemService
		if (!mProjectionGrant.requiresForegroundService()) {
		return;
		}
		}

		// Run outside the lock when calling into ActivityManagerService.
		if (mActivityManagerInternal.hasRunningForegroundService(
		uid, ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PROJECTION)) {
		// If there is any process within this UID running a FGS
		@@ -246,9 +254,12 @@ public final class MediaProjectionManagerService extends SystemService
		return;
		}

		synchronized (mLock) {
		if (mProjectionGrant != null) {
		mProjectionGrant.stop();
		}
		}
		}

		private void startProjectionLocked(final MediaProjection projection) {
		if (mProjectionGrant != null) {
		@@ -854,7 +865,6 @@ public final class MediaProjectionManagerService extends SystemService
		mTargetSdkVersion = targetSdkVersion;
		mIsPrivileged = isPrivileged;
		mCreateTimeMs = mClock.uptimeMillis();
		// TODO(b/267740338): Add unit test.
		mActivityManagerInternal.notifyMediaProjectionEvent(uid, asBinder(),
		MEDIA_PROJECTION_TOKEN_EVENT_CREATED);
		}
		@@ -911,6 +921,10 @@ public final class MediaProjectionManagerService extends SystemService
		if (callback == null) {
		throw new IllegalArgumentException("callback must not be null");
		}
		// Cache result of calling into ActivityManagerService outside of the lock, to prevent
		// deadlock with WindowManagerService.
		final boolean hasFGS = mActivityManagerInternal.hasRunningForegroundService(
		uid, ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PROJECTION);
		synchronized (mLock) {
		if (isCurrentProjection(asBinder())) {
		Slog.w(TAG, "UID " + Binder.getCallingUid()
		@@ -922,9 +936,7 @@ public final class MediaProjectionManagerService extends SystemService
		}

		if (REQUIRE_FG_SERVICE_FOR_PROJECTION
		&& requiresForegroundService()
		&& !mActivityManagerInternal.hasRunningForegroundService(
		uid, ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PROJECTION)) {
		&& requiresForegroundService() && !hasFGS) {
		throw new SecurityException("Media projections require a foreground service"
		+ " of type ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PROJECTION");
		}
		@@ -1013,10 +1025,11 @@ public final class MediaProjectionManagerService extends SystemService
		mToken = null;
		unregisterCallback(mCallback);
		mCallback = null;
		// TODO(b/267740338): Add unit test.
		mActivityManagerInternal.notifyMediaProjectionEvent(uid, asBinder(),
		MEDIA_PROJECTION_TOKEN_EVENT_DESTROYED);
		}
		// Run on a separate thread, to ensure no lock is held when calling into
		// ActivityManagerService.
		mHandler.post(() -> mActivityManagerInternal.notifyMediaProjectionEvent(uid, asBinder(),
		MEDIA_PROJECTION_TOKEN_EVENT_DESTROYED));
		}

		@Override // Binder call

services/core/java/com/android/server/media/projection/mediaprojection.md

+5 −0

Original line number	Diff line number	Diff line
		@@ -11,6 +11,11 @@ Calls must follow the below invocation order while holding locks:

		`WindowManagerService -> MediaProjectionManagerService -> DisplayManagerService`

		`MediaProjectionManagerService` should never lock when calling into a service that may acquire
		the `WindowManagerService` global lock (for example,
		`MediaProjectionManagerService -> ActivityManagerService` may result in deadlock, since
		`ActivityManagerService -> WindowManagerService`).

		### Justification

		`MediaProjectionManagerService` calls into `WindowManagerService` in the below cases. While handling