Merge "Fix deadlock in binder death handling" into main (9ca08656) · Commits · e / os / android_frameworks_base

services/core/java/com/android/server/display/DisplayManagerService.java

+39 −28

Original line number	Diff line number	Diff line
		@@ -4188,6 +4188,9 @@ public final class DisplayManagerService extends SystemService {
		}
		}

		/**
		* This method must not be called with mCallback held or deadlock will ensue.
		*/
		@Override
		public void binderDied() {
		synchronized (mCallback) {
		@@ -4248,17 +4251,8 @@ public final class DisplayManagerService extends SystemService {
		}
		}

		return transmitDisplayEvent(displayId, event);
		}

		/**
		* Transmit a single display event. The client is presumed ready. Return true on success
		* and false if the client died.
		*/
		private boolean transmitDisplayEvent(int displayId, @DisplayEvent int event) {
		// The client is ready to receive the event.
		try {
		mCallback.onDisplayEvent(displayId, event);
		transmitDisplayEvent(displayId, event);
		return true;
		} catch (RemoteException ex) {
		Slog.w(TAG, "Failed to notify process "
		@@ -4268,6 +4262,18 @@ public final class DisplayManagerService extends SystemService {
		}
		}

		/**
		* Transmit a single display event. The client is presumed ready. This throws if the
		* client has died; callers must catch and handle the exception. The exception cannot be
		* handled directly here because {@link #binderDied()} must not be called whilst holding
		* the mCallback lock.
		*/
		private void transmitDisplayEvent(int displayId, @DisplayEvent int event)
		throws RemoteException {
		// The client is ready to receive the event.
		mCallback.onDisplayEvent(displayId, event);
		}

		/**
		* Return true if the client is interested in this event.
		*/
		@@ -4376,6 +4382,7 @@ public final class DisplayManagerService extends SystemService {
		// would be unusual to do so. The method returns true on success.
		// This is only used if {@link deferDisplayEventsWhenFrozen()} is true.
		public boolean dispatchPending() {
		try {
		synchronized (mCallback) {
		if (mPendingEvents == null \|\| mPendingEvents.isEmpty() \|\| !mAlive) {
		return true;
		@@ -4390,14 +4397,18 @@ public final class DisplayManagerService extends SystemService {
		+ displayEvent.displayId + "/"
		+ displayEvent.event + " to " + mUid + "/" + mPid);
		}
		if (!transmitDisplayEvent(displayEvent.displayId, displayEvent.event)) {
		Slog.d(TAG, "Drop pending events for dead process " + mPid);
		break;
		}
		transmitDisplayEvent(displayEvent.displayId, displayEvent.event);
		}
		mPendingEvents.clear();
		return true;
		}
		} catch (RemoteException ex) {
		Slog.w(TAG, "Failed to notify process "
		+ mPid + " that display topology changed, assuming it died.", ex);
		binderDied();
		return false;

		}
		}

		// Return a string suitable for dumpsys.