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Commit 0fd2afe0 authored by Atneya Nair's avatar Atneya Nair
Browse files

Prevent deadlock in binderDied in validation layer 

In binderDied, we hold the validation layer lock as we call unloadModel,
which blocks on callbacks, violating our lock ordering.

As a temporary fix, cache the currently loaded models, and unload them.

Bug: 237602275
Test: Compiles
Change-Id: I5091cb152765ea1f78958108a331d75951b8b717
parent d4384a5f

services/core/java/com/android/server/soundtrigger_middleware/SoundTriggerMiddlewareValidation.java

+32 −7
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ import android.os.IBinder; 
import android.os.RemoteException;

import android.os.ServiceSpecificException;

import android.util.Log;

import android.util.SparseArray;



import com.android.internal.util.Preconditions;
@@ -829,17 +830,41 @@ public class SoundTriggerMiddlewareValidation implements ISoundTriggerMiddleware 
            @Override

            public void binderDied() {

                // This is called whenever our client process dies.

                SparseArray<ModelState.Activity> cachedMap =

                        new SparseArray<ModelState.Activity>();

                synchronized (SoundTriggerMiddlewareValidation.this) {

                    try {

                        // Gracefully stop all active recognitions and unload the models.

                        // Copy the relevant state under the lock, so we can call back without

                        // holding a lock. This exposes us to a potential race, but the client is

                        // dead so we don't expect one.

                        // TODO(240613068) A more resilient fix for this.

                        for (Map.Entry<Integer, ModelState> entry :

                                mLoadedModels.entrySet()) {

                            if (entry.getValue().activityState == ModelState.Activity.ACTIVE) {

                                mDelegate.stopRecognition(entry.getKey());

                            cachedMap.put(entry.getKey(), entry.getValue().activityState);

                        }

                }

                try {

                    // Gracefully stop all active recognitions and unload the models.

                    for (int i = 0; i < cachedMap.size(); i++) {

                        if (cachedMap.valueAt(i) == ModelState.Activity.ACTIVE) {

                            mDelegate.stopRecognition(cachedMap.keyAt(i));

                        }

                            mDelegate.unloadModel(entry.getKey());

                        mDelegate.unloadModel(cachedMap.keyAt(i));

                    }

                        // Detach.

                } catch (Exception e) {

                    throw handleException(e);

                }

                synchronized (SoundTriggerMiddlewareValidation.this) {

                   // Check if state updated unexpectedly to log race conditions.

                    for (Map.Entry<Integer, ModelState> entry : mLoadedModels.entrySet()) {

                        if (cachedMap.get(entry.getKey()) != entry.getValue().activityState) {

                            Log.e(TAG, "Unexpected state update in binderDied. Race occurred!");

                        }

                    }

                    if (mLoadedModels.size() != cachedMap.size()) {

                        Log.e(TAG, "Unexpected state update in binderDied. Race occurred!");

                    }

                    try {

                        // Detach

                        detachInternal();

                    } catch (Exception e) {

                        throw handleException(e);