Merge "Revert "Avoid wm<->am deadlock when checking uri permission"" into rvc-dev am: 6b937bab

import com.android.internal.util.function.HexFunction;

import com.android.internal.util.function.QuadFunction;

import com.android.internal.util.function.TriFunction;

import com.android.internal.util.function.pooled.PooledLambda;

import com.android.server.AlarmManagerInternal;

import com.android.server.AttributeCache;

import com.android.server.DeviceIdleInternal;

        @Override

        public int checkContentProviderUriPermission(Uri uri, int userId,

                int callingUid, int modeFlags) {

            final Object wmLock = mActivityTaskManager.getGlobalLock();

            if (Thread.currentThread().holdsLock(wmLock)

                    && !Thread.currentThread().holdsLock(ActivityManagerService.this)) {

                // We can find ourselves needing to check Uri permissions while already holding the

                // WM lock, which means reaching back here for the AM lock would cause an inversion.

                // The WM team has requested that we use the strategy below instead of shifting

                // where Uri grants are calculated.

                synchronized (wmLock) {

                    final int[] result = new int[1];

                    final Message msg = PooledLambda.obtainMessage(

                            LocalService::checkContentProviderUriPermission,

                            this, uri, userId, callingUid, modeFlags, wmLock, result);

                    mHandler.sendMessage(msg);

                    try {

                        wmLock.wait();

                    } catch (InterruptedException ignore) {

                    }

                    return result[0];

                }

            } else {

            // We can find ourselves needing to check Uri permissions while

            // already holding the WM lock, which means reaching back here for

            // the AM lock would cause an inversion. The WM team has requested

            // that we use the strategy below instead of shifting where Uri

            // grants are calculated.

            // Since we could also arrive here while holding the AM lock, we

            // can't always delegate the call through the handler, and we need

            // to delicately dance between the deadlocks.

            if (Thread.currentThread().holdsLock(ActivityManagerService.this)) {

                return ActivityManagerService.this.checkContentProviderUriPermission(uri,

                        userId, callingUid, modeFlags);

            }

        }

        void checkContentProviderUriPermission(

                Uri uri, int userId, int callingUid, int modeFlags, Object wmLock, int[] result) {

            synchronized (ActivityManagerService.this) {

                synchronized (wmLock) {

                    result[0] = ActivityManagerService.this.checkContentProviderUriPermission(

                                    uri, userId, callingUid, modeFlags);

                    wmLock.notify();

            } else {

                final CompletableFuture<Integer> res = new CompletableFuture<>();

                mHandler.post(() -> {

                    res.complete(ActivityManagerService.this.checkContentProviderUriPermission(uri,

                            userId, callingUid, modeFlags));

                });

                try {

                    return res.get();

                } catch (InterruptedException | ExecutionException e) {

                    throw new RuntimeException(e);

                }

            }

        }