diff options
| -rw-r--r-- | services/core/java/com/android/server/pm/ComponentResolver.java | 35 | ||||
| -rw-r--r-- | services/core/java/com/android/server/pm/PackageManagerService.java | 3 |
2 files changed, 35 insertions, 3 deletions
diff --git a/services/core/java/com/android/server/pm/ComponentResolver.java b/services/core/java/com/android/server/pm/ComponentResolver.java index 2b2db6277f52..7d762d98e6f6 100644 --- a/services/core/java/com/android/server/pm/ComponentResolver.java +++ b/services/core/java/com/android/server/pm/ComponentResolver.java @@ -115,7 +115,36 @@ public class ComponentResolver { private static UserManagerService sUserManager; private static PackageManagerInternal sPackageManagerInternal; - private final Object mLock = new Object(); + /** + * Locking within package manager is going to get worse before it gets better. Currently, + * we need to share the {@link PackageManagerService} lock to prevent deadlocks. This occurs + * because in order to safely query the resolvers, we need to obtain this lock. However, + * during resolution, we call into the {@link PackageManagerService}. This is _not_ to + * operate on data controlled by the service proper, but, to check the state of package + * settings [contained in a {@link Settings} object]. However, the {@link Settings} object + * happens to be protected by the main {@link PackageManagerService} lock. + * <p> + * There are a couple potential solutions. + * <ol> + * <li>Split all of our locks into reader/writer locks. This would allow multiple, + * simultaneous read operations and means we don't have to be as cautious about lock + * layering. Only when we want to perform a write operation will we ever be in a + * position to deadlock the system.</li> + * <li>Use the same lock across all classes within the {@code com.android.server.pm} + * package. By unifying the lock object, we remove any potential lock layering issues + * within the package manager. However, we already have a sense that this lock is + * heavily contended and merely adding more dependencies on it will have further + * impact.</li> + * <li>Implement proper lock ordering within the package manager. By defining the + * relative layer of the component [eg. {@link PackageManagerService} is at the top. + * Somewhere in the middle would be {@link ComponentResolver}. At the very bottom + * would be {@link Settings}.] The ordering would allow higher layers to hold their + * lock while calling down. Lower layers must relinquish their lock before calling up. + * Since {@link Settings} would live at the lowest layer, the {@link ComponentResolver} + * would be able to hold its lock while checking the package setting state.</li> + * </ol> + */ + private final Object mLock; /** All available activities, for your resolving pleasure. */ @GuardedBy("mLock") @@ -153,9 +182,11 @@ public class ComponentResolver { private List<PackageParser.ActivityIntentInfo> mProtectedFilters; ComponentResolver(UserManagerService userManager, - PackageManagerInternal packageManagerInternal) { + PackageManagerInternal packageManagerInternal, + Object lock) { sPackageManagerInternal = packageManagerInternal; sUserManager = userManager; + mLock = lock; } /** Returns the given activity */ diff --git a/services/core/java/com/android/server/pm/PackageManagerService.java b/services/core/java/com/android/server/pm/PackageManagerService.java index 924460b1840e..29255230eeb9 100644 --- a/services/core/java/com/android/server/pm/PackageManagerService.java +++ b/services/core/java/com/android/server/pm/PackageManagerService.java @@ -2369,7 +2369,8 @@ public class PackageManagerService extends IPackageManager.Stub sUserManager = new UserManagerService(context, this, new UserDataPreparer(mInstaller, mInstallLock, mContext, mOnlyCore), mPackages); mComponentResolver = new ComponentResolver(sUserManager, - LocalServices.getService(PackageManagerInternal.class)); + LocalServices.getService(PackageManagerInternal.class), + mPackages); mPermissionManager = PermissionManagerService.create(context, new DefaultPermissionGrantedCallback() { @Override |