commit 51b839544b7bc8f7285baa3b405ab7b28172b470
author Svet Ganov <svetoslavganov@google.com> Wed Jul 06 12:16:53 2016 -0700
committer Svetoslav Ganov <svetoslavganov@google.com> Wed Jul 06 19:52:36 2016 +0000
tree 011b471db0adea0a704fe1057a7e6d1ec2eee749
parent 4c78b8e5444def1f581e98f4d338a9bd86d59359

Use proper lock when accessing the generation registry

We use 'this' for synchronization in NameValueCache but some code
that accesses the generation registry uses 'this' in a different
context ending up syncing on the wrong instance. This is why
sync on this is just a bad idea.

bug:29956424

Change-Id: Ide2d4f07a5f40cb3f0e8f50e4c8de216d15a31ee

core/java/android/provider/Settings.java

diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 293eb9b..9c567a9 100755
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -1548,7 +1548,7 @@
 
         private IContentProvider lazyGetProvider(ContentResolver cr) {
             IContentProvider cp = null;
-            synchronized (this) {
+            synchronized (NameValueCache.this) {
                 cp = mContentProvider;
                 if (cp == null) {
                     cp = mContentProvider = cr.acquireProvider(mUri.getAuthority());
@@ -1575,7 +1575,7 @@
         public String getStringForUser(ContentResolver cr, String name, final int userHandle) {
             final boolean isSelf = (userHandle == UserHandle.myUserId());
             if (isSelf) {
-                synchronized (this) {
+                synchronized (NameValueCache.this) {
                     if (mGenerationTracker != null) {
                         if (mGenerationTracker.isGenerationChanged()) {
                             if (DEBUG) {
@@ -1608,7 +1608,7 @@
                         args.putInt(CALL_METHOD_USER_KEY, userHandle);
                     }
                     boolean needsGenerationTracker = false;
-                    synchronized (this) {
+                    synchronized (NameValueCache.this) {
                         if (isSelf && mGenerationTracker == null) {
                             needsGenerationTracker = true;
                             if (args == null) {
@@ -1627,7 +1627,7 @@
                         String value = b.getString(Settings.NameValueTable.VALUE);
                         // Don't update our cache for reads of other users' data
                         if (isSelf) {
-                            synchronized (this) {
+                            synchronized (NameValueCache.this) {
                                 if (needsGenerationTracker) {
                                     MemoryIntArray array = b.getParcelable(
                                             CALL_METHOD_TRACK_GENERATION_KEY);
@@ -1644,7 +1644,7 @@
                                         }
                                         mGenerationTracker = new GenerationTracker(array, index,
                                                 generation, () -> {
-                                            synchronized (this) {
+                                            synchronized (NameValueCache.this) {
                                                 Log.e(TAG, "Error accessing generation"
                                                         + " tracker - removing");
                                                 if (mGenerationTracker != null) {
@@ -1685,7 +1685,7 @@
                 }
 
                 String value = c.moveToNext() ? c.getString(0) : null;
-                synchronized (this) {
+                synchronized (NameValueCache.this) {
                     mValues.put(name, value);
                 }
                 if (LOCAL_LOGV) {