Fix deadlock in WindowManagerService.reenableKeyguard()
If reenableKeyguard() is called before the previous disableKeyguard() call is processed,
then TokenWatcher.sendNotificationLocked() will cancel the request, resulting in neither
the TokenWatcher acquired() or released() methods being called.
In that case, reenableKeyguard() will hang waiting for released() to set
mWaitingUntilKeyguardReenabled to false. Now we only wait in reenableKeyguard()
if the TokenWatcher acquired() method is called and the keyguard has actually been disabled.
This should fix bug b/2270192
Change-Id: Id886fb28df607dbb4543124f2db6997121d6a682
Signed-off-by: Mike Lockwood <lockwood@android.com>
diff --git a/services/java/com/android/server/WindowManagerService.java b/services/java/com/android/server/WindowManagerService.java
index 887c46d..c009ea2 100644
--- a/services/java/com/android/server/WindowManagerService.java
+++ b/services/java/com/android/server/WindowManagerService.java
@@ -224,20 +224,22 @@
/**
* Condition waited on by {@link #reenableKeyguard} to know the call to
* the window policy has finished.
+ * This is set to true only if mKeyguardTokenWatcher.acquired() has
+ * actually disabled the keyguard.
*/
- private boolean mWaitingUntilKeyguardReenabled = false;
+ private boolean mKeyguardDisabled = false;
-
- final TokenWatcher mKeyguardDisabled = new TokenWatcher(
- new Handler(), "WindowManagerService.mKeyguardDisabled") {
+ final TokenWatcher mKeyguardTokenWatcher = new TokenWatcher(
+ new Handler(), "WindowManagerService.mKeyguardTokenWatcher") {
public void acquired() {
mPolicy.enableKeyguard(false);
+ mKeyguardDisabled = true;
}
public void released() {
mPolicy.enableKeyguard(true);
- synchronized (mKeyguardDisabled) {
- mWaitingUntilKeyguardReenabled = false;
- mKeyguardDisabled.notifyAll();
+ synchronized (mKeyguardTokenWatcher) {
+ mKeyguardDisabled = false;
+ mKeyguardTokenWatcher.notifyAll();
}
}
};
@@ -4040,8 +4042,8 @@
!= PackageManager.PERMISSION_GRANTED) {
throw new SecurityException("Requires DISABLE_KEYGUARD permission");
}
- synchronized (mKeyguardDisabled) {
- mKeyguardDisabled.acquire(token, tag);
+ synchronized (mKeyguardTokenWatcher) {
+ mKeyguardTokenWatcher.acquire(token, tag);
}
}
@@ -4050,16 +4052,20 @@
!= PackageManager.PERMISSION_GRANTED) {
throw new SecurityException("Requires DISABLE_KEYGUARD permission");
}
- synchronized (mKeyguardDisabled) {
- mKeyguardDisabled.release(token);
+ synchronized (mKeyguardTokenWatcher) {
+ mKeyguardTokenWatcher.release(token);
- if (!mKeyguardDisabled.isAcquired()) {
- // if we are the last one to reenable the keyguard wait until
- // we have actaully finished reenabling until returning
- mWaitingUntilKeyguardReenabled = true;
- while (mWaitingUntilKeyguardReenabled) {
+ if (!mKeyguardTokenWatcher.isAcquired()) {
+ // If we are the last one to reenable the keyguard wait until
+ // we have actaully finished reenabling until returning.
+ // It is possible that reenableKeyguard() can be called before
+ // the previous disableKeyguard() is handled, in which case
+ // neither mKeyguardTokenWatcher.acquired() or released() would
+ // be called. In that case mKeyguardDisabled will be false here
+ // and we have nothing to wait for.
+ while (mKeyguardDisabled) {
try {
- mKeyguardDisabled.wait();
+ mKeyguardTokenWatcher.wait();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
@@ -10863,7 +10869,7 @@
public void monitor() {
synchronized (mWindowMap) { }
- synchronized (mKeyguardDisabled) { }
+ synchronized (mKeyguardTokenWatcher) { }
synchronized (mKeyWaiter) { }
}