Commit 4a0256ee authored May 13, 2010 by Christopher Lais Committed by Steve Kondik May 13, 2010

Ignore the system uid to avoid deadlocks

The ActivityManagerService can acquire or release wake locks with the
ActivityManagerService locked. Now that the PowerManagerService
notifies it of wakelocks, this can cause a deadlock. Prevent this
situation by ignoring wakelocks from the system uid, which should be
never be killed anyway.

The deadlock occurs when the ActivityManagerService is locked and
the WakeLock acquire/release locks PowerManagerService.mLocks. Another
thread may have locked them in a different order at the same time.

Signed-off-by: Christopher Lais <chris+android@zenthought.org>

parent 59be77fd

services/java/com/android/server/am/ActivityManagerService.java

+6 −0

Original line number	Diff line number	Diff line
		@@ -4259,6 +4259,9 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
		}

		public void noteStartWakeLock(int uid, String tag, int type) {
		if (uid == Process.SYSTEM_UID)
		return;

		Integer iuid = Integer.valueOf(uid);
		synchronized (this) {
		Integer count = mUidWakeLocks.get(iuid);
		@@ -4274,6 +4277,9 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
		}

		public void noteStopWakeLock(int uid, String tag, int type) {
		if (uid == Process.SYSTEM_UID)
		return;

		Integer iuid = Integer.valueOf(uid);
		synchronized (this) {
		Integer count = mUidWakeLocks.get(iuid);