HintManagerService: only check isolated process for app uid

system_server can initiate ADPF session, which may cause deadlock on
chain AMS -> WMS -> graphics -> HintManagerService -> AMS.
This CL is to skip the AMS call when calling from system.

Test: Boot
Bug: 195257481
Signed-off-by: Wei Wang <wvw@google.com>
Change-Id: I6c8f431193b31d7643d3782563b9f6c33fe69da0

services/core/java/com/android/server/power/hint/HintManagerService.java

@@ -255,7 +255,11 @@ public final class HintManagerService extends SystemService {
     private boolean checkTidValid(int uid, int tgid, int [] tids) {
         // Make sure all tids belongs to the same UID (including isolated UID),
         // tids can belong to different application processes.
-        List<Integer> eligiblePids = mAmInternal.getIsolatedProcesses(uid);
+        List<Integer> eligiblePids = null;
+        // To avoid deadlock, do not call into AMS if the call is from system.
+        if (uid != Process.SYSTEM_UID) {
+            eligiblePids = mAmInternal.getIsolatedProcesses(uid);
+        }
         if (eligiblePids == null) {
             eligiblePids = new ArrayList<>();
         }