From 5a8ea8c619132b48d279be5fd7761538caf02ec9 Mon Sep 17 00:00:00 2001
From: Andreas Gampe <agampe@google.com>
Date: Wed, 14 Mar 2018 23:13:28 -0700
Subject: [PATCH] Frameworks: Fix system server profiling

Avoid a race to close the profiling file descriptor.

Bug: 74883338
Test: m
Test: am profile start `pid system_server` /data/local/tmp/test.trace && sleep 5s && am profile stop `pid system_server` && adb pull /data/local/tmp/test.trace && [[ $(find test.trace -size +1K) ]] && echo Success
Change-Id: Ib506ce38ac1ac7c0b91079ba9b35aca6ae289d22
---
 core/java/android/app/ActivityThread.java                 | 2 +-
 .../com/android/server/am/ActivityManagerService.java     | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/core/java/android/app/ActivityThread.java b/core/java/android/app/ActivityThread.java
index 565eaeb632b1d..bae2a26a6f32e 100644
--- a/core/java/android/app/ActivityThread.java
+++ b/core/java/android/app/ActivityThread.java
@@ -612,7 +612,7 @@ public final class ActivityThread {
                         streamingOutput);
                 profiling = true;
             } catch (RuntimeException e) {
-                Slog.w(TAG, "Profiling failed on path " + profileFile);
+                Slog.w(TAG, "Profiling failed on path " + profileFile, e);
                 try {
                     profileFd.close();
                     profileFd = null;
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 6c60b74bbd24f..4d839d20c49ac 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -23603,6 +23603,14 @@ public class ActivityManagerService extends IActivityManager.Stub
                     } catch (IOException e) {
                     }
                     mProfilerInfo.profileFd = null;
+
+                    if (proc.pid == MY_PID) {
+                        // When profiling the system server itself, avoid closing the file
+                        // descriptor, as profilerControl will not create a copy.
+                        // Note: it is also not correct to just set profileFd to null, as the
+                        //       whole ProfilerInfo instance is passed down!
+                        profilerInfo = null;
+                    }
                 } else {
                     stopProfilerLocked(proc, profileType);
                     if (profilerInfo != null && profilerInfo.profileFd != null) {