From f760f7f10d26588e52c38fcdf7cb8b68c723c5ad Mon Sep 17 00:00:00 2001
From: Tim Murray <timmurray@google.com>
Date: Fri, 10 Feb 2023 17:08:04 -0800
Subject: [PATCH] Freezer: release AM lock while checking /proc/locks

Checking /proc/locks can take a long time if new file locks are being
added. Hoist that outside of the AM lock to make sure that
system_server doesn't stall unnecessarily.

Test: device functions with short freezer timeout
Bug: 269207437
Change-Id: I5bab77281992d0e826427e458025103500fc0869
Merged-in: I5bab77281992d0e826427e458025103500fc0869
---
 .../android/server/am/CachedAppOptimizer.java | 64 +++++++++++--------
 1 file changed, 37 insertions(+), 27 deletions(-)

diff --git a/services/core/java/com/android/server/am/CachedAppOptimizer.java b/services/core/java/com/android/server/am/CachedAppOptimizer.java
index 913f151496467..f4685f0f6125f 100644
--- a/services/core/java/com/android/server/am/CachedAppOptimizer.java
+++ b/services/core/java/com/android/server/am/CachedAppOptimizer.java
@@ -1921,9 +1921,26 @@ public final class CachedAppOptimizer {
         public void handleMessage(Message msg) {
             switch (msg.what) {
                 case SET_FROZEN_PROCESS_MSG:
+                {
+                    ProcessRecord proc = (ProcessRecord) msg.obj;
+                    int pid = proc.getPid();
+                    final String name = proc.processName;
                     synchronized (mAm) {
-                        freezeProcess((ProcessRecord) msg.obj);
+                        freezeProcess(proc);
                     }
+                    try {
+                        // post-check to prevent deadlock
+                        mProcLocksReader.handleBlockingFileLocks(this);
+                    } catch (Exception e) {
+                        Slog.e(TAG_AM, "Unable to check file locks for "
+                                + name + "(" + pid + "): " + e);
+                        synchronized (mAm) {
+                            synchronized (mProcLock) {
+                                unfreezeAppLSP(proc, OomAdjuster.OOM_ADJ_REASON_NONE);
+                            }
+                        }
+                    }
+                }
                     break;
                 case REPORT_UNFREEZE_MSG:
                     int pid = msg.arg1;
@@ -2057,16 +2074,6 @@ public final class CachedAppOptimizer {
                     }
                 });
             }
-
-            try {
-                // post-check to prevent deadlock
-                mProcLocksReader.handleBlockingFileLocks(this);
-            } catch (Exception e) {
-                Slog.e(TAG_AM, "Unable to check file locks for " + name + "(" + pid + "): " + e);
-                synchronized (mProcLock) {
-                    unfreezeAppLSP(proc, OomAdjuster.OOM_ADJ_REASON_NONE);
-                }
-            }
         }
 
         private void reportUnfreeze(int pid, int frozenDuration, String processName,
@@ -2123,22 +2130,25 @@ public final class CachedAppOptimizer {
             if (DEBUG_FREEZER) {
                 Slog.d(TAG_AM, "Blocking file lock found: " + pids);
             }
-            synchronized (mProcLock) {
-                int pid = pids.get(0);
-                ProcessRecord app = mFrozenProcesses.get(pid);
-                ProcessRecord pr;
-                if (app != null) {
-                    for (int i = 1; i < pids.size(); i++) {
-                        int blocked = pids.get(i);
-                        synchronized (mAm.mPidsSelfLocked) {
-                            pr = mAm.mPidsSelfLocked.get(blocked);
-                        }
-                        if (pr != null && pr.mState.getCurAdj() < ProcessList.CACHED_APP_MIN_ADJ) {
-                            Slog.d(TAG_AM, app.processName + " (" + pid + ") blocks "
-                                    + pr.processName + " (" + blocked + ")");
-                            // Found at least one blocked non-cached process
-                            unfreezeAppLSP(app, OomAdjuster.OOM_ADJ_REASON_NONE);
-                            break;
+            synchronized (mAm) {
+                synchronized (mProcLock) {
+                    int pid = pids.get(0);
+                    ProcessRecord app = mFrozenProcesses.get(pid);
+                    ProcessRecord pr;
+                    if (app != null) {
+                        for (int i = 1; i < pids.size(); i++) {
+                            int blocked = pids.get(i);
+                            synchronized (mAm.mPidsSelfLocked) {
+                                pr = mAm.mPidsSelfLocked.get(blocked);
+                            }
+                            if (pr != null
+                                    && pr.mState.getCurAdj() < ProcessList.CACHED_APP_MIN_ADJ) {
+                                Slog.d(TAG_AM, app.processName + " (" + pid + ") blocks "
+                                        + pr.processName + " (" + blocked + ")");
+                                // Found at least one blocked non-cached process
+                                unfreezeAppLSP(app, OomAdjuster.OOM_ADJ_REASON_NONE);
+                                break;
+                            }
                         }
                     }
                 }