Merge "Fix the race condition between creating and killing process group" into udc-dev am: c601737f60

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22970327

Change-Id: Ic6263f1a6362009e254b6734d0b08481748c5f04
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

services/core/java/com/android/server/am/ProcessList.java

@@ -2300,6 +2300,8 @@ public final class ProcessList {
 
             final Process.ProcessStartResult startResult;
             boolean regularZygote = false;
+            app.mProcessGroupCreated = false;
+            app.mSkipProcessGroupCreation = false;
             if (hostingRecord.usesWebviewZygote()) {
                 startResult = startWebView(entryPoint,
                         app.processName, uid, uid, gids, runtimeFlags, mountExternal,
@@ -2328,19 +2330,29 @@ public final class ProcessList {
                         isTopApp, app.getDisabledCompatChanges(), pkgDataInfoMap,
                         allowlistedAppDataInfoMap, bindMountAppsData, bindMountAppStorageDirs,
                         new String[]{PROC_START_SEQ_IDENT + app.getStartSeq()});
+                // By now the process group should have been created by zygote.
+                app.mProcessGroupCreated = true;
             }
 
             if (!regularZygote) {
                 // webview and app zygote don't have the permission to create the nodes
+                synchronized (app) {
+                    if (!app.mSkipProcessGroupCreation) {
+                        // If we're not told to skip the process group creation, go create it.
                         final int res = Process.createProcessGroup(uid, startResult.pid);
                         if (res < 0) {
                             if (res == -OsConstants.ESRCH) {
-                        Slog.e(ActivityManagerService.TAG, "Unable to create process group for "
+                                Slog.e(ActivityManagerService.TAG,
+                                        "Unable to create process group for "
                                         + app.processName + " (" + startResult.pid + ")");
                             } else {
                                 throw new AssertionError("Unable to create process group for "
                                     + app.processName + " (" + startResult.pid + ")");
                             }
+                        } else {
+                            app.mProcessGroupCreated = true;
+                        }
+                    }
                 }
             }
 

services/core/java/com/android/server/am/ProcessRecord.java

@@ -424,6 +424,16 @@ class ProcessRecord implements WindowProcessListener {
      */
     Runnable mSuccessorStartRunnable;
 
+    /**
+     * Whether or not the process group of this process has been created.
+     */
+    volatile boolean mProcessGroupCreated;
+
+    /**
+     * Whether or not we should skip the process group creation.
+     */
+    volatile boolean mSkipProcessGroupCreation;
+
     void setStartParams(int startUid, HostingRecord hostingRecord, String seInfo,
             long startUptime, long startElapsedTime) {
         this.mStartUid = startUid;
@@ -1192,8 +1202,26 @@ class ProcessRecord implements WindowProcessListener {
                 EventLog.writeEvent(EventLogTags.AM_KILL,
                         userId, mPid, processName, mState.getSetAdj(), reason);
                 Process.killProcessQuiet(mPid);
-                if (!asyncKPG) Process.sendSignalToProcessGroup(uid, mPid, OsConstants.SIGKILL);
+                final boolean killProcessGroup;
+                if (mHostingRecord != null
+                        && (mHostingRecord.usesWebviewZygote() || mHostingRecord.usesAppZygote())) {
+                    synchronized (ProcessRecord.this) {
+                        killProcessGroup = mProcessGroupCreated;
+                        if (!killProcessGroup) {
+                            // The process group hasn't been created, request to skip it.
+                            mSkipProcessGroupCreation = true;
+                        }
+                    }
+                } else {
+                    killProcessGroup = true;
+                }
+                if (killProcessGroup) {
+                    if (asyncKPG) {
                         ProcessList.killProcessGroup(uid, mPid);
+                    } else {
+                        Process.sendSignalToProcessGroup(uid, mPid, OsConstants.SIGKILL);
+                    }
+                }
             } else {
                 mPendingStart = false;
             }