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Commit 2b5d6707 authored by Yasin Kilicdere's avatar Yasin Kilicdere
Browse files

Serialize concurrent user switch requests. 

If a user switch request comes during an ongoing user switch, it's
possible that the UserSwitchObservers which are registered for the
previous one are not informed and this causes a timeout for them. We
can postpone the request if that's the case, so that the requests are
serialised one after another.

Bug: 280672682
Test: atest com.android.server.pm.UserManagerTest#testConcurrentUserSwitch
Test: adb shell pm create-user user10
   && adb shell pm create-user user11
   && adb shell pm create-user user12
   && adb shell am switch-user -w 0  # switch to user0 and wait
   && adb shell am switch-user 10    # switch to user10
   && adb shell am switch-user 11    # this will be queued
   && adb shell am switch-user -w 12 # this will be queued
Change-Id: Ibfacd4193b66a4adb313085899d584f442893910
parent b6379cdc

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

+26 −3
Original line number Diff line number Diff line
@@ -126,6 +126,7 @@ import com.android.internal.annotations.VisibleForTesting; 
import com.android.internal.policy.IKeyguardDismissCallback;

import com.android.internal.util.ArrayUtils;

import com.android.internal.util.FrameworkStatsLog;

import com.android.internal.util.ObjectUtils;

import com.android.internal.util.Preconditions;

import com.android.internal.widget.LockPatternUtils;

import com.android.server.FactoryResetter;
@@ -146,6 +147,7 @@ import com.android.server.wm.ActivityTaskManagerInternal; 
import com.android.server.wm.WindowManagerService;



import java.io.PrintWriter;

import java.util.ArrayDeque;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Iterator;
@@ -259,6 +261,10 @@ class UserController implements Handler.Callback { 
    // once target user goes into the foreground. Use mLock when updating

    @GuardedBy("mLock")

    private volatile int mTargetUserId = UserHandle.USER_NULL;

    // If a user switch request comes during an ongoing user switch, it is postponed to the end of

    // the current switch, and this variable holds those user ids. Use mLock when updating

    @GuardedBy("mLock")

    private final ArrayDeque<Integer> mPendingTargetUserIds = new ArrayDeque<>();



    /**

     * Which users have been started, so are allowed to run code.
@@ -1691,7 +1697,6 @@ class UserController implements Handler.Callback { 
                boolean userSwitchUiEnabled;

                synchronized (mLock) {

                    mCurrentUserId = userId;

                    mTargetUserId = UserHandle.USER_NULL; // reset, mCurrentUserId has caught up

                    userSwitchUiEnabled = mUserSwitchUiEnabled;

                }

                mInjector.updateUserConfiguration();
@@ -1819,8 +1824,7 @@ class UserController implements Handler.Callback { 
        boolean success = startUser(targetUserId, USER_START_MODE_FOREGROUND);

        if (!success) {

            mInjector.getWindowManager().setSwitchingUser(false);

            mTargetUserId = UserHandle.USER_NULL;

            dismissUserSwitchDialog(null);

            dismissUserSwitchDialog(this::endUserSwitch);

        }

    }
@@ -1948,6 +1952,12 @@ class UserController implements Handler.Callback { 
                        + ": UserController not ready yet");

                return false;

            }

            if (mTargetUserId != UserHandle.USER_NULL) {

                Slogf.w(TAG, "There is already an ongoing user switch to User #" + mTargetUserId

                        + ". User #" + targetUserId + " will be added to the queue.");

                mPendingTargetUserIds.offer(targetUserId);

                return true;

            }

            mTargetUserId = targetUserId;

            userSwitchUiEnabled = mUserSwitchUiEnabled;

        }
@@ -2014,6 +2024,19 @@ class UserController implements Handler.Callback { 
        sendUserSwitchBroadcasts(oldUserId, newUserId);

        t.traceEnd();

        t.traceEnd();



        endUserSwitch();

    }



    private void endUserSwitch() {

        final int nextUserId;

        synchronized (mLock) {

            nextUserId = ObjectUtils.getOrElse(mPendingTargetUserIds.poll(), UserHandle.USER_NULL);

            mTargetUserId = UserHandle.USER_NULL;

        }

        if (nextUserId != UserHandle.USER_NULL) {

            switchUser(nextUserId);

        }

    }



    private void dispatchLockedBootComplete(@UserIdInt int userId) {

services/tests/servicestests/src/com/android/server/pm/UserManagerTest.java

+18 −0
Original line number Diff line number Diff line
@@ -1276,6 +1276,24 @@ public final class UserManagerTest { 
        assertThrows(IllegalArgumentException.class, () -> mActivityManager.switchUser(null));

    }



    @MediumTest

    @Test

    public void testConcurrentUserSwitch() {

        final int startUser = ActivityManager.getCurrentUser();

        final UserInfo user1 = createUser("User 1", 0);

        assertThat(user1).isNotNull();

        final UserInfo user2 = createUser("User 2", 0);

        assertThat(user2).isNotNull();

        final UserInfo user3 = createUser("User 3", 0);

        assertThat(user3).isNotNull();



        // Switch to the users just created without waiting for the completion of the previous one.

        switchUserThenRun(user1.id, () -> switchUserThenRun(user2.id, () -> switchUser(user3.id)));



        // Switch back to the starting user.

        switchUser(startUser);

    }



    @MediumTest

    @Test

    public void testConcurrentUserCreate() throws Exception {