启动AP导致system_server挂掉

错误现象

在Setting中打开AP开关，过一会AP关闭，无法连接。屏幕黑屏。

错误分析

屏幕黑屏，大概率是system_server 进行重启了。从log中看是获取android.hardware.tetheroffload.config@1.0::IOffloadConfig/default失败。然后watchdog直接拉掉system_server。
至于AP关闭，则是system_server在重启过程中拉起WifiService。做初始的时候，将wlan0 节点给disable。

//WifiService 起来的时候重新 disable wlan0
09-09 16:22:12.316  5483  5483 I WifiService: WifiService starting up with Wi-Fi disabled
09-09 16:22:12.316     0     0 I init    : starting service 'vendor.netmgrd'...
09-09 16:22:12.320  5483  5606 I android_os_HwBinder: HwBinder: Starting thread pool for default::android.hidl.manager@1.0::IServiceManager
09-09 16:22:12.322  5483  5622 D HalDevMgr: IWifi registration notification: fqName=android.hardware.wifi@1.0::IWifi, name=default, preexisting=true
09-09 16:22:12.323  5483  5606 I android_os_HwBinder: HwBinder: Starting thread pool for default::android.hardware.wifi@1.0::IWifi
09-09 16:22:12.324  5483  5619 I am_proc_bound: [0,5625,com.android.car]
09-09 16:22:12.325   425   425 I WifiHAL : Sent msg on exit sock to unblock poll()
09-09 16:22:12.325   425  4344 I WifiHAL : exit_event_handler, buf=E
09-09 16:22:12.325   425  4344 E WifiHAL : 1 events were leftover without being freed
09-09 16:22:12.325  5483  5619 I service_manager_stats: [100,16,250848]
09-09 16:22:12.325   425  4344 I android.hardware.wifi@1.0-service: Legacy HAL stop complete callback received
09-09 16:22:12.337   656   738 I LOWI-8.6.0.46: [LOWIController] isWifiEnabled: Wifi is now disabled
09-09 16:22:12.337  5428  5439 E Netd    : Removing unknown address fe80::2e7:9dff:fe73:17f/64 from ifindex 13
09-09 16:22:12.337   656  4345 I LOWI-8.6.0.46: [LOWIScanResultReceiver] Thread terminate was requested
09-09 16:22:12.338  4361  4361 I hostapd : wlan0: INTERFACE-DISABLED 

//watchdog 直接挂了system_server
W ServiceManagement: Waited one second for android.hardware.tetheroffload.config@1.0::IOffloadConfig/default. Waiting another...

09-09 16:21:59.478  1881  2605 W Watchdog: *** WATCHDOG KILLING SYSTEM PROCESS: Blocked in handler on i/o thread (android.io)
09-09 16:21:59.478  1881  2605 W Watchdog: android.io annotated stack trace:
09-09 16:21:59.478  1881  2605 W Watchdog:     at com.android.server.connectivity.tethering.OffloadHardwareInterface.configOffload(Native Method)
09-09 16:21:59.478  1881  2605 W Watchdog:     at com.android.server.connectivity.tethering.OffloadHardwareInterface.initOffloadConfig(OffloadHardwareInterface.java:99)
09-09 16:21:59.478  1881  2605 W Watchdog:     at com.android.server.connectivity.tethering.OffloadController.start(OffloadController.java:140)
09-09 16:21:59.478  1881  2605 W Watchdog:     at com.android.server.connectivity.Tethering$TetherMasterSM$OffloadWrapper.start(Tethering.java:1742)
09-09 16:21:59.479  1881  2605 W Watchdog:     at com.android.server.connectivity.Tethering$TetherMasterSM$TetherModeAliveState.enter(Tethering.java:1539)
09-09 16:21:59.479  1881  2605 W Watchdog:     at com.android.internal.util.StateMachine$SmHandler.invokeEnterMethods(StateMachine.java:1037)
09-09 16:21:59.479  1881  2605 W Watchdog:     at com.android.internal.util.StateMachine$SmHandler.performTransitions(StateMachine.java:879)
09-09 16:21:59.479  1881  2605 W Watchdog:     at com.android.internal.util.StateMachine$SmHandler.handleMessage(StateMachine.java:819)
09-09 16:21:59.479  1881  2605 W Watchdog:     at android.os.Handler.dispatchMessage(Handler.java:106)
09-09 16:21:59.479  1881  2605 W Watchdog:     at android.os.Looper.loop(Looper.java:193)
09-09 16:21:59.479  1881  2605 W Watchdog:     at android.os.HandlerThread.run(HandlerThread.java:65)
09-09 16:21:59.479  1881  2605 W Watchdog:     at com.android.server.ServiceThread.run(ServiceThread.java:44)
09-09 16:21:59.479  1881  2605 W Watchdog: *** GOODBYE!
09-09 16:21:59.479  1881  2605 I Process : Sending signal. PID: 1881 SIG: 9

附此服务的作用说明

详细请移步Google官网：[网络共享硬件分流] (https://source.android.google.cn/devices/tech/connect/tethering-offload?hl=zh-cn)

解决方案

• 1
  根据出错行，定位是在OffloadHardwareInterface.java 的 initOffloadConfig() 报错。然后发现在这之前会有开关，判断offload是否可行。而这个offload则是根据全局的数据库来决定了。那么就好办了，这个值大概率是在可以在Setting中设置的，然后再Setting中全局搜一下哪里设置这个属性。

最后发现是在开发者模式下面
Developer Options -> Networking -> Terthering hardware acceleration

代码跟踪：

// OffloadController.java
    public boolean start() {
        if (started()) return true;
        // 拦截处
        if (isOffloadDisabled()) {
            mLog.i("tethering offload disabled");
            return false;
        }

        if (!mConfigInitialized) {
           // 出错处
            mConfigInitialized = mHwInterface.initOffloadConfig();
            if (!mConfigInitialized) {
                mLog.i("tethering offload config not supported");
                stop();
                return false;
            }
        }
        ...
        return isStarted;
    }

    private boolean isOffloadDisabled() {
        final int defaultDisposition = mHwInterface.getDefaultTetherOffloadDisabled();
        return (Settings.Global.getInt(
                mContentResolver, TETHER_OFFLOAD_DISABLED, defaultDisposition) != 0);
    }

//Setting Package  TetheringHardwareAccelPreferenceController.java
    public void updateState(Preference preference) {
        final int tetheringMode = Settings.Global.getInt(
                mContext.getContentResolver(),
                Settings.Global.TETHER_OFFLOAD_DISABLED, 0 /* default */);
        ((SwitchPreference) mPreference).setChecked(tetheringMode != SETTING_VALUE_OFF);
    }

本文地址：https://blog.csdn.net/github_33381613/article/details/108733399