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Commit 4195049f authored by Philip Cuadra's avatar Philip Cuadra
Browse files

Allow Bluetooth CAP_SYS_NICE, set RT priority for Bluetooth HAL 

Bluetooth needs CAP_SYS_NICE in order to make important threads use RT
scheduling policy.

SchedulingPolicyService should set RT priority for the Bluetooth HAL.

Bug 37518404

Test: Play Bluetooth audio, confirm RT priority in systrace
Change-Id: I0ee55a2f2cfd80cbb066d9c034bb85d8d85ba470
parent 3d5f41bb

core/jni/com_android_internal_os_Zygote.cpp

+3 −0
Original line number Diff line number Diff line
@@ -685,11 +685,14 @@ static jint com_android_internal_os_Zygote_nativeForkAndSpecialize( 


    // Grant CAP_WAKE_ALARM to the Bluetooth process.

    // Additionally, allow bluetooth to open packet sockets so it can start the DHCP client.

    // Grant CAP_SYS_NICE to allow Bluetooth to set RT priority for

    // audio-related threads.

    // TODO: consider making such functionality an RPC to netd.

    if (multiuser_get_app_id(uid) == AID_BLUETOOTH) {

      capabilities |= (1LL << CAP_WAKE_ALARM);

      capabilities |= (1LL << CAP_NET_RAW);

      capabilities |= (1LL << CAP_NET_BIND_SERVICE);

      capabilities |= (1LL << CAP_SYS_NICE);

    }



    // Grant CAP_BLOCK_SUSPEND to processes that belong to GID "wakelock"

services/core/java/com/android/server/os/SchedulingPolicyService.java

+15 −5
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ import android.content.pm.PackageManager; 
import android.os.Binder;

import android.os.ISchedulingPolicyService;

import android.os.Process;

import android.util.Log;



/**

 * The implementation of the scheduling policy service interface.
@@ -52,14 +53,22 @@ public class SchedulingPolicyService extends ISchedulingPolicyService.Stub { 
                prio > PRIORITY_MAX || Process.getThreadGroupLeader(tid) != pid) {

           return PackageManager.PERMISSION_DENIED;

        }

        if (Binder.getCallingUid() != Process.BLUETOOTH_UID) {

            try {

                // make good use of our CAP_SYS_NICE capability

                Process.setThreadGroup(tid, !isForApp ?

                  Process.THREAD_GROUP_AUDIO_SYS : Process.THREAD_GROUP_AUDIO_APP);

            } catch (RuntimeException e) {

                Log.e(TAG, "Failed setThreadGroup: " + e);

                return PackageManager.PERMISSION_DENIED;

           }

        }

        try {

            // must be in this order or it fails the schedulability constraint

            Process.setThreadScheduler(tid, Process.SCHED_FIFO | Process.SCHED_RESET_ON_FORK,

                                       prio);

        } catch (RuntimeException e) {

            Log.e(TAG, "Failed setThreadScheduler: " + e);

            return PackageManager.PERMISSION_DENIED;

        }

        return PackageManager.PERMISSION_GRANTED;
@@ -74,6 +83,7 @@ public class SchedulingPolicyService extends ISchedulingPolicyService.Stub { 
        switch (Binder.getCallingUid()) {

        case Process.AUDIOSERVER_UID: // fastcapture, fastmixer

        case Process.CAMERASERVER_UID: // camera high frame rate recording

        case Process.BLUETOOTH_UID: // Bluetooth audio playback

            return true;

        default:

            return false;