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Commit 160edb36 authored by Christopher Tate's avatar Christopher Tate
Browse files

Add ability to guard a thread against setting its own prio to bg 

The guard is compiled out by default because it adds overhead to
android.os.Process.setPriority().

Change-Id: Ibb2a648c6349b381abb7ae62a358888b04fba871
parent c6e1d880

core/java/android/os/Process.java

+9 −0
Original line number Diff line number Diff line
@@ -625,6 +625,15 @@ public class Process { 
    public static final native void setThreadPriority(int tid, int priority)

            throws IllegalArgumentException, SecurityException;



    /**

     * Call with 'false' to cause future calls to {@link #setThreadPriority(int)} to

     * throw an exception if passed a background-level thread priority.  This is only

     * effective if the JNI layer is built with GUARD_THREAD_PRIORITY defined to 1.

     *

     * @hide

     */

    public static final native void setCanSelfBackground(boolean backgroundOk);



    /**

     * Sets the scheduling group for a thread.

     * @hide

core/jni/android_util_Process.cpp

+39 −0
Original line number Diff line number Diff line
@@ -52,9 +52,15 @@ pid_t gettid() { return syscall(__NR_gettid);} 
#endif



#define POLICY_DEBUG 0

#define GUARD_THREAD_PRIORITY 0



using namespace android;



#if GUARD_THREAD_PRIORITY

Mutex gKeyCreateMutex;

static pthread_key_t gBgKey = -1;

#endif



static void signalExceptionForPriorityError(JNIEnv* env, jobject obj, int err)

{

    switch (err) {
@@ -264,9 +270,41 @@ void android_os_Process_setProcessGroup(JNIEnv* env, jobject clazz, int pid, jin 
    closedir(d);

}



static void android_os_Process_setCanSelfBackground(JNIEnv* env, jobject clazz, jboolean bgOk) {

    // Establishes the calling thread as illegal to put into the background.

    // Typically used only for the system process's main looper.

#if GUARD_THREAD_PRIORITY

    LOGV("Process.setCanSelfBackground(%d) : tid=%d", bgOk, androidGetTid());

    {

        Mutex::Autolock _l(gKeyCreateMutex);

        if (gBgKey == -1) {

            pthread_key_create(&gBgKey, NULL);

        }

    }



    // inverted:  not-okay, we set a sentinel value

    pthread_setspecific(gBgKey, (void*)(bgOk ? 0 : 0xbaad));

#endif

}



void android_os_Process_setThreadPriority(JNIEnv* env, jobject clazz,

                                              jint pid, jint pri)

{

#if GUARD_THREAD_PRIORITY

    // if we're putting the current thread into the background, check the TLS

    // to make sure this thread isn't guarded.  If it is, raise an exception.

    if (pri >= ANDROID_PRIORITY_BACKGROUND) {

        if (pid == androidGetTid()) {

            void* bgOk = pthread_getspecific(gBgKey);

            if (bgOk == ((void*)0xbaad)) {

                LOGE("Thread marked fg-only put self in background!");

                jniThrowException(env, "java/lang/SecurityException", "May not put this thread into background");

                return;

            }

        }

    }

#endif



    int rc = androidSetThreadPriority(pid, pri);

    if (rc != 0) {

        if (rc == INVALID_OPERATION) {
@@ -852,6 +890,7 @@ static const JNINativeMethod methods[] = { 
    {"getUidForName",       "(Ljava/lang/String;)I", (void*)android_os_Process_getUidForName},

    {"getGidForName",       "(Ljava/lang/String;)I", (void*)android_os_Process_getGidForName},

    {"setThreadPriority",   "(II)V", (void*)android_os_Process_setThreadPriority},

    {"setCanSelfBackground", "(Z)V", (void*)android_os_Process_setCanSelfBackground},

    {"setThreadPriority",   "(I)V", (void*)android_os_Process_setCallingThreadPriority},

    {"getThreadPriority",   "(I)I", (void*)android_os_Process_getThreadPriority},

    {"setThreadGroup",      "(II)V", (void*)android_os_Process_setThreadGroup},

services/java/com/android/server/SystemServer.java

+2 −1
Original line number Diff line number Diff line
@@ -80,6 +80,7 @@ class ServerThread extends Thread { 
                android.os.Process.THREAD_PRIORITY_FOREGROUND);



        BinderInternal.disableBackgroundScheduling(true);

        android.os.Process.setCanSelfBackground(false);



        String factoryTestStr = SystemProperties.get("ro.factorytest");

        int factoryTest = "".equals(factoryTestStr) ? SystemServer.FACTORY_TEST_OFF

services/java/com/android/server/WindowManagerService.java

+2 −0
Original line number Diff line number Diff line
@@ -572,6 +572,7 @@ public class WindowManagerService extends IWindowManager.Stub 
                    mHaveInputMethods);

            android.os.Process.setThreadPriority(

                    android.os.Process.THREAD_PRIORITY_DISPLAY);

            android.os.Process.setCanSelfBackground(false);















            synchronized (this) {















                mService = s;










@@ -607,6 +608,7 @@ public class WindowManagerService extends IWindowManager.Stub













            //        Log.VERBOSE, "WindowManagerPolicy", Log.LOG_ID_SYSTEM));















            android.os.Process.setThreadPriority(















                    android.os.Process.THREAD_PRIORITY_FOREGROUND);













            android.os.Process.setCanSelfBackground(false);















            mPolicy.init(mContext, mService, mPM);





























            synchronized (this) {

































services/java/com/android/server/am/ActivityManagerService.java



+1
−0




























Original line number
Diff line number
Diff line








@@ -1259,6 +1259,7 @@ public final class ActivityManagerService extends ActivityManagerNative implemen





























            android.os.Process.setThreadPriority(















                    android.os.Process.THREAD_PRIORITY_FOREGROUND);













            android.os.Process.setCanSelfBackground(false);































            ActivityManagerService m = new ActivityManagerService();