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Commit 23ee42f9 authored by Mike Lockwood's avatar Mike Lockwood
Browse files

MTP: Fix some thread safety issues in MTP server start/stop sequence. 



Change-Id: Ied1cddc6220fa7394e8de99df9bc37a1208b04ff
Signed-off-by: default avatarMike Lockwood <lockwood@android.com>
parent d4b50201

media/jni/android_media_MtpServer.cpp

+56 −38
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ using namespace android; 
// ----------------------------------------------------------------------------



static jfieldID field_context;

static Mutex    sMutex;



// in android_media_MtpDatabase.cpp

extern MtpDatabase* getMtpDatabase(JNIEnv *env, jobject database);
@@ -55,61 +56,78 @@ private: 
    MtpServer*      mServer;

    String8         mStoragePath;

    bool            mDone;

    Mutex           mMutex;

    jobject         mJavaServer;



public:

    MtpThread(MtpDatabase* database, const char* storagePath)

        : mDatabase(database), mServer(NULL), mStoragePath(storagePath), mDone(false)

    MtpThread(MtpDatabase* database, const char* storagePath, jobject javaServer)

        : mDatabase(database),

            mServer(NULL),

            mStoragePath(storagePath),

            mDone(false),

            mJavaServer(javaServer)

    {

    }



    virtual bool threadLoop() {

        while (1) {

            int fd = open("/dev/mtp_usb", O_RDWR);

            printf("open returned %d\n", fd);

            if (fd < 0) {

                LOGE("could not open MTP driver\n");

            return false;

                break;

            }



        mMutex.lock();

            sMutex.lock();

            mServer = new MtpServer(fd, mDatabase, AID_SDCARD_RW, 0664, 0775);

            mServer->addStorage(mStoragePath);

        mMutex.unlock();

            sMutex.unlock();



            LOGD("MtpThread mServer->run");

            mServer->run();

            close(fd);



        mMutex.lock();

            sMutex.lock();

            delete mServer;

            mServer = NULL;

        mMutex.unlock();

            if (mDone)

                goto done;

            sMutex.unlock();

            // wait a bit before retrying

            sleep(1);

        }



        bool done = mDone;

        if (done)

            delete this;

        LOGD("threadLoop returning %s", (done ? "false" : "true"));

        return !done;

        sMutex.lock();

done:

        JNIEnv* env = AndroidRuntime::getJNIEnv();

        env->SetIntField(mJavaServer, field_context, 0);

        env->DeleteGlobalRef(mJavaServer);

        sMutex.unlock();



        LOGD("threadLoop returning");

        return false;

    }



    void setDone() { mDone = true; }

    void setDone() {

        LOGD("setDone");

        mDone = true; 

    }



    void sendObjectAdded(MtpObjectHandle handle) {

        mMutex.lock();

        sMutex.lock();

        if (mServer)

            mServer->sendObjectAdded(handle);

        else

            LOGE("sendObjectAdded called while disconnected\n");

        mMutex.unlock();

        sMutex.unlock();

    }



    void sendObjectRemoved(MtpObjectHandle handle) {

        mMutex.lock();

        sMutex.lock();

        if (mServer)

            mServer->sendObjectRemoved(handle);

        else

            LOGE("sendObjectRemoved called while disconnected\n");

        mMutex.unlock();

        sMutex.unlock();

    }

};
@@ -124,7 +142,7 @@ android_media_MtpServer_setup(JNIEnv *env, jobject thiz, jobject javaDatabase, j 
    MtpDatabase* database = getMtpDatabase(env, javaDatabase);

    const char *storagePathStr = env->GetStringUTFChars(storagePath, NULL);



    MtpThread* thread = new MtpThread(database, storagePathStr);

    MtpThread* thread = new MtpThread(database, storagePathStr, env->NewGlobalRef(thiz));

    env->SetIntField(thiz, field_context, (int)thread);



    env->ReleaseStringUTFChars(storagePath, storagePathStr);
@@ -153,11 +171,11 @@ android_media_MtpServer_stop(JNIEnv *env, jobject thiz) 
{

#ifdef HAVE_ANDROID_OS

    LOGD("stop\n");

    sMutex.lock();

    MtpThread *thread = (MtpThread *)env->GetIntField(thiz, field_context);

    if (thread) {

    if (thread)

        thread->setDone();

        env->SetIntField(thiz, field_context, 0);

    }

    sMutex.unlock();

#endif

}