Merge "Prevent framework from stucking at communicating with HIDL HAL"

}

Return<void> Sensors::poll(int32_t maxCount, poll_cb _hidl_cb) {

    hidl_vec<Event> out;

    hidl_vec<SensorInfo> dynamicSensorsAdded;

    if (maxCount <= 0) {

        _hidl_cb(Result::BAD_VALUE, out, dynamicSensorsAdded);

        return Void();

    }

    std::unique_ptr<sensors_event_t[]> data;

    int err = android::NO_ERROR;

    int bufferSize = maxCount <= kPollMaxBufferSize ? maxCount : kPollMaxBufferSize;

    { // scope of reentry lock

    std::unique_ptr<sensors_event_t[]> data(new sensors_event_t[bufferSize]);

        // This enforces a single client, meaning that a maximum of one client can call poll().

        // If this function is re-entred, it means that we are stuck in a state that may prevent

        // the system from proceeding normally.

        //

        // Exit and let the system restart the sensor-hal-implementation hidl service.

        //

        // This function must not call _hidl_cb(...) or return until there is no risk of blocking.

        std::unique_lock<std::mutex> lock(mPollLock, std::try_to_lock);

        if(!lock.owns_lock()){

            // cannot get the lock, hidl service will go into deadlock if it is not restarted.

            // This is guaranteed to not trigger in passthrough mode.

            LOG(FATAL) <<

                    "ISensors::poll() re-entry. I do not know what to do except killing myself.";

        }

    int err = mSensorDevice->poll(

        if (maxCount <= 0) {

            err = android::BAD_VALUE;

        } else {

            int bufferSize = maxCount <= kPollMaxBufferSize ? maxCount : kPollMaxBufferSize;

            data.reset(new sensors_event_t[bufferSize]);

            err = mSensorDevice->poll(

                    reinterpret_cast<sensors_poll_device_t *>(mSensorDevice),

                    data.get(), bufferSize);

        }

    }

    if (err < 0) {

        _hidl_cb(ResultFromStatus(err), out, dynamicSensorsAdded);

#include <android/hardware/sensors/1.0/ISensors.h>

#include <hardware/sensors.h>

#include <mutex>

namespace android {

namespace hardware {

    status_t mInitCheck;

    sensors_module_t *mSensorModule;

    sensors_poll_device_1_t *mSensorDevice;

    std::mutex mPollLock;

    int getHalDeviceVersion() const;