RTOS/MSP430F5529: GPIO Button interrupt callback function with multiple parameters

Tool/software: TI-RTOS

Hello everyone, 

i'm attempting to establish an interrupt for Start Button and Stop Button, so the idea here is if the Start Button is pressed a callback function called StartTest () will be called to change the state variable from Ready_state to Testing_state and then, whatever the value of the state variable,  if Stop Button is pressed a callback function called StopTest () will be called to change the state variable from ( Testing_state or Passed_state or Failed_state ) to Ready_state.

How can i can use a callback function that takes two parameters ( Gpio Index and state variable ) ? i'm using  GPIO_setCallback(unsigned int index, GPIO_CallbackFxn callback) and GPIO_enableInt(unsigned int index) functions. is there any wrong in passing parameters like i did ? 

this is my code : 

void StartTest (unsigned int index, state_enum state)
{
state = TESTING_STATE;
System_printf("Linking with Testing State\n");

}

void StopTest (unsigned int index, state_enum state)
{
state = READY_STATE;
System_printf("Linking with Ready State\n");

}

int main(void)
{

/* Initial State of the tester */
state_enum state = READY_STATE ;

Task_Params taskParams;

/* Call board init functions */
Board_initGeneral();
Board_initGPIO();

while (1)
{
switch(state)
{

case READY_STATE:

GPIO_write(ready_led, 1);

/* install "Start Button" callback */

GPIO_setCallback(start_button, StartTest(state));

/* Enable interrupts */
GPIO_enableInt(start_button);