serial: Add barrier to synchronize

Add a pthread barrier to synchronize the Rx/Tx threads and remove the
Tx pipe as it becomes useless.

This fixes the issue when the serial test is run inside bit.

BCS 746-000147

testcases/serial/serial.c

@@ -28,7 +28,7 @@ struct serial_test_data {
 	int result_error;
 	int result_package_duration;
 	int rx_ctrl_fds[2];
-	int tx_ctrl_fds[2];
+	pthread_barrier_t barrier;
 };
 
 enum{
@@ -117,8 +117,6 @@ void cleanup(void * data)
 {
 	struct serial_test_data * test_data = (struct serial_test_data * ) data;
 
-	close_fd(&test_data->tx_ctrl_fds[1]);
-	close_fd(&test_data->tx_ctrl_fds[0]);
 	close_fd(&test_data->rx_ctrl_fds[1]);
 	close_fd(&test_data->rx_ctrl_fds[0]);
 	close_fd(&test_data->tty_fd);
@@ -248,9 +246,8 @@ static void * setup(int argc, char **argv)
 	if (pipe(test_data->rx_ctrl_fds))
 		goto error;
 	ioctl(test_data->rx_ctrl_fds[0], FIONBIO, &nbio);
-	if (pipe(test_data->tx_ctrl_fds))
-		goto error;
-	ioctl(test_data->tx_ctrl_fds[0], FIONBIO, &nbio);
+	/* Barrier fo the send and receive thread */
+	if (pthread_barrier_init(&test_data->barrier, NULL, 2)) { tst_print(TBROK, "Unable to create barrier. Error:%d, %s", errno, strerror(errno)); goto error; }
 	if (tcflush(test_data->tty_fd, TCIOFLUSH)) { tst_print(TBROK, "Unable to flush the serial file descriptor. Error:%d, %s", errno, strerror(errno)); goto error; }
 
 	return test_data;
@@ -274,47 +271,22 @@ void *receive_thread(void *data)
 	};
 	tst_print(DEBUG, "%30s %d %s",__FILE__,  __LINE__, __func__);
 
-	while (test_data->packages_sent < test_data->count) {
-		const int tx_send = TX_STATE_START_SENDING;
+	while (true) {
 		struct timeval timeout = timeout_const;
 		int pipe_status = RX_STATE_START;
 		int bytes_received = 0, duration = 0;
 
-		// Sync with transmitting thread
-		if(write(test_data->tx_ctrl_fds[1], &tx_send, sizeof(tx_send))<0)
-			tst_print(TBROK, "Unable to send tx sync signal %i %s", errno, strerror(errno));
-		do {
-			FD_ZERO(&rfds);
-			FD_SET(test_data->rx_ctrl_fds[0], &rfds);
-			timeout = timeout_const;
-			retval = select(test_data->rx_ctrl_fds[0]+1, &rfds, NULL, NULL, &timeout);
-			if (retval < 0) {
-				tst_print(TBROK, "Unable to synchonize RX thread: %i %s", errno, strerror(errno));
-				continue;
-			}
-			else if (retval == 0) {
-				tst_print(TINFO,"Rx sync timeout!");
-				continue;
-			}
-			if (FD_ISSET(test_data->rx_ctrl_fds[0], &rfds)) {
-				// Consume all signals
-				while(read(test_data->rx_ctrl_fds[0], &pipe_status, sizeof(pipe_status))>0) {
-					if (pipe_status == RX_STATE_EXIT)
-						return NULL;
-				}
-			}
-		} while (pipe_status != RX_STATE_RECEIVING);
+		pthread_barrier_wait(&test_data->barrier);
+		while(read(test_data->rx_ctrl_fds[0], &pipe_status, sizeof(pipe_status))>0) {
+			if (pipe_status == RX_STATE_EXIT)
+				return NULL;
+		}
 
 		gettimeofday( &rx_started, NULL);
 		while (bytes_received < test_data->nbytes) {
 			FD_ZERO(&rfds);
 			FD_SET(test_data->tty_fd, &rfds);
 			maxrfd = test_data->tty_fd;
-			// Let the timeout or reception handle the exit
-			if(pipe_status != RX_STATE_EXIT) {
-				FD_SET(test_data->rx_ctrl_fds[0], &rfds);
-				maxrfd = MAX(maxrfd, test_data->rx_ctrl_fds[0]);
-			}
 
 			timeout = timeout_const;
 			retval = select(maxrfd+1, &rfds, NULL, NULL, &timeout);
@@ -347,15 +319,6 @@ void *receive_thread(void *data)
 						bytes_received += ret;
 				}
 			}
-			if(pipe_status != RX_STATE_EXIT &&
-			   FD_ISSET(test_data->rx_ctrl_fds[0], &rfds)) {
-				int bytes_read = read(test_data->rx_ctrl_fds[0], &pipe_status, sizeof(pipe_status));
-				if (bytes_read != sizeof(pipe_status)) {
-					tst_print(TBROK, "Could not read bytes from input: %i %s", errno, strerror(errno));
-				}
-				if(write(test_data->rx_ctrl_fds[1], &pipe_status, sizeof(pipe_status))<0)
-					tst_print(TBROK, "Unable to re-send pipe status signal %i %s", errno, strerror(errno));
-			}
 		}
 		duration = time_ms_since( &rx_started );
 		// validate the data
@@ -378,9 +341,8 @@ void *receive_thread(void *data)
 void transmit(struct serial_test_data * test_data)
 {
 	const int rx_state_exit = RX_STATE_EXIT;
-	const int rx_state_rcv = RX_STATE_RECEIVING;
 	int bytes_sent;
-	fd_set rfds, wfds;
+	fd_set wfds;
 	int retval=0;
 	const struct timeval timeout_const = {
 		.tv_sec=test_data->timeout/1000,
@@ -390,7 +352,6 @@ void transmit(struct serial_test_data * test_data)
 
 	do{
 		struct timeval tx_timeout = timeout_const;
-		int pipe_status = TX_STATE_IDLE;
 
 		bytes_sent = 0;
 
@@ -400,26 +361,7 @@ void transmit(struct serial_test_data * test_data)
 
 		// Sync with receiver thread
 		tcdrain(test_data->tty_fd);
-		do{
-			FD_ZERO(&rfds);
-			FD_SET(test_data->tx_ctrl_fds[0], &rfds);
-			tx_timeout = timeout_const;
-			retval = select(test_data->tx_ctrl_fds[0]+1, &rfds, NULL, NULL, &tx_timeout);
-			if (retval < 0) {
-				tst_print(TBROK, "Could not read bytes from input: %i %s", errno, strerror(errno));
-				continue;
-			}
-			else if (retval == 0) {
-				tst_print(TINFO,"Tx sync timeout!");
-				continue;
-			}
-			if (FD_ISSET(test_data->tx_ctrl_fds[0], &rfds)) {
-				// Consume all signals
-				while(read(test_data->tx_ctrl_fds[0], &pipe_status, sizeof(pipe_status))>0);
-			}
-		} while (pipe_status != TX_STATE_START_SENDING);
-		if(write(test_data->rx_ctrl_fds[1], &rx_state_rcv, sizeof(rx_state_rcv))<0)
-			tst_print(TBROK, "Unable to send rx sync signal %i %s", errno, strerror(errno));
+		pthread_barrier_wait(&test_data->barrier);
 
 		tst_print(DEBUG, "%d tx: Sending ...", __LINE__);
 		fill_transmit_buffer(test_data->send_buffer, test_data->nbytes);
@@ -459,6 +401,7 @@ void transmit(struct serial_test_data * test_data)
 
 	if(write(test_data->rx_ctrl_fds[1], &rx_state_exit, sizeof(rx_state_exit))<0)
 		tst_print(TBROK, "Unable to send rx exit signal %i %s", errno, strerror(errno));
+	pthread_barrier_wait(&test_data->barrier);
 	return;
 }