TTY: switch tty_flip_buffer_push

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/mfd.c

@@ -388,12 +388,8 @@ void hsu_dma_rx(struct uart_hsu_port *up, u32 int_sts)
 	struct hsu_dma_chan *chan = up->rxc;
 	struct uart_port *port = &up->port;
 	struct tty_port *tport = &port->state->port;
-	struct tty_struct *tty = tport->tty;
 	int count;
 
-	if (!tty)
-		return;
-
 	/*
 	 * First need to know how many is already transferred,
 	 * then check if its a timeout DMA irq, and return
@@ -438,7 +434,7 @@ void hsu_dma_rx(struct uart_hsu_port *up, u32 int_sts)
 					 | (0x1 << 16)
 					 | (0x1 << 24)	/* timeout bit, see HSU Errata 1 */
 					 );
-	tty_flip_buffer_push(tty);
+	tty_flip_buffer_push(tport);
 
 	chan_writel(chan, HSU_CH_CR, 0x3);
 
@@ -461,13 +457,9 @@ static void serial_hsu_stop_rx(struct uart_port *port)
 
 static inline void receive_chars(struct uart_hsu_port *up, int *status)
 {
-	struct tty_struct *tty = up->port.state->port.tty;
 	unsigned int ch, flag;
 	unsigned int max_count = 256;
 
-	if (!tty)
-		return;
-
 	do {
 		ch = serial_in(up, UART_RX);
 		flag = TTY_NORMAL;
@@ -523,7 +515,7 @@ static inline void receive_chars(struct uart_hsu_port *up, int *status)
 	ignore_char:
 		*status = serial_in(up, UART_LSR);
 	} while ((*status & UART_LSR_DR) && max_count--);
-	tty_flip_buffer_push(tty);
+	tty_flip_buffer_push(&up->port.state->port);
 }
 
 static void transmit_chars(struct uart_hsu_port *up)