tty: make receive_buf() return the amout of bytes received

it makes it simpler to keep track of the amount of
bytes received and simplifies how flush_to_ldisc counts
the remaining bytes. It also fixes a bug of lost bytes
on n_tty when flushing too many bytes via the USB
serial gadget driver.

Tested-by: Stefan Bigler <stefan.bigler@keymile.com>
Tested-by: Toby Gray <toby.gray@realvnc.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/bluetooth/hci_ldisc.c

@@ -357,22 +357,26 @@ static void hci_uart_tty_wakeup(struct tty_struct *tty)
  *     
  * Return Value:    None
  */
-static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data, char *flags, int count)
+static unsigned int hci_uart_tty_receive(struct tty_struct *tty,
+		const u8 *data, char *flags, int count)
 {
 	struct hci_uart *hu = (void *)tty->disc_data;
+	int received;
 
 	if (!hu || tty != hu->tty)
-		return;
+		return -ENODEV;
 
 	if (!test_bit(HCI_UART_PROTO_SET, &hu->flags))
-		return;
+		return -EINVAL;
 
 	spin_lock(&hu->rx_lock);
-	hu->proto->recv(hu, (void *) data, count);
+	received = hu->proto->recv(hu, (void *) data, count);
 	hu->hdev->stat.byte_rx += count;
 	spin_unlock(&hu->rx_lock);
 
 	tty_unthrottle(tty);
+
+	return received;
 }
 
 static int hci_uart_register_dev(struct hci_uart *hu)

drivers/input/serio/serport.c

@@ -120,17 +120,21 @@ static void serport_ldisc_close(struct tty_struct *tty)
  * 'interrupt' routine.
  */
 
-static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
+static unsigned int serport_ldisc_receive(struct tty_struct *tty,
+		const unsigned char *cp, char *fp, int count)
 {
 	struct serport *serport = (struct serport*) tty->disc_data;
 	unsigned long flags;
 	unsigned int ch_flags;
+	int ret = 0;
 	int i;
 
 	spin_lock_irqsave(&serport->lock, flags);
 
-	if (!test_bit(SERPORT_ACTIVE, &serport->flags))
+	if (!test_bit(SERPORT_ACTIVE, &serport->flags)) {
+		ret = -EINVAL;
 		goto out;
+	}
 
 	for (i = 0; i < count; i++) {
 		switch (fp[i]) {
@@ -152,6 +156,8 @@ static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *c
 
 out:
 	spin_unlock_irqrestore(&serport->lock, flags);
+
+	return ret == 0 ? count : ret;
 }
 
 /*

drivers/isdn/gigaset/ser-gigaset.c

@@ -674,7 +674,7 @@ gigaset_tty_ioctl(struct tty_struct *tty, struct file *file,
  *	cflags	buffer containing error flags for received characters (ignored)
  *	count	number of received characters
  */
-static void
+static unsigned int
 gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
 		    char *cflags, int count)
 {
@@ -683,12 +683,12 @@ gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
 	struct inbuf_t *inbuf;
 
 	if (!cs)
-		return;
+		return -ENODEV;
 	inbuf = cs->inbuf;
 	if (!inbuf) {
 		dev_err(cs->dev, "%s: no inbuf\n", __func__);
 		cs_put(cs);
-		return;
+		return -EINVAL;
 	}
 
 	tail = inbuf->tail;
@@ -725,6 +725,8 @@ gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
 	gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
 	gigaset_schedule_event(cs);
 	cs_put(cs);
+
+	return count;
 }
 
 /*

drivers/misc/ti-st/st_core.c

@@ -744,8 +744,8 @@ static void st_tty_close(struct tty_struct *tty)
 	pr_debug("%s: done ", __func__);
 }
 
-static void st_tty_receive(struct tty_struct *tty, const unsigned char *data,
-			   char *tty_flags, int count)
+static unsigned int st_tty_receive(struct tty_struct *tty,
+		const unsigned char *data, char *tty_flags, int count)
 {
 #ifdef VERBOSE
 	print_hex_dump(KERN_DEBUG, ">in>", DUMP_PREFIX_NONE,
@@ -758,6 +758,8 @@ static void st_tty_receive(struct tty_struct *tty, const unsigned char *data,
 	 */
 	st_recv(tty->disc_data, data, count);
 	pr_debug("done %s", __func__);
+
+	return count;
 }
 
 /* wake-up function called in from the TTY layer

drivers/net/caif/caif_serial.c

@@ -167,8 +167,8 @@ static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
 
 #endif
 
-static void ldisc_receive(struct tty_struct *tty, const u8 *data,
-			char *flags, int count)
+static unsigned int ldisc_receive(struct tty_struct *tty,
+		const u8 *data, char *flags, int count)
 {
 	struct sk_buff *skb = NULL;
 	struct ser_device *ser;
@@ -215,6 +215,8 @@ static void ldisc_receive(struct tty_struct *tty, const u8 *data,
 	} else
 		++ser->dev->stats.rx_dropped;
 	update_tty_status(ser);
+
+	return count;
 }
 
 static int handle_tx(struct ser_device *ser)

drivers/net/can/slcan.c

@@ -425,16 +425,17 @@ static void slc_setup(struct net_device *dev)
  * in parallel
  */
 
-static void slcan_receive_buf(struct tty_struct *tty,
+static unsigned int slcan_receive_buf(struct tty_struct *tty,
 			      const unsigned char *cp, char *fp, int count)
 {
 	struct slcan *sl = (struct slcan *) tty->disc_data;
+	int bytes = count;
 
 	if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
-		return;
+		return -ENODEV;
 
 	/* Read the characters out of the buffer */
-	while (count--) {
+	while (bytes--) {
 		if (fp && *fp++) {
 			if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 				sl->dev->stats.rx_errors++;
@@ -443,6 +444,8 @@ static void slcan_receive_buf(struct tty_struct *tty,
 		}
 		slcan_unesc(sl, *cp++);
 	}
+
+	return count;
 }
 
 /************************************

drivers/net/hamradio/6pack.c

@@ -456,19 +456,19 @@ static void sixpack_write_wakeup(struct tty_struct *tty)
  * a block of 6pack data has been received, which can now be decapsulated
  * and sent on to some IP layer for further processing.
  */
-static void sixpack_receive_buf(struct tty_struct *tty,
+static unsigned int sixpack_receive_buf(struct tty_struct *tty,
 	const unsigned char *cp, char *fp, int count)
 {
 	struct sixpack *sp;
 	unsigned char buf[512];
 	int count1;
 
 	if (!count)
-		return;
+		return 0;
 
 	sp = sp_get(tty);
 	if (!sp)
-		return;
+		return -ENODEV;
 
 	memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
 
@@ -487,6 +487,8 @@ static void sixpack_receive_buf(struct tty_struct *tty,
 
 	sp_put(sp);
 	tty_unthrottle(tty);
+
+	return count1;
 }
 
 /*

drivers/net/hamradio/mkiss.c

@@ -923,13 +923,14 @@ static long mkiss_compat_ioctl(struct tty_struct *tty, struct file *file,
  * a block of data has been received, which can now be decapsulated
  * and sent on to the AX.25 layer for further processing.
  */
-static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp,
-	char *fp, int count)
+static unsigned int mkiss_receive_buf(struct tty_struct *tty,
+		const unsigned char *cp, char *fp, int count)
 {
 	struct mkiss *ax = mkiss_get(tty);
+	int bytes = count;
 
 	if (!ax)
-		return;
+		return -ENODEV;
 
 	/*
 	 * Argh! mtu change time! - costs us the packet part received
@@ -939,7 +940,7 @@ static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 		ax_changedmtu(ax);
 
 	/* Read the characters out of the buffer */
-	while (count--) {
+	while (bytes--) {
 		if (fp != NULL && *fp++) {
 			if (!test_and_set_bit(AXF_ERROR, &ax->flags))
 				ax->dev->stats.rx_errors++;
@@ -952,6 +953,8 @@ static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 
 	mkiss_put(ax);
 	tty_unthrottle(tty);
+
+	return count;
 }
 
 /*

drivers/net/irda/irtty-sir.c

@@ -216,23 +216,23 @@ static int irtty_do_write(struct sir_dev *dev, const unsigned char *ptr, size_t
  * usbserial:	urb-complete-interrupt / softint
  */
 
-static void irtty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
-			      char *fp, int count) 
+static unsigned int irtty_receive_buf(struct tty_struct *tty,
+		const unsigned char *cp, char *fp, int count)
 {
 	struct sir_dev *dev;
 	struct sirtty_cb *priv = tty->disc_data;
 	int	i;
 
-	IRDA_ASSERT(priv != NULL, return;);
-	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
+	IRDA_ASSERT(priv != NULL, return -ENODEV;);
+	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -EINVAL;);
 
 	if (unlikely(count==0))		/* yes, this happens */
-		return;
+		return 0;
 
 	dev = priv->dev;
 	if (!dev) {
 		IRDA_WARNING("%s(), not ready yet!\n", __func__);
-		return;
+		return -ENODEV;
 	}
 
 	for (i = 0; i < count; i++) {
@@ -242,11 +242,13 @@ static void irtty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
  		if (fp && *fp++) { 
 			IRDA_DEBUG(0, "Framing or parity error!\n");
 			sirdev_receive(dev, NULL, 0);	/* notify sir_dev (updating stats) */
-			return;
+			return -EINVAL;
  		}
 	}
 
 	sirdev_receive(dev, cp, count);
+
+	return count;
 }
 
 /*

drivers/net/ppp_async.c

@@ -340,22 +340,24 @@ ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
 }
 
 /* May sleep, don't call from interrupt level or with interrupts disabled */
-static void
+static unsigned int
 ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
 		  char *cflags, int count)
 {
 	struct asyncppp *ap = ap_get(tty);
 	unsigned long flags;
 
 	if (!ap)
-		return;
+		return -ENODEV;
 	spin_lock_irqsave(&ap->recv_lock, flags);
 	ppp_async_input(ap, buf, cflags, count);
 	spin_unlock_irqrestore(&ap->recv_lock, flags);
 	if (!skb_queue_empty(&ap->rqueue))
 		tasklet_schedule(&ap->tsk);
 	ap_put(ap);
 	tty_unthrottle(tty);
+
+	return count;
 }
 
 static void

drivers/net/ppp_synctty.c

@@ -381,22 +381,24 @@ ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
 }
 
 /* May sleep, don't call from interrupt level or with interrupts disabled */
-static void
+static unsigned int
 ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
 		  char *cflags, int count)
 {
 	struct syncppp *ap = sp_get(tty);
 	unsigned long flags;
 
 	if (!ap)
-		return;
+		return -ENODEV;
 	spin_lock_irqsave(&ap->recv_lock, flags);
 	ppp_sync_input(ap, buf, cflags, count);
 	spin_unlock_irqrestore(&ap->recv_lock, flags);
 	if (!skb_queue_empty(&ap->rqueue))
 		tasklet_schedule(&ap->tsk);
 	sp_put(ap);
 	tty_unthrottle(tty);
+
+	return count;
 }
 
 static void

drivers/net/slip.c

@@ -670,16 +670,17 @@ static void sl_setup(struct net_device *dev)
  * in parallel
  */
 
-static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
-							char *fp, int count)
+static unsigned int slip_receive_buf(struct tty_struct *tty,
+		const unsigned char *cp, char *fp, int count)
 {
 	struct slip *sl = tty->disc_data;
+	int bytes = count;
 
 	if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
-		return;
+		return -ENODEV;
 
 	/* Read the characters out of the buffer */
-	while (count--) {
+	while (bytes--) {
 		if (fp && *fp++) {
 			if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 				sl->dev->stats.rx_errors++;
@@ -693,6 +694,8 @@ static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 #endif
 			slip_unesc(sl, *cp++);
 	}
+
+	return count;
 }
 
 /************************************

drivers/net/wan/x25_asy.c

@@ -517,17 +517,18 @@ static int x25_asy_close(struct net_device *dev)
  * and sent on to some IP layer for further processing.
  */
 
-static void x25_asy_receive_buf(struct tty_struct *tty,
+static unsigned int x25_asy_receive_buf(struct tty_struct *tty,
 				const unsigned char *cp, char *fp, int count)
 {
 	struct x25_asy *sl = tty->disc_data;
+	int bytes = count;
 
 	if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
 		return;
 
 
 	/* Read the characters out of the buffer */
-	while (count--) {
+	while (bytes--) {
 		if (fp && *fp++) {
 			if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 				sl->dev->stats.rx_errors++;
@@ -536,6 +537,8 @@ static void x25_asy_receive_buf(struct tty_struct *tty,
 		}
 		x25_asy_unesc(sl, *cp++);
 	}
+
+	return count;
 }
 
 /*