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>

1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 48ad2a7ab080..0d4da5e14ba0 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/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)