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, 6 insertions, 4 deletions

diff --git a/drivers/tty/n_r3964.c b/drivers/tty/n_r3964.c
index 5c6c31459a2f..a4bc39c21a43 100644
--- a/drivers/tty/n_r3964.c
+++ b/drivers/tty/n_r3964.c
@@ -139,8 +139,8 @@ static int r3964_ioctl(struct tty_struct *tty, struct file *file,
 static void r3964_set_termios(struct tty_struct *tty, struct ktermios *old);
 static unsigned int r3964_poll(struct tty_struct *tty, struct file *file,
                 struct poll_table_struct *wait);
-static void r3964_receive_buf(struct tty_struct *tty, const unsigned char *cp,
-                char *fp, int count);
+static unsigned int r3964_receive_buf(struct tty_struct *tty,
+                const unsigned char *cp, char *fp, int count);
 
 static struct tty_ldisc_ops tty_ldisc_N_R3964 = {
         .owner = THIS_MODULE,
@@ -1239,8 +1239,8 @@ static unsigned int r3964_poll(struct tty_struct *tty, struct file *file,
         return result;
 }
 
-static void r3964_receive_buf(struct tty_struct *tty, const unsigned char *cp,
-                        char *fp, int count)
+static unsigned int r3964_receive_buf(struct tty_struct *tty,
+                const unsigned char *cp, char *fp, int count)
 {
         struct r3964_info *pInfo = tty->disc_data;
         const unsigned char *p;
@@ -1257,6 +1257,8 @@ static void r3964_receive_buf(struct tty_struct *tty, const unsigned char *cp,
                 }
 
         }
+
+        return count;
 }
 
 MODULE_LICENSE("GPL");