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, 4 insertions, 2 deletions

diff --git a/drivers/misc/ti-st/st_core.c b/drivers/misc/ti-st/st_core.c
index 486117f72c9f..cb98a7da98ef 100644
--- a/drivers/misc/ti-st/st_core.c
+++ b/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