USB: serial: fix generic chars_in_buffer

Make sure chars_in_buffer accounts also for data in host stack queues.

This fixes the problem with tty_wait_until_sent returning too soon at
close which could cause the final write urb to be cancelled.

Reported-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 4 deletions

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index a5e610976689..8f78d7b8e888 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -309,10 +309,14 @@ static int usb_serial_generic_write_start(struct usb_serial_port *port)
                 /* don't have to grab the lock here, as we will
                    retry if != 0 */
                 port->write_urb_busy = 0;
-        } else
-                result = count;
+                return result;
+        }
 
-        return result;
+        spin_lock_irqsave(&port->lock, flags);
+        port->tx_bytes_flight += count;
+        spin_unlock_irqrestore(&port->lock, flags);
+
+        return count;
 }
 
 /**
@@ -400,7 +404,7 @@ int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
         if (serial->type->max_in_flight_urbs)
                 chars = port->tx_bytes_flight;
         else
-                chars = kfifo_len(&port->write_fifo);
+                chars = kfifo_len(&port->write_fifo) + port->tx_bytes_flight;
         spin_unlock_irqrestore(&port->lock, flags);
 
         dbg("%s - returns %d", __func__, chars);
@@ -510,7 +514,10 @@ void usb_serial_generic_write_bulk_callback(struct urb *urb)
                         port->urbs_in_flight = 0;
                 spin_unlock_irqrestore(&port->lock, flags);
         } else {
+                spin_lock_irqsave(&port->lock, flags);
+                port->tx_bytes_flight -= urb->transfer_buffer_length;
                 port->write_urb_busy = 0;
+                spin_unlock_irqrestore(&port->lock, flags);
 
                 if (status)
                         kfifo_reset_out(&port->write_fifo);