Commit 4746b6c6efcdc3f5ef84f0bc2c39707c6b4e5e24 upstream.
Backported for 3.9-stable. Adjusted context.
From: Johan Hovold <jhovold@xxxxxxxxx>
No need to grab disconnect mutex in chars_in_buffer now that no
sub-driver is or should be querying hardware buffers anymore. (They
should use wait_until_sent.)
Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Lingzhu Xiang <lxiang@xxxxxxxxxx>
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 42de53c..d0742e8 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -363,20 +363,13 @@ static int serial_chars_in_buffer(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
struct usb_serial *serial = port->serial;
- int count = 0;
dev_dbg(tty->dev, "%s - port %d\n", __func__, port->number);
- mutex_lock(&serial->disc_mutex);
- /* if the device was unplugged then any remaining characters
- fell out of the connector ;) */
if (serial->disconnected)
- count = 0;
- else
- count = serial->type->chars_in_buffer(tty);
- mutex_unlock(&serial->disc_mutex);
+ return 0;
- return count;
+ return serial->type->chars_in_buffer(tty);
}
static void serial_wait_until_sent(struct tty_struct *tty, int timeout)
--
1.7.11.7
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