[PATCH v6 1/7] usb: gadget: u_serial: add missing port entry locking

[MichaÅ MirosÅaw]

gserial_alloc_line() misses locking (for a release barrier) while
resetting port entry on TTY allocation failure. Fix this.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: MichaÅ MirosÅaw <mirq-linux@xxxxxxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Tested-by: Ladislav Michl <ladis@xxxxxxxxxxxxxx>

---
  v6: rebased on balbi/testing/next
  v5: no changes
  v4: no changes
  v3: cc-stable
  v2: no changes

---
 drivers/usb/gadget/function/u_serial.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 65f634ec7fc2..bb1e2e1d0076 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -1239,8 +1239,10 @@ int gserial_alloc_line(unsigned char *line_num)
 				__func__, port_num, PTR_ERR(tty_dev));
 
 		ret = PTR_ERR(tty_dev);
+		mutex_lock(&ports[port_num].lock);
 		port = ports[port_num].port;
 		ports[port_num].port = NULL;
+		mutex_unlock(&ports[port_num].lock);
 		gserial_free_port(port);
 		goto err;
 	}
-- 
2.20.1