usb: gadget: function: phonet: balance usb_ep_disable calls

commit 9ec36f7fe20ef919cc15171e1da1b6739222541a upstream.

f_phonet's ->set_alt() method will call usb_ep_disable()
potentially on an endpoint which is already disabled. That's
something the gadget/function driver must guarantee that it's
always balanced.

In order to balance the calls, just make sure the endpoint
was enabled before by means of checking the validity of
driver_data.

Reported-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
[ luis: backported to 3.16:
  - file rename: drivers/usb/gadget/function/f_phonet.c ->
    drivers/usb/gadget/f_phonet.c ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/usb/gadget/f_phonet.c b/drivers/usb/gadget/f_phonet.c
index f2b781773eed39da911bd7a6a4f4f5500e46fbbf..c2f12c85c6f8d62d5d83ccd7fe053116609a08ae 100644 (file)
--- a/drivers/usb/gadget/f_phonet.c
+++ b/drivers/usb/gadget/f_phonet.c
@@ -417,7 +417,10 @@ static int pn_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
                        return -EINVAL;
 
                spin_lock(&port->lock);
-               __pn_reset(f);
+
+               if (fp->in_ep->driver_data)
+                       __pn_reset(f);
+
                if (alt == 1) {
                        int i;