[media] DVB: dvb_frontend: update locking in dvb_frontend_{add, get_event}

  - fepriv->parameters_out isn't protected by events->mtx, so
    move the call to fe->ops.get_frontend out of the locked area.
  - move the assignment of e->status into the locked area.

  - use direct assignment instead of memcpy.

  - use mutex_lock instead of mutex_lock_interruptible, because
    all code paths protected by this mutex won't block.

Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/dvb-core/dvb_frontend.c

@@ -149,30 +149,25 @@ static void dvb_frontend_add_event(struct dvb_frontend *fe, fe_status_t status)
 
 	dprintk ("%s\n", __func__);
 
-	if (mutex_lock_interruptible (&events->mtx))
-		return;
+	if ((status & FE_HAS_LOCK) && fe->ops.get_frontend)
+		fe->ops.get_frontend(fe, &fepriv->parameters_out);
 
-	wp = (events->eventw + 1) % MAX_EVENT;
+	mutex_lock(&events->mtx);
 
+	wp = (events->eventw + 1) % MAX_EVENT;
 	if (wp == events->eventr) {
 		events->overflow = 1;
 		events->eventr = (events->eventr + 1) % MAX_EVENT;
 	}
 
 	e = &events->events[events->eventw];
-
-	if (status & FE_HAS_LOCK)
-		if (fe->ops.get_frontend)
-			fe->ops.get_frontend(fe, &fepriv->parameters_out);
-
+	e->status = status;
 	e->parameters = fepriv->parameters_out;
 
 	events->eventw = wp;
 
 	mutex_unlock(&events->mtx);
 
-	e->status = status;
-
 	wake_up_interruptible (&events->wait_queue);
 }
 
@@ -207,14 +202,9 @@ static int dvb_frontend_get_event(struct dvb_frontend *fe,
 			return ret;
 	}
 
-	if (mutex_lock_interruptible (&events->mtx))
-		return -ERESTARTSYS;
-
-	memcpy (event, &events->events[events->eventr],
-		sizeof(struct dvb_frontend_event));
-
+	mutex_lock(&events->mtx);
+	*event = events->events[events->eventr];
 	events->eventr = (events->eventr + 1) % MAX_EVENT;
-
 	mutex_unlock(&events->mtx);
 
 	return 0;