[PATCH 4/4] DVB: dvb_frontend: update locking in dvb_frontend_{add,get_event}

[Andreas Oberritter <obi@xxxxxxxxxxx>]

- dvb_frontend_add_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.

- dvb_frontend_get_event:
  - use direct assignment instead of memcpy.

- dvb_frontend_add_event and dvb_frontend_get_event:
  - 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@xxxxxxxxxxx>
---
 drivers/media/dvb/dvb-core/dvb_frontend.c |   24 +++++++-----------------
 1 files changed, 7 insertions(+), 17 deletions(-)

diff --git a/drivers/media/dvb/dvb-core/dvb_frontend.c b/drivers/media/dvb/dvb-core/dvb_frontend.c
index 4102311..d02c32e 100644
--- a/drivers/media/dvb/dvb-core/dvb_frontend.c
+++ b/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;
-- 
1.7.2.5

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