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Commit 77b1e2fb authored by Andreas Oberritter's avatar Andreas Oberritter Committed by Mauro Carvalho Chehab
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[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: default avatarAndreas Oberritter <obi@linuxtv.org>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 20640bea

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

+7 −17
Original line number Diff line number Diff line
@@ -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;