Re: [PATCH] iio: trigger: free trigger resource correctly

From: Alison Schofield
Date: Wed Jan 18 2017 - 18:12:11 EST


On Wed, Jan 18, 2017 at 12:56:29PM +0300, Dan Carpenter wrote:
> On Tue, Jan 17, 2017 at 07:00:28PM -0800, Alison Schofield wrote:
> > Using iio_trigger_put() to free a trigger leads to release of
> > a resource we never held. Replace with iio_trigger_free().
>
> They're basically the same except iio_trigger_put() puts the module and
> the device and free only puts the device.
>
> I've looked at this briefly, but I can't figure out how iio_trigger_get/
> iio_trigger_put is supposed to be used. There isn't any documentation.
> I'm trying to review this code, but I can't figure out where we *are*
> supposed to be doing the put.
>
> For example, iio_device_unregister_trigger_consumer() takes a put, but
> iio_device_register_trigger_consumer() doesn't do a get... It's all
> very confusing.
>
> You seem like you know what's going on. Can we get some documentation?
>
Dan,
Although I'm comfortable within the bounds of this fix (pair the
alloc & free's and do not _put the module resource we never _get'd)
beyond that, not so much. I'm just figuring it out myself.

linux-iio experts...pointers, help?

alisons


> >
> > Signed-off-by: Alison Schofield <amsfield22@xxxxxxxxx>
> > ---
> > Patches to use devm_* funcs are ready to follow this for
> > the interrupt & bfin-timer triggers.
> >
> > drivers/iio/trigger/iio-trig-interrupt.c | 4 ++--
> > drivers/iio/trigger/iio-trig-sysfs.c | 2 +-
> > drivers/staging/iio/trigger/iio-trig-bfin-timer.c | 4 ++--
> > 3 files changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/iio/trigger/iio-trig-interrupt.c b/drivers/iio/trigger/iio-trig-interrupt.c
> > index 572bc6f..b18e50d 100644
> > --- a/drivers/iio/trigger/iio-trig-interrupt.c
> > +++ b/drivers/iio/trigger/iio-trig-interrupt.c
> > @@ -84,7 +84,7 @@ static int iio_interrupt_trigger_probe(struct platform_device *pdev)
> > error_free_trig_info:
> > kfree(trig_info);
> > error_put_trigger:
> > - iio_trigger_put(trig);
> > + iio_trigger_free(trig);
>
>
> We could rename this label.
>
> regards,
> dan carpenter
>