linux-kernel - Re: [PATCH] staging: iio: adis16203: Use devm_iio_device

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Message-ID: <alpine.DEB.2.02.1407172306230.1976@localhost6.localdomain6>
Date:	Thu, 17 Jul 2014 23:08:00 +0200 (CEST)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	Lars-Peter Clausen <lars@...afoo.de>
cc:	Himangi Saraogi <himangi774@...il.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-iio@...r.kernel.org, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: iio: adis16203: Use devm_iio_device_register



On Thu, 17 Jul 2014, Lars-Peter Clausen wrote:

> On 07/17/2014 10:40 PM, Himangi Saraogi wrote:
> > This patch introduces the use of iio_device_register and does away with
> > the call to the corressponding unregister function in the probe and
> > remove functions of the driver respectively.
> > 
> > Signed-off-by: Himangi Saraogi <himangi774@...il.com>
> > Acked-by: Julia Lawall <julia.lawall@...6.fr>
> 
> No, you changed the relative order in which iio_device_unregister() and
> adis_cleanup_buffer_and_trigger() are called, this opens up the way for race
> conditions. Rule of thumb: Don't convert drivers to managed functions if this
> will change the order in which functions will called on device removal.

Thanks for the information.  I was indeed not sure about this.

Unfortunately, removal code is not always perfectly written, and the 
operations are not always done in the right order...

julia

> - Lars
> 
> > ---
> >   drivers/staging/iio/accel/adis16203_core.c | 3 +--
> >   1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/staging/iio/accel/adis16203_core.c
> > b/drivers/staging/iio/accel/adis16203_core.c
> > index 409a28e..5077779 100644
> > --- a/drivers/staging/iio/accel/adis16203_core.c
> > +++ b/drivers/staging/iio/accel/adis16203_core.c
> > @@ -175,7 +175,7 @@ static int adis16203_probe(struct spi_device *spi)
> >   	if (ret)
> >   		goto error_cleanup_buffer_trigger;
> > 
> > -	ret = iio_device_register(indio_dev);
> > +	ret = devm_iio_device_register(&spi->dev, indio_dev);
> >   	if (ret)
> >   		goto error_cleanup_buffer_trigger;
> > 
> > @@ -191,7 +191,6 @@ static int adis16203_remove(struct spi_device *spi)
> >   	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> >   	struct adis *st = iio_priv(indio_dev);
> > 
> > -	iio_device_unregister(indio_dev);
> >   	adis_cleanup_buffer_and_trigger(st, indio_dev);
> > 
> >   	return 0;
> > 
> 
> 
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