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Message-ID: <20180318102243.4cb99daa@archlinux>
Date: Sun, 18 Mar 2018 10:22:43 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc: linux-iio@...r.kernel.org, Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
Peter Meerwald-Stadler <pmeerw@...erw.net>,
LKML <linux-kernel@...r.kernel.org>,
kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] iio/adc/nau7802: Improve unlocking of a mutex in
nau7802_read_raw()
On Tue, 13 Mar 2018 20:56:25 +0100
SF Markus Elfring <elfring@...rs.sourceforge.net> wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Tue, 13 Mar 2018 20:52:26 +0100
>
> * Add a jump target so that a call of the function "mutex_unlock" is stored
> only once in this function implementation.
>
> * Replace two calls by goto statements.
>
> This issue was detected by using the Coccinelle software.
>
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
Similar to other cases, this non obvious error handling flow rather implies
that this block of code might work better as a utility function called from
the case statement.
> ---
> drivers/iio/adc/nau7802.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iio/adc/nau7802.c b/drivers/iio/adc/nau7802.c
> index 8997e74a8847..68d06a492760 100644
> --- a/drivers/iio/adc/nau7802.c
> +++ b/drivers/iio/adc/nau7802.c
> @@ -303,10 +303,8 @@ static int nau7802_read_raw(struct iio_dev *indio_dev,
> * - Channel 2 is value 1 in the CHS register
> */
> ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_CTRL2);
> - if (ret < 0) {
> - mutex_unlock(&st->lock);
> - return ret;
> - }
> + if (ret < 0)
> + goto unlock;
>
> if (((ret & NAU7802_CTRL2_CHS_BIT) && !chan->channel) ||
> (!(ret & NAU7802_CTRL2_CHS_BIT) &&
> @@ -316,18 +314,15 @@ static int nau7802_read_raw(struct iio_dev *indio_dev,
> NAU7802_REG_CTRL2,
> NAU7802_CTRL2_CHS(chan->channel) |
> NAU7802_CTRL2_CRS(st->sample_rate));
> -
> - if (ret < 0) {
> - mutex_unlock(&st->lock);
> - return ret;
> - }
> + if (ret < 0)
> + goto unlock;
> }
>
> if (st->client->irq)
> ret = nau7802_read_irq(indio_dev, chan, val);
> else
> ret = nau7802_read_poll(indio_dev, chan, val);
> -
> +unlock:
> mutex_unlock(&st->lock);
blank line before simple returns. It isn't a major enough part to be
worth the noise of adding them to existing code, but there is no reason
to take them out!
> return ret;
>
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