linux-kernel - Re: [patch v2] [patch] staging: iio: ad799x: remove some unneeded IS

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Date:	Wed, 30 Apr 2014 23:52:57 +0200
From:	Hartmut Knaack <knaack.h@....de>
To:	Dan Carpenter <dan.carpenter@...cle.com>,
	Jonathan Cameron <jic23@...nel.org>
CC:	Lars-Peter Clausen <lars@...afoo.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Aida Mynzhasova <ai.c.c0der@...il.com>,
	Masanari Iida <standby24x7@...il.com>,
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [patch v2] [patch] staging: iio: ad799x: remove some unneeded
 IS_ERR() checks

Dan Carpenter schrieb:
> My static checker is upset that we check IS_ERR(t->reg) when we know it
> is not an ERR_PTR.
>
> Checking for IS_ERR() twice is often a sign of confusion and buggy code.
> In this case, if the call to "ret = regulator_enable(st->vref);" fails,
> then we call "regulator_disable(st->vref);" and that's a mistake because
> "st->vref" is not enabled.
>
> I fixed these problems and Hartmut Knaack pointed out a couple unneeded
> IS_ERR() checks in ad799x_remove() so I have removed those as well.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Acked-by: Hartmut Knaack <knaack.h@....de>
> ---
> v2: remove the unneeded checks in ad799x_remove() as well.  Updated the
>     commit message to say that it's actually a small bug fix.
>
> diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
> index 16a8b14..39b4cb4 100644
> --- a/drivers/iio/adc/ad799x.c
> +++ b/drivers/iio/adc/ad799x.c
> @@ -717,7 +717,7 @@ static int ad799x_probe(struct i2c_client *client,
>  	ret = iio_triggered_buffer_setup(indio_dev, NULL,
>  		&ad799x_trigger_handler, NULL);
>  	if (ret)
> -		goto error_disable_reg;
> +		goto error_disable_vref;
>  
>  	if (client->irq > 0) {
>  		ret = devm_request_threaded_irq(&client->dev,
> @@ -739,11 +739,10 @@ static int ad799x_probe(struct i2c_client *client,
>  
>  error_cleanup_ring:
>  	iio_triggered_buffer_cleanup(indio_dev);
> +error_disable_vref:
> +	regulator_disable(st->vref);
>  error_disable_reg:
> -	if (!IS_ERR(st->vref))
> -		regulator_disable(st->vref);
> -	if (!IS_ERR(st->reg))
> -		regulator_disable(st->reg);
> +	regulator_disable(st->reg);
>  
>  	return ret;
>  }
> @@ -756,10 +755,8 @@ static int ad799x_remove(struct i2c_client *client)
>  	iio_device_unregister(indio_dev);
>  
>  	iio_triggered_buffer_cleanup(indio_dev);
> -	if (!IS_ERR(st->vref))
> -		regulator_disable(st->vref);
> -	if (!IS_ERR(st->reg))
> -		regulator_disable(st->reg);
> +	regulator_disable(st->vref);
> +	regulator_disable(st->reg);
>  	kfree(st->rx_buf);
>  
>  	return 0;
> --
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>

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