linux-kernel - Re: [PATCH v2 3/9] iio: inkern: Check error explicitly in iio_channel_read

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Date:   Sun, 28 May 2023 18:32:21 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Herve Codina <herve.codina@...tlin.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v2 3/9] iio: inkern: Check error explicitly in
 iio_channel_read_max()

On Tue, 23 May 2023 17:12:17 +0200
Herve Codina <herve.codina@...tlin.com> wrote:

> The current implementation returns the error code as part of the
> default switch case.
> This can lead to returning an incorrect positive value in case of
> iio_avail_type enum entries evolution.
> 
> In order to avoid this case, be more strict in error checking.
> 
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
It's an odd code construct, so in the interests of robustness this
looks like a good improvement to me.

Given the later patch you need for this series will see some fuzz
I think if I pick this up separately I'll currently assume this whole
series will go together.

Acked-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

> ---
>  drivers/iio/inkern.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index 872fd5c24147..f738db9a0c04 100644
> --- a/drivers/iio/inkern.c
> +++ b/drivers/iio/inkern.c
> @@ -858,6 +858,9 @@ static int iio_channel_read_max(struct iio_channel *chan,
>  		val2 = &unused;
>  
>  	ret = iio_channel_read_avail(chan, &vals, type, &length, info);
> +	if (ret < 0)
> +		return ret;
> +
>  	switch (ret) {
>  	case IIO_AVAIL_RANGE:
>  		switch (*type) {
> @@ -888,7 +891,7 @@ static int iio_channel_read_max(struct iio_channel *chan,
>  		return 0;
>  
>  	default:
> -		return ret;
> +		return -EINVAL;
>  	}
>  }
>