linux-kernel - Re: [PATCH v2] iio: adc: mcp3911: simplify code with guard macro

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Date:   Mon, 4 Dec 2023 12:23:09 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Marcus Folkesson <marcus.folkesson@...il.com>
Cc:     Kent Gustavsson <kent@...oris.se>,
        Lars-Peter Clausen <lars@...afoo.de>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: adc: mcp3911: simplify code with guard macro

On Mon, 27 Nov 2023 08:38:22 +0100
Marcus Folkesson <marcus.folkesson@...il.com> wrote:

> Use the guard(mutex) macro for handle mutex lock/unlocks.
> 
> Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>

Oddly this doesn't apply. Also some comments inline.
> ---
> Changes in v2:
> - Return directly instead of goto label
> - Link to v1: https://lore.kernel.org/r/20231125-mcp3911-guard-v1-1-2748d16a3f3f@gmail.com
> ---
>  drivers/iio/adc/mcp3911.c | 27 ++++++++++-----------------
>  1 file changed, 10 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
> index 974c5bd923a6..30836725ef9a 100644
> --- a/drivers/iio/adc/mcp3911.c
> +++ b/drivers/iio/adc/mcp3911.c
> @@ -7,6 +7,7 @@
>   */
>  #include <linux/bitfield.h>
>  #include <linux/bits.h>
> +#include <linux/cleanup.h>
>  #include <linux/clk.h>
>  #include <linux/delay.h>
>  #include <linux/err.h>
> @@ -168,13 +169,13 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev,
>  	struct mcp3911 *adc = iio_priv(indio_dev);
>  	int ret = -EINVAL;
>  
> -	mutex_lock(&adc->lock);
> +	guard(mutex)(&adc->lock);
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
>  		ret = mcp3911_read(adc,
>  				   MCP3911_CHANNEL(channel->channel), val, 3);
>  		if (ret)
> -			goto out;
> +			return ret;
>  
>  		*val = sign_extend32(*val, 23);
This should go further.  Return early in the good paths as well
		return IIO_VAL_INT;
a few lines later than this.