linux-kernel - Re: [PATCH v6 4/4] iio: accel: sca3000: use sysfs_emit

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Message-ID: <20250621185824.69a11319@jic23-huawei>
Date: Sat, 21 Jun 2025 18:58:24 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Andrew Ijano <andrew.ijano@...il.com>
Cc: andrew.lopes@...mni.usp.br, gustavobastos@....br, dlechner@...libre.com,
 nuno.sa@...log.com, andy@...nel.org, jstephan@...libre.com,
 linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 4/4] iio: accel: sca3000: use sysfs_emit_at() instead
 of sprintf()

On Wed, 18 Jun 2025 00:12:19 -0300
Andrew Ijano <andrew.ijano@...il.com> wrote:

> Use sysfs_emit_at() instead of sprintf() for sysfs operations as
> suggested in the documentation, since it is aware of PAGE_SIZE buffer.
> 
> Signed-off-by: Andrew Ijano <andrew.lopes@...mni.usp.br>
> Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Hi.

A few comments inline,

Thanks,

J
> ---
>  drivers/iio/accel/sca3000.c | 22 +++++++++-------------
>  1 file changed, 9 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iio/accel/sca3000.c b/drivers/iio/accel/sca3000.c
> index 058a2d67c91c..bc0046b19511 100644
> --- a/drivers/iio/accel/sca3000.c
> +++ b/drivers/iio/accel/sca3000.c
> @@ -423,16 +423,16 @@ sca3000_show_available_3db_freqs(struct device *dev,
>  {
>  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>  	struct sca3000_state *st = iio_priv(indio_dev);
> -	int len;
> +	unsigned int len = 0;

No need to initialize as set on the next line

>  
> -	len = sprintf(buf, "%d", st->info->measurement_mode_3db_freq);
> +	len = sysfs_emit_at(buf, len, "%d", st->info->measurement_mode_3db_freq);

sysfs_emit() when you know you are at the start.


>  	if (st->info->option_mode_1)
> -		len += sprintf(buf + len, " %d",
> +		len += sysfs_emit_at(buf, len, " %d",
>  			       st->info->option_mode_1_3db_freq);
Fix alignment.

>  	if (st->info->option_mode_2)
> -		len += sprintf(buf + len, " %d",
> +		len += sysfs_emit_at(buf, len, " %d",
>  			       st->info->option_mode_2_3db_freq);

same here.

> -	len += sprintf(buf + len, "\n");
> +	len += sysfs_emit_at(buf, len, "\n");
>  
>  	return len;
>  }
> @@ -783,7 +783,6 @@ static ssize_t sca3000_read_av_freq(struct device *dev,
>  {
>  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>  	struct sca3000_state *st = iio_priv(indio_dev);
> -	unsigned int len = 0;
>  	int ret;
>  
>  	scoped_guard(mutex, &st->lock) {
> @@ -794,25 +793,22 @@ static ssize_t sca3000_read_av_freq(struct device *dev,
>  
>  	switch (ret & SCA3000_REG_MODE_MODE_MASK) {
>  	case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
> -		len += sprintf(buf + len, "%d %d %d\n",
> +		return sysfs_emit(buf, "%d %d %d\n",
>  			       st->info->measurement_mode_freq,
>  			       st->info->measurement_mode_freq / 2,
>  			       st->info->measurement_mode_freq / 4);
> -		break;
>  	case SCA3000_REG_MODE_MEAS_MODE_OP_1:
> -		len += sprintf(buf + len, "%d %d %d\n",
> +		return sysfs_emit(buf, "%d %d %d\n",
>  			       st->info->option_mode_1_freq,
>  			       st->info->option_mode_1_freq / 2,
>  			       st->info->option_mode_1_freq / 4);
> -		break;
>  	case SCA3000_REG_MODE_MEAS_MODE_OP_2:
> -		len += sprintf(buf + len, "%d %d %d\n",
> +		return sysfs_emit(buf, "%d %d %d\n",
>  			       st->info->option_mode_2_freq,
>  			       st->info->option_mode_2_freq / 2,
>  			       st->info->option_mode_2_freq / 4);
> -		break;
>  	}
> -	return len;
> +	return 0;
>  }
>  
>  /*