linux-kernel - Re: [PATCH 16/28] iio: imu: inv_icm42600: use = { } instead of memset()

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Message-ID: <20250614132150.6f4a29a3@jic23-huawei>
Date: Sat, 14 Jun 2025 13:21:50 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: David Lechner <dlechner@...libre.com>
Cc: Michael Hennerich <michael.hennerich@...log.com>, Lars-Peter Clausen
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Subject: Re: [PATCH 16/28] iio: imu: inv_icm42600: use = { } instead of
 memset()

On Wed, 11 Jun 2025 17:39:08 -0500
David Lechner <dlechner@...libre.com> wrote:

> Use { } instead of memset() to zero-initialize stack memory to simplify
> the code.

This one isn't as obvious as many as the zeroing was in a loop
and now it's at declaration.

It's fine because we always copy over the same elements.

I'll leave this whole series a little longer in case we are missing
subtle cases like this. (but ones where it actually does make a difference!)

Jonathan


> 
> Signed-off-by: David Lechner <dlechner@...libre.com>
> ---
>  drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c | 5 ++---
>  drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c  | 5 ++---
>  2 files changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
> index e6cd9dcb0687d19554e63a69dc60f065c58d70ee..dbd315ad3c4d2bd5085f7cd3cdc6de4391b1c896 100644
> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
> @@ -902,7 +902,8 @@ int inv_icm42600_accel_parse_fifo(struct iio_dev *indio_dev)
>  	const int8_t *temp;
>  	unsigned int odr;
>  	int64_t ts_val;
> -	struct inv_icm42600_accel_buffer buffer;
> +	/* buffer is copied to userspace, zeroing it to avoid any data leak */
> +	struct inv_icm42600_accel_buffer buffer = { };
>  
>  	/* parse all fifo packets */
>  	for (i = 0, no = 0; i < st->fifo.count; i += size, ++no) {
> @@ -921,8 +922,6 @@ int inv_icm42600_accel_parse_fifo(struct iio_dev *indio_dev)
>  			inv_sensors_timestamp_apply_odr(ts, st->fifo.period,
>  							st->fifo.nb.total, no);
>  
> -		/* buffer is copied to userspace, zeroing it to avoid any data leak */
> -		memset(&buffer, 0, sizeof(buffer));
>  		memcpy(&buffer.accel, accel, sizeof(buffer.accel));
>  		/* convert 8 bits FIFO temperature in high resolution format */
>  		buffer.temp = temp ? (*temp * 64) : 0;
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c
> index b4d7ce1432a4f4d096599877040a89ede0625e0b..4058eca076d8b03a2290535eedffa0a74098d739 100644
> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c
> @@ -806,7 +806,8 @@ int inv_icm42600_gyro_parse_fifo(struct iio_dev *indio_dev)
>  	const int8_t *temp;
>  	unsigned int odr;
>  	int64_t ts_val;
> -	struct inv_icm42600_gyro_buffer buffer;
> +	/* buffer is copied to userspace, zeroing it to avoid any data leak */
> +	struct inv_icm42600_gyro_buffer buffer = { };
>  
>  	/* parse all fifo packets */
>  	for (i = 0, no = 0; i < st->fifo.count; i += size, ++no) {
> @@ -825,8 +826,6 @@ int inv_icm42600_gyro_parse_fifo(struct iio_dev *indio_dev)
>  			inv_sensors_timestamp_apply_odr(ts, st->fifo.period,
>  							st->fifo.nb.total, no);
>  
> -		/* buffer is copied to userspace, zeroing it to avoid any data leak */
> -		memset(&buffer, 0, sizeof(buffer));
>  		memcpy(&buffer.gyro, gyro, sizeof(buffer.gyro));
>  		/* convert 8 bits FIFO temperature in high resolution format */
>  		buffer.temp = temp ? (*temp * 64) : 0;
>