linux-kernel - Re: [PATCH] HID: ft260: Use sysfs_emit to write formatted data to user buffer in sysfs show function.

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Message-ID: <2025092316-pasta-parachute-737e@gregkh>
Date: Tue, 23 Sep 2025 16:56:01 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Bhanu Seshu Kumar Valluri <bhanuseshukumar@...il.com>
Cc: Michael Zaidman <michael.zaidman@...il.com>,
	Jiri Kosina <jikos@...nel.org>,
	Benjamin Tissoires <bentiss@...nel.org>, linux-i2c@...r.kernel.org,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	skhan@...uxfoundation.org, linux-kernel-mentees@...ts.linux.dev
Subject: Re: [PATCH] HID: ft260: Use sysfs_emit to write formatted data to
 user buffer in sysfs show function.

On Tue, Sep 23, 2025 at 08:19:26PM +0530, Bhanu Seshu Kumar Valluri wrote:
> Inline with sysfs documentation, sysfs_emit is used in show function
> to write formatted data into user buffer. sysfs_emit is already PAGE_SIZE
> aware.
> 
> Signed-off-by: Bhanu Seshu Kumar Valluri <bhanuseshukumar@...il.com>
> ---
>  Note: Patch is compile tested and verified with checkpatch.
> 
>  drivers/hid/hid-ft260.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
> index 333341e80b0e..8677bea46bea 100644
> --- a/drivers/hid/hid-ft260.c
> +++ b/drivers/hid/hid-ft260.c
> @@ -826,7 +826,7 @@ static int ft260_byte_show(struct hid_device *hdev, int id, u8 *cfg, int len,
>  	if (ret < 0)
>  		return ret;
>  
> -	return scnprintf(buf, PAGE_SIZE, "%d\n", *field);
> +	return sysfs_emit(buf, "%d\n", *field);
>  }
>  
>  static int ft260_word_show(struct hid_device *hdev, int id, u8 *cfg, int len,
> @@ -838,7 +838,7 @@ static int ft260_word_show(struct hid_device *hdev, int id, u8 *cfg, int len,
>  	if (ret < 0)
>  		return ret;
>  
> -	return scnprintf(buf, PAGE_SIZE, "%d\n", le16_to_cpu(*field));
> +	return sysfs_emit(buf, "%d\n", le16_to_cpu(*field));

There's no need to change existing users in the kernel for stuff like
this, only try to do this for new sysfs files.  We've had too many bugs
where "simple" changes like this cause problems (recently in the USB
core for example.)

thanks,

greg k-h