linux-kernel - Re: [PATCH 11/42] drivers/hid: Convert snprintf to sysfs

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Date: Sat, 24 Feb 2024 17:59:29 +0100
From: Bruno Prémont <bonbons@...ophe.eu>
To: Li Zhijian <lizhijian@...itsu.com>
Cc: linux-kernel@...r.kernel.org, Jiri Kosina <jikos@...nel.org>, Benjamin
 Tissoires <benjamin.tissoires@...hat.com>, Jonathan Cameron
 <jic23@...nel.org>, Srinivas Pandruvada
 <srinivas.pandruvada@...ux.intel.com>, linux-input@...r.kernel.org
Subject: Re: [PATCH 11/42] drivers/hid: Convert snprintf to sysfs_emit

Hi Li,

While only looking for the snprintf() in your coccinelle analysis you
probably also want to look for sprintf() (see e.g. else clause in
hid-sensor-custom.c and scnprintf() (see picolcd_fb_update_rate_show
in hid-picolcd_fb.c) to replace more s*printf() calls with sysfs_emit*
variants.



diff --git a/drivers/hid/hid-picolcd_fb.c b/drivers/hid/hid-picolcd_fb.c
index d726aaafb146..03074d25d662 100644
--- a/drivers/hid/hid-picolcd_fb.c
+++ b/drivers/hid/hid-picolcd_fb.c
@@ -459,9 +459,9 @@ static ssize_t picolcd_fb_update_rate_show(struct device *dev,
 		if (ret >= PAGE_SIZE)
 			break;
 		else if (i == fb_update_rate)
-			ret += scnprintf(buf+ret, PAGE_SIZE-ret, "[%u] ", i);
+			ret += sysfs_emit_at(buf, ret, "[%u] ", i);
 		else
-			ret += scnprintf(buf+ret, PAGE_SIZE-ret, "%u ", i);
+			ret += sysfs_emit_at(buf, ret, "%u ", i);
 	if (ret > 0)
 		buf[min(ret, (size_t)PAGE_SIZE)-1] = '\n';
 	return ret;


For hid-picolcd-*.c,
  Acked-by: Bruno Prémont <bonbons@...ux-vserver.org>
but preferably with the scnprintf() case is covered too.


Cheers,
Bruno

On Tue, 16 Jan 2024 12:51:20 +0800 Li Zhijian wrote:
> Per Documentation/filesystems/sysfs.rst, show() should only use sysfs_emit()
> or sysfs_emit_at() when formatting the value to be returned to user space.
> 
> coccinelle complains that there are still a couple of functions that use
> snprintf(). Convert them to sysfs_emit().
> 
> > ./drivers/hid/hid-picolcd_core.c:259:9-17: WARNING: please use sysfs_emit
> > ./drivers/hid/hid-picolcd_core.c:304:8-16: WARNING: please use sysfs_emit
> > ./drivers/hid/hid-sensor-custom.c:375:10-18: WARNING: please use sysfs_emi  
> 
> No functional change intended
> 
> CC: "Bruno Prémont" <bonbons@...ux-vserver.org>
> CC: Jiri Kosina <jikos@...nel.org>
> CC: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> CC: Jonathan Cameron <jic23@...nel.org>
> CC: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> CC: linux-input@...r.kernel.org
> Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
> ---
>  drivers/hid/hid-picolcd_core.c  | 6 +++---
>  drivers/hid/hid-sensor-custom.c | 3 +--
>  2 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/hid/hid-picolcd_core.c b/drivers/hid/hid-picolcd_core.c
> index bbda231a7ce3..fa46fb6eab3f 100644
> --- a/drivers/hid/hid-picolcd_core.c
> +++ b/drivers/hid/hid-picolcd_core.c
> @@ -256,9 +256,9 @@ static ssize_t picolcd_operation_mode_show(struct device *dev,
>  	struct picolcd_data *data = dev_get_drvdata(dev);
>  
>  	if (data->status & PICOLCD_BOOTLOADER)
> -		return snprintf(buf, PAGE_SIZE, "[bootloader] lcd\n");
> +		return sysfs_emit(buf, "[bootloader] lcd\n");
>  	else
> -		return snprintf(buf, PAGE_SIZE, "bootloader [lcd]\n");
> +		return sysfs_emit(buf, "bootloader [lcd]\n");
>  }
>  
>  static ssize_t picolcd_operation_mode_store(struct device *dev,
> @@ -301,7 +301,7 @@ static ssize_t picolcd_operation_mode_delay_show(struct device *dev,
>  {
>  	struct picolcd_data *data = dev_get_drvdata(dev);
>  
> -	return snprintf(buf, PAGE_SIZE, "%hu\n", data->opmode_delay);
> +	return sysfs_emit(buf, "%hu\n", data->opmode_delay);
>  }
>  
>  static ssize_t picolcd_operation_mode_delay_store(struct device *dev,
> diff --git a/drivers/hid/hid-sensor-custom.c b/drivers/hid/hid-sensor-custom.c
> index d85398721659..4fe8dccf671d 100644
> --- a/drivers/hid/hid-sensor-custom.c
> +++ b/drivers/hid/hid-sensor-custom.c
> @@ -372,8 +372,7 @@ static ssize_t show_value(struct device *dev, struct device_attribute *attr,
>  				     sizeof(struct hid_custom_usage_desc),
>  				     usage_id_cmp);
>  		if (usage_desc)
> -			return snprintf(buf, PAGE_SIZE, "%s\n",
> -					usage_desc->desc);
> +			return sysfs_emit(buf, "%s\n", usage_desc->desc);
>  		else
>  			return sprintf(buf, "not-specified\n");

Shouldn't the sprintf() in the else clause be replaced as well?

>  	 } else