linux-kernel - Re: [PATCH] watchdog: Use sysfs_emit() and sysfs_emit

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Date:   Wed, 12 May 2021 21:48:37 -0700
From:   Joe Perches <joe@...ches.com>
To:     Juerg Haefliger <juerg.haefliger@...onical.com>,
        wim@...ux-watchdog.org, linux@...ck-us.net, joel@....id.au,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-aspeed@...ts.ozlabs.org
Cc:     andrew@...id.au, linux-kernel@...r.kernel.org,
        Juerg Haefliger <juergh@...onical.com>
Subject: Re: [PATCH] watchdog: Use sysfs_emit() and sysfs_emit_at() in
 "show" functions

On Tue, 2021-05-11 at 08:18 +0200, Juerg Haefliger wrote:
> Convert sprintf() in sysfs "show" functions to sysfs_emit() and
> sysfs_emit_at() in order to check for buffer overruns in sysfs outputs.
[]
> diff --git a/drivers/watchdog/ziirave_wdt.c b/drivers/watchdog/ziirave_wdt.c
[]
> @@ -445,8 +445,9 @@ static ssize_t ziirave_wdt_sysfs_show_firm(struct device *dev,
>  	if (ret)
>  		return ret;
>  
> 
> -	ret = sprintf(buf, ZIIRAVE_FW_VERSION_FMT, w_priv->firmware_rev.major,
> -		      w_priv->firmware_rev.minor);
> +	ret = sysfs_emit(buf, ZIIRAVE_FW_VERSION_FMT,
> +			 w_priv->firmware_rev.major,
> +			 w_priv->firmware_rev.minor);
>  
> 
>  	mutex_unlock(&w_priv->sysfs_mutex);
>  
> 
> @@ -468,8 +469,9 @@ static ssize_t ziirave_wdt_sysfs_show_boot(struct device *dev,
>  	if (ret)
>  		return ret;
>  
> 
> -	ret = sprintf(buf, ZIIRAVE_BL_VERSION_FMT, w_priv->bootloader_rev.major,
> -		      w_priv->bootloader_rev.minor);
> +	ret = sysfs_emit(buf, ZIIRAVE_BL_VERSION_FMT,
> +			 w_priv->bootloader_rev.major,
> +			 w_priv->bootloader_rev.minor);
>  
> 
>  	mutex_unlock(&w_priv->sysfs_mutex);
>  
> 
> @@ -491,7 +493,7 @@ static ssize_t ziirave_wdt_sysfs_show_reason(struct device *dev,
>  	if (ret)
>  		return ret;
>  
> 
> -	ret = sprintf(buf, "%s", ziirave_reasons[w_priv->reset_reason]);
> +	ret = sysfs_emit(buf, "%s", ziirave_reasons[w_priv->reset_reason]);

All of these formats should probably end with a newline
and the ZIIRAVE_<FOO>_VERSION_FMT defines are to me unnecessary.