linux-kernel - Re: [PATCH 1/2] net: dsa: use DEVICE_ATTR_RW to declare temp1

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Message-ID: <20150416212434.GA2587@roeck-us.net>
Date:	Thu, 16 Apr 2015 14:24:34 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Florian Fainelli <f.fainelli@...il.com>,
	kernel@...oirfairelinux.com
Subject: Re: [PATCH 1/2] net: dsa: use DEVICE_ATTR_RW to declare temp1_max

On Thu, Apr 16, 2015 at 02:38:18PM -0400, Vivien Didelot wrote:
> Since commit da4759c, sysfs will only use the permissions returned by
> is_visible, instead of OR'ing them with the default file mode.
> 
> This allows us to declare temp1_max with the DEVICE_ATTR_RW macro and
> just return the desired permissions for the hwmon sysfs attributes in
> dsa_hwmon_attrs_visible.
> 
> Also, allow temp1_max to be write-only if set_temp_limit is provided,
> but not get_temp_limit.
> 
Hi Vivien,

This would be a first for the entire hwmon subsystem and doesn't really
make sense.

Guenter

> Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>
> ---
>  net/dsa/dsa.c | 24 ++++++++++++++++--------
>  1 file changed, 16 insertions(+), 8 deletions(-)
> 
> diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
> index 5eaadab..67d2983 100644
> --- a/net/dsa/dsa.c
> +++ b/net/dsa/dsa.c
> @@ -124,7 +124,7 @@ static ssize_t temp1_max_store(struct device *dev,
>  
>  	return count;
>  }
> -static DEVICE_ATTR(temp1_max, S_IRUGO, temp1_max_show, temp1_max_store);
> +static DEVICE_ATTR_RW(temp1_max);
>  
>  static ssize_t temp1_max_alarm_show(struct device *dev,
>  				    struct device_attribute *attr, char *buf)
> @@ -154,16 +154,24 @@ static umode_t dsa_hwmon_attrs_visible(struct kobject *kobj,
>  	struct device *dev = container_of(kobj, struct device, kobj);
>  	struct dsa_switch *ds = dev_get_drvdata(dev);
>  	struct dsa_switch_driver *drv = ds->drv;
> -	umode_t mode = attr->mode;
> +	umode_t mode = 0;
>  
> -	if (index == 1) {
> -		if (!drv->get_temp_limit)
> -			mode = 0;
> -		else if (drv->set_temp_limit)
> +	switch (index) {
> +	case 1: /* temp1_max */
> +		if (drv->get_temp_limit)
> +			mode |= S_IRUGO;
> +		if (drv->set_temp_limit)
>  			mode |= S_IWUSR;
> -	} else if (index == 2 && !drv->get_temp_alarm) {
> -		mode = 0;
> +		break;
> +	case 2: /* temp1_max_alarm */
> +		if (drv->get_temp_alarm)
> +			mode |= S_IRUGO;
> +		break;
> +	default:
> +		mode = attr->mode;
> +		break;
>  	}
> +
>  	return mode;
>  }
>  
> -- 
> 2.3.5
> 
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