[PATCH] add sysfs attribute 'carrier' for net devices - try 2.

[Jesper Juhl <juhl-lkml@dif.dk>]

On Tue, 28 Sep 2004, Jesper Juhl wrote:

> On Mon, 27 Sep 2004, Stephen Hemminger wrote:
> 
> > Date: Mon, 27 Sep 2004 10:29:13 -0700
> > From: Stephen Hemminger <shemminger@osdl.org>
> > To: Jesper Juhl <juhl-lkml@dif.dk>
> > Cc: linux-kernel <linux-kernel@vger.kernel.org>,
> >     Nico Schottelius <nico-kernel@schottelius.org>
> > Subject: Re: [PATCH] add sysfs attribute 'carrier' for net devices
> > 
> > On Mon, 2004-09-27 at 00:51 +0200, Jesper Juhl wrote:
> > >  
> > > +static ssize_t show_carrier(struct class_device *dev, char *buf)
> > > +{
> > > +	struct net_device *net = to_net_dev(dev);
> > > +	if (netif_running(net)) {
> > > +		if (netif_carrier_ok(net))
> > > +			return snprintf(buf, 3, "%d\n", 1);
> > > +		else
> > > +			return snprintf(buf, 3, "%d\n", 0);
> > 
> > Using snprintf in this way is kind of silly. since buffer is PAGESIZE.
> > The most concise format of this would be:
> > 	return sprintf(buf, dec_fmt, !!netif_carrier_ok(dev));
> > 
> 
> I see your point and I'll create a new patch this evening when I get home 
> from work.
> Thank you for your feedback.
> 

Here's a second try at a patch to properly implement a 'carrier' sysfs 
attribute for net devices.

Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>

diff -u linux-2.6.9-rc2-bk14-orig/net/core/net-sysfs.c linux-2.6.9-rc2-bk14/net/core/net-sysfs.c
--- linux-2.6.9-rc2-bk14-orig/net/core/net-sysfs.c	2004-09-14 23:19:53.000000000 +0200
+++ linux-2.6.9-rc2-bk14/net/core/net-sysfs.c	2004-09-28 19:37:45.000000000 +0200
@@ -126,8 +126,18 @@
 	return -EINVAL;
 }
 
+static ssize_t show_carrier(struct class_device *dev, char *buf)
+{
+	struct net_device *netdev = to_net_dev(dev);
+	if (netif_running(netdev)) {
+		return sprintf(buf, fmt_dec, !!netif_carrier_ok(netdev));
+	}
+	return -EINVAL;
+}
+
 static CLASS_DEVICE_ATTR(address, S_IRUGO, show_address, NULL);
 static CLASS_DEVICE_ATTR(broadcast, S_IRUGO, show_broadcast, NULL);
+static CLASS_DEVICE_ATTR(carrier, S_IRUGO, show_carrier, NULL);
 
 /* read-write attributes */
 NETDEVICE_SHOW(mtu, fmt_dec);
@@ -186,6 +196,7 @@
 	&class_device_attr_type,
 	&class_device_attr_address,
 	&class_device_attr_broadcast,
+	&class_device_attr_carrier,
 	NULL
 };