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

From: Jesper Juhl
Date: Tue Sep 28 2004 - 14:17:43 EST


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@xxxxxxxx>
> > To: Jesper Juhl <juhl-lkml@xxxxxx>
> > Cc: linux-kernel <linux-kernel@xxxxxxxxxxxxxxx>,
> > Nico Schottelius <nico-kernel@xxxxxxxxxxxxxxx>
> > 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@xxxxxx>

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
};


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