netdev - Re: [net-next PATCH 1/1] e1000e: Expose MDI-X state via sysfs

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Message-ID: <9929d2390905191455i3103ead3p13c0b4c51be29b5@mail.gmail.com>
Date:	Tue, 19 May 2009 14:55:54 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	Chaitanya Lala <clala@...erbed.com>
Cc:	netdev@...r.kernel.org
Subject: Re: [net-next PATCH 1/1] e1000e: Expose MDI-X state via sysfs

On Tue, May 19, 2009 at 2:05 PM, Chaitanya Lala <clala@...erbed.com> wrote:
> While debugging network connectivity problems, it is often helpful
> to report the MDI-X state. The is_mdix variable holds the current
> state which we expose on a per-interface basis as a sysfs attribute.
> We use sysfs over methods such as netlink due to the convenience of
> reading a file (using the cat command) as opposed to connecting to a
> netlink socket. If we use a fiber PHY then is_mdix will always be zero
> as the mdi-x feature only applies to copper PHYs.
>
> Signed-off-by: Chaitanya Lala <clala@...erbed.com>
> Signed-off-by: Arthur Jones <ajones@...erbed.com>
> ---

NAK.  We do not want to be adding sysfs entries for every little piece
of information in the driver.  Instead, I would suggest looking at
enhancing existing tools like ethtool to get that sort of information
in a more generic way which is not driver specific.

>  drivers/net/e1000e/netdev.c |   35 +++++++++++++++++++++++++++++++++++
>  1 files changed, 35 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
> index ccaaee0..1c131b6 100644
> --- a/drivers/net/e1000e/netdev.c
> +++ b/drivers/net/e1000e/netdev.c
> @@ -4765,6 +4765,32 @@ static const struct net_device_ops e1000e_netdev_ops = {
>  #endif
>  };
>
> +static ssize_t e1000e_show_is_mdix(struct device *dev,
> +    struct device_attribute *attr, char *buf)
> +{
> +       struct net_device *netdev = container_of(dev, struct net_device, dev);
> +       struct e1000_adapter *adapter;
> +       struct e1000_hw *hw;
> +       ssize_t ret = -EINVAL;
> +
> +       if (!buf)
> +               goto err;
> +
> +       read_lock(&dev_base_lock);
> +       if (NETREG_REGISTERED == netdev->reg_state) {
> +               adapter = netdev_priv(netdev);
> +               hw = &adapter->hw;
> +               ret = sprintf(buf, "%d\n", (hw->phy.is_mdix ? 1 : 0));
> +       }
> +       read_unlock(&dev_base_lock);
> +err:
> +       return ret;
> +}
> +
> +/* Export attributes for the device */
> +static struct device_attribute device_attr_is_mdix =
> +    __ATTR(is_mdix, S_IRUGO, e1000e_show_is_mdix, NULL);
> +
>  /**
>  * e1000_probe - Device Initialization Routine
>  * @pdev: PCI device information struct
> @@ -5046,6 +5072,10 @@ static int __devinit e1000_probe(struct pci_dev *pdev,
>        if (err)
>                goto err_register;
>
> +       err = device_create_file(&netdev->dev, &device_attr_is_mdix);
> +       if (err)
> +               goto err_sys_attr;
> +
>        /* carrier off reporting is important to ethtool even BEFORE open */
>        netif_carrier_off(netdev);
>
> @@ -5053,6 +5083,9 @@ static int __devinit e1000_probe(struct pci_dev *pdev,
>
>        return 0;
>
> +err_sys_attr:
> +       unregister_netdev(netdev);
> +
>  err_register:
>        if (!(adapter->flags & FLAG_HAS_AMT))
>                e1000_release_hw_control(adapter);
> @@ -5105,6 +5138,8 @@ static void __devexit e1000_remove(struct pci_dev *pdev)
>
>        flush_scheduled_work();
>
> +       device_remove_file(&netdev->dev, &device_attr_is_mdix);
> +
>        /*
>         * Release control of h/w to f/w.  If f/w is AMT enabled, this
>         * would have already happened in close and is redundant.
> --
> 1.6.0.4
>
> --
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-- 
Cheers,
Jeff
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