Re: [PATCH net-next] net-sysfs: restore behavior for not running devices

[Antoine Tenart <atenart@kernel.org>]

Quoting Eric Dumazet (2025-02-21 06:12:23)
> modprobe dummy dumdummies=1
> 
> Old behavior :
> 
> $ cat /sys/class/net/dummy0/carrier
> cat: /sys/class/net/dummy0/carrier: Invalid argument
> 
> After blamed commit, an empty string is reported.
> 
> $ cat /sys/class/net/dummy0/carrier
> $
> 
> In this commit, I restore the old behavior for carrier,
> speed and duplex attributes.
> 
> Fixes: 79c61899b5ee ("net-sysfs: remove rtnl_trylock from device attributes")
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Antoine Tenart <atenart@kernel.org>

Thanks!

> ---
>  net/core/net-sysfs.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 3fe2c521e5740436687f09c572754c5d071038f4..f61c1d829811941671981a395fc4cbc57cf48d23 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -313,12 +313,13 @@ static ssize_t carrier_show(struct device *dev,
>                             struct device_attribute *attr, char *buf)
>  {
>         struct net_device *netdev = to_net_dev(dev);
> -       int ret = -EINVAL;
> +       int ret;
>  
>         ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
>         if (ret)
>                 return ret;
>  
> +       ret = -EINVAL;
>         if (netif_running(netdev)) {
>                 /* Synchronize carrier state with link watch,
>                  * see also rtnl_getlink().
> @@ -349,6 +350,7 @@ static ssize_t speed_show(struct device *dev,
>         if (ret)
>                 return ret;
>  
> +       ret = -EINVAL;
>         if (netif_running(netdev)) {
>                 struct ethtool_link_ksettings cmd;
>  
> @@ -376,6 +378,7 @@ static ssize_t duplex_show(struct device *dev,
>         if (ret)
>                 return ret;
>  
> +       ret = -EINVAL;
>         if (netif_running(netdev)) {
>                 struct ethtool_link_ksettings cmd;
>  
> -- 
> 2.48.1.601.g30ceb7b040-goog
> 
>