From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Privoznik Subject: [PATCH] net-sysfs: Report link speed only when possible Date: Fri, 6 Jun 2014 10:40:30 +0200 Message-ID: <771f792d4d4391c656305a522557c53c4e84a666.1402043894.git.mprivozn@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: gregkh@linuxfoundation.org, jiri@resnulli.us, linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: davem@davemloft.net Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org The link speed is available at /sys/class/net/$nic/speed. However, in some cases, depending on the driver, if the link is not plugged, -1 is reported (this is the case of e1000e for instance). To make things worse, the value is printed out as an unsigned integer, so you'll get this shady number which you can't evaluate correctly. This is actually a regression in 3.X kernels as the commit that broke things is 8ae6daca. With this change, you'll get -EINVAL whenever a -1 is to be printed out. Before the change: # cat /sys/class/net/eth0/speed 4294967295 After the change: # cat /sys/class/net/eth0/speed cat: /sys/class/net/eth0/speed: Invalid argument Signed-off-by: Michal Privoznik --- net/core/net-sysfs.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 1cac29e..ce4b298 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -172,8 +172,13 @@ static ssize_t speed_show(struct device *dev, if (netif_running(netdev)) { struct ethtool_cmd cmd; - if (!__ethtool_get_settings(netdev, &cmd)) - ret = sprintf(buf, fmt_udec, ethtool_cmd_speed(&cmd)); + if (!__ethtool_get_settings(netdev, &cmd)) { + __u32 speed = ethtool_cmd_speed(&cmd); + + if (speed != (__u32) -1) + ret = sprintf(buf, fmt_udec, + ethtool_cmd_speed(&cmd)); + } } rtnl_unlock(); return ret; -- 2.0.0