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SubjectRe: [PATCH] net-sysfs: Report link speed as signed integer
On 02.06.2014 16:35, Jiri Pirko wrote:
> Mon, Jun 02, 2014 at 04:25:15PM CEST, mprivozn@redhat.com wrote:
>> The link speed is available at /sys/class/net/$nic/speed.
>> However, the speed is printed in unsigned integer format. This
>> makes userspace applications read an incorrect value (which
>> moreover changes through several architectures) while in fact
>> '-1' should be reported.
>>
>> Before the change:
>> # cat /sys/class/net/eth0/speed
>> 4294967295
>>
>> After the change:
>> # cat /sys/class/net/eth0/speed
>> -1
>>
>> Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
>> ---
>> net/core/net-sysfs.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
>> index 1cac29e..99afdea 100644
>> --- a/net/core/net-sysfs.c
>> +++ b/net/core/net-sysfs.c
>> @@ -173,7 +173,7 @@ 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));
>> + ret = sprintf(buf, fmt_dec, ethtool_cmd_speed(&cmd));
>
> I wonder why this should be signed. What -1 means? What driver reports
> this?

This is e1000e. It seems like a default value. From e1000_get_settings()
in drivers/net/ethernet/intel/e1000e/ethtool.c:

speed = -1;
ecmd->duplex = -1;

if (netif_running(netdev)) {
if (netif_carrier_ok(netdev)) {
speed = adapter->link_speed;
ecmd->duplex = adapter->link_duplex - 1;
}
} else if (!pm_runtime_suspended(netdev->dev.parent)) {
...
}

ethtool_cmd_speed_set(ecmd, speed);

If I unplug the cord, NIC is nor running nor runtime suspended.

Michal


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