igb: Report speed and duplex as unknown when device is runtime suspended

commit 165ae7a8feb53dc47fb041357e4b253bfc927cf9 upstream.

igb device gets runtime suspended when there's no link partner. We can't
get correct speed under that state:
$ cat /sys/class/net/enp3s0/speed
1000

In addition to that, an error can also be spotted in dmesg:
[  385.991957] igb 0000:03:00.0 enp3s0: PCIe link lost

Since device can only be runtime suspended when there's no link partner,
we can skip reading register and let the following logic set speed and
duplex with correct status.

The more generic approach will be wrap get_link_ksettings() with begin()
and complete() callbacks. However, for this particular issue, begin()
calls igb_runtime_resume() , which tries to rtnl_lock() while the lock
is already hold by upper ethtool layer.

So let's take this approach until the igb_runtime_resume() no longer
needs to hold rtnl_lock.

CC: stable <stable@vger.kernel.org>
Suggested-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c
index 2529bc625de4532e78407500d4c43ba92714f06a..43561ccf4e4536adfbc6fed075746a4b3965fec8 100644 (file)
--- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
+++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
@@ -143,7 +143,8 @@ static int igb_get_settings(struct net_device *netdev, struct ethtool_cmd *ecmd)
        u32 status;
        u32 speed;
 
-       status = rd32(E1000_STATUS);
+       status = pm_runtime_suspended(&adapter->pdev->dev) ?
+                0 : rd32(E1000_STATUS);
        if (hw->phy.media_type == e1000_media_type_copper) {
 
                ecmd->supported = (SUPPORTED_10baseT_Half |