RE: [PATCH] e1000e: fix cyclic resets at link up with active tx

["Brown, Aaron F" <aaron.f.brown@intel.com>]

> -----Original Message-----
> From: netdev-owner@vger.kernel.org [mailto:netdev-
> owner@vger.kernel.org] On Behalf Of Konstantin Khlebnikov
> Sent: Monday, January 14, 2019 5:30 AM
> To: netdev@vger.kernel.org; intel-wired-lan@lists.osuosl.org; Kirsher,
> Jeffrey T <jeffrey.t.kirsher@intel.com>
> Cc: linux-kernel@vger.kernel.org; David S. Miller <davem@davemloft.net>
> Subject: [PATCH] e1000e: fix cyclic resets at link up with active tx
> 
> I'm seeing series of e1000e resets (sometimes endless) at system boot
> if something generates tx traffic at this time. In my case this is
> netconsole who sends message "e1000e 0000:02:00.0: Some CPU C-states
> have been disabled in order to enable jumbo frames" from e1000e itself.
> As result e1000_watchdog_task sees used tx buffer while carrier is off
> and start this reset cycle again.
> 
> [   17.794359] e1000e: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow
> Control: None
> [   17.794714] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready
> [   22.936455] e1000e 0000:02:00.0 eth1: changing MTU from 1500 to 9000
> [   23.033336] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   26.102364] e1000e: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow
> Control: None
> [   27.174495] 8021q: 802.1Q VLAN Support v1.8
> [   27.174513] 8021q: adding VLAN 0 to HW filter on device eth1
> [   30.671724] cgroup: cgroup: disabling cgroup2 socket matching due to
> net_prio or net_cls activation
> [   30.898564] netpoll: netconsole: local port 6666
> [   30.898566] netpoll: netconsole: local IPv6 address
> 2a02:6b8:0:80b:beae:c5ff:fe28:23f8
> [   30.898567] netpoll: netconsole: interface 'eth1'
> [   30.898568] netpoll: netconsole: remote port 6666
> [   30.898568] netpoll: netconsole: remote IPv6 address
> 2a02:6b8:b000:605c:e61d:2dff:fe03:3790
> [   30.898569] netpoll: netconsole: remote ethernet address b0:a8:6e:f4:ff:c0
> [   30.917747] console [netcon0] enabled
> [   30.917749] netconsole: network logging started
> [   31.453353] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   34.185730] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   34.321840] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   34.465822] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   34.597423] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   34.745417] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   34.877356] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   35.005441] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   35.157376] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   35.289362] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   35.417441] e1000e 0000:02:00.0: Some CPU C-states have been disabled in
> order to enable jumbo frames
> [   37.790342] e1000e: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow
> Control: None
> 
> This patch flushes tx buffers only once when carrier is off
> rather than at each watchdog iteration.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
> ---
>  drivers/net/ethernet/intel/e1000e/netdev.c |   15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)

Tested-by: Aaron Brown <aaron.f.brown@intel.com>