Hi, Emil

Thanks for your hard work.

With kernel 3.14, NETDEV_CHANGELOWERSTATE is not introduced. my user still confronted "bond_mii_monitor: bond0: link status definitely up for interface eth1, 0 Mbps full duplex".

How to explain it?

Would you like to make tests with kernel 3.14?

Thanks a lot.

Zhu Yanjun

On 02/04/2016 07:10 AM, Tantilov, Emil S wrote:
We are seeing an occasional issue where the bonding driver may report interface 
up with 0 Mbps:
bond0: link status definitely up for interface eth0, 0 Mbps full duplex

So far in all the failed traces I have collected this happens on 
NETDEV_CHANGELOWERSTATE event:

<...>-20533 [000] .... 81811.041241: ixgbe_service_task: eth1: NIC Link is Up 
10 Gbps, Flow Control: RX/TX
<...>-20533 [000] .... 81811.041257: ixgbe_check_vf_rate_limit 
<-ixgbe_service_task
<...>-20533 [000] .... 81811.041272: ixgbe_ping_all_vfs <-ixgbe_service_task
kworker/u48:0-7503  [010] .... 81811.041345: ixgbe_get_stats64 <-dev_get_stats
kworker/u48:0-7503  [010] .... 81811.041393: bond_netdev_event: eth1: event: 1b
kworker/u48:0-7503  [010] .... 81811.041394: bond_netdev_event: eth1: IFF_SLAVE
kworker/u48:0-7503  [010] .... 81811.041395: bond_netdev_event: eth1: 
slave->speed = ffffffff
<...>-20533 [000] .... 81811.041407: ixgbe_ptp_overflow_check 
<-ixgbe_service_task
kworker/u48:0-7503  [010] .... 81811.041407: bond_mii_monitor: bond0: link 
status definitely up for interface eth1, 0 Mbps full duplex

As a proof of concept I added NETDEV_CHANGELOWERSTATE in 
bond_slave_netdev_event() along with NETDEV_UP/CHANGE:

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 56b5605..a9dac4c 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3014,6 +3014,7 @@ static int bond_slave_netdev_event(unsigned long event,
                break;
        case NETDEV_UP:
        case NETDEV_CHANGE:
+       case NETDEV_CHANGELOWERSTATE:
                bond_update_speed_duplex(slave);
                if (BOND_MODE(bond) == BOND_MODE_8023AD)
                        bond_3ad_adapter_speed_duplex_changed(slave);

With this change I have not seen 0 Mbps reported by the bonding driver (around 
12 hour test up to this point
vs. 2-3 hours otherwise). Although I suppose it could also be some sort of 
race/timing issue with bond_mii_monitor().

This test is with current bonding driver from net-next (top commit 03d84a5f83).

The bond is configured as such:

mode = 802.3ad
lacp_rate = fast
miimon = 100
xmit_hash_policy = layer3+4

I should note that the speed is reported correctly in /proc/net/bonding/bond0 
once the bond0 interface is up,
so this seems to be just an issue with the initial detection of the speed. At 
least from what I have seen so far.

Thanks,
Emil



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