ifenslave fails to set xmit_hash_policy

[Debabrata Banerjee]

This bug is present in 16.04 as well as 18.04, including the upstream version of ifenslave as far as I can tell. But as a formality let's assume ifenslave-2.9ubuntu1

/etc/network/if-pre-up.d/ifenslave assumes xmit_hash_policy can be set in any order, as below:

        # xmit_hash_policy can be set anytime.
        # Changing xmit_hash_policy requires $BOND_MASTER to be down.
        sysfs_change_down xmit_hash_policy "$IF_BOND_XMIT_HASH_POLICY"

However, this comment is not true. For example when trying to create the following in /etc/network/interfaces:

iface bond0 inet manual
        bond-slaves none
        bond-mode balance-tlb
        bond-miimon 100
        bond-xmit_hash_policy 1

Results in this error in dmesg on boot, since the mode balance-tlb is set after xmit_hash_policy:

[ 15.210041] xmit_hash_policy param is irrelevant in mode load balancing (round-robin)

The script should set xmit_hash_policy after setting mode.

An ugly workaround at the moment is to do:

iface bond0 inet manual
        bond-slaves none
        bond-miimon 100
        pre-up /bin/echo 5 > /sys/class/net/bond0/bonding/mode; /bin/echo
1 > /sys/class/net/bond0/bonding/xmit_hash_policy

[Debabrata Banerjee (dbanerje)]

I have fixes for this, but it's unclear how/where to contribute this code.

[Debabrata Banerjee (dbanerje)]

Patch was accepted into https://salsa.debian.org/debian/ifenslave