Re: net: bridge: propagate error code and extack from br_mc_disabled_update

[Florian Fainelli <f.fainelli@gmail.com>]

On 4/21/2021 11:35 AM, Christian Borntraeger wrote:
> 
> 
> On 21.04.21 20:18, Christian Borntraeger wrote:
>> Whatever version landed in next, according to bisect this broke
>> libvirt/kvms use of bridges:
>>
>>
>> # virsh start s31128001
>> error: Failed to start domain 's31128001'
>> error: Unable to add bridge virbr1 port vnet0: Operation not supported
>>
>> # grep vnet0 /var/log/libvirt/libvirtd.log
>>
>> 2021-04-21 07:43:09.453+0000: 2460: info : virNetDevTapCreate:240 :
>> created device: 'vnet0'
>> 2021-04-21 07:43:09.453+0000: 2460: debug :
>> virNetDevSetMACInternal:287 : SIOCSIFHWADDR vnet0
>> MAC=fe:bb:83:28:01:02 - Success
>> 2021-04-21 07:43:09.453+0000: 2460: error : virNetDevBridgeAddPort:633
>> : Unable to add bridge virbr1 port vnet0: Operation not supported
>> 2021-04-21 07:43:09.466+0000: 2543: debug : udevHandleOneDevice:1695 :
>> udev action: 'add': /sys/devices/virtual/net/vnet0
>>
>> Christian
>>
> 
> For reference:
> 
> ae1ea84b33dab45c7b6c1754231ebda5959b504c is the first bad commit
> commit ae1ea84b33dab45c7b6c1754231ebda5959b504c
> Author: Florian Fainelli <f.fainelli@gmail.com>
> Date:   Wed Apr 14 22:22:57 2021 +0300
> 
>    net: bridge: propagate error code and extack from br_mc_disabled_update
>       Some Ethernet switches might only be able to support disabling
> multicast
>    snooping globally, which is an issue for example when several bridges
>    span the same physical device and request contradictory settings.
>       Propagate the return value of br_mc_disabled_update() such that this
>    limitation is transmitted correctly to user-space.
>       Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
>    Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
>    Signed-off-by: David S. Miller <davem@davemloft.net>
> 
> net/bridge/br_multicast.c | 28 +++++++++++++++++++++-------
> net/bridge/br_netlink.c   |  4 +++-
> net/bridge/br_private.h   |  3 ++-
> net/bridge/br_sysfs_br.c  |  8 +-------
> 4 files changed, 27 insertions(+), 16 deletions(-)
> 
> not sure if it matters this is on s390.
> A simple reproducer is virt-install, e.g.
> virt-install --name test --disk size=12 --memory=2048 --vcpus=2
> --location
> http://ports.ubuntu.com/ubuntu-ports/dists/bionic/main/installer-s390x/

Thanks, I will kick off a reproducer and let you know.
-- 
Florian