linux-next: umh: fix processed error when UMH_WAIT_PROC is used seems to break linux bridge on s390x (bisected)

[Christian Borntraeger]

On 23.06.20 16:23, Christian Borntraeger wrote:
> 
> 
> On 23.06.20 16:11, Christian Borntraeger wrote:
>> Jens Markwardt reported a regression in the linux-next runs.  with "umh: fix
>> processed error when UMH_WAIT_PROC is used" (from linux-next) a linux bridge
>> with an KVM guests no longer activates :
>>
>> without patch
>> # ip addr show dev virbr1
>> 6: virbr1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
>>     link/ether 52:54:00:1e:3f:c0 brd ff:ff:ff:ff:ff:ff
>>     inet 192.168.254.254/24 brd 192.168.254.255 scope global virbr1
>>        valid_lft forever preferred_lft forever
>>
>> with this patch the bridge stays DOWN with NO-CARRIER
>>
>> # ip addr show dev virbr1
>> 6: virbr1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
>>     link/ether 52:54:00:1e:3f:c0 brd ff:ff:ff:ff:ff:ff
>>     inet 192.168.254.254/24 brd 192.168.254.255 scope global virbr1
>>        valid_lft forever preferred_lft forever
>>
>> This was bisected in linux-next. Reverting from linux-next also fixes the issue.
>>
>> Any idea?
> 
> FWIW, s390 is big endian. Maybe some of the shifts inn the __KW* macros are wrong.

Does anyone have an idea why "umh: fix processed error when UMH_WAIT_PROC is used" breaks the
linux-bridge on s390?