Re: [PATCH v2] tests/acceptance: test hot(un)plug of ccw devices

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 7 Dec 2020 19:40:36 +0100
Thomas Huth <thuth@redhat.com> wrote:

> On 07/12/2020 17.34, Thomas Huth wrote:
> > On 07/12/2020 17.30, Cornelia Huck wrote:  
> >> On Mon, 7 Dec 2020 15:28:47 +0100
> >> Thomas Huth <thuth@redhat.com> wrote:
> >>  
> >>> On 04/12/2020 13.14, Cornelia Huck wrote:  
> >>>> Hotplug a virtio-net-ccw device, and then hotunplug it again.
> >>>>
> >>>> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> >>>> ---  
> >  
> [...]
> >>>> +        exec_command_and_wait_for_pattern(self, 'ls /sys/bus/ccw/devices/',
> >>>> +                                          '0.0.4711')
> >>>> +        # and detach it again
> >>>> +        exec_command_and_wait_for_pattern(self, 'dmesg -c', ' ')    
> >>>
> >>> If adapt my above change, you could also get rid of this dmesg -c here
> >>> (since it's done in the while loop already)  
> >>
> >> I don't think so (there are two CRWs posted, and the loop might have
> >> caught the first one only.)  
> > 
> > Oh, you're right. So let's better be safe than sorry and keep this dmesg -c.  
> 
> Ok, as we had to discover during some testing, it's a bad idea to only wait
> for ' ' after the 'dmesg -c' since it matches too early, so that the device
> gets added while the dmesg command is still running.
> 
> The following code is working for me instead:
> 
>          # add another device
>          exec_command_and_wait_for_pattern(self,
>                      'dmesg -c > /dev/null; echo dm-clear\ 1', 'dm-clear 1')
>          self.vm.command('device_add', driver='virtio-net-ccw',
>                          devno='fe.0.4711', id='net_4711')
>          exec_command_and_wait_for_pattern(self,
>                          'while ! (dmesg -c | grep CRW) ; do sleep 1 ; done',
>                          'CRW reports')
>          exec_command_and_wait_for_pattern(self, 'ls /sys/bus/ccw/devices/',
>                                            '0.0.4711')
>          # and detach it again
>          exec_command_and_wait_for_pattern(self,
>                      'dmesg -c > /dev/null; echo dm-clear\ 2', 'dm-clear 2')
>          self.vm.command('device_del', id='net_4711')
>          self.vm.event_wait(name='DEVICE_DELETED',
>                             match={'data': {'device': 'net_4711'}})
>          exec_command_and_wait_for_pattern(self,
>                          'while ! (dmesg -c | grep CRW) ; do sleep 1 ; done',
>                          'CRW reports')
>          exec_command_and_wait_for_pattern(self,
>                                            'ls /sys/bus/ccw/devices/0.0.4711',
>                                            'No such file or directory')

Thanks for tracking this down, this works for me as well. I'll send a
v3.