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

[Thomas Huth]

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')

 HTH,
  Thomas