Re: [PATCH 1/3] tests/avocado: reverse_debugging drain console to prevent hang

[Ani Sinha]

> On 16-Nov-2023, at 7:01 PM, Ani Sinha <anisinha@redhat.com> wrote:
> 
> 
> 
>> On 16-Nov-2023, at 6:56 PM, Ani Sinha <anisinha@redhat.com> wrote:
>> 
>> 
>> 
>>> On 16-Nov-2023, at 5:23 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
>>> 
>>> Like replay_linux.py, reverse_debugging.py starts the vm with console
>>> set but does not interact with it (e.g., with wait_for_console_pattern).
>>> In this situation, the console should have a drainer attached so the
>>> socket does not fill. replay_linux.py has a drainer, but it is missing
>>> from reverse_debugging.py.
>>> 
>>> Per analysis in Link: this can cause the console socket/pipe to fill and
>>> QEMU get stuck in qemu_chr_write_buffer, leading to strange test case
>>> failures (ppc64 fails because it prints a lot to console in early bios).
>>> Attaching a drainer prevents this.
>>> 
>>> Note, this commit does not fix bugs introduced by the commits referenced
>>> in the first two Fixes: tags, but together those commits conspire to
>>> irritate the problem and cause test case failure, which this commit
>>> fixes.
>>> 
>>> Link: ZVT-bY9YOr69QTPX@redhat.com/">https://lore.kernel.org/qemu-devel/ZVT-bY9YOr69QTPX@redhat.com/
>>> Fixes: 1d4796cd0083 ("python/machine: use socketpair() for console 
>>> connections")
>>> Fixes: 761a13b23946 ("tests/avocado: ppc64 reverse debugging tests for 
>>> pseries and powernv")
>>> Fixes: be52eca30978 ("tests/acceptance: add reverse debugging test")
>>> Tested-by: Thomas Huth <thuth@redhat.com>
>>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>> 
>> Reviewed-by: Ani Sinha <anisinha@redhat.com <mailto:anisinha@redhat.com>>
> 
> This bs started happening recently once I upgraded my OS. Sorry about that.
> 
> Reviewed-by: Ani Sinha <anisinha@redhat.com <mailto:anisinha@redhat.com>>

Trying again    

Reviewed-by: Ani Sinha <anisinha@redhat.com>


> 
> 
>> 
>>> ---
>>> tests/avocado/reverse_debugging.py | 5 +++++
>>> 1 file changed, 5 insertions(+)
>>> 
>>> diff --git a/tests/avocado/reverse_debugging.py 
>>> b/tests/avocado/reverse_debugging.py
>>> index fc47874eda..128d85bc0e 100644
>>> --- a/tests/avocado/reverse_debugging.py
>>> +++ b/tests/avocado/reverse_debugging.py
>>> @@ -12,6 +12,7 @@
>>> 
>>> from avocado import skipIf
>>> from avocado_qemu import BUILD_DIR
>>> +from avocado.utils import datadrainer
>>> from avocado.utils import gdb
>>> from avocado.utils import process
>>> from avocado.utils.network.ports import find_free_port
>>> @@ -52,6 +53,10 @@ def run_vm(self, record, shift, args, replay_path, 
>>> image_path, port):
>>>       if args:
>>>           vm.add_args(*args)
>>>       vm.launch()
>>> +        console_drainer = 
>>> datadrainer.LineLogger(vm.console_socket.fileno(),
>>> +                                    logger=self.log.getChild('console'),
>>> +                                    stop_check=(lambda : not 
>>> vm.is_running()))
>>> +        console_drainer.start()
>>>       return vm
>>> 
>>>   @staticmethod
>>> -- 
>>> 2.42.0