Re: [PATCH 2/3] tests/acceptance/machine_s390_ccw_virtio: Test virtio-rng via /dev/hwrng

[Wainer dos Santos Moschetta]

On 12/12/20 4:10 AM, Thomas Huth wrote:
> On 11/12/2020 21.30, Wainer dos Santos Moschetta wrote:
> > Hi,
> >
> > On 12/11/20 2:31 PM, Thomas Huth wrote:
> > > /dev/hwrng is only functional if virtio-rng is working right, so let's
> > > add a sanity check for this device node.
> > Good idea.
> >
> > > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > > ---
> > >    tests/acceptance/machine_s390_ccw_virtio.py | 17 +++++++++++++++--
> > >    1 file changed, 15 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/tests/acceptance/machine_s390_ccw_virtio.py
> > > b/tests/acceptance/machine_s390_ccw_virtio.py
> > > index 733a7ca24a..7d0a78139b 100644
> > > --- a/tests/acceptance/machine_s390_ccw_virtio.py
> > > +++ b/tests/acceptance/machine_s390_ccw_virtio.py
> > > @@ -64,9 +64,9 @@ class S390CCWVirtioMachine(Test):
> > >                             '-append', kernel_command_line,
> > >                             '-device', 'virtio-net-ccw,devno=fe.1.1111',
> > >                             '-device',
> > > -                         'virtio-rng-ccw,devno=fe.2.0000,max_revision=0',
> > > +
> > > 'virtio-rng-ccw,devno=fe.2.0000,max_revision=0,id=rn1',
> > >                             '-device',
> > > -                         'virtio-rng-ccw,devno=fe.3.1234,max_revision=2',
> > > +
> > > 'virtio-rng-ccw,devno=fe.3.1234,max_revision=2,id=rn2',
> > >                             '-device', 'zpci,uid=5,target=zzz',
> > >                             '-device', 'virtio-net-pci,id=zzz',
> > >                             '-device', 'zpci,uid=0xa,fid=12,target=serial',
> > > @@ -96,6 +96,19 @@ class S390CCWVirtioMachine(Test):
> > >            exec_command_and_wait_for_pattern(self,
> > >                            'cat
> > > /sys/bus/ccw/devices/0.3.1234/virtio?/features',
> > >                            virtio_rng_features)
> > > +        # check that /dev/hwrng works - and that it's gone after ejecting
> > > +        exec_command_and_wait_for_pattern(self,
> > > +                        'dd if=/dev/hwrng of=/tmp/out.dat bs=1k count=10',
> > > +                        '10+0 records out')
> > > +        self.clear_guests_dmesg()
> > > +        self.vm.command('device_del', id='rn1')
> > > +        self.wait_for_crw_reports()
> > > +        self.clear_guests_dmesg()
> > > +        self.vm.command('device_del', id='rn2')
> > > +        self.wait_for_crw_reports()
> > > +        exec_command_and_wait_for_pattern(self,
> > > +                        'dd if=/dev/hwrng of=/tmp/out.dat bs=1k count=10',
> > > +                        'dd: /dev/hwrng: No such device')
> > Maybe the expected pattern is too fragile. On my Fedora 33 system, 'dd' will
> > print a different message.
> We are running this test with a well-defined kernel + initrd, so I don't
> think we have to care of other versions of dd here.

I was thinking in the case someone change the kernel+initrd for this 
test. Well, in that case the same person will have to make the 
adjustments. So,

Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>

> > What if it checks for the presence of the device file, e.g:
> >
> > ... self, 'test -c /dev/hwrng; echo $?', '1')
> That doesn't work, the /dev/hwrng is still there (so test -c succeeds),
> since this initrd uses static device nodes for this in /dev. /dev/hwrng just
> can not be opened anymore after the device has been removed.
>
>   Thomas