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 <th...@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 <waine...@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