Wait for the destination VM to close itself instead of racing to shut it
down first, which produces different error log messages from AQMP
depending on precisely when we tried to shut it down.

(For example: We may try to issue 'quit' immediately prior to the target
VM closing its QMP socket, which will cause an ECONNRESET error to be
logged. Waiting for the VM to exit itself avoids the race on shutdown
behavior.)

Reported-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 tests/qemu-iotests/300 | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/tests/qemu-iotests/300 b/tests/qemu-iotests/300
index 10f9f2a8da6..dbd28384ec3 100755
--- a/tests/qemu-iotests/300
+++ b/tests/qemu-iotests/300
@@ -24,8 +24,6 @@ import random
 import re
 from typing import Dict, List, Optional
 
-from qemu.machine import machine
-
 import iotests
 
 
@@ -461,12 +459,11 @@ class TestBlockBitmapMappingErrors(TestDirtyBitmapMigration):
                       f"'{self.src_node_name}': Name is longer than 255 bytes",
                       log)
 
-        # Expect abnormal shutdown of the destination VM because of
-        # the failed migration
-        try:
-            self.vm_b.shutdown()
-        except machine.AbnormalShutdown:
-            pass
+        # Destination VM will terminate w/ error of its own accord
+        # due to the failed migration.
+        self.vm_b.wait()
+        rc = self.vm_b.exitcode()
+        assert rc is not None and rc > 0
 
     def test_aliased_bitmap_name_too_long(self) -> None:
         # Longer than the maximum for bitmap names
-- 
2.31.1

Am 26.10.2021 um 19:56 hat John Snow geschrieben:
> Wait for the destination VM to close itself instead of racing to shut it
> down first, which produces different error log messages from AQMP
> depending on precisely when we tried to shut it down.
> 
> (For example: We may try to issue 'quit' immediately prior to the target
> VM closing its QMP socket, which will cause an ECONNRESET error to be
> logged. Waiting for the VM to exit itself avoids the race on shutdown
> behavior.)
> 
> Reported-by: Hanna Reitz <hreitz@redhat.com>
> Signed-off-by: John Snow <jsnow@redhat.com>

I think this will still expose the race I described in my comment on
patch 2.

Kevin

On Wed, Oct 27, 2021 at 8:56 AM Kevin Wolf <kwolf@redhat.com> wrote:

> Am 26.10.2021 um 19:56 hat John Snow geschrieben:
> > Wait for the destination VM to close itself instead of racing to shut it
> > down first, which produces different error log messages from AQMP
> > depending on precisely when we tried to shut it down.
> >
> > (For example: We may try to issue 'quit' immediately prior to the target
> > VM closing its QMP socket, which will cause an ECONNRESET error to be
> > logged. Waiting for the VM to exit itself avoids the race on shutdown
> > behavior.)
> >
> > Reported-by: Hanna Reitz <hreitz@redhat.com>
> > Signed-off-by: John Snow <jsnow@redhat.com>
>
> I think this will still expose the race I described in my comment on
> patch 2.
>
> Kevin
>
>
I wrote a long, meandering explanation of how I think things work in reply
to that comment. TLDR: I didn't see the problem.

Here in reply to this comment I'll just ask: what exactly *is* the race you
see happening here even with this patch? I'm not sure I see it.

--js