Re: [kvm-unit-tests PATCH v1] arch-run: Wait for incoming socket being removed

["Nicholas Piggin" <npiggin@gmail.com>]

On Wed Mar 6, 2024 at 12:11 AM AEST, Nico Boehr wrote:
> Sometimes, QEMU needs a bit longer to remove the incoming migration
> socket. This happens in some environments on s390x for the
> migration-skey-sequential test.
>
> Instead of directly erroring out, wait for the removal of the socket.
>
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>

It's interesting that the incoming socket is not removed after
QMP says migration complete. I guess that's by design, but have
you checked the QEMU code whether it's intentional?

I guess it's code like this - in migration/migration.c

    /*
     * This must happen after any state changes since as soon as an external
     * observer sees this event they might start to prod at the VM assuming
     * it's ready to use.
     */
    migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                      MIGRATION_STATUS_COMPLETED);
    migration_incoming_state_destroy();

So, it looks like a good fix. And probably not just s390x specific
it might be just unlucky timing.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

> ---
>  scripts/arch-run.bash | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/scripts/arch-run.bash b/scripts/arch-run.bash
> index 2214d940cf7d..413f3eda8cb8 100644
> --- a/scripts/arch-run.bash
> +++ b/scripts/arch-run.bash
> @@ -237,12 +237,8 @@ do_migration ()
>  	echo > ${dst_infifo}
>  	rm ${dst_infifo}
>  
> -	# Ensure the incoming socket is removed, ready for next destination
> -	if [ -S ${dst_incoming} ] ; then
> -		echo "ERROR: Incoming migration socket not removed after migration." >& 2
> -		qmp ${dst_qmp} '"quit"'> ${dst_qmpout} 2>/dev/null
> -		return 2
> -	fi
> +	# Wait for the incoming socket being removed, ready for next destination
> +	while [ -S ${dst_incoming} ] ; do sleep 0.1 ; done
>  
>  	wait ${live_pid}
>  	ret=$?