Re: [PATCH] automation: fix race condition in adl-suspend test

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Sat, Oct 28, 2023 at 05:33:57AM +0200, Marek Marczykowski-Górecki wrote:
> If system suspends too quickly, the message for the test controller to
> wake up the system may be not sent to the console before suspending.
> This will cause the test to timeout.
> 
> Fix this by waiting a bit after printing the message. The test
> controller then resumes the system 30s after the message, so as long as
> the delay + suspending takes less time it is okay.
> 
> Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> This is consistent with the observation that sync_console "fixes" the
> issue.
> ---
>  automation/scripts/qubes-x86-64.sh | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/automation/scripts/qubes-x86-64.sh 
> b/automation/scripts/qubes-x86-64.sh
> index 26131b082671..a34db96e4585 100755
> --- a/automation/scripts/qubes-x86-64.sh
> +++ b/automation/scripts/qubes-x86-64.sh
> @@ -54,11 +54,11 @@ until grep 'domU started' 
> /var/log/xen/console/guest-domU.log; do
>      sleep 1
>  done
>  echo \"${wait_and_wakeup}\"
> +# let the above message flow to console, then suspend
> +sleep 5

Could you use `sync /dev/stdout`?  I guess that might not be enough,
since the sync won't be propagated to the hypervisor, and hence even
if flushed from Linux, we have no guarantee that the hypervisor has
also flushed it.

Xen should flush the buffer when a newline character is found, but I
have no idea whether context could return to guest while the buffer is
still in the process of being fully flushed.

Anyway, adding the extra sync might be good regardless, and keeping
the sleep.

Thanks, Roger.