Re: [Qemu-devel] [PATCH v11 5/8] qemu.py: use poll() instead of 'returncode'

[Eduardo Habkost]

On Tue, Nov 14, 2017 at 11:22:43AM +0100, Amador Pahim wrote:
> The 'returncode' Popen attribute is not guaranteed to be updated. It
> actually depends on a call to either poll(), wait() or communicate().
> 
> On the other hand, poll() will: "Check if child process has terminated.
> Set and return returncode attribute."
> 
> Let's use the poll() to check whether the process is running and to get
> the updated process exit code, when the process is finished.
> 
> Reviewed-by: Fam Zheng <address@hidden>
> Signed-off-by: Amador Pahim <address@hidden>
> ---
>  scripts/qemu.py | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/qemu.py b/scripts/qemu.py
> index 7bd10b1a1d..d3824a7a0b 100644
> --- a/scripts/qemu.py
> +++ b/scripts/qemu.py
> @@ -149,12 +149,12 @@ class QEMUMachine(object):
>              raise
>  
>      def is_running(self):
> -        return self._popen is not None and self._popen.returncode is None
> +        return self._popen is not None and self._popen.poll() is None

This should be safe now, after patch 4/8.

Reviewed-by: Eduardo Habkost <address@hidden>

-- 
Eduardo