Re: [PATCH v2 1/1] util/async-teardown: wire up query-command-line-options

[Thomas Huth]

On 20/03/2023 16.31, Markus Armbruster wrote:
> Claudio Imbrenda <imbrenda@linux.ibm.com> writes:
>
> > The recently introduced -async-teardown commandline option was not
> > wired up properly and did not show up in the output of the QMP command
> > query-command-line-options. This means that libvirt will have no way to
> > discover whether the feature is supported.
>
> There was nothing improper in its wiring.  The issue is that
> query-command-line-options is junk.  See my recent post
>
>      Subject: query-command-line-options (was: [PATCH 1/7] qemu: capabilities: 
> Introduce QEMU_CAPS_MACHINE_ACPI)
>      Date: Tue, 07 Mar 2023 10:40:23 +0100
>      Message-ID: <87jzzsc320.fsf_-_@pond.sub.org>
>
> > This patch fixes the issue by correctly wiring up the commandline
> > option so that it appears in the output of query-command-line-options.
> >
> > Reported-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
> > Fixes: c891c24b1a ("os-posix: asynchronous teardown for shutdown on Linux")
> > Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> > ---
> >   util/async-teardown.c | 17 +++++++++++++++++
> >   1 file changed, 17 insertions(+)
> >
> > diff --git a/util/async-teardown.c b/util/async-teardown.c
> > index 62cdeb0f20..c9b9a3cdb2 100644
> > --- a/util/async-teardown.c
> > +++ b/util/async-teardown.c
> > @@ -12,6 +12,9 @@
> >    */
> >   
> >   #include "qemu/osdep.h"
> > +#include "qemu/config-file.h"
> > +#include "qemu/option.h"
> > +#include "qemu/module.h"
> >   #include <dirent.h>
> >   #include <sys/prctl.h>
> >   #include <sched.h>
> > @@ -144,3 +147,17 @@ void init_async_teardown(void)
> >       clone(async_teardown_fn, new_stack_for_clone(), CLONE_VM, NULL);
> >       sigprocmask(SIG_SETMASK, &old_signals, NULL);
> >   }
> > +
> > +static QemuOptsList qemu_async_teardown_opts = {
> > +    .name = "async-teardown",
> > +    .head = QTAILQ_HEAD_INITIALIZER(qemu_async_teardown_opts.head),
> > +    .desc = {
> > +        { /* end of list */ }
> > +    },
> > +};
> > +
> > +static void register_async_teardown(void)
> > +{
> > +    qemu_add_opts(&qemu_async_teardown_opts);
> > +}
> > +opts_init(register_async_teardown);
>
> Now it *is* improperly wired up :)
>
> You're defining new QemuOpts config group "async-teardown" with
> arbitrary option parameters, but don't actually use it for parsing or
> recording the option.  I figure because you can't: there is no option
> argument to parse and record, which is what QemuOpts is designed to do.
>
> If you need the feature to be visible in query-command-line-options, you
> should make it an option parameter (a KEY, not a GROUP), preferably of
> an existing group / option.

Would it make sense to add it e.g. to "-action" instead, i.e. something like 
"-action teardown=async" ?

 Thomas