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Date: Tue, 2 Jul 2013 10:09:03 -0400
From: Luiz Capitulino <lcapitulino@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v4 08/10] qemu-ga: call Windows VSS
 requester in fsfreeze command handler
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To: Laszlo Ersek <lersek@redhat.com>
Cc: "libaiqing@huawei.com" <libaiqing@huawei.com>, "stefanha@gmail.com" <stefanha@gmail.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "mdroth@linux.vnet.ibm.com" <mdroth@linux.vnet.ibm.com>, "vrozenfe@redhat.com" <vrozenfe@redhat.com>, Tomoki Sekiyama <tomoki.sekiyama@hds.com>, "pbonzini@redhat.com" <pbonzini@redhat.com>, Seiji Aguchi <seiji.aguchi@hds.com>, "areis@redhat.com" <areis@redhat.com>

On Tue, 02 Jul 2013 08:36:11 +0200
Laszlo Ersek <lersek@redhat.com> wrote:

> On 07/01/13 19:59, Tomoki Sekiyama wrote:
> > On 7/1/13 9:29 , "Laszlo Ersek" <lersek@redhat.com> wrote:
> > 
> >>> +error:
> >>> +    qmp_guest_fsfreeze_thaw(NULL);
> >>
> >> Passing NULL here as "errp" concerns me slightly. I've been assuming
> >> that "errp" is never NULL due to the outermost QMP layer always wanting
> >> to receive errors and to serialize them.
> >>
> >> Specifically, a NULL "errp" would turn all error_set*(errp, ...) calls
> >> into no-ops under qmp_guest_fsfreeze_thaw(), and all error_is_set(errp)
> >> questions would answer with false. That said, nothing seems to be
> >> affected right now.
> >>
> >> Maybe a dummy local variable would be more future-proof... OTOH it would
> >> be stylistically questionable :)
> > 
> > OK, then it should be:
> >     Error *local_err = NULL;
> > ...
> > error:
> >     qmp_guest_fsfreeze_thaw(&local_err);
> >     if (error_is_set(&local_err)) {
> >         error_free(local_err);
> >     }
> 
> I think so, yes.
> 
> You could also log it before freeing it I guess:
> 
>     g_debug("cleanup thaw: %s", error_get_pretty(local_err));
> 
> or some such, but it's probably not important.

I'd rather do something like that, otherwise it doesn't seem to
make sense to pass Error as qmp_guest_fsfreeze_thaw() does
use a local Error.