Re: [Qemu-devel] [PULL 06/18] COLO: Introduce checkpointing protocol

[Hailiang Zhang]

On 2016/11/1 2:25, Eduardo Habkost wrote:
> On Sun, Oct 30, 2016 at 04:16:58PM +0530, Amit Shah wrote:
> [...]
> > +static void colo_wait_handle_message(QEMUFile *f, int *checkpoint_request,
> > +                                     Error **errp)
> > +{
> > +    COLOMessage msg;
> > +    Error *local_err = NULL;
> > +
> > +    msg = colo_receive_message(f, &local_err);
> > +    if (local_err) {
> > +        error_propagate(errp, local_err);
> > +        return;
> > +    }
> > +
> > +    switch (msg) {
> > +    case COLO_MESSAGE_CHECKPOINT_REQUEST:
> > +        *checkpoint_request = 1;
> > +        break;
> > +    default:
> > +        *checkpoint_request = 0;
> > +        error_setg(errp, "Got unknown COLO message: %d", msg);
> > +        break;
> > +    }
> > +}
> [...]
> > +        colo_wait_handle_message(mis->from_src_file, &request, &local_err);
> > +        if (local_err) {
> > +            goto out;
> > +        }
> > +        assert(request);
>
> GCC 4.8.5 doesn't seem to be smart enough to notice that request
> will be always initialized:
>
>    /root/qemu/migration/colo.c: In function ‘colo_process_incoming_thread’:
>    /root/qemu/migration/colo.c:448:33: error: ‘request’ may be used 
> uninitialized in this function [-Werror=maybe-uninitialized]
>             assert(request);
>                                     ^
>    cc1: all warnings being treated as errors
>
>    $ gcc --version
>    gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4)

Yes, you are right, Jeff has sent a patch to fix this
'[PATCH 1/1] migration: fix compiler warning on uninitialized variable'

Thanks,
Hailiang