Re: [Xen-devel] [PATCH v3 COLOPre 07/26] libxc/restore: fix error handle of process_record

[Yang Hongyang <yanghy@xxxxxxxxxxxxxx>]

On 06/30/2015 05:45 PM, Yang Hongyang wrote:
> On 06/30/2015 12:07 AM, Ian Campbell wrote:
> > On Thu, 2015-06-25 at 14:25 +0800, Yang Hongyang wrote:
> >
> > ITYM "handling" in the subject. And perhaps "change" rather than "fix"?
> >
> > > If the err is RECORD_NOT_PROCESSED, and it is an optional record,
> > > restore will still fail. There're two options to fix this,
> > >    a, setting rc to 0 when it is an optional record.
> > >    b, do the error handling in the caller.
> > > We choose b because:
> > > There will be another error type in COLO, which indicates a failover,
> > > that needs to be handled in restore(), so moving the error handling out
> > > to make the logic clearer...Otherwise, in process_record,
> > > RECORD_NOT_PROCESSED is handled, and in restore another error type
> > > returned from process_record is handled.
> > >
> > > Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
> > > CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> > > CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> > > CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > > ---
> > >   tools/libxc/xc_sr_restore.c | 28 ++++++++++++++--------------
> > >   1 file changed, 14 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/tools/libxc/xc_sr_restore.c b/tools/libxc/xc_sr_restore.c
> > > index fd45775..d5645e0 100644
> > > --- a/tools/libxc/xc_sr_restore.c
> > > +++ b/tools/libxc/xc_sr_restore.c
> > > @@ -569,19 +569,6 @@ static int process_record(struct xc_sr_context *ctx,
> > > struct xc_sr_record *rec)
> > >       free(rec->data);
> > >       rec->data = NULL;
> > >
> > > -    if ( rc == RECORD_NOT_PROCESSED )
> > > -    {
> > > -        if ( rec->type & REC_TYPE_OPTIONAL )
> > > -            DPRINTF("Ignoring optional record %#x (%s)",
> > > -                    rec->type, rec_type_to_str(rec->type));
> > > -        else
> > > -        {
> > > -            ERROR("Mandatory record %#x (%s) not handled",
> > > -                  rec->type, rec_type_to_str(rec->type));
> > > -            rc = -1;
> > > -        }
> > > -    }
> > > -
> > >       return rc;
> > >   }
> > >
> > > @@ -669,7 +656,20 @@ static int restore(struct xc_sr_context *ctx)
> > There is a second caller of process_record in handle_checkpoint, so this
> > change will result in a change of behaviour for that case, I think.
> Ah, seems I missed the other caller, good catch, and I will fix it in the
> next version.
>
> > If that is intentional then it ought to be mentioned in the commit log,
I rechecked the process_record in handle_checkpoint, it just return the error
code, finally, the error will be handled by the upper caller in restore(),
so it is intentional, I wll mention this in the commit log.

> > since otherwise it looks a lot like this change is supposed to result in
> > no overall difference.
> >
> > Ian.
> >
> >
> > >           else
> > >           {
> > >               rc = process_record(ctx, &rec);
> > > -            if ( rc )
> > > +            if ( rc == RECORD_NOT_PROCESSED )
> > > +            {
> > > +                if ( rec.type & REC_TYPE_OPTIONAL )
> > > +                    DPRINTF("Ignoring optional record %#x (%s)",
> > > +                            rec.type, rec_type_to_str(rec.type));
> > > +                else
> > > +                {
> > > +                    ERROR("Mandatory record %#x (%s) not handled",
> > > +                          rec.type, rec_type_to_str(rec.type));
> > > +                    rc = -1;
> > > +                    goto err;
> > > +                }
> > > +            }
> > > +            else if ( rc )
> > >                   goto err;
> > >           }
> >
> > .
--
Thanks,
Yang.

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