Re: [Qemu-devel] [PATCH v5 02/24] vmstate: add VMS_MUST_EXIST

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) wrote:
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > Can be used to verify a required field exists or validate
> > state in some other way.
> >
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> 
> What should this do?
> 
> We can change the semantics of ->field_exist() to add this functionality
> if needed, no?

Well that's what Michael is doing; he's changing the use of ->field_exist()
here, so that if this flag is set then a failure of field_exist causes a migration
failure.

Dave

> 
> > ---
> >  include/migration/vmstate.h |  1 +
> >  vmstate.c                   | 10 ++++++++++
> >  2 files changed, 11 insertions(+)
> >
> > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> > index e7e1705..de970ab 100644
> > --- a/include/migration/vmstate.h
> > +++ b/include/migration/vmstate.h
> > @@ -100,6 +100,7 @@ enum VMStateFlags {
> >      VMS_MULTIPLY         = 0x200,  /* multiply "size" field by field_size */
> >      VMS_VARRAY_UINT8     = 0x400,  /* Array with size in uint8_t field*/
> >      VMS_VARRAY_UINT32    = 0x800,  /* Array with size in uint32_t field*/
> > +    VMS_MUST_EXIST       = 0x1000, /* Field must exist in input */
> >  };
> >  
> >  typedef struct {
> > diff --git a/vmstate.c b/vmstate.c
> > index dd6f834..f019228 100644
> > --- a/vmstate.c
> > +++ b/vmstate.c
> > @@ -102,6 +102,10 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >                      return ret;
> >                  }
> >              }
> > +        } else if (field->flags & VMS_MUST_EXIST) {
> > +            fprintf(stderr, "Input validation failed: %s/%s\n",
> > +                    vmsd->name, field->name);
> > +            return -1;
> >          }
> >          field++;
> >      }
> > @@ -142,6 +146,12 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> >                      field->info->put(f, addr, size);
> >                  }
> >              }
> > +        } else {
> > +            if (field->flags & VMS_MUST_EXIST) {
> > +                fprintf(stderr, "Output state validation failed: %s/%s\n",
> > +                        vmsd->name, field->name);
> > +                assert(!(field->flags & VMS_MUST_EXIST));
> > +            }
> >          }
> >          field++;
> >      }
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK