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Tue, 31 Aug 2021 05:43:17 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxzRACOxcOlVEzDQzpVTAtvx5GlBYCHk8FbAN7AnbfIC49dfVpR6k6V55OZ13wfZiHKQOhtHR6S+suyESFey14= X-Received: by 2002:a17:902:7203:b0:133:ec6b:6c16 with SMTP id ba3-20020a170902720300b00133ec6b6c16mr4511091plb.67.1630413797476; Tue, 31 Aug 2021 05:43:17 -0700 (PDT) MIME-Version: 1.0 References: <20210724085453.16791-1-pbonzini@redhat.com> <20210724085453.16791-9-pbonzini@redhat.com> In-Reply-To: From: Paolo Bonzini Date: Tue, 31 Aug 2021 14:43:05 +0200 Message-ID: Subject: Re: [PULL 8/9] qapi: introduce forwarding visitor To: Peter Maydell Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/alternative; boundary="0000000000003c5d1705cada4bab" Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.391, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eric Blake , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --0000000000003c5d1705cada4bab Content-Type: text/plain; charset="UTF-8" Will look at it next week. Paolo Il lun 30 ago 2021, 17:37 Peter Maydell ha scritto: > On Mon, 9 Aug 2021 at 11:40, Peter Maydell > wrote: > > > > On Sat, 24 Jul 2021 at 10:00, Paolo Bonzini wrote: > > > > > > This new adaptor visitor takes a single field of the adaptee, and > exposes it > > > with a different name. > > > > > > This will be used for QOM alias properties. Alias targets can of > course > > > have a different name than the alias property itself (e.g. a machine's > > > pflash0 might be an alias of a property named 'drive'). When the > target's > > > getter or setter invokes the visitor, it will use a different name than > > > what the caller expects, and the visitor will not be able to find it > > > (or will consume erroneously). > > > > > > The solution is for alias getters and setters to wrap the incoming > > > visitor, and forward the sole field that the target is expecting while > > > renaming it appropriately. > > > > > > Reviewed-by: Eric Blake > > > Signed-off-by: Paolo Bonzini > > > > Hi; Coverity complains here (CID 1459068) that the call to > > visit_optional() is ignoring its return value (which we check > > in 983 out of the other 989 callsites). > > Ping? It would be nice to either confirm this is a false > positive or else fix it. > > > > +static void forward_field_optional(Visitor *v, const char *name, bool > *present) > > > +{ > > > + ForwardFieldVisitor *ffv = to_ffv(v); > > > + > > > + if (!forward_field_translate_name(ffv, &name, NULL)) { > > > + *present = false; > > > + return; > > > + } > > > + visit_optional(ffv->target, name, present); > > > +} > > > > Is it right, or is this its "looks like this is returning an error > > indication" heuristic misfiring again ? > > > > My guess is the latter and it's caused by a mismatch > > between the prototype of visit_optional() (returns a > > status both by setting *present and in its return value) > > and the Visitor::optional method (returns a status only > > by setting *present, return void). I guess ideally we'd > > standardize on whether these things were intended to return > > a value or not. > > thanks > -- PMM > > --0000000000003c5d1705cada4bab Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Will look at it next week.

Paolo

Il lun 30 ago 2021, 17:37 Peter Maydell <peter.maydell@linaro.org> ha = scritto:
On Mon, 9 Aug 2021 at 11:4= 0, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Sat, 24 Jul 2021 at 10:00, Paolo Bonzini <pbonzini@redhat.com> wrote:
> >
> > This new adaptor visitor takes a single field of the adaptee, and= exposes it
> > with a different name.
> >
> > This will be used for QOM alias properties.=C2=A0 Alias targets c= an of course
> > have a different name than the alias property itself (e.g. a mach= ine's
> > pflash0 might be an alias of a property named 'drive').= =C2=A0 When the target's
> > getter or setter invokes the visitor, it will use a different nam= e than
> > what the caller expects, and the visitor will not be able to find= it
> > (or will consume erroneously).
> >
> > The solution is for alias getters and setters to wrap the incomin= g
> > visitor, and forward the sole field that the target is expecting = while
> > renaming it appropriately.
> >
> > Reviewed-by: Eric Blake <eblake@redhat.com>
> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>
> Hi; Coverity complains here (CID 1459068) that the call to
> visit_optional() is ignoring its return value (which we check
> in 983 out of the other 989 callsites).

Ping? It would be nice to either confirm this is a false
positive or else fix it.

> > +static void forward_field_optional(Visitor *v, const char *name,= bool *present)
> > +{
> > +=C2=A0 =C2=A0 ForwardFieldVisitor *ffv =3D to_ffv(v);
> > +
> > +=C2=A0 =C2=A0 if (!forward_field_translate_name(ffv, &name, = NULL)) {
> > +=C2=A0 =C2=A0 =C2=A0 =C2=A0 *present =3D false;
> > +=C2=A0 =C2=A0 =C2=A0 =C2=A0 return;
> > +=C2=A0 =C2=A0 }
> > +=C2=A0 =C2=A0 visit_optional(ffv->target, name, present);
> > +}
>
> Is it right, or is this its "looks like this is returning an erro= r
> indication" heuristic misfiring again ?
>
> My guess is the latter and it's caused by a mismatch
> between the prototype of visit_optional() (returns a
> status both by setting *present and in its return value)
> and the Visitor::optional method (returns a status only
> by setting *present, return void). I guess ideally we'd
> standardize on whether these things were intended to return
> a value or not.

thanks
-- PMM

--0000000000003c5d1705cada4bab--