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Tue, 20 Oct 2020 10:51:37 +0200 (CEST) From: Markus Armbruster To: Eric Blake Subject: Re: [PATCH v4 4/7] nbd: Update qapi to support exporting multiple bitmaps References: <20201009215533.1194742-1-eblake@redhat.com> <20201009215533.1194742-5-eblake@redhat.com> <6ee3ac4f-65c3-fdfd-9adb-9bea5f5739e3@virtuozzo.com> <56b413b5-2213-1b4e-5cac-865d8f0e0689@redhat.com> Date: Tue, 20 Oct 2020 10:51:37 +0200 In-Reply-To: <56b413b5-2213-1b4e-5cac-865d8f0e0689@redhat.com> (Eric Blake's message of "Mon, 19 Oct 2020 16:45:36 -0500") Message-ID: <87lfg1gu06.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/20 01:16:16 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: kwolf@redhat.com, Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, qemu-devel@nongnu.org, rjones@redhat.com, stefanha@redhat.com, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Eric Blake writes: > On 10/14/20 7:15 AM, Vladimir Sementsov-Ogievskiy wrote: >> 10.10.2020 00:55, Eric Blake wrote: >>> Since 'nbd-server-add' is deprecated, and 'block-export-add' is new to >>> 5.2, we can still tweak the interface.=C2=A0 Allowing 'bitmaps':['str']= is >>> nicer than 'bitmap':'str'.=C2=A0 This wires up the qapi and qemu-nbd >>> changes to permit passing multiple bitmaps as distinct metadata >>> contexts that the NBD client may request, but the actual support for >>> more than one will require a further patch to the server. >>> >>> Signed-off-by: Eric Blake >>> --- >> [..] >>=20 >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0 break; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 case 'B': >>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bit= map =3D optarg; >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 tmp= =3D g_new(strList, 1); >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 tmp= ->value =3D g_strdup(optarg); >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 tmp= ->next =3D bitmaps; >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bit= maps =3D tmp; >> If publish QAPI_LIST_ADD, defined in block.c, it would look like: >> =C2=A0=C2=A0=C2=A0 QAPI_LIST_ADD(bitmaps, g_strdup(optarg)); > > #define QAPI_LIST_ADD(list, element) do { \ > typeof(list) _tmp =3D g_new(typeof(*(list)), 1); \ > _tmp->value =3D (element); \ > _tmp->next =3D (list); \ > (list) =3D _tmp; \ > } while (0) > > > Markus, thoughts on if we should publish this macro, If it's widely useful. "git-grep -- '->value =3D'" matches ~200 times. A patch converting these to the macro where possible would make a strong case for having the macro. > and if so, which > header would be best? The macro is generic: @list's type may be any of the struct TYPEList we generate for the QAPI type ['TYPE']. We don't want to generate this macro next to each of these struct definitions. A non-generic macro would go there, but let's not generate almost a hundred non-generic macros where a single generic one can do the job. The closest we have to a common base is GenericList. It's in in visitor.h because it's only used by visitors so far. Adding the macro next it is not so smart, because we don't want non-visitor code to include visitor.h just for this macro. Perhaps the macro should go into qapi/util.h, and perhaps GenericList and GenericAlternate should move there, too. [...]