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Wed, 15 Oct 2025 06:56:18 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.19]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 176A219560AD; Wed, 15 Oct 2025 06:56:18 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 9133F21E6A27; Wed, 15 Oct 2025 08:56:15 +0200 (CEST) From: Markus Armbruster To: Vladimir Sementsov-Ogievskiy Cc: marcandre.lureau@redhat.com, pbonzini@redhat.com, berrange@redhat.com, eduardo@habkost.net, qemu-devel@nongnu.org, raphael@enfabrica.net, yc-core@yandex-team.ru, d-tatianin@yandex-team.ru Subject: Re: [PATCH v3 7/7] chardev: introduce DEFINE_PROP_CHR_NO_CONNECT In-Reply-To: <20251014152644.954762-8-vsementsov@yandex-team.ru> (Vladimir Sementsov-Ogievskiy's message of "Tue, 14 Oct 2025 18:26:44 +0300") References: <20251014152644.954762-1-vsementsov@yandex-team.ru> <20251014152644.954762-8-vsementsov@yandex-team.ru> Date: Wed, 15 Oct 2025 08:56:15 +0200 Message-ID: <87tt00irg0.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Vladimir Sementsov-Ogievskiy writes: > For further vhost-user-blk backend-transfer migration realization we > want to give it (vhost-user-blk) a possibility (and responsibility) to > decide when do connect. > > For incoming migration we'll need to postpone connect at least until > early stage of migrate-incoming command, when we already know all > migration parameters and can decide, are we going to do incoming > backend-transfer (and get chardev fd from incoming stream), or we > finally need to connect. > > With this patch, we only provide new macro, to define chardev property, > later it will be used in vhost-user-blk instead of DEFINE_PROP_CHR. There is no "later" in this series. The new macro is called DEFINE_PROP_CHR_NO_CONNECT(). > Then, vhost-user-blk will call qemu_chr_connect() by hand when needed > (for example through qemu_chr_fe_wait_connected(), which is already > called in vhost_user_blk_realize_connect()). > > Signed-off-by: Vladimir Sementsov-Ogievskiy Excuse my quick & ignorant questions... I understand ChardevClass provides either methods init() and connect(), or method open(). Is a ChardevClass providing open() usable with DEFINE_PROP_CHR_NO_CONNECT()? Is a ChardevClass providing init() and connect() usable with DEFINE_PROP_CHR()? Could the code do the right thing based on presence of open() vs. init() and connect() instead of DEFINE_PROP_CHR() vs. DEFINE_PROP_CHR_NO_CONNECT()?