From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0A6DCCCD185 for ; Wed, 15 Oct 2025 07:50:34 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v8wGX-0003DX-J4; Wed, 15 Oct 2025 03:49:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v8wGW-0003DP-1C for qemu-devel@nongnu.org; Wed, 15 Oct 2025 03:49:44 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v8wGT-0004hB-4k for qemu-devel@nongnu.org; Wed, 15 Oct 2025 03:49:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760514576; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=209SPIqSN3v9lT+ktBqCQwf8SocoS3T27DeJ7bLeSPI=; b=VpTqG6RN5vIkUJb1KnEoByCm82M0puiC+7zk/+GrhiFDdBJSvM7ahm0utbWtKuAIjGRb2N kTgoPrJq3X2lyBiNH8sE6UzrBQBXjItF14HXUfrzPlGxmLvtVxpCitH0PI/dIcauZ2dsrr x1uyg4KN9tXd8VY37hFKIjDvL2DhV0Q= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-304-y7KCTQX0N0amfAp90oUtwg-1; Wed, 15 Oct 2025 03:49:32 -0400 X-MC-Unique: y7KCTQX0N0amfAp90oUtwg-1 X-Mimecast-MFC-AGG-ID: y7KCTQX0N0amfAp90oUtwg_1760514571 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DFD2519560A7; Wed, 15 Oct 2025 07:49:30 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.19]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EE7BA1800446; Wed, 15 Oct 2025 07:49:29 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 578B621E6A27; Wed, 15 Oct 2025 09:49:27 +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 5/7] chardev/char: introduce .init() + .connect() initialization interface In-Reply-To: <76945924-ed5e-4365-95c8-a8f752d7ad03@yandex-team.ru> (Vladimir Sementsov-Ogievskiy's message of "Wed, 15 Oct 2025 09:58:39 +0300") References: <20251014152644.954762-1-vsementsov@yandex-team.ru> <20251014152644.954762-6-vsementsov@yandex-team.ru> <87y0pcirp0.fsf@pond.sub.org> <76945924-ed5e-4365-95c8-a8f752d7ad03@yandex-team.ru> Date: Wed, 15 Oct 2025 09:49:27 +0200 Message-ID: <87plaofvug.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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_DNSWL_NONE=-0.0001, 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: > On 15.10.25 09:50, Markus Armbruster wrote: >> Vladimir Sementsov-Ogievskiy writes: >>=20 >>> We'll need a possibility to postpone connect step to later point in >>> time to implement backend-transfer migration feature for vhost-user-blk >>> in further commits. Let's start with new char interface for backends. >>> >>> .init() takes QAPI parameters and should parse them, called early >>> >>> .connect() should actually establish a connection, and postponed to >>> the point of attaching to frontend. Called at later point, either >>> at time of attaching frontend, either from qemu_chr_wait_connected(). >>> >>> Signed-off-by: Vladimir Sementsov-Ogievskiy >>> Reviewed-by: Marc-Andr=C3=A9 Lureau >> [...] >>=20 >>> diff --git a/include/chardev/char.h b/include/chardev/char.h >>> index 429852f8d9..ebadaf3482 100644 >>> --- a/include/chardev/char.h >>> +++ b/include/chardev/char.h >>> @@ -63,6 +63,7 @@ struct Chardev { >>> CharBackend *be; >>> char *label; >>> char *filename; >>> + bool connect_postponed; >>> int logfd; >>> int be_open; >>> /* used to coordinate the chardev-change special-case: */ >>> @@ -225,6 +226,7 @@ QemuOpts *qemu_chr_parse_compat(const char *label, = const char *filename, >>> bool permit_mux_mon); >>> int qemu_chr_write(Chardev *s, const uint8_t *buf, int len, bool write= _all); >>> #define qemu_chr_write_all(s, buf, len) qemu_chr_write(s, buf, len, tr= ue) >>> +bool qemu_chr_connect(Chardev *chr, Error **errp); >>> int qemu_chr_wait_connected(Chardev *chr, Error **errp); >>> >>> #define TYPE_CHARDEV "chardev" >>> @@ -259,10 +261,28 @@ struct ChardevClass { >>> /* parse command line options and populate QAPI @backend */ >>> void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **err= p); >>> >>> - /* called after construction, open/starts the backend */ >>> + /* >>> + * Called after construction, create and open/starts the backend, >> >> What to do mean by "create and open/starts"? >> Maybe "create and start"? > > Yes, sounds good. > >>> + * mutual exclusive with .init. .connect must not be defined when >> >> mutually >>=20 >>> + * .open is defined. >>> + */ >> >> Suggest to use @name to refer to a member name. We do that elsewhere, >> and it's easier on the eyes than dots. >>=20 >>> void (*open)(Chardev *chr, ChardevBackend *backend, >>> bool *be_opened, Error **errp); >>> + /* >>> + * Called after construction, create the backend, mutual exclusive >> >> mutually >>=20 >>> + * with .open, and must be accompanied by .connect. >> >> Is it okay to destroy after init() without connect()? >> If yes, "must" is misleading. > > Hmm. "should" is OK then? "Should be followed by connect()" would work. Or something like "The backend still needs to be started with init()." >>> + * Must set chr-filename. >> >> What's chr-filename? > > Type. That should be chr->filename. Or better @chr->filename ? There is no member @chr. I figure it's CharBackend member @chr. Perhaps "the CharBackend's chr->filename".=20 [...] > Thanks for reviewing! You're welcome!