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 lists1p.gnu.org (lists1p.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 D05C6C43458 for ; Tue, 30 Jun 2026 12:44:27 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1weXon-0006PS-8O; Tue, 30 Jun 2026 08:44:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1weXoZ-0006Ol-9o for qemu-devel@nongnu.org; Tue, 30 Jun 2026 08:43:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1weXoX-0002BR-1g for qemu-devel@nongnu.org; Tue, 30 Jun 2026 08:43:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1782823423; h=from:from:reply-to: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=VIMFFc/RnWR5N1EsN5P+Jp60EIpB3vAIIs8hpyb+4Yw=; b=etanXiW/cqJ8mMHQOLWh7YJ3Lwhzp7E3yxQEPxSOug7uAeVxIqt3BbWpWmKhXwgFBUeHQm Aw6zohOXqh9vmcpC3hwlWfAgmYcy68bduAwVImAFe9AilPQfdInQng0SaKa1N38KYiRSVu DU75jgT4nTCj2oYkKeGq+C3QX+V8ZvA= 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-645-HZl-VoE1On6CDUtS1kImkQ-1; Tue, 30 Jun 2026 08:43:37 -0400 X-MC-Unique: HZl-VoE1On6CDUtS1kImkQ-1 X-Mimecast-MFC-AGG-ID: HZl-VoE1On6CDUtS1kImkQ_1782823416 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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 9FF871955F1F; Tue, 30 Jun 2026 12:43:35 +0000 (UTC) Received: from redhat.com (unknown [10.44.50.20]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 13E8F1955F6F; Tue, 30 Jun 2026 12:43:31 +0000 (UTC) Date: Tue, 30 Jun 2026 13:43:28 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Cc: qemu-devel@nongnu.org, devel@lists.libvirt.org, =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Paolo Bonzini , "Dr. David Alan Gilbert" , Alex =?utf-8?Q?Benn=C3=A9e?= , Christian Brauner , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Peter Krempa Subject: Re: [PATCH v5 05/35] monitor: minimal conversion of monitors to QOM Message-ID: References: <20260624173752.2928717-1-berrange@redhat.com> <20260624173752.2928717-6-berrange@redhat.com> <87o6gs1buf.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87o6gs1buf.fsf@pond.sub.org> User-Agent: Mutt/2.3.2 (2026-04-26) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 8 X-Spam_score: 0.8 X-Spam_bar: / X-Spam_report: (0.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, 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_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Jun 30, 2026 at 01:55:52PM +0200, Markus Armbruster wrote: > Daniel P. Berrangé writes: > > > This introduces a Monitor QOM object, with MonitorHMP and > > MonitorQMP subclasses. This is the bare minimum conversion > > of just the type declarations and replacing g_new/g_free > > with object_new/object_unref. > > > > Reviewed-by: Marc-André Lureau > > Tested-by: Peter Krempa > > Signed-off-by: Daniel P. Berrangé > > --- > > include/monitor/monitor.h | 11 ++++++++++- > > monitor/hmp.c | 29 +++++++++++++++++++++++++++-- > > monitor/monitor-internal.h | 18 ++++++++++++++++-- > > monitor/monitor.c | 18 ++++++++++++++++-- > > monitor/qmp-cmds.c | 15 ++++++++------- > > monitor/qmp.c | 29 +++++++++++++++++++++++++++-- > > 6 files changed, 104 insertions(+), 16 deletions(-) > > > > diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h > > index b9642b58ba..2e9f9e12e9 100644 > > --- a/include/monitor/monitor.h > > +++ b/include/monitor/monitor.h > > @@ -5,8 +5,17 @@ > > #include "qapi/qapi-types-misc.h" > > #include "qemu/readline.h" > > #include "exec/hwaddr.h" > > +#include "qom/object.h" > > + > > +#define TYPE_MONITOR "monitor" > > +OBJECT_DECLARE_TYPE(Monitor, MonitorClass, MONITOR); > > + > > +#define TYPE_MONITOR_HMP "monitor-hmp" > > +OBJECT_DECLARE_TYPE(MonitorHMP, MonitorHMPClass, MONITOR_HMP); > > + > > +#define TYPE_MONITOR_QMP "monitor-qmp" > > +OBJECT_DECLARE_TYPE(MonitorQMP, MonitorQMPClass, MONITOR_QMP); > > > > -typedef struct MonitorHMP MonitorHMP; > > typedef struct MonitorOptions MonitorOptions; > > > > #define QMP_REQ_QUEUE_LEN_MAX 8 > > diff --git a/monitor/hmp.c b/monitor/hmp.c > > index 4e4468424a..81047d2513 100644 > > --- a/monitor/hmp.c > > +++ b/monitor/hmp.c > > @@ -43,6 +43,20 @@ > > #include "system/block-backend.h" > > #include "trace.h" > > > > +OBJECT_DEFINE_TYPE(MonitorHMP, monitor_hmp, MONITOR_HMP, MONITOR); > > + > > +static void monitor_hmp_finalize(Object *obj) > > +{ > > +} > > + > > +static void monitor_hmp_class_init(ObjectClass *cls, const void *data) > > +{ > > +} > > + > > +static void monitor_hmp_init(Object *obj) > > +{ > > +} > > + > > static void monitor_command_cb(void *opaque, const char *cmdline, > > void *readline_opaque) > > { > > @@ -1526,10 +1540,21 @@ static void monitor_readline_flush(void *opaque) > > > > void monitor_new_hmp(Chardev *chr, bool use_readline, Error **errp) > > { > > - MonitorHMP *mon = g_new0(MonitorHMP, 1); > > + MonitorHMP *mon; > > + static int counter; > > + g_autofree char *id = g_strdup_printf("hmpcompat%d", counter++); > > Hmm. The system picking IDs is problematic when they can clash with the > user's IDs. If we had an ounce of common sense, we'd restrict both > across the board so they cannot clash. But we don't. > > We need an ID here, because we need to make the new object the child of > something (actually: child of /objects/), which requires a child name. > > Non-problem with -object / object-add, because @id is mandatory there. > > Non-problem with -device / device_add, because we use separate parents > for devices with and without @id (/machine/peripheral/ and > /machine/peripheral-anon/, plus the /machine/unattached/ orphanage). > > Example for an existing problem: > > $ qemu-system-x86_64 -nodefaults -monitor stdio -chardev null,id=chr0 -mon id=compat_monitor0,chardev=chr0 > qemu-system-x86_64: -mon id=compat_monitor0,chardev=chr0: Duplicate ID 'compat_monitor0' for mon > > Example for a problem created by this series: > > $ qemu-system-x86_64 -nodefaults -display none -S -monitor stdio -chardev null,id=chr0 -object monitor-hmp,id=hmpcompat0,chardev=chr0 > qemu-system-x86_64: -monitor stdio: attempt to add duplicate property 'hmpcompat0' to object (type 'container') > > I readily admit that these clashes are *unlikely*. Still, do we really > want to define an interface that claims to let you pick any ID, then > rejects some of them sometimes? Feels rather 1990s to me. At the very > least, cover the wart in the commit message. The way I looked at it was aything using -object with the new monitor-qmp/monitor-hmp types is new code. They can: 1. Trivially abide the warning about "hmpcompatNN" / "qmpcompatNN" being internal usage for compat syntax 2. Not use both -monitor and -object on the same QEMU instance so not have a clash between the two to begin with The remaining danger where is some existing code using -object with a *non-monitor* type, and calling it "hmpcompatNN" / "qmpcompatNN", which would be insanity. Never say never, but I think that's an acceptable risk. > This existing problem example leads me to the next mess: interaction > with monitors' *other* ID. > > qemu-system-FOO's -mon accepts an optional "id" parameter. It goes into > its QemuOpts, and from there into MonitorOptions member @id. Arrrggggggghh. That is not documented for -mon at all AFAICT $ qemu-system-x86_64 -help 2>&1 | grep -- -mon -monitor dev redirect the monitor to char device 'dev' -qmp dev like -monitor but opens in 'control' mode -mon [chardev=]name[,mode=readline|control][,pretty[=on|off]] but yeah as you say, it exists, and in fact libvirt even uses it despite it being undocumented. > qemu-storage-daemon's --monitor is similar, except it bypasses QemuOpts. > > qemu-system-FOO provides convenience options -monitor, -qmp, > -qmp-pretty. > > Their argument may refer to an existing chardev by ID, like > "chardev:ID". This creates a monitor with that same[*] QemuOpts and > MonitorOptions ID. > > Else, their argument is character device configuration in legacy syntax, > like "stdio". This creates both a monitor and a character device, with > ID "compat_monitorN", where N counts up from zero. The character device > is visible in "info chardev", as always. > > Aside: in both cases we use the same ID for two different objects, which > feels unadvisable. Agreed, that's awful. > Aside: we have code checking whether a QemuOpts or character device ID > starts with "compat_monitor", which is horryfying. Eww. > Your series does not mess with this at all. Understandable; I stay out > of this swamp when I can, too. I didn't realize the swap was there in this case ! > However, it results in monitors having two IDs, namely the one in > MonitorOptions, and the one in /object/. This is confusing. > > Perhaps we should we'd get rid of the one in MonitorOptions. May well > be more trouble than it's worth. > > Could we at least make the two IDs the same? Since -mon has an existing ID, we might as well pass it through to use as the child prop name for the objects. > > diff --git a/monitor/monitor.c b/monitor/monitor.c > > index a87597e606..a497c25c54 100644 > > --- a/monitor/monitor.c > > +++ b/monitor/monitor.c > > @@ -73,6 +73,20 @@ static GHashTable *coroutine_mon; /* Maps Coroutine* to Monitor* */ > > MonitorList mon_list; > > static bool monitor_destroyed; > > > > +OBJECT_DEFINE_TYPE(Monitor, monitor, MONITOR, OBJECT); > > + > > +static void monitor_finalize(Object *obj) > > +{ > > +} > > + > > +static void monitor_class_init(ObjectClass *cls, const void *data) > > +{ > > +} > > + > > +static void monitor_init(Object *obj) > > +{ > > +} > > + > > Monitor *monitor_cur(void) > > { > > Monitor *mon; > > @@ -598,7 +612,7 @@ void monitor_list_append(Monitor *mon) > > > > if (mon) { > > monitor_data_destroy(mon); > > - g_free(mon); > > + object_unparent(OBJECT(mon)); > > } > > } > > > > @@ -680,7 +694,7 @@ void monitor_cleanup(void) > > monitor_flush(mon); > > monitor_data_destroy(mon); > > qemu_mutex_lock(&monitor_lock); > > - g_free(mon); > > + object_unparent(OBJECT(mon)); > > } > > qemu_mutex_unlock(&monitor_lock); > > > > Hmm... > > {"execute": "qom-list-types", "arguments": {"implements": "monitor"}} > {"return": [{"name": "monitor-hmp", "parent": "monitor"}, {"name": "monitor-qmp", "parent": "monitor"}, {"name": "monitor", "parent": "object"}]} > > Shouldn't type "monitor" be abstract? Yes it absolutely should be, and I'd swear it *was* abstract at some point in my work, but I guess I lost it along the way. With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|