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 X-Spam-Level: X-Spam-Status: No, score=-15.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4AECDC433ED for ; Tue, 13 Apr 2021 08:59:15 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id D73836135C for ; Tue, 13 Apr 2021 08:59:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D73836135C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39046 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lWEt8-00083D-19 for qemu-devel@archiver.kernel.org; Tue, 13 Apr 2021 04:59:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:55694) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lWEsL-0007eO-Ax for qemu-devel@nongnu.org; Tue, 13 Apr 2021 04:58:25 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:56852) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lWEsJ-0002sC-9d for qemu-devel@nongnu.org; Tue, 13 Apr 2021 04:58:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618304302; 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=7Pwon+f6yZeWGXz1ACEZEg379BeoU0XfKBZXQeRMSs4=; b=SRUJRTQTnOWS8Oqd3MaEGSp0pCvkQI8L3uExtuh4JO2FvoPIdpu8QPrALAfxGvlbg3TU+f JFkPXcfGuDlgTCP0s/l5EwZm5EfVSmgdMxAh9CiToQWayJmFkGw2+DJcxB+iFlp+XG4vt9 v8qdG3E3Swihc9elLs6QDB/1Rs6ceGg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-153-YR06YNe1PMWQz_cAwKX3yw-1; Tue, 13 Apr 2021 04:58:11 -0400 X-MC-Unique: YR06YNe1PMWQz_cAwKX3yw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9C9EA881276; Tue, 13 Apr 2021 08:58:09 +0000 (UTC) Received: from redhat.com (ovpn-114-58.ams2.redhat.com [10.36.114.58]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 43F5439A60; Tue, 13 Apr 2021 08:58:01 +0000 (UTC) Date: Tue, 13 Apr 2021 09:57:58 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Subject: Re: [PATCH 2/2] Support monitor chardev hotswap with QMP Message-ID: References: <20210315170636.704201-1-zhlcindy@gmail.com> <20210315170636.704201-2-zhlcindy@gmail.com> <8735vu1ybo.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <8735vu1ybo.fsf@dusky.pond.sub.org> User-Agent: Mutt/2.0.5 (2021-01-21) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: lukasstraub2@web.de, alexandr.iarygin@profitbricks.com, qemu-devel@nongnu.org, Li Zhang , pankaj.gupta@cloud.ionos.com, Li Zhang , marcandre.lureau@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Apr 13, 2021 at 08:40:59AM +0200, Markus Armbruster wrote: > Li Zhang writes: > > > From: Li Zhang > > > > For some scenarios, it needs to hot-add a monitor device. > > But QEMU doesn't support hotplug yet. It also works by adding > > a monitor with null backend by default and then change its > > backend to socket by QMP command "chardev-change". If you need ability to hot-add monitor instances, why not just implement that feature directly, instead of pre-creating monitors with null backends and then later changing the backend ? > > > > So this patch is to support monitor chardev hotswap with QMP. > > > > Signed-off-by: Li Zhang > > I think what what you're trying to say is that chardev-change does not > work when the character device changes is used by a QMP monitor. > Correct? > > If yes, how exactly does it misbehave? > > Does it work with an HMP monitor? > > > --- > > monitor/monitor-internal.h | 3 +++ > > monitor/monitor.c | 2 +- > > monitor/qmp.c | 42 +++++++++++++++++++++++++++++++++++--- > > 3 files changed, 43 insertions(+), 4 deletions(-) > > > > diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h > > index 40903d6386..2df6dd21de 100644 > > --- a/monitor/monitor-internal.h > > +++ b/monitor/monitor-internal.h > > @@ -186,4 +186,7 @@ int hmp_compare_cmd(const char *name, const char *list); > > void qmp_query_qmp_schema(QDict *qdict, QObject **ret_data, > > Error **errp); > > > > +gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond, > > + void *opaque); > > + > > #endif > > diff --git a/monitor/monitor.c b/monitor/monitor.c > > index e94f532cf5..2d255bab18 100644 > > --- a/monitor/monitor.c > > +++ b/monitor/monitor.c > > @@ -157,7 +157,7 @@ static inline bool monitor_is_hmp_non_interactive(const Monitor *mon) > > > > static void monitor_flush_locked(Monitor *mon); > > > > -static gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond, > > +gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond, > > void *opaque) > > { > > Monitor *mon = opaque; > > diff --git a/monitor/qmp.c b/monitor/qmp.c > > index 2326bd7f9b..55cfb230d9 100644 > > --- a/monitor/qmp.c > > +++ b/monitor/qmp.c > > @@ -44,6 +44,7 @@ struct QMPRequest { > > Error *err; > > }; > > typedef struct QMPRequest QMPRequest; > > +static void monitor_qmp_set_handlers_bh(void *opaque); > > > > QmpCommandList qmp_commands, qmp_cap_negotiation_commands; > > > > @@ -480,7 +481,35 @@ void monitor_data_destroy_qmp(MonitorQMP *mon) > > g_queue_free(mon->qmp_requests); > > } > > > > -static void monitor_qmp_setup_handlers_bh(void *opaque) > > +static int monitor_qmp_change(void *opaque) > > +{ > > + MonitorQMP *mon = opaque; > > + > > + mon->common.use_io_thread = > > + qemu_chr_has_feature(mon->common.chr.chr, QEMU_CHAR_FEATURE_GCONTEXT); > > + > > + if (mon->common.use_io_thread) { > > + aio_bh_schedule_oneshot(iothread_get_aio_context(mon_iothread), > > + monitor_qmp_set_handlers_bh, mon); > > + } else { > > + qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read, > > + monitor_qmp_read, monitor_qmp_event, > > + monitor_qmp_change, &mon->common, NULL, true); > > + } > > + > > + if (mon->common.out_watch) { > > + g_source_remove(mon->common.out_watch); > > All other updates of @out_watch are under @mon_lock. Why not this one? > > I have no idea whether g_source_remove() is the right function to call. > Its documentation says "You must use g_source_destroy() for sources > added to a non-default main context." The qemu_chr_fe_set_handlers() > contract is of no help. > > Documentation of g_source_destroy() confuses some more: "This does not > unref the GSource: if you still hold a reference, use g_source_unref() > to drop it. > > Marc-André, can you help? > > > + qemu_mutex_lock(&mon->common.mon_lock); > > + mon->common.out_watch = > > + qemu_chr_fe_add_watch(&mon->common.chr, G_IO_OUT | G_IO_HUP, > > + monitor_unblocked, &mon->common); > > Bad indentation. Better: > > mon->common.out_watch = > qemu_chr_fe_add_watch(&mon->common.chr, G_IO_OUT | G_IO_HUP, > monitor_unblocked, &mon->common); > > or > > mon->common.out_watch = qemu_chr_fe_add_watch(&mon->common.chr, > G_IO_OUT | G_IO_HUP, > monitor_unblocked, > &mon->common); > > or > > mon->common.out_watch = qemu_chr_fe_add_watch(&mon->common.chr, > G_IO_OUT | G_IO_HUP, > monitor_unblocked, &mon->common); > > > + qemu_mutex_unlock(&mon->common.mon_lock); > > + } > > + > > + return 0; > > +} > > This function copies from monitor_data_init(), monitor_init_qmp(), and > monitor_flush_locked(). Feels like a refactoring would be in order. > Possibly on top. > > > + > > +static void monitor_qmp_set_handlers_bh(void *opaque) > > { > > MonitorQMP *mon = opaque; > > GMainContext *context; > > @@ -490,7 +519,14 @@ static void monitor_qmp_setup_handlers_bh(void *opaque) > > assert(context); > > qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read, > > monitor_qmp_read, monitor_qmp_event, > > - NULL, &mon->common, context, true); > > + monitor_qmp_change, &mon->common, context, true); > > + > > +} > > + > > +static void monitor_qmp_setup_handlers_bh(void *opaque) > > +{ > > + MonitorQMP *mon = opaque; > > + monitor_qmp_set_handlers_bh(mon); > > monitor_list_append(&mon->common); > > } > > > > @@ -531,7 +567,7 @@ void monitor_init_qmp(Chardev *chr, bool pretty, Error **errp) > > } else { > > qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read, > > monitor_qmp_read, monitor_qmp_event, > > - NULL, &mon->common, NULL, true); > > + monitor_qmp_change, &mon->common, NULL, true); > > monitor_list_append(&mon->common); > > } > > } > > Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|