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=-13.5 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 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 A9960C433ED for ; Fri, 16 Apr 2021 14:52:31 +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 13F0C61166 for ; Fri, 16 Apr 2021 14:52:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 13F0C61166 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]:47840 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lXPpe-0005yZ-45 for qemu-devel@archiver.kernel.org; Fri, 16 Apr 2021 10:52:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51266) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lXPnk-0004cN-N4 for qemu-devel@nongnu.org; Fri, 16 Apr 2021 10:50:32 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:55825) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lXPng-0004Xz-2s for qemu-devel@nongnu.org; Fri, 16 Apr 2021 10:50:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618584625; 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=39ZlW7vA61JuQOYIbXgtQZsCCh/Ldi6b55pngNBQJQQ=; b=RwirOaU3cZyBlflsvJbJuirzN28xS5Er5d0uIOOk4cYhWyFK7io5vCSB713YU0dlnHg4AI bj1EWxFh06kKrFAWhc3V5BiZvB8gqryMQyyQhdvyj2SYeDvGXXxGi5Q9MHcFEtrojeS6VR pouhaVAhu5VKyCiGxIHJoEIgpV7G0WY= 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-570-gNQM95lHMDmd_3CdCwG5pw-1; Fri, 16 Apr 2021 10:50:23 -0400 X-MC-Unique: gNQM95lHMDmd_3CdCwG5pw-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 0890E83DD20; Fri, 16 Apr 2021 14:50:22 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-114-17.ams2.redhat.com [10.36.114.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B504F69FB4; Fri, 16 Apr 2021 14:50:13 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 35249113525D; Fri, 16 Apr 2021 16:50:08 +0200 (CEST) From: Markus Armbruster To: Li Zhang Subject: Re: [PATCHv2 1/1] Support monitor chardev hotswap with QMP References: <20210413213459.629963-1-li.zhang@cloud.ionos.com> Date: Fri, 16 Apr 2021 16:50:08 +0200 In-Reply-To: <20210413213459.629963-1-li.zhang@cloud.ionos.com> (Li Zhang's message of "Tue, 13 Apr 2021 23:34:59 +0200") Message-ID: <875z0m4733.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 10.5.11.11 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=63.128.21.124; envelope-from=armbru@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: , Cc: marcandre.lureau@redhat.com, qemu-devel@nongnu.org, Pankaj Gupta , Li Zhang Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Marc-Andr=C3=A9, I'd like your opinion for this one, in particular the use = of g_source_remove(). Li Zhang writes: > 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". > > So this patch is to support monitor chardev hotswap with QMP. > > Signed-off-by: Li Zhang > Reviewed-by: Pankaj Gupta Your commit message starts with a brief description of the problem. Appreciated! But I think it could be a bit clearer. What about this: qmp: Support chardev-change For some scenarios, we'd like to hot-add a monitor device. But QEMU doesn't support that, yet. It does support hot-swapping character backends with QMP command chardev-change. This lets us pre-add a monitor with a null character backend, then chardev-change to a socket backend. Except the chardev-change fails with "Chardev user does not support chardev hotswap" because monitors don't provide the required callback. Implement it for QMP monitors. > --- > v1 -> v2:=20 > - Change mutex lock mon_lock section > - Fix indentation problems > > monitor/monitor-internal.h | 3 +++ > monitor/monitor.c | 2 +- > monitor/qmp.c | 43 +++++++++++++++++++++++++++++++++++--- > 3 files changed, 44 insertions(+), 4 deletions(-) > > diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h > index 9c3a09cb01..1b80c74883 100644 > --- a/monitor/monitor-internal.h > +++ b/monitor/monitor-internal.h > @@ -183,4 +183,7 @@ void help_cmd(Monitor *mon, const char *name); > void handle_hmp_command(MonitorHMP *mon, const char *cmdline); > int hmp_compare_cmd(const char *name, const char *list); > =20 > +gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond, > + void *opaque); > + > #endif > diff --git a/monitor/monitor.c b/monitor/monitor.c > index 636bcc81c5..16a3620d02 100644 > --- a/monitor/monitor.c > +++ b/monitor/monitor.c > @@ -157,7 +157,7 @@ static inline bool monitor_is_hmp_non_interactive(con= st Monitor *mon) > =20 > static void monitor_flush_locked(Monitor *mon); > =20 > -static gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond, > +gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond, > void *opaque) > { > Monitor *mon =3D opaque; > diff --git a/monitor/qmp.c b/monitor/qmp.c > index 2b0308f933..5fa65401ae 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); > =20 > QmpCommandList qmp_commands, qmp_cap_negotiation_commands; > =20 > @@ -477,7 +478,36 @@ void monitor_data_destroy_qmp(MonitorQMP *mon) > g_queue_free(mon->qmp_requests); > } > =20 > -static void monitor_qmp_setup_handlers_bh(void *opaque) > +static int monitor_qmp_change (void *opaque) > +{ > + MonitorQMP *mon =3D opaque; > + > + mon->common.use_io_thread =3D qemu_chr_has_feature(mon->common.chr.c= hr, > + 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); > + } > + > + qemu_mutex_lock(&mon->common.mon_lock); > + if (mon->common.out_watch) { > + g_source_remove(mon->common.out_watch); > + mon->common.out_watch =3D qemu_chr_fe_add_watch(&mon->common.chr= , > + G_IO_OUT | G_IO_HUP, > + monitor_unblocked, > + &mon->common); Visually align the arguments: mon->common.out_watch =3D qemu_chr_fe_add_watch(&mon->common.chr, G_IO_OUT | G_IO_HUP, monitor_unblocked, &mon->common); You may reduce argument indentation some to gain extra space, but keep the arguments more indented than the function: mon->common.out_watch =3D qemu_chr_fe_add_watch(&mon->common.chr, G_IO_OUT | G_IO_HUP, monitor_unblocked, &mon->common); Do this only when you actually use the extra space for readability. > + } > + qemu_mutex_unlock(&mon->common.mon_lock); > + > + return 0; > +} As I wrote in my review of v1, this function copies from monitor_data_init(), monitor_init_qmp(), and monitor_flush_locked(). Feels like a refactoring would be in order. Doing it on top might be easier. > + > +static void monitor_qmp_set_handlers_bh(void *opaque) > { > MonitorQMP *mon =3D opaque; > GMainContext *context; > @@ -487,7 +517,14 @@ static void monitor_qmp_setup_handlers_bh(void *opaq= ue) > 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 =3D opaque; > + monitor_qmp_set_handlers_bh(mon); > monitor_list_append(&mon->common); > } > =20 > @@ -528,7 +565,7 @@ void monitor_init_qmp(Chardev *chr, bool pretty, Erro= r **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); > } > }