[{"id":3676402,"web_url":"http://patchwork.ozlabs.org/comment/3676402/","msgid":"","list_archive_url":null,"date":"2026-04-13T01:28:13","subject":"Re: [PATCH 05/17] monitor: remove 'skip_flush' field","submitter":{"id":86099,"url":"http://patchwork.ozlabs.org/api/people/86099/","name":"Dr. David Alan Gilbert","email":"dave@treblig.org"},"content":"* Daniel P. Berrangé (berrange@redhat.com) wrote:\n> The 'skip_flush' field is set on the dummy throwaway HMP monitor\n> object created by QMP's 'human-monitor-command', as an indication\n> not to try to write data to the chardev. Instead the QMP command\n> impl will grab the data straight out of the in-memory buffer.\n> \n> The flag is redundant, however, as the monitor code could instead\n> simply check the 'fe_is_open' field on the CharFrontend, which\n> will be false in the same scenarios that 'skip_flush' is true.\n\nFor monitors on sockets where the other end isn't connected, does that\nchange the behaviour? Does that also have !fe_is_open and can that hit this\ncase?\n\nDave\n\n> Signed-off-by: Daniel P. Berrangé \n> ---\n> monitor/hmp.c | 2 +-\n> monitor/monitor-internal.h | 4 +---\n> monitor/monitor.c | 11 +++++++----\n> monitor/qmp-cmds.c | 2 +-\n> monitor/qmp.c | 2 +-\n> 5 files changed, 11 insertions(+), 10 deletions(-)\n> \n> diff --git a/monitor/hmp.c b/monitor/hmp.c\n> index 614d9a3707..72f8303662 100644\n> --- a/monitor/hmp.c\n> +++ b/monitor/hmp.c\n> @@ -1539,7 +1539,7 @@ void monitor_new_hmp(Chardev *chr, bool use_readline, Error **errp)\n> return;\n> }\n> \n> - monitor_data_init(&mon->parent, false, false, false);\n> + monitor_data_init(&mon->parent, false, false);\n> \n> mon->use_readline = use_readline;\n> if (mon->use_readline) {\n> diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h\n> index 25320928a7..84117805b7 100644\n> --- a/monitor/monitor-internal.h\n> +++ b/monitor/monitor-internal.h\n> @@ -102,7 +102,6 @@ struct Monitor {\n> CharFrontend chr;\n> int suspend_cnt; /* Needs to be accessed atomically */\n> bool is_qmp;\n> - bool skip_flush;\n> bool use_io_thread;\n> \n> char *mon_cpu_path;\n> @@ -183,8 +182,7 @@ extern QmpCommandList qmp_commands, qmp_cap_negotiation_commands;\n> extern QemuMutex monitor_lock;\n> extern MonitorList mon_list;\n> \n> -void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,\n> - bool use_io_thread);\n> +void monitor_data_init(Monitor *mon, bool is_qmp, bool use_io_thread);\n> void monitor_data_destroy(Monitor *mon);\n> int monitor_can_read(void *opaque);\n> void monitor_list_append(Monitor *mon);\n> diff --git a/monitor/monitor.c b/monitor/monitor.c\n> index 7936e2ab22..f7e3708d2f 100644\n> --- a/monitor/monitor.c\n> +++ b/monitor/monitor.c\n> @@ -167,7 +167,12 @@ void monitor_flush_locked(Monitor *mon)\n> size_t len;\n> const char *buf;\n> \n> - if (mon->skip_flush) {\n> + /*\n> + * When used by QMP human-monitor-command, no chardev\n> + * will be connected, as we want to just collect the\n> + * output in the buffer\n> + */\n> + if (!mon->chr.fe_is_open) {\n> return;\n> }\n> \n> @@ -621,8 +626,7 @@ static void monitor_iothread_init(void)\n> mon_iothread = iothread_create(\"mon_iothread\", &error_abort);\n> }\n> \n> -void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,\n> - bool use_io_thread)\n> +void monitor_data_init(Monitor *mon, bool is_qmp, bool use_io_thread)\n> {\n> if (use_io_thread && !mon_iothread) {\n> monitor_iothread_init();\n> @@ -630,7 +634,6 @@ void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,\n> qemu_mutex_init(&mon->mon_lock);\n> mon->is_qmp = is_qmp;\n> mon->outbuf = g_string_new(NULL);\n> - mon->skip_flush = skip_flush;\n> mon->use_io_thread = use_io_thread;\n> }\n> \n> diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c\n> index d0ed241d6a..be2bd985b7 100644\n> --- a/monitor/qmp-cmds.c\n> +++ b/monitor/qmp-cmds.c\n> @@ -168,7 +168,7 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,\n> char *output = NULL;\n> MonitorHMP *hmp = MONITOR_HMP(object_new(TYPE_MONITOR_HMP));\n> \n> - monitor_data_init(&hmp->parent, false, true, false);\n> + monitor_data_init(&hmp->parent, false, false);\n> \n> if (has_cpu_index) {\n> int ret = monitor_set_cpu(&hmp->parent, cpu_index);\n> diff --git a/monitor/qmp.c b/monitor/qmp.c\n> index 36cb078f30..fe2aec9ce9 100644\n> --- a/monitor/qmp.c\n> +++ b/monitor/qmp.c\n> @@ -538,7 +538,7 @@ void monitor_new_qmp(Chardev *chr, bool pretty, Error **errp)\n> qemu_chr_fe_set_echo(&mon->parent.chr, true);\n> \n> /* Note: we run QMP monitor in I/O thread when @chr supports that */\n> - monitor_data_init(&mon->parent, true, false,\n> + monitor_data_init(&mon->parent, true,\n> qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT));\n> \n> mon->pretty = pretty;\n> -- \n> 2.53.0\n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=treblig.org header.i=@treblig.org header.a=rsa-sha256\n header.s=bytemarkmx header.b=DHGrwZyz;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists1p.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)"],"Received":["from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fv8vx4GVrz1yDF\n\tfor ; Mon, 13 Apr 2026 11:29:31 +1000 (AEST)","from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists1p.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1wC66D-0003fC-Ar; Sun, 12 Apr 2026 21:28:25 -0400","from eggs.gnu.org ([2001:470:142:3::10])\n by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wC669-0003er-Nf; Sun, 12 Apr 2026 21:28:21 -0400","from mx.treblig.org ([2a00:1098:5b::1])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wC667-0005jG-3O; Sun, 12 Apr 2026 21:28:21 -0400","from dg by mx.treblig.org with local (Exim 4.98.2)\n (envelope-from ) id 1wC661-00000007rno-2xil;\n Mon, 13 Apr 2026 01:28:13 +0000"],"DKIM-Signature":"v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=treblig.org\n ; s=bytemarkmx;\n h=Content-Type:MIME-Version:Message-ID:Subject:From:Date:From\n :Subject; bh=mf2gmiwYTaAAfCw01jy17/m2CBty+lUI4Fl6BoD39Gw=; b=DHGrwZyz++kxcfqq\n Mmwf1DI8LVajZh0QJtFX/aXUpD1NpOfuJd/0GujVifnSrnQEOZ0xmYfPopVPBNu2vFNOoJ/ZWB6AL\n zDNXTWeM1tJEQYzfq6lS4juW3ATBkbW3G5JFLLVQQ/19hG4VFhb4u8G3CAh7KGeeycQ0ByjEea334\n cH6qRa7SHb5njmwFYOhweeH/X46QBab6cS+Xv58PUFKLtqaV1MVi2Q3okFwlNQkALW5qnKRBfYE2A\n EOgOSUIuEtn9MlbevrEk6Div1y6iElXyXz8zt1XLDbdoEu6BYuCrrrwD9/PXyVY9sAduooYgOUWr9\n Xae2q9YU+X/rpICEnw==;","Date":"Mon, 13 Apr 2026 01:28:13 +0000","From":"\"Dr. David Alan Gilbert\" ","To":"Daniel =?iso-8859-1?q?P=2E_Berrang=E9?= ","Cc":"qemu-devel@nongnu.org, Paolo Bonzini ,\n Markus Armbruster ,\n Christian Brauner ,\n Alex =?iso-8859-1?q?Benn=E9e?= , Philippe\n\t=?iso-8859-1?q?Mathieu-Daud=E9?= ,\n Fabiano Rosas ,\n =?iso-8859-1?q?Marc-Andr=E9?= Lureau ,\n Peter Xu , Kevin Wolf ,\n qemu-block@nongnu.org, Eric Blake ","Subject":"Re: [PATCH 05/17] monitor: remove 'skip_flush' field","Message-ID":"","References":"<20260410160458.3778874-1-berrange@redhat.com>\n <20260410160458.3778874-6-berrange@redhat.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=iso-8859-1","Content-Disposition":"inline","Content-Transfer-Encoding":"8bit","In-Reply-To":"<20260410160458.3778874-6-berrange@redhat.com>","X-Chocolate":"70 percent or better cocoa solids preferably","X-Operating-System":"Linux/6.12.74+deb13+1-amd64 (x86_64)","X-Uptime":"01:27:03 up 31 days, 2:40, 2 users, load average: 0.08, 0.11,\n 0.05","User-Agent":"Mutt/2.2.13 (2024-03-09)","Received-SPF":"pass client-ip=2a00:1098:5b::1; envelope-from=dg@treblig.org;\n helo=mx.treblig.org","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, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001,\n 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":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"}},{"id":3676625,"web_url":"http://patchwork.ozlabs.org/comment/3676625/","msgid":"","list_archive_url":null,"date":"2026-04-13T10:00:21","subject":"Re: [PATCH 05/17] monitor: remove 'skip_flush' field","submitter":{"id":2694,"url":"http://patchwork.ozlabs.org/api/people/2694/","name":"Daniel P. Berrangé","email":"berrange@redhat.com"},"content":"On Mon, Apr 13, 2026 at 01:28:13AM +0000, Dr. David Alan Gilbert wrote:\n> * Daniel P. Berrangé (berrange@redhat.com) wrote:\n> > The 'skip_flush' field is set on the dummy throwaway HMP monitor\n> > object created by QMP's 'human-monitor-command', as an indication\n> > not to try to write data to the chardev. Instead the QMP command\n> > impl will grab the data straight out of the in-memory buffer.\n> > \n> > The flag is redundant, however, as the monitor code could instead\n> > simply check the 'fe_is_open' field on the CharFrontend, which\n> > will be false in the same scenarios that 'skip_flush' is true.\n> \n> For monitors on sockets where the other end isn't connected, does that\n> change the behaviour? Does that also have !fe_is_open and can that hit this\n> case?\n\nThe only place that sets fe_is_open is qemu_chr_fe_set_open,\nwhich is called by qemu_chr_fe_set_handlers_full.\n\nIOW, it merely reflects the fact that some frontend (the\nmonitor in this case) and configured the chardev for use,\nand is separate from any notion of whether the chardev\nbackend is open/connected.\n\n\n\n> \n> Dave\n> \n> > Signed-off-by: Daniel P. Berrangé \n> > ---\n> > monitor/hmp.c | 2 +-\n> > monitor/monitor-internal.h | 4 +---\n> > monitor/monitor.c | 11 +++++++----\n> > monitor/qmp-cmds.c | 2 +-\n> > monitor/qmp.c | 2 +-\n> > 5 files changed, 11 insertions(+), 10 deletions(-)\n> > \n> > diff --git a/monitor/hmp.c b/monitor/hmp.c\n> > index 614d9a3707..72f8303662 100644\n> > --- a/monitor/hmp.c\n> > +++ b/monitor/hmp.c\n> > @@ -1539,7 +1539,7 @@ void monitor_new_hmp(Chardev *chr, bool use_readline, Error **errp)\n> > return;\n> > }\n> > \n> > - monitor_data_init(&mon->parent, false, false, false);\n> > + monitor_data_init(&mon->parent, false, false);\n> > \n> > mon->use_readline = use_readline;\n> > if (mon->use_readline) {\n> > diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h\n> > index 25320928a7..84117805b7 100644\n> > --- a/monitor/monitor-internal.h\n> > +++ b/monitor/monitor-internal.h\n> > @@ -102,7 +102,6 @@ struct Monitor {\n> > CharFrontend chr;\n> > int suspend_cnt; /* Needs to be accessed atomically */\n> > bool is_qmp;\n> > - bool skip_flush;\n> > bool use_io_thread;\n> > \n> > char *mon_cpu_path;\n> > @@ -183,8 +182,7 @@ extern QmpCommandList qmp_commands, qmp_cap_negotiation_commands;\n> > extern QemuMutex monitor_lock;\n> > extern MonitorList mon_list;\n> > \n> > -void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,\n> > - bool use_io_thread);\n> > +void monitor_data_init(Monitor *mon, bool is_qmp, bool use_io_thread);\n> > void monitor_data_destroy(Monitor *mon);\n> > int monitor_can_read(void *opaque);\n> > void monitor_list_append(Monitor *mon);\n> > diff --git a/monitor/monitor.c b/monitor/monitor.c\n> > index 7936e2ab22..f7e3708d2f 100644\n> > --- a/monitor/monitor.c\n> > +++ b/monitor/monitor.c\n> > @@ -167,7 +167,12 @@ void monitor_flush_locked(Monitor *mon)\n> > size_t len;\n> > const char *buf;\n> > \n> > - if (mon->skip_flush) {\n> > + /*\n> > + * When used by QMP human-monitor-command, no chardev\n> > + * will be connected, as we want to just collect the\n> > + * output in the buffer\n> > + */\n> > + if (!mon->chr.fe_is_open) {\n> > return;\n> > }\n> > \n> > @@ -621,8 +626,7 @@ static void monitor_iothread_init(void)\n> > mon_iothread = iothread_create(\"mon_iothread\", &error_abort);\n> > }\n> > \n> > -void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,\n> > - bool use_io_thread)\n> > +void monitor_data_init(Monitor *mon, bool is_qmp, bool use_io_thread)\n> > {\n> > if (use_io_thread && !mon_iothread) {\n> > monitor_iothread_init();\n> > @@ -630,7 +634,6 @@ void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,\n> > qemu_mutex_init(&mon->mon_lock);\n> > mon->is_qmp = is_qmp;\n> > mon->outbuf = g_string_new(NULL);\n> > - mon->skip_flush = skip_flush;\n> > mon->use_io_thread = use_io_thread;\n> > }\n> > \n> > diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c\n> > index d0ed241d6a..be2bd985b7 100644\n> > --- a/monitor/qmp-cmds.c\n> > +++ b/monitor/qmp-cmds.c\n> > @@ -168,7 +168,7 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,\n> > char *output = NULL;\n> > MonitorHMP *hmp = MONITOR_HMP(object_new(TYPE_MONITOR_HMP));\n> > \n> > - monitor_data_init(&hmp->parent, false, true, false);\n> > + monitor_data_init(&hmp->parent, false, false);\n> > \n> > if (has_cpu_index) {\n> > int ret = monitor_set_cpu(&hmp->parent, cpu_index);\n> > diff --git a/monitor/qmp.c b/monitor/qmp.c\n> > index 36cb078f30..fe2aec9ce9 100644\n> > --- a/monitor/qmp.c\n> > +++ b/monitor/qmp.c\n> > @@ -538,7 +538,7 @@ void monitor_new_qmp(Chardev *chr, bool pretty, Error **errp)\n> > qemu_chr_fe_set_echo(&mon->parent.chr, true);\n> > \n> > /* Note: we run QMP monitor in I/O thread when @chr supports that */\n> > - monitor_data_init(&mon->parent, true, false,\n> > + monitor_data_init(&mon->parent, true,\n> > qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT));\n> > \n> > mon->pretty = pretty;\n> > -- \n> > 2.53.0\n> > \n> -- \n> -----Open up your eyes, open up your mind, open up your code ------- \n> / Dr. David Alan Gilbert | Running GNU/Linux | Happy \\ \n> \\ dave @ treblig.org | | In Hex /\n> \\ _________________________|_____ http://www.treblig.org |_______/\n> \n\nWith regards,\nDaniel","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=b0TW/Lsl;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists1p.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)"],"Received":["from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fvNG22kPZz1xtJ\n\tfor ; Mon, 13 Apr 2026 20:00:58 +1000 (AEST)","from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists1p.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1wCE62-0004Ke-Sq; Mon, 13 Apr 2026 06:00:46 -0400","from eggs.gnu.org ([2001:470:142:3::10])\n by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wCE5y-0004IL-5h\n for qemu-devel@nongnu.org; Mon, 13 Apr 2026 06:00:43 -0400","from us-smtp-delivery-124.mimecast.com ([170.10.129.124])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wCE5r-0003bI-KD\n for qemu-devel@nongnu.org; Mon, 13 Apr 2026 06:00:40 -0400","from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com\n (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by\n relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3,\n cipher=TLS_AES_256_GCM_SHA384) id us-mta-683-ebbZnXXwOMCbVKfj6N9NWg-1; Mon,\n 13 Apr 2026 06:00:29 -0400","from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com\n (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest\n SHA256)\n (No client certificate requested)\n by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS\n id 1E3021800741; Mon, 13 Apr 2026 10:00:28 +0000 (UTC)","from redhat.com (headnet01.pony-001.prod.iad2.dc.redhat.com\n [10.2.32.101])\n by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with\n ESMTPS\n id BF8181800594; Mon, 13 Apr 2026 10:00:24 +0000 (UTC)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1776074433;\n h=from:from:reply-to:reply-to:subject:subject:date:date:\n message-id:message-id:to:to:cc:cc:mime-version:mime-version:\n content-type:content-type:\n content-transfer-encoding:content-transfer-encoding:\n in-reply-to:in-reply-to:references:references;\n bh=v8IIXypvTFSbFFYLtuWzV10yJ6eGgj1z63sXTkL82/k=;\n b=b0TW/LslGIcPYly6ku7Aj/ZjtntyzLbA//28khPp9TDBKUkPa6WpnDSm+TdwOB4Dju4OqT\n Bksp4Dy5ZqnXHmtlIy4fs6MXsgb6PulHtP8oBwvsOevK5Rleu4Z6862Ao7d18uzU7bI9Ye\n TIOflf+Fcdq0ap6L8f/pjgyiFfydqiE=","X-MC-Unique":"ebbZnXXwOMCbVKfj6N9NWg-1","X-Mimecast-MFC-AGG-ID":"ebbZnXXwOMCbVKfj6N9NWg_1776074428","Date":"Mon, 13 Apr 2026 11:00:21 +0100","From":"Daniel =?utf-8?b?UC4gQmVycmFuZ8Op?= ","To":"\"Dr. David Alan Gilbert\" ","Cc":"qemu-devel@nongnu.org, Paolo Bonzini ,\n Markus Armbruster ,\n Christian Brauner ,\n Alex =?utf-8?q?Benn=C3=A9e?= , Philippe =?utf-8?q?M?=\n\t=?utf-8?q?athieu-Daud=C3=A9?= ,\n Fabiano Rosas ,\n =?utf-8?q?Marc-Andr=C3=A9?= Lureau ,\n Peter Xu , Kevin Wolf ,\n qemu-block@nongnu.org, Eric Blake ","Subject":"Re: [PATCH 05/17] monitor: remove 'skip_flush' field","Message-ID":"","References":"<20260410160458.3778874-1-berrange@redhat.com>\n <20260410160458.3778874-6-berrange@redhat.com>\n ","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","Content-Transfer-Encoding":"8bit","In-Reply-To":"","User-Agent":"Mutt/2.2.14 (2025-02-20)","X-Scanned-By":"MIMEDefang 3.4.1 on 10.30.177.111","Received-SPF":"pass client-ip=170.10.129.124;\n envelope-from=berrange@redhat.com;\n helo=us-smtp-delivery-124.mimecast.com","X-Spam_score_int":"-25","X-Spam_score":"-2.6","X-Spam_bar":"--","X-Spam_report":"(-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.54,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001,\n 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":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Reply-To":"Daniel =?utf-8?b?UC4gQmVycmFuZ8Op?= ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"}},{"id":3676819,"web_url":"http://patchwork.ozlabs.org/comment/3676819/","msgid":"","list_archive_url":null,"date":"2026-04-13T15:22:54","subject":"Re: [PATCH 05/17] monitor: remove 'skip_flush' field","submitter":{"id":86099,"url":"http://patchwork.ozlabs.org/api/people/86099/","name":"Dr. David Alan Gilbert","email":"dave@treblig.org"},"content":"* Daniel P. Berrangé (berrange@redhat.com) wrote:\n> On Mon, Apr 13, 2026 at 01:28:13AM +0000, Dr. David Alan Gilbert wrote:\n> > * Daniel P. Berrangé (berrange@redhat.com) wrote:\n> > > The 'skip_flush' field is set on the dummy throwaway HMP monitor\n> > > object created by QMP's 'human-monitor-command', as an indication\n> > > not to try to write data to the chardev. Instead the QMP command\n> > > impl will grab the data straight out of the in-memory buffer.\n> > > \n> > > The flag is redundant, however, as the monitor code could instead\n> > > simply check the 'fe_is_open' field on the CharFrontend, which\n> > > will be false in the same scenarios that 'skip_flush' is true.\n> > \n> > For monitors on sockets where the other end isn't connected, does that\n> > change the behaviour? Does that also have !fe_is_open and can that hit this\n> > case?\n> \n> The only place that sets fe_is_open is qemu_chr_fe_set_open,\n> which is called by qemu_chr_fe_set_handlers_full.\n> \n> IOW, it merely reflects the fact that some frontend (the\n> monitor in this case) and configured the chardev for use,\n> and is separate from any notion of whether the chardev\n> backend is open/connected.\n\nAh ok, in which case,\n\n\nReviewed-by: Dr. David Alan Gilbert \n\n> \n> \n> \n> > \n> > Dave\n> > \n> > > Signed-off-by: Daniel P. Berrangé \n> > > ---\n> > > monitor/hmp.c | 2 +-\n> > > monitor/monitor-internal.h | 4 +---\n> > > monitor/monitor.c | 11 +++++++----\n> > > monitor/qmp-cmds.c | 2 +-\n> > > monitor/qmp.c | 2 +-\n> > > 5 files changed, 11 insertions(+), 10 deletions(-)\n> > > \n> > > diff --git a/monitor/hmp.c b/monitor/hmp.c\n> > > index 614d9a3707..72f8303662 100644\n> > > --- a/monitor/hmp.c\n> > > +++ b/monitor/hmp.c\n> > > @@ -1539,7 +1539,7 @@ void monitor_new_hmp(Chardev *chr, bool use_readline, Error **errp)\n> > > return;\n> > > }\n> > > \n> > > - monitor_data_init(&mon->parent, false, false, false);\n> > > + monitor_data_init(&mon->parent, false, false);\n> > > \n> > > mon->use_readline = use_readline;\n> > > if (mon->use_readline) {\n> > > diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h\n> > > index 25320928a7..84117805b7 100644\n> > > --- a/monitor/monitor-internal.h\n> > > +++ b/monitor/monitor-internal.h\n> > > @@ -102,7 +102,6 @@ struct Monitor {\n> > > CharFrontend chr;\n> > > int suspend_cnt; /* Needs to be accessed atomically */\n> > > bool is_qmp;\n> > > - bool skip_flush;\n> > > bool use_io_thread;\n> > > \n> > > char *mon_cpu_path;\n> > > @@ -183,8 +182,7 @@ extern QmpCommandList qmp_commands, qmp_cap_negotiation_commands;\n> > > extern QemuMutex monitor_lock;\n> > > extern MonitorList mon_list;\n> > > \n> > > -void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,\n> > > - bool use_io_thread);\n> > > +void monitor_data_init(Monitor *mon, bool is_qmp, bool use_io_thread);\n> > > void monitor_data_destroy(Monitor *mon);\n> > > int monitor_can_read(void *opaque);\n> > > void monitor_list_append(Monitor *mon);\n> > > diff --git a/monitor/monitor.c b/monitor/monitor.c\n> > > index 7936e2ab22..f7e3708d2f 100644\n> > > --- a/monitor/monitor.c\n> > > +++ b/monitor/monitor.c\n> > > @@ -167,7 +167,12 @@ void monitor_flush_locked(Monitor *mon)\n> > > size_t len;\n> > > const char *buf;\n> > > \n> > > - if (mon->skip_flush) {\n> > > + /*\n> > > + * When used by QMP human-monitor-command, no chardev\n> > > + * will be connected, as we want to just collect the\n> > > + * output in the buffer\n> > > + */\n> > > + if (!mon->chr.fe_is_open) {\n> > > return;\n> > > }\n> > > \n> > > @@ -621,8 +626,7 @@ static void monitor_iothread_init(void)\n> > > mon_iothread = iothread_create(\"mon_iothread\", &error_abort);\n> > > }\n> > > \n> > > -void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,\n> > > - bool use_io_thread)\n> > > +void monitor_data_init(Monitor *mon, bool is_qmp, bool use_io_thread)\n> > > {\n> > > if (use_io_thread && !mon_iothread) {\n> > > monitor_iothread_init();\n> > > @@ -630,7 +634,6 @@ void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,\n> > > qemu_mutex_init(&mon->mon_lock);\n> > > mon->is_qmp = is_qmp;\n> > > mon->outbuf = g_string_new(NULL);\n> > > - mon->skip_flush = skip_flush;\n> > > mon->use_io_thread = use_io_thread;\n> > > }\n> > > \n> > > diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c\n> > > index d0ed241d6a..be2bd985b7 100644\n> > > --- a/monitor/qmp-cmds.c\n> > > +++ b/monitor/qmp-cmds.c\n> > > @@ -168,7 +168,7 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,\n> > > char *output = NULL;\n> > > MonitorHMP *hmp = MONITOR_HMP(object_new(TYPE_MONITOR_HMP));\n> > > \n> > > - monitor_data_init(&hmp->parent, false, true, false);\n> > > + monitor_data_init(&hmp->parent, false, false);\n> > > \n> > > if (has_cpu_index) {\n> > > int ret = monitor_set_cpu(&hmp->parent, cpu_index);\n> > > diff --git a/monitor/qmp.c b/monitor/qmp.c\n> > > index 36cb078f30..fe2aec9ce9 100644\n> > > --- a/monitor/qmp.c\n> > > +++ b/monitor/qmp.c\n> > > @@ -538,7 +538,7 @@ void monitor_new_qmp(Chardev *chr, bool pretty, Error **errp)\n> > > qemu_chr_fe_set_echo(&mon->parent.chr, true);\n> > > \n> > > /* Note: we run QMP monitor in I/O thread when @chr supports that */\n> > > - monitor_data_init(&mon->parent, true, false,\n> > > + monitor_data_init(&mon->parent, true,\n> > > qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT));\n> > > \n> > > mon->pretty = pretty;\n> > > -- \n> > > 2.53.0\n> > > \n> > -- \n> > -----Open up your eyes, open up your mind, open up your code ------- \n> > / Dr. David Alan Gilbert | Running GNU/Linux | Happy \\ \n> > \\ dave @ treblig.org | | In Hex /\n> > \\ _________________________|_____ http://www.treblig.org |_______/\n> > \n> \n> With regards,\n> Daniel\n> -- \n> |: https://berrange.com ~~ https://hachyderm.io/@berrange :|\n> |: https://libvirt.org ~~ https://entangle-photo.org :|\n> |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|\n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=treblig.org header.i=@treblig.org header.a=rsa-sha256\n header.s=bytemarkmx header.b=W3K0d5AS;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists1p.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)"],"Received":["from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fvWQk72tXz1y2d\n\tfor ; Tue, 14 Apr 2026 01:23:57 +1000 (AEST)","from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists1p.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1wCJ7y-0005R7-Kd; Mon, 13 Apr 2026 11:23:06 -0400","from eggs.gnu.org ([2001:470:142:3::10])\n by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wCJ7w-0005Qg-32; Mon, 13 Apr 2026 11:23:04 -0400","from mx.treblig.org ([2a00:1098:5b::1])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wCJ7q-0008Nk-9D; Mon, 13 Apr 2026 11:23:00 -0400","from dg by mx.treblig.org with local (Exim 4.98.2)\n (envelope-from ) id 1wCJ7m-000000081Ul-1xVC;\n Mon, 13 Apr 2026 15:22:54 +0000"],"DKIM-Signature":"v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=treblig.org\n ; s=bytemarkmx;\n h=Content-Type:MIME-Version:Message-ID:Subject:From:Date:From\n :Subject; bh=tTucvl7BRw4RPnkprViEL7BGBp/YOb1uNjVLYq4B8/I=; b=W3K0d5ASN7fSLnbj\n PMttQ8+ms2o3DC22evWol+o/MQefT1QAXn46q4S5KlbTLYxTzKufE8kXxDUr/QZQyIdbprPIDiemC\n /wwe2GsfzEk6gO6GYwXI1SJ+c/EGRjzpQD6Ob8JFIuQLAlVvKOZqAsztDxMC+fdLvWGRTqBA23Xsz\n q/cAmu7w7Bzi4OO+e8BuzC4lGomMlsKlZ1I1A8tlVtgY7VQ3y1mjUTeMZBrQSR1MENIE7kW/8tseN\n 5sxZsyTqPn8xq9TmFzWNXlv0FsOuOAUjdnH560+Kr5b1TLdTaxH6qg3urJesO2MLV+tkiTGZgP2LA\n riQFQdVEH8kZ/81a9Q==;","Date":"Mon, 13 Apr 2026 15:22:54 +0000","From":"\"Dr. David Alan Gilbert\" ","To":"Daniel =?iso-8859-1?q?P=2E_Berrang=E9?= ","Cc":"qemu-devel@nongnu.org, Paolo Bonzini ,\n Markus Armbruster ,\n Christian Brauner ,\n Alex =?iso-8859-1?q?Benn=E9e?= , Philippe\n\t=?iso-8859-1?q?Mathieu-Daud=E9?= ,\n Fabiano Rosas ,\n =?iso-8859-1?q?Marc-Andr=E9?= Lureau ,\n Peter Xu , Kevin Wolf ,\n qemu-block@nongnu.org, Eric Blake ","Subject":"Re: [PATCH 05/17] monitor: remove 'skip_flush' field","Message-ID":"","References":"<20260410160458.3778874-1-berrange@redhat.com>\n <20260410160458.3778874-6-berrange@redhat.com>\n ","MIME-Version":"1.0","Content-Type":"text/plain; charset=iso-8859-1","Content-Disposition":"inline","Content-Transfer-Encoding":"8bit","In-Reply-To":"","X-Chocolate":"70 percent or better cocoa solids preferably","X-Operating-System":"Linux/6.12.74+deb13+1-amd64 (x86_64)","X-Uptime":"15:22:46 up 31 days, 16:36, 2 users, load average: 0.02, 0.05,\n 0.01","User-Agent":"Mutt/2.2.13 (2024-03-09)","Received-SPF":"pass client-ip=2a00:1098:5b::1; envelope-from=dg@treblig.org;\n helo=mx.treblig.org","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, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001,\n 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":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"}}]