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 927A2CAC592 for ; Fri, 19 Sep 2025 12:46:08 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uzaT5-0003gE-0g; Fri, 19 Sep 2025 08:44:03 -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 1uzaT3-0003fE-Qm for qemu-devel@nongnu.org; Fri, 19 Sep 2025 08:44:01 -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 1uzaSx-0003I6-6F for qemu-devel@nongnu.org; Fri, 19 Sep 2025 08:43:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758285829; 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=cZH6M/G8z9UjjpH8Vku58fpTVtFVYrf5nk3lrykAhzw=; b=hYwxdTovW6m6LCtSKBfhyZEQ1wk628ele/ZJHpsDyC4FkrLpMUFPjXUFqdaW1wX+HYILrr HJ58Ht0OGgadrem/uO15x3EyHmksKanVk0r+OhEAlP8YQdcD06KPQFXqv3UDJB2cYTr/NJ L0C/XydxBfpwnj9ggKLhgi8KOA6REXY= 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-576-imrxfF8OOhyS_cPHXcTYOw-1; Fri, 19 Sep 2025 08:43:46 -0400 X-MC-Unique: imrxfF8OOhyS_cPHXcTYOw-1 X-Mimecast-MFC-AGG-ID: imrxfF8OOhyS_cPHXcTYOw_1758285825 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 AAECC19560B1; Fri, 19 Sep 2025 12:43:44 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.33]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 386ED1955F21; Fri, 19 Sep 2025 12:43:44 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 7C17421E6A27; Fri, 19 Sep 2025 14:43:41 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Hanna Reitz , Kevin Wolf , =?utf-8?Q?Marc-Andr?= =?utf-8?Q?=C3=A9?= Lureau , Christian Schoenebeck , Richard Henderson , Manos Pitsidianakis , Stefan Weil , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Gerd Hoffmann , Paolo Bonzini , "Dr. David Alan Gilbert" Subject: Re: [PATCH v3 12/20] monitor: introduce monitor_cur_hmp() function In-Reply-To: <20250910180357.320297-13-berrange@redhat.com> ("Daniel P. =?utf-8?Q?Berrang=C3=A9=22's?= message of "Wed, 10 Sep 2025 19:03:49 +0100") References: <20250910180357.320297-1-berrange@redhat.com> <20250910180357.320297-13-berrange@redhat.com> Date: Fri, 19 Sep 2025 14:43:41 +0200 Message-ID: <87zfaqwr2a.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 3.0 on 10.30.177.17 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: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.105, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_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 Daniel P. Berrang=C3=A9 writes: > A number of callers use monitor_cur() followed by !monitor_cur_is_qmp(). "A number of"? I can see just one: int error_vprintf(const char *fmt, va_list ap) { Monitor *cur_mon =3D monitor_cur(); if (cur_mon && !monitor_cur_is_qmp()) { return monitor_vprintf(cur_mon, fmt, ap); } return vfprintf(stderr, fmt, ap); } > This is undesirable because monitor_cur_is_qmp() will itself call > monitor_cur() again, and monitor_cur() must acquire locks and do > hash table lookups. Introducing a monitor_cur_hmp() helper will > combine the two operations into one reducing cost. This made me expect the patch replaces the undesirable uses. It does not; the new function remains unused for now. > Signed-off-by: Daniel P. Berrang=C3=A9 > --- > include/monitor/monitor.h | 1 + > monitor/monitor.c | 14 ++++++++++++++ > stubs/monitor-core.c | 5 +++++ > tests/unit/test-util-sockets.c | 1 + > 4 files changed, 21 insertions(+) > > diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h > index 296690e1f1..c3b79b960a 100644 > --- a/include/monitor/monitor.h > +++ b/include/monitor/monitor.h > @@ -14,6 +14,7 @@ typedef struct MonitorOptions MonitorOptions; > extern QemuOptsList qemu_mon_opts; >=20=20 > Monitor *monitor_cur(void); > +Monitor *monitor_cur_hmp(void); > Monitor *monitor_set_cur(Coroutine *co, Monitor *mon); > bool monitor_cur_is_qmp(void); >=20=20 > diff --git a/monitor/monitor.c b/monitor/monitor.c > index e1e5dbfcbe..cff502c53e 100644 > --- a/monitor/monitor.c > +++ b/monitor/monitor.c > @@ -84,6 +84,20 @@ Monitor *monitor_cur(void) > return mon; > } >=20=20 > +Monitor *monitor_cur_hmp(void) > +{ > + Monitor *mon; > + > + qemu_mutex_lock(&monitor_lock); > + mon =3D g_hash_table_lookup(coroutine_mon, qemu_coroutine_self()); > + if (mon && monitor_is_qmp(mon)) { > + mon =3D NULL; > + } > + qemu_mutex_unlock(&monitor_lock); > + > + return mon; > +} > + > /** > * Sets a new current monitor and returns the old one. > * > diff --git a/stubs/monitor-core.c b/stubs/monitor-core.c > index b498a0f1af..1e0b11ec29 100644 > --- a/stubs/monitor-core.c > +++ b/stubs/monitor-core.c > @@ -7,6 +7,11 @@ Monitor *monitor_cur(void) > return NULL; > } >=20=20 > +Monitor *monitor_cur_hmp(void) > +{ > + return NULL; > +} > + > bool monitor_cur_is_qmp(void) > { > return false; > diff --git a/tests/unit/test-util-sockets.c b/tests/unit/test-util-socket= s.c > index bd48731ea2..d40813c682 100644 > --- a/tests/unit/test-util-sockets.c > +++ b/tests/unit/test-util-sockets.c > @@ -72,6 +72,7 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Er= ror **errp) > * otherwise we get duplicate syms at link time. > */ > Monitor *monitor_cur(void) { return cur_mon; } > +Monitor *monitor_cur_hmp(void) { return cur_mon; } @cur_mon is a fake here. Why do you make this fake monitor HMP? If we somehow call error_vprintf(), it'll call monitor_vprintf(), which will dereference the fake monitor. Best possible outcome would be an immediate crash. > bool monitor_cur_is_qmp(void) { return false; } > Monitor *monitor_set_cur(Coroutine *co, Monitor *mon) { abort(); } > int monitor_vprintf(Monitor *mon, const char *fmt, va_list ap) { abort()= ; }