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 9CB8DC61DA4 for ; Tue, 14 Feb 2023 14:14:47 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pRvRK-0000mM-Nv; Tue, 14 Feb 2023 08:33:46 -0500 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 1pRvRG-0000lh-Uk for qemu-devel@nongnu.org; Tue, 14 Feb 2023 08:33:44 -0500 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 1pRvRE-0006R5-L9 for qemu-devel@nongnu.org; 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Tue, 14 Feb 2023 13:33:37 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.13]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C9294400D927; Tue, 14 Feb 2023 13:33:36 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id B3D5421E6A1F; Tue, 14 Feb 2023 14:33:35 +0100 (CET) From: Markus Armbruster To: marcandre.lureau@redhat.com Cc: qemu-devel@nongnu.org, Beraldo Leal , Eric Blake , Stefan Weil , Alex =?utf-8?Q?Benn?= =?utf-8?Q?=C3=A9e?= , Paolo Bonzini , Laurent Vivier , "Dr. David Alan Gilbert" , Gerd Hoffmann , Michael Roth , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Daniel P. =?utf-8?Q?Berrang=C3=A9?= , Thomas Huth , Wainer dos Santos Moschetta Subject: Re: [PATCH v3 06/10] monitor: release the lock before calling close() References: <20230207142535.1153722-1-marcandre.lureau@redhat.com> <20230207142535.1153722-7-marcandre.lureau@redhat.com> Date: Tue, 14 Feb 2023 14:33:35 +0100 In-Reply-To: <20230207142535.1153722-7-marcandre.lureau@redhat.com> (marcandre lureau's message of "Tue, 7 Feb 2023 18:25:31 +0400") Message-ID: <873578id74.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, 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_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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: 2.1.29 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 marcandre.lureau@redhat.com writes: > From: Marc-Andr=C3=A9 Lureau > > As per comment, presumably to avoid syscall in critical section. > > Fixes: 0210c3b39bef08 ("monitor: Use LOCK_GUARD macros") > Signed-off-by: Marc-Andr=C3=A9 Lureau > --- > monitor/fds.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/monitor/fds.c b/monitor/fds.c > index 26b39a0ce6..03c5e97c35 100644 > --- a/monitor/fds.c > +++ b/monitor/fds.c > @@ -80,7 +80,7 @@ void qmp_getfd(const char *fdname, Error **errp) > return; > } >=20=20 > - QEMU_LOCK_GUARD(&cur_mon->mon_lock); > + qemu_mutex_lock(&cur_mon->mon_lock); > QLIST_FOREACH(monfd, &cur_mon->fds, next) { > if (strcmp(monfd->name, fdname) !=3D 0) { > continue; > @@ -88,6 +88,7 @@ void qmp_getfd(const char *fdname, Error **errp) >=20=20 > tmp_fd =3D monfd->fd; > monfd->fd =3D fd; > + qemu_mutex_unlock(&cur_mon->mon_lock); > /* Make sure close() is outside critical section */ > close(tmp_fd); > return; > @@ -98,6 +99,7 @@ void qmp_getfd(const char *fdname, Error **errp) > monfd->fd =3D fd; >=20=20 > QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next); > + qemu_mutex_unlock(&cur_mon->mon_lock); > } >=20=20 > void qmp_closefd(const char *fdname, Error **errp) This confused me. I think I understand now, but let's double-check. You're reverting commit 0210c3b39bef08 for qmp_getfd() because it extended the criticial section beyond the close(), invalidating the comment. Correct? Did it actually break anything?