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Mon, 6 Mar 2023 15:44:25 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.193.92]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3F0C9440DF; Mon, 6 Mar 2023 15:44:25 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 2077121E6A1F; Mon, 6 Mar 2023 16:44:24 +0100 (CET) From: Markus Armbruster To: Markus Armbruster Cc: marcandre.lureau@redhat.com, qemu-devel@nongnu.org, Thomas Huth , Gerd Hoffmann , Alex =?utf-8?Q?B?= =?utf-8?Q?enn=C3=A9e?= , Michael Roth , Paolo Bonzini , Laurent Vivier , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Beraldo Leal , Wainer dos Santos Moschetta , Stefan Weil , Daniel P. =?utf-8?Q?Berrang=C3=A9?= , Eric Blake , "Dr. David Alan Gilbert" Subject: Re: [PATCH v4 06/11] monitor: release the lock before calling close() References: <20230306122751.2355515-1-marcandre.lureau@redhat.com> <20230306122751.2355515-7-marcandre.lureau@redhat.com> <87v8jdj3u3.fsf@pond.sub.org> Date: Mon, 06 Mar 2023 16:44:24 +0100 In-Reply-To: <87v8jdj3u3.fsf@pond.sub.org> (Markus Armbruster's message of "Mon, 06 Mar 2023 16:29:24 +0100") Message-ID: <874jqxj353.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 10.11.54.5 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 Markus Armbruster writes: > 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 >> Reviewed-by: Philippe Mathieu-Daud=C3=A9 >> --- >> monitor/fds.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/monitor/fds.c b/monitor/fds.c >> index 26b39a0ce6..7daf1064e1 100644 >> --- a/monitor/fds.c >> +++ b/monitor/fds.c >> @@ -80,7 +80,8 @@ void qmp_getfd(const char *fdname, Error **errp) >> return; >> } >>=20=20 >> - QEMU_LOCK_GUARD(&cur_mon->mon_lock); >> + /* See close() call below. */ >> + qemu_mutex_lock(&cur_mon->mon_lock); >> QLIST_FOREACH(monfd, &cur_mon->fds, next) { >> if (strcmp(monfd->name, fdname) !=3D 0) { >> continue; >> @@ -88,6 +89,7 @@ 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; > > Not changed by your patch, but odd: when no fd named @fdname exists, the > command does nothing silently. Shouldn't it fail then? Alex confused me. Ignore this. >> @@ -98,6 +100,7 @@ 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) > > Alex suggested a different way to do this in reply to v3 of this patch. > Please have a look and reply there.