From nobody Mon Feb 9 12:10:21 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1520586852182850.9016941780441; Fri, 9 Mar 2018 01:14:12 -0800 (PST) Received: from localhost ([::1]:43926 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1euE6N-0001e4-C6 for importer@patchew.org; Fri, 09 Mar 2018 04:14:11 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41779) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1euDtz-0008AR-OE for qemu-devel@nongnu.org; Fri, 09 Mar 2018 04:01:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1euDty-0008Da-Pz for qemu-devel@nongnu.org; Fri, 09 Mar 2018 04:01:23 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:39642 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1euDty-0008DE-KC for qemu-devel@nongnu.org; Fri, 09 Mar 2018 04:01:22 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B97DD8424D; Fri, 9 Mar 2018 09:01:21 +0000 (UTC) Received: from xz-mi.redhat.com (ovpn-12-92.pek2.redhat.com [10.72.12.92]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6185A202322A; Fri, 9 Mar 2018 09:01:17 +0000 (UTC) From: Peter Xu To: qemu-devel@nongnu.org Date: Fri, 9 Mar 2018 16:59:55 +0800 Message-Id: <20180309090006.10018-13-peterx@redhat.com> In-Reply-To: <20180309090006.10018-1-peterx@redhat.com> References: <20180309090006.10018-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 09 Mar 2018 09:01:21 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 09 Mar 2018 09:01:21 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'peterx@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH v8 12/23] monitor: let suspend_cnt be thread safe X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Fam Zheng , Juan Quintela , mdroth@linux.vnet.ibm.com, peterx@redhat.com, Markus Armbruster , marcandre.lureau@redhat.com, Stefan Hajnoczi , Paolo Bonzini , "Dr . David Alan Gilbert" Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Monitor code now can be run in more than one thread. Let it be thread safe when accessing suspend_cnt counter. Reviewed-by: Eric Blake Reviewed-by: Stefan Hajnoczi Signed-off-by: Peter Xu --- monitor.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/monitor.c b/monitor.c index 6959e963e2..71b696c8f3 100644 --- a/monitor.c +++ b/monitor.c @@ -194,7 +194,7 @@ struct Monitor { CharBackend chr; int reset_seen; int flags; - int suspend_cnt; + int suspend_cnt; /* Needs to be accessed atomically */ bool skip_flush; bool use_io_thr; =20 @@ -3816,7 +3816,7 @@ static int monitor_can_read(void *opaque) { Monitor *mon =3D opaque; =20 - return (mon->suspend_cnt =3D=3D 0) ? 1 : 0; + return !atomic_mb_read(&mon->suspend_cnt); } =20 /* @@ -3948,7 +3948,7 @@ int monitor_suspend(Monitor *mon) { if (!mon->rs) return -ENOTTY; - mon->suspend_cnt++; + atomic_inc(&mon->suspend_cnt); return 0; } =20 @@ -3956,8 +3956,9 @@ void monitor_resume(Monitor *mon) { if (!mon->rs) return; - if (--mon->suspend_cnt =3D=3D 0) + if (atomic_dec_fetch(&mon->suspend_cnt) =3D=3D 0) { readline_show_prompt(mon->rs); + } } =20 static QObject *get_qmp_greeting(Monitor *mon) @@ -4022,19 +4023,19 @@ static void monitor_event(void *opaque, int event) monitor_resume(mon); monitor_flush(mon); } else { - mon->suspend_cnt =3D 0; + atomic_mb_set(&mon->suspend_cnt, 0); } break; =20 case CHR_EVENT_MUX_OUT: if (mon->reset_seen) { - if (mon->suspend_cnt =3D=3D 0) { + if (atomic_mb_read(&mon->suspend_cnt) =3D=3D 0) { monitor_printf(mon, "\n"); } monitor_flush(mon); monitor_suspend(mon); } else { - mon->suspend_cnt++; + atomic_inc(&mon->suspend_cnt); } qemu_mutex_lock(&mon->out_lock); mon->mux_out =3D 1; --=20 2.14.3