From nobody Wed Nov 5 15:09:07 2025 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 1534940165227486.67325845364803; Wed, 22 Aug 2018 05:16:05 -0700 (PDT) Received: from localhost ([::1]:58722 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fsS3Q-00047Q-4P for importer@patchew.org; Wed, 22 Aug 2018 08:16:04 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39117) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fsRpX-00070M-LS for qemu-devel@nongnu.org; Wed, 22 Aug 2018 08:01:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fsRpV-0000IN-PT for qemu-devel@nongnu.org; Wed, 22 Aug 2018 08:01:43 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:46218 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 1fsRpV-0000Hu-GL for qemu-devel@nongnu.org; Wed, 22 Aug 2018 08:01:41 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 07F0C7A7ED; Wed, 22 Aug 2018 12:01:41 +0000 (UTC) Received: from secure.mitica (ovpn-116-35.ams2.redhat.com [10.36.116.35]) by smtp.corp.redhat.com (Postfix) with ESMTP id EDF7EA9E68; Wed, 22 Aug 2018 12:01:36 +0000 (UTC) From: Juan Quintela To: qemu-devel@nongnu.org Date: Wed, 22 Aug 2018 14:00:50 +0200 Message-Id: <20180822120050.12694-21-quintela@redhat.com> In-Reply-To: <20180822120050.12694-1-quintela@redhat.com> References: <20180822120050.12694-1-quintela@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 22 Aug 2018 12:01:41 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 22 Aug 2018 12:01:41 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'quintela@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 20/20] migration: hold the lock only if it is really needed 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: lvivier@redhat.com, Xiao Guangrong , dgilbert@redhat.com, peterx@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RDMRC_1 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Xiao Guangrong Try to hold src_page_req_mutex only if the queue is not empty Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Peter Xu Signed-off-by: Xiao Guangrong Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- include/qemu/queue.h | 1 + migration/ram.c | 4 ++++ 2 files changed, 5 insertions(+) diff --git a/include/qemu/queue.h b/include/qemu/queue.h index 59fd1203a1..ac418efc43 100644 --- a/include/qemu/queue.h +++ b/include/qemu/queue.h @@ -341,6 +341,7 @@ struct { = \ /* * Simple queue access methods. */ +#define QSIMPLEQ_EMPTY_ATOMIC(head) (atomic_read(&((head)->sqh_first)) =3D= =3D NULL) #define QSIMPLEQ_EMPTY(head) ((head)->sqh_first =3D=3D NULL) #define QSIMPLEQ_FIRST(head) ((head)->sqh_first) #define QSIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next) diff --git a/migration/ram.c b/migration/ram.c index 40013e68a1..79c89425a3 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2033,6 +2033,10 @@ static RAMBlock *unqueue_page(RAMState *rs, ram_addr= _t *offset) { RAMBlock *block =3D NULL; =20 + if (QSIMPLEQ_EMPTY_ATOMIC(&rs->src_page_requests)) { + return NULL; + } + qemu_mutex_lock(&rs->src_page_req_mutex); if (!QSIMPLEQ_EMPTY(&rs->src_page_requests)) { struct RAMSrcPageRequest *entry =3D --=20 2.17.1