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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E89FC7618B for ; Fri, 26 Jul 2019 09:11:54 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 143E42238C for ; Fri, 26 Jul 2019 09:11:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 143E42238C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37594 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqwGW-0005tq-AO for qemu-devel@archiver.kernel.org; Fri, 26 Jul 2019 05:11:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60565) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqwGA-0004b4-9U for qemu-devel@nongnu.org; Fri, 26 Jul 2019 05:11:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hqwG8-0004zO-3w for qemu-devel@nongnu.org; Fri, 26 Jul 2019 05:11:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36978) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hqwG7-0004sb-T2 for qemu-devel@nongnu.org; Fri, 26 Jul 2019 05:11:28 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3E4508665A for ; Fri, 26 Jul 2019 09:11:26 +0000 (UTC) Received: from localhost (ovpn-117-212.ams2.redhat.com [10.36.117.212]) by smtp.corp.redhat.com (Postfix) with ESMTP id C6D211001938; Fri, 26 Jul 2019 09:11:25 +0000 (UTC) From: Stefan Hajnoczi To: virtio-fs@redhat.com, qemu-devel@nongnu.org Date: Fri, 26 Jul 2019 10:11:01 +0100 Message-Id: <20190726091103.23503-4-stefanha@redhat.com> In-Reply-To: <20190726091103.23503-1-stefanha@redhat.com> References: <20190726091103.23503-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 26 Jul 2019 09:11:26 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 3/5] virtiofsd: make lo_release() atomic X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Dr. David Alan Gilbert" , Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hold the lock across both lo_map_get() and lo_map_remove() to prevent races between two FUSE_RELEASE requests. In this case I don't see a serious bug but it's safer to do things atomically. Signed-off-by: Stefan Hajnoczi --- contrib/virtiofsd/passthrough_ll.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passt= hrough_ll.c index 277a17fc03..c1500e092d 100644 --- a/contrib/virtiofsd/passthrough_ll.c +++ b/contrib/virtiofsd/passthrough_ll.c @@ -1759,14 +1759,18 @@ static void lo_open(fuse_req_t req, fuse_ino_t in= o, struct fuse_file_info *fi) static void lo_release(fuse_req_t req, fuse_ino_t ino, struct fuse_file_= info *fi) { struct lo_data *lo =3D lo_data(req); - int fd; + struct lo_map_elem *elem; + int fd =3D -1; =20 (void) ino; =20 - fd =3D lo_fi_fd(req, fi); - pthread_mutex_lock(&lo->mutex); - lo_map_remove(&lo->fd_map, fi->fh); + elem =3D lo_map_get(&lo->fd_map, fi->fh); + if (elem) { + fd =3D elem->fd; + elem =3D NULL; + lo_map_remove(&lo->fd_map, fi->fh); + } pthread_mutex_unlock(&lo->mutex); =20 close(fd); --=20 2.21.0