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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 4F656C32751 for ; Wed, 31 Jul 2019 16:57:13 +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 23CC0206B8 for ; Wed, 31 Jul 2019 16:57:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23CC0206B8 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]:43048 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsrua-0007GM-Bv for qemu-devel@archiver.kernel.org; Wed, 31 Jul 2019 12:57:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:55530) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsru8-0006pv-0i for qemu-devel@nongnu.org; Wed, 31 Jul 2019 12:56:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hsru7-00043v-3z for qemu-devel@nongnu.org; Wed, 31 Jul 2019 12:56:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53220) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hsru6-00040e-Ub for qemu-devel@nongnu.org; Wed, 31 Jul 2019 12:56:43 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1642419CF7A for ; Wed, 31 Jul 2019 16:56:42 +0000 (UTC) Received: from work-vm (ovpn-116-252.ams2.redhat.com [10.36.116.252]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BA1096012E; Wed, 31 Jul 2019 16:56:36 +0000 (UTC) Date: Wed, 31 Jul 2019 17:56:33 +0100 From: "Dr. David Alan Gilbert" To: Stefan Hajnoczi Message-ID: <20190731165633.GJ3203@work-vm> References: <20190726091103.23503-1-stefanha@redhat.com> <20190726091103.23503-4-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190726091103.23503-4-stefanha@redhat.com> User-Agent: Mutt/1.12.0 (2019-05-25) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 31 Jul 2019 16:56:42 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [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: virtio-fs@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Stefan Hajnoczi (stefanha@redhat.com) wrote: > 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 OK, although I suspect there are lots of places the inode pointers are passed without the lock, so it might not help much. Reviewed-by: Dr. David Alan Gilbert and applied > --- > contrib/virtiofsd/passthrough_ll.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passthrough_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 ino, 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 = lo_data(req); > - int fd; > + struct lo_map_elem *elem; > + int fd = -1; > > (void) ino; > > - fd = lo_fi_fd(req, fi); > - > pthread_mutex_lock(&lo->mutex); > - lo_map_remove(&lo->fd_map, fi->fh); > + elem = lo_map_get(&lo->fd_map, fi->fh); > + if (elem) { > + fd = elem->fd; > + elem = NULL; > + lo_map_remove(&lo->fd_map, fi->fh); > + } > pthread_mutex_unlock(&lo->mutex); > > close(fd); > -- > 2.21.0 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK