From patchwork Thu Jan 23 11:58:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Dr. David Alan Gilbert" X-Patchwork-Id: 1227981 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=GzkQBQxz; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 483NqV1tGMz9sSP for ; Fri, 24 Jan 2020 00:47:02 +1100 (AEDT) Received: from localhost ([::1]:57266 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iucp1-0001P3-60 for incoming@patchwork.ozlabs.org; Thu, 23 Jan 2020 08:46:59 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41491) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iubAW-00046T-0A for qemu-devel@nongnu.org; Thu, 23 Jan 2020 07:01:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iubAU-0006Pq-Ou for qemu-devel@nongnu.org; Thu, 23 Jan 2020 07:01:03 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:25412 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iubAU-0006PL-LC for qemu-devel@nongnu.org; Thu, 23 Jan 2020 07:01:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579780862; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=H+lsqLvEJ0+MjVyMcNzat6sKkhsnsZbPamB7jAxb+Nw=; b=GzkQBQxzhz8z5A76F25MVK0vE18CYUVt7H//Z5QevGjQ4mntjoAFwhMQKJBA3Pi5Ws7JrP h7lEUrqQ7UEF1hxRa79YUleDXl2R6FnGdEv8gjIiMmMnFrHh00tV/hTEwazuHIGpghQ2Oi 4YBR/jv5QEFKCcwFaNL1kaQt/koVSZ0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-221-4AmW8YgDOTq8MGX8ZCXBXg-1; Thu, 23 Jan 2020 07:00:59 -0500 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6153318A6ED2 for ; Thu, 23 Jan 2020 12:00:58 +0000 (UTC) Received: from dgilbert-t580.localhost (unknown [10.36.118.0]) by smtp.corp.redhat.com (Postfix) with ESMTP id AF25385750; Thu, 23 Jan 2020 12:00:57 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com Subject: [PULL 090/111] virtiofsd: make lo_release() atomic Date: Thu, 23 Jan 2020 11:58:20 +0000 Message-Id: <20200123115841.138849-91-dgilbert@redhat.com> In-Reply-To: <20200123115841.138849-1-dgilbert@redhat.com> References: <20200123115841.138849-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: 4AmW8YgDOTq8MGX8ZCXBXg-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 207.211.31.120 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: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Stefan Hajnoczi 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 Reviewed-by: Daniel P. Berrangé Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/passthrough_ll.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 9414935b52..690edbc4c5 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -1772,14 +1772,18 @@ 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);