From patchwork Tue Oct 1 05:15:58 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josh Durgin X-Patchwork-Id: 2968311 Return-Path: X-Original-To: patchwork-ceph-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id C86D9BFF0B for ; Tue, 1 Oct 2013 06:00:01 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C17852037D for ; Tue, 1 Oct 2013 06:00:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D01D520377 for ; Tue, 1 Oct 2013 05:59:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751281Ab3JAF7q (ORCPT ); Tue, 1 Oct 2013 01:59:46 -0400 Received: from mail.hq.newdream.net ([66.33.206.127]:55871 "EHLO mail.hq.newdream.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751117Ab3JAF7p (ORCPT ); Tue, 1 Oct 2013 01:59:45 -0400 Received: from mail.hq.newdream.net (localhost [127.0.0.1]) by mail.hq.newdream.net (Postfix) with ESMTP id 99AF1264C6; Mon, 30 Sep 2013 23:05:46 -0700 (PDT) Received: from vit.ops.newdream.net (unknown [38.122.20.226]) by mail.hq.newdream.net (Postfix) with ESMTPSA id 84CB4264B9; Mon, 30 Sep 2013 23:05:46 -0700 (PDT) From: Josh Durgin To: ceph-devel@vger.kernel.org Cc: Josh Durgin Subject: [PATCH 1/2] rbd: move calls that may sleep out of spin lock range Date: Mon, 30 Sep 2013 22:15:58 -0700 Message-Id: <1380604559-5331-2-git-send-email-josh.durgin@inktank.com> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1379993136-29246-1-git-send-email-guangliang@unitedstack.com> References: <1379993136-29246-1-git-send-email-guangliang@unitedstack.com> Sender: ceph-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP get_user() and set_disk_ro() may allocate memory, leading to a potential deadlock if theye are called while a spin lock is held. Move the acquisition and release of rbd_dev->lock from rbd_ioctl() into rbd_ioctl_set_ro(), so it can occur between get_user() and set_disk_ro(). Signed-off-by: Josh Durgin Reviewed-by: Alex Elder --- drivers/block/rbd.c | 36 +++++++++++++++++++++++------------- 1 files changed, 23 insertions(+), 13 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 34bcdb7..b3b1b57 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -510,23 +510,42 @@ static void rbd_release(struct gendisk *disk, fmode_t mode) static int rbd_ioctl_set_ro(struct rbd_device *rbd_dev, unsigned long arg) { + int ret = 0; int val; bool ro; + bool ro_changed = false; + /* get_user() may sleep, so call it before taking rbd_dev->lock */ if (get_user(val, (int __user *)(arg))) return -EFAULT; + spin_lock_irq(&rbd_dev->lock); + /* prevent others open this device */ + if (rbd_dev->open_count > 1) { + ret = -EBUSY; + goto out; + } + ro = val ? true : false; /* Snapshot doesn't allow to write*/ - if (rbd_dev->spec->snap_id != CEPH_NOSNAP && !ro) - return -EROFS; + if (rbd_dev->spec->snap_id != CEPH_NOSNAP && !ro) { + ret = -EROFS; + goto out; + } if (rbd_dev->mapping.read_only != ro) { rbd_dev->mapping.read_only = ro; - set_disk_ro(rbd_dev->disk, ro ? 1 : 0); + ro_changed = true; } - return 0; +out: + spin_unlock_irq(&rbd_dev->lock); + /* set_disk_ro() may sleep, so call it after releasing rbd_dev->lock */ + if (ret == 0 && ro_changed) + set_disk_ro(rbd_dev->disk, ro ? 1 : 0); + + + return ret; } static int rbd_ioctl(struct block_device *bdev, fmode_t mode, @@ -535,13 +554,6 @@ static int rbd_ioctl(struct block_device *bdev, fmode_t mode, struct rbd_device *rbd_dev = bdev->bd_disk->private_data; int ret = 0; - spin_lock_irq(&rbd_dev->lock); - /* prevent others open this device */ - if (rbd_dev->open_count > 1) { - ret = -EBUSY; - goto out; - } - switch (cmd) { case BLKROSET: ret = rbd_ioctl_set_ro(rbd_dev, arg); @@ -550,8 +562,6 @@ static int rbd_ioctl(struct block_device *bdev, fmode_t mode, ret = -ENOTTY; } -out: - spin_unlock_irq(&rbd_dev->lock); return ret; }