From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756123AbbALSyH (ORCPT ); Mon, 12 Jan 2015 13:54:07 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:58153 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755039AbbALSaO (ORCPT ); Mon, 12 Jan 2015 13:30:14 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Mikulas Patocka , Mike Snitzer , Luis Henriques Subject: [PATCH 3.16.y-ckt 152/216] dm thin: fix a race in thin_dtr Date: Mon, 12 Jan 2015 18:28:50 +0000 Message-Id: <1421087394-2712-40-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1421085933-32536-1-git-send-email-luis.henriques@canonical.com> References: <1421085933-32536-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit 17181fb7a0c3a279196c0eeb2caba65a1519614b upstream. As long as struct thin_c is in the list, anyone can grab a reference of it. Consequently, we must wait for the reference count to drop to zero *after* we remove the structure from the list, not before. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Luis Henriques --- drivers/md/dm-thin.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index df898e0db419..6f75083a81cc 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -3183,14 +3183,14 @@ static void thin_dtr(struct dm_target *ti) struct thin_c *tc = ti->private; unsigned long flags; - thin_put(tc); - wait_for_completion(&tc->can_destroy); - spin_lock_irqsave(&tc->pool->lock, flags); list_del_rcu(&tc->list); spin_unlock_irqrestore(&tc->pool->lock, flags); synchronize_rcu(); + thin_put(tc); + wait_for_completion(&tc->can_destroy); + mutex_lock(&dm_thin_pool_table.mutex); __pool_dec(tc->pool); -- 2.1.4