From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753405Ab3BCBVr (ORCPT ); Sat, 2 Feb 2013 20:21:47 -0500 Received: from mail-pb0-f43.google.com ([209.85.160.43]:63549 "EHLO mail-pb0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752552Ab3BCBVW (ORCPT ); Sat, 2 Feb 2013 20:21:22 -0500 From: Tejun Heo To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, rusty@rustcorp.com.au, bfields@fieldses.org, skinsbursky@parallels.com, ebiederm@xmission.com, jmorris@namei.org, axboe@kernel.dk, Tejun Heo , stable@vger.kernel.org Subject: [PATCH 06/62] block: fix synchronization and limit check in blk_alloc_devt() Date: Sat, 2 Feb 2013 17:20:07 -0800 Message-Id: <1359854463-2538-7-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.8.1 In-Reply-To: <1359854463-2538-1-git-send-email-tj@kernel.org> References: <1359854463-2538-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org idr allocation in blk_alloc_devt() wasn't synchronized against lookup and removal, and its limit check was off by one - 1 << MINORBITS is the number of minors allowed, not the maximum allowed minor. Add locking and rename MAX_EXT_DEVT to NR_EXT_DEVT and fix limit checking. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: stable@vger.kernel.org --- block/genhd.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 9a289d7..49abda1 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -25,7 +25,7 @@ static DEFINE_MUTEX(block_class_lock); struct kobject *block_depr; /* for extended dynamic devt allocation, currently only one major is used */ -#define MAX_EXT_DEVT (1 << MINORBITS) +#define NR_EXT_DEVT (1 << MINORBITS) /* For extended devt allocation. ext_devt_mutex prevents look up * results from going away underneath its user. @@ -420,17 +420,18 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt) do { if (!idr_pre_get(&ext_devt_idr, GFP_KERNEL)) return -ENOMEM; + mutex_lock(&ext_devt_mutex); rc = idr_get_new(&ext_devt_idr, part, &idx); + if (!rc && idx >= NR_EXT_DEVT) { + idr_remove(&ext_devt_idr, idx); + rc = -EBUSY; + } + mutex_unlock(&ext_devt_mutex); } while (rc == -EAGAIN); if (rc) return rc; - if (idx > MAX_EXT_DEVT) { - idr_remove(&ext_devt_idr, idx); - return -EBUSY; - } - *devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx)); return 0; } -- 1.8.1