Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756367Ab3CDDni (ORCPT ); Sun, 3 Mar 2013 22:43:38 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:32803 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756325Ab3CDDne (ORCPT ); Sun, 3 Mar 2013 22:43:34 -0500 Message-Id: <20130304033718.509647354@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 04 Mar 2013 03:38:58 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, Tejun Heo , Jens Axboe , Linus Torvalds Subject: [ 111/153] block: fix synchronization and limit check in blk_alloc_devt() In-Reply-To: <20130304033707.648729212@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:a11:96ff:fec6:70c4 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2026 Lines: 66 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tejun Heo commit ce23bba842aee98092225d9576dba47c82352521 upstream. 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 Acked-by: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- block/genhd.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) --- a/block/genhd.c +++ b/block/genhd.c @@ -26,7 +26,7 @@ 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. @@ -423,19 +423,16 @@ int blk_alloc_devt(struct hd_struct *par 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) { - mutex_lock(&ext_devt_mutex); - idr_remove(&ext_devt_idr, idx); - mutex_unlock(&ext_devt_mutex); - return -EBUSY; - } - *devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx)); return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/