| From ce23bba842aee98092225d9576dba47c82352521 Mon Sep 17 00:00:00 2001 |
| From: Tejun Heo <tj@kernel.org> |
| Date: Wed, 27 Feb 2013 17:03:56 -0800 |
| Subject: block: fix synchronization and limit check in blk_alloc_devt() |
| |
| From: Tejun Heo <tj@kernel.org> |
| |
| 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 <tj@kernel.org> |
| Acked-by: Jens Axboe <axboe@kernel.dk> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| block/genhd.c | 13 +++++-------- |
| 1 file changed, 5 insertions(+), 8 deletions(-) |
| |
| --- 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. |
| @@ -422,19 +422,16 @@ 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; |
| } |
