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authorTejun Heo <tj@kernel.org>2013-02-27 17:03:56 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-27 19:10:14 -0800
commitce23bba842aee98092225d9576dba47c82352521 (patch)
tree5642d356f830bc3987f65f6879249cf96bf24df2 /block/genhd.c
parentd5c7409f79e14db49d00785692334657592c07ff (diff)
downloadkernel-ce23bba842aee98092225d9576dba47c82352521.tar.gz
block: fix synchronization and limit check in blk_alloc_devt()
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> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'block/genhd.c')
-rw-r--r--block/genhd.c13
1 files changed, 5 insertions, 8 deletions
diff --git a/block/genhd.c b/block/genhd.c
index cd65b97e84d4..841b3037d866 100644
--- 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.
@@ -425,19 +425,16 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
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;
}