diff options
| author | Tejun Heo <tj@kernel.org> | 2013-02-27 17:03:56 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-04 06:03:35 +0800 |
| commit | ca4e7610b166ff557a5f357bac6f12ec66a1ac1a (patch) | |
| tree | 9375191b66927a7e0a2d4dc23886d8f8044e7b0e | |
| parent | bf9493433113145c9aa9a622d0c9dcc7b51c5d83 (diff) | |
block: fix synchronization and limit check in blk_alloc_devt()
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>
| -rw-r--r-- | block/genhd.c | 13 |
1 files changed, 5 insertions, 8 deletions
diff --git a/block/genhd.c b/block/genhd.c index 35d0290885a..7dcfdd84efc 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. @@ -424,19 +424,16 @@ 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; } |