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| author | Tejun Heo <tj@kernel.org> | 2013-02-27 17:03:56 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-27 19:10:14 -0800 |
| commit | ce23bba842aee98092225d9576dba47c82352521 (patch) | |
| tree | 5642d356f830bc3987f65f6879249cf96bf24df2 /block/genhd.c | |
| parent | d5c7409f79e14db49d00785692334657592c07ff (diff) | |
| download | linux-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.c | 13 |
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; } |