Messages in this thread Patch in this message | | | Date | Fri, 24 Feb 2006 12:27:34 -0500 | From | "Jun'ichi Nomura" <> | Subject | [PATCH] dm free minor after unlink gendisk |
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Hello,
free_dev() releases minor number before unregistering gendisk. It creates a window where two registered gendisk with same number exist, which will cause problem.
Typically, if you run the following script, you will hit WARN_ON() in kref_get().
#!/bin/sh (while dmsetup create a --notable; do dmsetup remove a; done) & (while dmsetup create b --notable; do dmsetup remove b; done) &
Attached patch fixes this problem.
-- Jun'ichi Nomura, NEC Solutions (America), Inc. minor number should be freed after del_gendisk(). Otherwise, there could be a window where 2 registered gendisk has same minor number.
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
--- linux-2.6.15.orig/drivers/md/dm.c 2006-02-24 11:05:05.000000000 -0500 +++ linux-2.6.15/drivers/md/dm.c 2006-02-24 11:17:54.000000000 -0500 @@ -812,14 +812,16 @@ static struct mapped_device *alloc_dev(u static void free_dev(struct mapped_device *md) { + unsigned int minor = md->disk->first_minor; + if (md->suspended_bdev) { thaw_bdev(md->suspended_bdev, NULL); bdput(md->suspended_bdev); } - free_minor(md->disk->first_minor); mempool_destroy(md->tio_pool); mempool_destroy(md->io_pool); del_gendisk(md->disk); + free_minor(minor); put_disk(md->disk); blk_put_queue(md->queue); kfree(md); | |