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[PATCH] dm: add module ref counting

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The reference counting on dm-mod is zero if no mapped devices are open.  This
is incorrect, and can lead to an oops if the module is unloaded while mapped
devices exist.

This patch claims a reference to the module whenever a device is created, and
drops it again when the device is freed.

Devices must be removed before dm-mod is unloaded.

[akpm: too late for 2.6.17 - suitable for 2.6.17.x after it has settled]

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jeff Mahoney 2006-06-26 00:27:25 -07:00 committed by Linus Torvalds
parent 7ec75f2547
commit 10da4f795f
1 changed files with 6 additions and 0 deletions
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6
drivers/md/dm.c
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@ -852,6 +852,9 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
return NULL;
}
if (!try_module_get(THIS_MODULE))
goto bad0;
/* get a minor number for the dev */
r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor);
if (r < 0)
@ -918,6 +921,8 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
blk_cleanup_queue(md->queue);
free_minor(minor);
bad1:
module_put(THIS_MODULE);
bad0:
kfree(md);
return NULL;
}
@ -941,6 +946,7 @@ static void free_dev(struct mapped_device *md)
put_disk(md->disk);
blk_cleanup_queue(md->queue);
module_put(THIS_MODULE);
kfree(md);
}