Commit 10da4f79 authored Jun 26, 2006 by Jeff Mahoney Committed by Linus Torvalds Jun 26, 2006

[PATCH] dm: add module ref counting



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>

parent 7ec75f25

drivers/md/dm.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}

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