Messages in this thread Patch in this message | | | Date | Thu, 25 May 2006 20:18:48 +0100 | From | Alasdair G Kergon <> | Subject | [PATCH 8/10] dm: add module ref counting |
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From: Jeff Mahoney <jeffm@suse.com>
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.
Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-Off-By: Alasdair G Kergon <agk@redhat.com>
Index: linux-2.6.17-rc4/drivers/md/dm.c =================================================================== --- linux-2.6.17-rc4.orig/drivers/md/dm.c 2006-05-23 18:18:25.000000000 +0100 +++ linux-2.6.17-rc4/drivers/md/dm.c 2006-05-23 19:37:14.000000000 +0100 @@ -852,6 +852,9 @@ static struct mapped_device *alloc_dev(u 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(u 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_devic put_disk(md->disk); blk_cleanup_queue(md->queue); + module_put(THIS_MODULE); kfree(md); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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