Module reference counting appropriately occurs when the block device is
opened, but dm devices exist outside of the device actually being opened.
Currently, in certain situations, unloading the dm-mod module will result
in an oops. This patch claims a reference to the module when a device
is created, and drops it when the device is freed.
This is one possible implementation. Another could be to do an internal
"dmsetup remove_all" when the module is unloaded. Comments welcome.
Signed-off-by: Jeff Mahoney <[email protected]>
--
drivers/md/dm.c | 6 ++++++
1 files changed, 6 insertions(+)
diff -ruNpX ../dontdiff linux-2.6.16-staging1/drivers/md/dm.c linux-2.6.16-staging2/drivers/md/dm.c
--- linux-2.6.16-staging1/drivers/md/dm.c 2006-04-13 16:18:23.000000000 -0400
+++ linux-2.6.16-staging2/drivers/md/dm.c 2006-04-13 16:18:23.000000000 -0400
@@ -796,6 +796,9 @@ 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)
@@ -862,6 +865,8 @@ static struct mapped_device *alloc_dev(u
blk_put_queue(md->queue);
free_minor(minor);
bad1:
+ module_put(THIS_MODULE);
+ bad0:
kfree(md);
return NULL;
}
@@ -885,6 +890,7 @@ static void free_dev(struct mapped_devic
put_disk(md->disk);
blk_put_queue(md->queue);
+ module_put(THIS_MODULE);
kfree(md);
}
-
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