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DragonFly kernel List (threaded) for 2006-06
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Re: kernel module event handler question

From: "Thomas E. Spanjaard" <tgen@xxxxxxxxxxxxx>
Date: Sat, 17 Jun 2006 12:53:35 +0000

YONETANI Tomokazu wrote:
If the event handler in a kernel module returns an error upon registration,
isn't the module supposed to be removed from the kldstat's list?

I wrote a simple kernel module(attached) which always returns EOPNOTSUPP
for MOD_LOAD event.  It adds two sysctl nodes debug.test and debug.test_int.
Reading from or writing to debug.test calls test_sysctl_proc() function.
When loaded, although module_register_init prints an error message, the
modules sits there, and I can even set different values to debug.test.

Is this an expected behavior?  Do I need to do something special to
unregister my kernel module when something went wrong?

I guess the reference count of the module is still >0. in module_register_init(), mod_release() is called on the module if an error occurred, but it seems the reference count is still >0 after the call. This seems wrong, since a module which fails loading can never be useful. Also, you do see the 'kldunload'ing OK' printf()? And the error from module_register_init()?

        Thomas E. Spanjaard

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