linux-kernel - [Patch -mm 0/3] RFC: module unloading vs. release function

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Message-ID: <20070416193619.4659a847@gondolin.boeblingen.de.ibm.com>
Date:	Mon, 16 Apr 2007 19:36:19 +0200
From:	Cornelia Huck <cornelia.huck@...ibm.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	Alan Stern <stern@...land.harvard.edu>, Greg K-H <greg@...ah.com>,
	Tejun Heo <htejun@...il.com>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: [Patch -mm 0/3] RFC: module unloading vs. release function

Hi,

based on the discussion in "How should an exit routine wait for
release() callbacks?", I've cooked up some patches that make module
unload wait until the last reference for a kobject has been dropped.
This should plug the "release function in already deleted module" race;
however, if the last kobject_put() from the module containing the
release function is not in the module's exit function, there's still a
small window (not sure if and how to plug this).

This new refcounting still needs to be exploited (i. e. a driver
actually setting kobject->owner). Whether we need to set the owner for
kobject or if for device would be sufficient is also still open to
debate.

[1/3] Use module->mkobj even if !CONFIG_SYSFS.
[2/3] Expose module->mkobj reference count.
[3/3] Introduce kobject->owner for refcounting.

Patchset is only slightly tested, but comments are welcome :)
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