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

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Message-ID: <d120d5000704161130j7ae89a1eyef89e015f0a3e97f@mail.gmail.com>
Date:	Mon, 16 Apr 2007 14:30:17 -0400
From:	"Dmitry Torokhov" <dmitry.torokhov@...il.com>
To:	"Cornelia Huck" <cornelia.huck@...ibm.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	"Alan Stern" <stern@...land.harvard.edu>,
	"Greg K-H" <greg@...ah.com>, "Tejun Heo" <htejun@...il.com>,
	"Rusty Russell" <rusty@...tcorp.com.au>
Subject: Re: [Patch -mm 0/3] RFC: module unloading vs. release function

On 4/16/07, Cornelia Huck <cornelia.huck@...ibm.com> wrote:
> 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).

Unfortunately all this "wait for refcount in module's exit" schemas
lead to the following deadlock:

        rmmod my_module < /path/to/some/file/incrementing/my/refcount

-- 
Dmitry
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