linux-kernel - Re: [PATCH v3] slow-work: add (module*)work->owner to fix races with module clients

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Message-ID: <17232.1246020736@redhat.com>
Date:	Fri, 26 Jun 2009 13:52:16 +0100
From:	David Howells <dhowells@...hat.com>
To:	Gregory Haskins <ghaskins@...ell.com>
Cc:	dhowells@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] slow-work: add (module*)work->owner to fix races with module clients

Gregory Haskins <ghaskins@...ell.com> wrote:

> The slow_work facility was designed to use reference counting instead of
> barriers for synchronization.  The reference counting mechanism is
> implemented as a vtable op (->get_ref, ->put_ref) callback.  This is
> problematic for module use of the slow_work facility because it is
> impossible to synchronize against the .text installed in the callbacks:
> There is no way to ensure that the slow-work threads have completely
> exited the .text in question and rmmod may yank it out from under the
> slow_work thread.

This seems reasonable.  I'll get round to testing it if I can find the OOM bug
that's nobbling by test machine.

David
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