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From: Ryan Cumming <bodnar42@phalynx.dhs.org>
To: "David C. Hansen" <haveblue@us.ibm.com>
Subject: Re: [RFC] Change locking in block_dev.c:do_open()
Date: Wed, 12 Dec 2001 17:01:43 -0800
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On December 12, 2001 16:39, David C. Hansen wrote:
> Let's assume that the BKL is not held here, at least over the whole
> thing.  First, what do we need to do to keep the module from getting
> unloaded after the request_module() in get_blkfops()?
>
> We can add a semaphore which must be acquired before a module can be
> unloaded, and hold it over the area where the module must not be
> unloaded.  We could replace the unload_lock spinlock with a semaphore,
> which I'll call it unload_sem here.  It would look something like this:

Why not use a read-write semaphore? The sections that require the module to 
stay resident use a read lock, and module unloading aquires a write lock. In 
addition to containing the evil, evil BKL, you might actually get a tangiable 
scalability gain out of it. 

-Ryan
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