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Date: Mon, 31 Jan 2011 19:35:07 +0000
From: "Serge E. Hallyn" <serge@hallyn.com>
To: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Soren Hansen <soren@linux2go.dk>, linux-kernel@vger.kernel.org,
        Dave Hansen <haveblue@us.ibm.com>, Arnd Bergmann <arnd@arndb.de>
Subject: Re: nbd locking problems
Message-ID: <20110131193507.GA19778@mail.hallyn.com>
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Quoting Serge E. Hallyn (serge@hallyn.com):
> Quoting Soren Hansen (soren@linux2go.dk):

(Sorry, I seem to have stupidly deleted later replies)

> 
> As Dave just explained to me, BKL is released when you sleep :)  I
> assume that's how it gets released around the kthread_create().  I
> *think* you're right that the new mutex is superfluous, but I'd like to
> look through the ioctl code and make sure there's no shared state which
> we need to protect.  I don't see how there could be, or rather, if there
> were, then it was broken before.

Yup, removing nbd_mutex should be safe.  Esp since the
bdev->bd_disk->private_data doesn't get changed outside
of nbd_init().  Removing it looks safe.

thanks,
-serge