linux-kernel - Re: nbd locking problems

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Message-ID: <20110131193507.GA19778@mail.hallyn.com>
Date:	Mon, 31 Jan 2011 19:35:07 +0000
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	"Serge E. Hallyn" <serge@...lyn.com>
Cc:	Soren Hansen <soren@...ux2go.dk>, linux-kernel@...r.kernel.org,
	Dave Hansen <haveblue@...ibm.com>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: nbd locking problems

Quoting Serge E. Hallyn (serge@...lyn.com):
> Quoting Soren Hansen (soren@...ux2go.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
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