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[Xen-devel] Re: you patch "block: push down BKL into .open and .release"

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: [Xen-devel] Re: you patch "block: push down BKL into .open and .release" and its changes to xen-blkfront.c
From: Jens Axboe <jaxboe@xxxxxxxxxxxx>
Date: Wed, 25 Aug 2010 13:02:09 +0200
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "arnd@xxxxxxxx" <arnd@xxxxxxxx>, Daniel Stodden <daniel.stodden@xxxxxxxxxx>
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On 2010-08-25 12:59, Jan Beulich wrote:
> Arnd,
> what was the point of adding {,un}lock_kernel() to blkif_open() and
> blkif_release()? Afaict, the associated bdev is protected by a mutex
> anyway, so even without Daniel's addition of a mutex to these
> paths I don't see the need for the BKL here.

I'll let Arnd answer for himself, but at least in general it's
much easier to let this sort of auditing and final cleanup
be done my the maintainer(s) of the driver in question, as they
are best positioned to verify that the BKL in fact isn't
really necessary in that path anymore.

Jens Axboe

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