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From: Nikanth Karthikesan <knikanth@suse.de>
Organization: suse.de
To: Zach Brown <zach.brown@oracle.com>
Subject: Re: [PATCH] aio: use cmpxchg in aio_read_evt() instead of aio_ring_info->ring_lock
Date: Tue, 1 Jul 2008 13:57:52 +0530
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Cc: linux-aio@kvack.org, linux-kernel@vger.kernel.org,
       Benjamin LaHaise <bcrl@kvack.org>, Jeff Moyer <jmoyer@redhat.com>
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On Monday 30 June 2008 23:33:52 Zach Brown wrote:
> Nikanth Karthikesan wrote:
> > Use cmpxchg in aio_read_evt() and remove the aio_ring_info->ring_lock
>
> I don't think this is safe because the cmpxhg() can't differentiate the
> 0 it read at one point with a 0 that it reads in the future after other
> racing threads have done enough work on the ring index to wrap it.
>

Yes, this is unsafe. Thanks for the review.

Thanks
Nikanth Karthikesan