linux-kernel - Re: [PATCH] aio: use cmpxchg in aio_read_evt() instead of aio_ring_info->ring

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Message-Id: <200807011357.52407.knikanth@suse.de>
Date:	Tue, 1 Jul 2008 13:57:52 +0530
From:	Nikanth Karthikesan <knikanth@...e.de>
To:	Zach Brown <zach.brown@...cle.com>
Cc:	linux-aio@...ck.org, linux-kernel@...r.kernel.org,
	Benjamin LaHaise <bcrl@...ck.org>,
	Jeff Moyer <jmoyer@...hat.com>
Subject: Re: [PATCH] aio: use cmpxchg in aio_read_evt() instead of aio_ring_info->ring_lock

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


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