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From: Wei Liu <wei.liu2@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>,
	Ian Campbell <Ian.Campbell@citrix.com>,
	Ian Jackson <Ian.Jackson@eu.citrix.com>,
	Xen-devel <xen-devel@lists.xen.org>,
	David Scott <dave@recoil.org>,
	Samuel Thibault <samuel.thibault@ens-lyon.org>
Subject: Re: [PATCH v2] tools/ocaml/xb: Correct calculations of data/space the ring
Date: Tue, 10 Nov 2015 14:59:17 +0000	[thread overview]
Message-ID: <20151110145917.GC28720@zion.uk.xensource.com> (raw)
In-Reply-To: <1447152404-3672-1-git-send-email-andrew.cooper3@citrix.com>

On Tue, Nov 10, 2015 at 10:46:44AM +0000, Andrew Cooper wrote:
> ml_interface_{read,write}() would miscalculate the quantity of
> data/space in the ring if it crossed the ring boundary, and incorrectly
> return a short read/write.
> 
> This causes a protocol stall, as either side of the ring ends up waiting
> for what they believe to be the other side needing to take the next
> action.
> 
> Correct the calculations to cope with crossing the ring boundary.
> 
> In addition, correct the error detection.  It is a hard error if the
> producer index gets more than a ring size ahead of the consumer, or if
> the consumer ever overtakes the producer.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

I think I will port this patch to cxenstored at some point. As far as I
can tell cxenstored's data / space calculation is bogus in the same way.

Wei.

  parent reply	other threads:[~2015-11-10 14:59 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-10 10:46 [PATCH v2] tools/ocaml/xb: Correct calculations of data/space the ring Andrew Cooper
2015-11-10 10:49 ` Wei Liu
2015-11-10 11:41 ` Samuel Thibault
2015-11-10 11:45   ` David Scott
2015-11-10 14:59 ` Wei Liu [this message]
2015-11-10 15:06   ` Samuel Thibault
2015-11-10 15:09     ` Wei Liu
2015-11-10 15:16       ` Samuel Thibault

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