[dpdk-dev] [PATCH] vhost: fix off-by-one error on nr_desc check

Yuanhan Liu yuanhan.liu at linux.intel.com
Mon Jul 25 17:24:12 CEST 2016


On Mon, Jul 25, 2016 at 04:09:58PM +0200, Maxime Coquelin wrote:
> nr_desc is not an index but the number of descriptors,
> so can be equal to the virtqueue size.
> 
> Fixes: a436f53ebfeb ("vhost: avoid dead loop chain")
> 
> Cc: Yuanhan Liu <yuanhan.liu at linux.intel.com>
> Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>

Thanks for catching it!

> ---
> Hi Yuanhan,
> 
> I faced the bug while testing my indirect descriptor patch, it happens
> as soon as the number of chained descritors is above 2.
> 
> But the bug may in theory also be faced with normal descriptors,

In theory, yes, and only in one case, that there is a Tx has 256
descriptors chained. If that happens, I doubt things work well.
So I would say it just happens __in theory__.

> so it might
> be good to have it 16.07?

Even though, it apparently fixes a bug, so I think we could have it
for 16.07.

Acked-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>

	--yliu


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