[dpdk-dev] [PATCH] ethdev: fix wrong memset

Yuanhan Liu yuanhan.liu at linux.intel.com
Mon Jan 23 12:24:45 CET 2017


On Mon, Jan 23, 2017 at 11:05:25AM +0000, Ferruh Yigit wrote:
> >>>>>>  lib/librte_ether/rte_ethdev.c | 2 +-
> >>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>>>>
> >>>>>> diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
> >>>>>> index 4790faf..61f44e2 100644
> >>>>>> --- a/lib/librte_ether/rte_ethdev.c
> >>>>>> +++ b/lib/librte_ether/rte_ethdev.c
> >>>>>> @@ -225,7 +225,7 @@ struct rte_eth_dev *
> >>>>>>  		return NULL;
> >>>>>>  	}
> >>>>>>  
> >>>>>> -	memset(&rte_eth_devices[port_id], 0, sizeof(*eth_dev->data));
> >>>>>> +	memset(&rte_eth_dev_data[port_id], 0, sizeof(struct rte_eth_dev_data));
> >>>>>
> >>>>> Not directly related to the this issue, but, after fix, this may have
> >>>>> issues with secondary process.
> >>>>>
> >>>>> There were patches sent to fix this.
> >>>>
> >>>> I mean this one:
> >>>> http://dpdk.org/ml/archives/dev/2017-January/054422.html
> >>>
> >>> d948f596fee2 ("ethdev: fix port data mismatched in multiple process
> >>> model") should have fixed it.
> >>
> >> Think about case, where secondary process uses a virtual PMD, which does
> >> a rte_eth_dev_allocate() call, shouldn't this corrupt primary process
> >> device data?
> > 
> > Yes, it may. However, I doubt that's the typical usage. 
> 
> But this is a use case, and broken now,

I thought it was broken since the beginning?

> and fix is known.

And there is already a fix?

> Should be
> fixed I think.

Sure.

> 
> > Besides that,
> > most of virtual PMDs don't support Multipleprocess: git grep shows pcap
> > is the only one that does claim Multipleprocess is supported.
> 
> I guess you searched for NIC feature documentation for this.

Yes.

> But as far
> as I know, all virtual drivers can be used in both primary and secondary
> process.

Maybe. But it becomes very error-prone to me then when vdev are involved
in both primary and secondary process. I don't think current code is (or
designed to be) strong enough to support that.

I don't know it's allowed to use hotplug or not in the multiple process
model. If yes, I think there would be many ways to break it.

Honestly, the multiple process doesn't look like a good/clean design to
me, especially when some piece of code claim to support it while some
other doesn't.

So my point was, yes, there is a bug, we should fix it. But it seems
that there could be so many bugs if we hugely expand the test coverage
of the multiple process feature.

	--yliu


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