[dpdk-dev] [memnic PATCH 1/5] pmd: fix race condition

[Hiroshi Shimamoto]

Hi,

> Subject: Re: [dpdk-dev] [memnic PATCH 1/5] pmd: fix race condition
> 
> Hi Hiroshi-san,
> 
> Please see my comments below.
> 
> On 03/11/2014 06:37 AM, Hiroshi Shimamoto wrote:
> > From: Hiroshi Shimamoto <h-shimamoto at ct.jp.nec.com>
> >
> > There is a race condition, on transmit to vSwitch.
> 
> I think we should not talk specifically about vSwitch, as
> another implementation of host memnic is possible. Maybe using
> the term "host" is more appropriate?
> 
> > +		if (idx != ACCESS_ONCE(adapter->down_idx)) {
> > +			/*
> > +			 * vSwitch freed this and got false positive,
> > +			 * need to recover the status and retry.
> > +			 */
> > +			p->status = MEMNIC_PKT_ST_FREE;
> > +			goto retry;
> > +		}
> > +
> 
> The patch indeed looks to improve reliability, even if it's
> difficult to me to be sure that there is no other race condition.
> Again, I would replace "vSwitch" by "host".

okay, I'm fine with that.
Do you want me resubmit update one?
If so, will do next week.

> 
> By the way, I guess the Linux code in linux/memnic_net.c should be
> modified in the same way.

Hm, yes, we should check kernel driver too.


thanks,
Hiroshi

> 
> Regards,
> Olivier